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LONG-TERM RESULTS OF CORONARY BALLOON Annu. Rev. Med. 1991.42:47-59. Downloaded from www.annualreviews.org Access provided by Carnegie Mellon University on 02/01/15. For personal use only.
ANGIOPLASTY B.
Meier, M.D.
Cardiology Center, University Hospital, 1211 Geneva 4, Switzerland KEY
WORDS:
percutaneous transluminal coronary angioplasty, coronary bal loon dilatation, late results after coronary angioplasty, follow-up after coronary angioplasty
ABSTRACT
Long-term results after coronary balloon angioplasty are characterized by an eventful early period up to six months, with about a 30% recurrence rate per lesion, and by a stable situation thereafter. Myocardial infarction due to the dilated site is extremely rare during follow-up because the smooth, elastic, inner lining of a restenosis is much less prone to thrombosis than the initial plaque. A positive effect of coronary angioplasty on survival has not been documented, but there is clear functional improvement over the natural course of the untreated disorder. The improvement is com parable to that attained by bypass surgery if repeat angioplasty during the first months is considered as part of the procedure rather than as proof of failure. INTRODUCTION
All procedures are ultimately judged by their long-term results. Coronary balloon angioplasty, in contrast to bypass surgery employing venous grafts, clusters virtually all follow-up problems into the first six months and exhibits thereafter a remarkably stable and favorable course. It is thus legitimate to confine oneself to the first year when assessing long-term outcome of coronary angioplasty. Later events are almost always due to disease progression on sites other than the ones subjected to the procedure. 47 0066-4219/91/0401-0047$02.00
MEIER
48
CLINICAL OUTCOME
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Mortality Survival and infarct-free survival two years after coronary angioplasty are about 98% and 94%, respectively (1). Risk factors for late mortality after angioplasty are the same as those for coronary artery disease in general: left main stem disease, multivessel disease, previous myocardial infarction, diminished left ventricular function, smoking, and hypertension. Unstable angina pectoris before angioplasty portends a higher late mortality as well (2). Male gender proved an additional risk factor for late mortality, quite in contrast to early mortality due to acute complications, for which female gender is a risk factor (3).
Other Cardiac Events The important cardiac events during the first year of follow-up reported from different centers are summarized in Table 1. The initial 133 successful patients of Andreas Gruentzig exhibited 30% recurrences within six months. Then followed more than three years without a single problem in the pertinent artery segments, after which time six more significant stenoses in these segments were found during seven years of follow-up (14). This reflects the peculiar but welcome fact that balloon angioplasty may well have a high initial recurrence rate as a result of intimal proliferation in Table 1
Cardiac events during first year following successful coronary balloon angioplasty
Source
Number
Repeat
Bypass
Year of
of
angioplasty
surgery
Infarction
Death
report
patients
(%)
(%)
(%)
(%)
10 12 10
18 9 23 13 15 19
10 11 12 5 1 55 5 8 5 10 6
3
0 2 2 2
15
7
2
2
1982 1984 1985 1986 1986 1986 1987 1988 1989 1989 1989
Zurich NHLBI reg! Rochester Rhode Island Lille Geneva Nieuwegein Atlanta London' Rotterdam NHLBI reg." Total or average "NHLBI reg.
=
134 906 153 141 130 282 1163 338 331 710 1405 5693
nrb
22
National Heart. Lung, and Blood Institute registry.
bnr = not reported. 'Single-vessel disease only.
3 3 4
3 2 0 2
1 2
2 3
Ref.
4 5 6 7 8 9 10 11 12 13
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
49
the weeks following the intervention, but once this "scarring" process terminates, the underlying plaque appears "frozen" for several years if not for ever. The late problems in the same artery segment may well be disease progression adjacent to the dilated site rather than resurgence of the initial plaque. Cardiac events such as death, myocardial infarction, and need for further angioplasty or bypass surgery are poor indicators of what is occurring at the dilated site since they are based on a mixture of restenosis, preexisting disease in other vessels, and disease progression. Death and myocardial infarction due to restenosis are extremely rare because recur rent stenoses exhibit a markedly reduced propensity to plaque rupture and thrombotic occlusion compared to genuine atherosclerotic plaques.
Even in the absence of an angiogram, reappearance of initially elim inated symptoms can be attributed with a high degree of accuracy to true restenosis if it occurs within six months and to disease progression thereafter.
Subjective Outcome The main goal of coronary revascularization is long-term clinical improve ment. A survey indicated that 84% of patients who had a successful coronary angioplasty felt improved an average of 14 months later. This was significantly inferior to the 94% of surgical patients making the same statement a mean of 26 months after their elective bypass operation (IS). Quite in contrast, another study with at least one year of follow-up found that 96% of patients with successful angioplasty felt improved compared to 88% of patients with failed angioplasty followed by bypass surgery and 20% of patients with failed angioplasty and medical treatment serving as controls (6). Results similar to those in the latter study emerged from a multicenter report (16) but seem optimistic in light of the fact that only half of patients with successful angioplasty are free of symptoms at one year according to the American registry (1), or 86% at 6 months (7), and 74% at 24 months (5) according to other studies if the beneficial influence of additional procedures is not considered.
Objective Outcome In the first 32 patients successfully treated with coronary angioplasty by its innovator, Andreas Gruentzig, 28 (88%) were functionally improved based on their New York Heart Association class for angina (subjective and stress test data) 3 to 18 months after angioplasty. However, three had had repeat angioplasty, two coronary bypass surgery, and one medical therapy for intercurrent exacerbation of symptoms (17). A lasting salutary effect of coronary angioplasty was clearly dem onstrated by an improvement from the pre-angioplasty to the one-year
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50
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follow-up exercise test in the first 132 patients treated successfully by Gruentzig (18). The amelioration was maintained at four years. A sig nificant improvement of the perfusion defects after exercise thallium-201 scintigraphy was demonstrated with serial tests up to a mean of 18 months after the procedure in patients without restenosis (19). Similar results were obtained with exercise tests combined with thallium201 scintigraphy at one, three, and six months after successful coronary angioplasty (20). The correlation between thallium-201 results and control angiography was fairly good. The American registry reported on paired nuclear stress tests before and an average of eight months after angioplasty on patients with persistently successful results (21). The tests were clinically and/or electrocardiographically positive in 68% before and in 7% at follow-up. All thallium-201 studies were normal at follow-up and the nuclear left ventricular exercise ejection fraction was improved. Yet, there was still some regional dysfunction in half of the patients. This may relate to a prior subendocardial infarction in some cases. Several studies permit comparison of late functional results of coronary angioplasty and bypass surgery. The comparison favors angioplasty slightly, probably because patients selected for angioplasty have less severe initial disease. Patients with bypass surgery followed over five years exhi bited a durable increase in work capacity of about 50% that was not present in randomized controls treated medically. No patients in the study had single-vessel disease, and the results were better in patients with com plete revascularization. Graft attrition rate was 15% at five years (22). In another randomized study comparing bypass surgery with medical treatment over five years, 31 % of surgical patients had positive stress test results at five years (63% before the operation) compared to 52% of the medical controls. The difference was significant in terms of chest pain but not in terms of electrocardiographic changes. There were 18% of patients with single-vessel disease, and complete revascularization was again iden tified as a favorable factor ( 23). The only study comparing long-term exercise test results of matched patients with coronary angioplasty or bypass surgery (about 50% single vessel disease) is hampered by the fact that the surgical patients are those with a failed angioplasty attempt and that almost half of them underwent a nonelective operation (18). The long-term functional results of the surgical patients in this study still compare favorably to those of the surgical patients without prior angioplasty attempts of other reports (22, 23), who admittedly had more severe disease. The exercise test was assessed as positive in the angioplasty patients in 97% before and in 34% a mean of 30 months after the intervention. The respective figures for bypass patients were almost identical with 96% and 36%. The target heart rate was reached
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
51
without pain and with a normal electrocardiogram in I % before and in 36% at follow-up in angioplasty and in 4% and 32%, respectively, in surgical patients ( 18). Another comparative study used the regional coronary flow reserve in 50 patients (24). The study included patients with atherosclerotic coronary disease before revascularization, patients late after coronary angioplasty, patients late after bypass surgery, and normal controls. The results were expressed by a ratio of flow velocity before and during hyperemia, induced by an injection of contrast medium. The coron"!-ry flow reserve in untreated diseased arteries was abolished. In patients late after coronary angioplasty and bypass surgery, flow reserve was improved to an identical degree but was still inferior to that of normal vessels. ANGIOGRAPHIC OUTCOME Follow-up angiography was initially recommended to all patients with successful coronary angioplasty. In light of the knowledge about the angio graphic late outcome gathered over the years and the increased number of angioplasties performed, it is now considered acceptable and is in fact economically necessary to restrict follow-up angiography to those patients with recurrent symptoms or signs of ischemia. Studies on patients with early and late follow-up angiography revealed that the majority of stenoses remain unchanged during the first months after angioplasty. Deterioration of stenosis (recurrence) is next in frequency. An improvement of more than 10% of the normal vessel diam eter was found in 23% of lesions studied immediately and three months after angioplasty (25). Additional angiograms in 22 of these patients at 12 and 42 months showed no diameter changes greater than 10% in either direction (26). Together with similar results of more recent studies per forming repeat angiograms in the first months after angioplasty on sep arate patient groups (27) or serially in a single patient group (28), this again underlines the remarkable stability of coronary sites treated with balloon dilatation after the initial 3-6 months.
VOCATIONAL REHABILITATION
Return to work rates (Table 2) depend on local health and welfare systems and economic situations as well as on the type of work. A wage earner supported by an excellent disability insurance system is more likely to stay disabled than a self-employed person eager to keep his or her business going. Extremely high return-to-work rates after coronary angioplasty were
52
MEIER
Table 2
Return to work after coronary revascularization
Source
Annu. Rev. Med. 1991.42:47-59. Downloaded from www.annualreviews.org Access provided by Carnegie Mellon University on 02/01/15. For personal use only.
Rochester NHLBI reg.c Frankfurt Geneva
Year of report
Number of patients·
Return to work (%)
Mean delay (days)
PTCA CABG
PTCA CABG
PTCA CABG
180
Rotterdam
1983 1984 1985 1985 1989
Baltimore
1989
82
Milwaukee
1982 1983 1983 1983
Atlanta Montreal
CASS reg.' Total or average
775
54 83 94
99b 262b
99 86 61 81 76
52b
113 125
b
52
267
148
IS
nr
31
d nr
nr
----
71
16
------
PTCA = percutaneous transluminal coronary angioplasty; CABG Surgery after failed angioplasty.
=
32 nr nr 141 nr
81 73 86
16 29 30
79
66
4896
60 73
25
81
-a
14 7
87 63
87 2229 1590 36 390
1268
97 81
Ref.
33 34 35 36
108 ------ ---
coronary artery bypass grafting.
"NHLBI reg. = National Heart, Lung, and Blood Institute registry. d nr = not reported. 'CASS reg. = Coronary Artery Surgery Study registry.
reported from private American hospitals (16). Return to work was 99% in patients with successful angioplasty, with an average delay of 14 days, and it was 97% in those with failed angioplasty followed by bypass surgery, whose average postoperative disability amounted to 60 days. The differ ence between patients with successful and failed angioplasty was more apparent in wage earners, whose return to work rates wcre 85% and 68%, respectively. Other pertinent studies unveil both coronary bypass surgery and cor onary angioplasty as rather poor means for vocational rehabilitation. Complete vocational rehabilitation, defined as return to an occupational activity equal or superior to that before the sick leave, was reported to be 43% in patients with successful angioplasty and 49% in patients with surgery (15). The American registry analyzed the return-to-work rate of patients with successful angioplasty, patients with failed angioplasty and bypass surgery, and patients with failed angioplasty and medical treatment (29). Initially, 68% of all patients were employed. They represent 100% of the following figures. A mean of 18 months after the procedure, employ ment rates were 86% in the group with successful angioplasty (mean postinterventional disability was 7 days), 81% in the group with surgery after failed angioplasty (73 days), and 83% in the group with medical
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
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treatment after failed angioplasty (13 days). All figures being inferior to 100%, they represent a net loss in the work force, a loss that is comparable among the three groups. The delay in work resumption was significantly prolonged by bypass surgery. Two studies compared the employment status during follow-up of randomized surgical and medical coronary patients and found no difference (35, 36). The following factors were identified as hindering vocational rehabili tation: long absence from work before the intervention, persistent or recurrent chest pain, incomplete revascularization, previous infarction, large number of drugs prescribed after the intervention, and personal dissatisfaction with the intervention. Delays of several weeks before returning to work after coronary angio piasty can hardly be explained on medical grounds. A few days of recov ery granted for organizational and emotional reasons are in order, although even physical work can be resumed the day after an uneventful angioplasty providing complete revascularization. Further education of patients and referring physicians may enhance early return to work, one of the major advantages of angioplasty. Physicians, for instance, are responsible for the number of drugs prescribed, which can negatively influence return to work (15) independently from chest pain, one of the strongest factors against reintegration (29, 34, 37). ECONOMIC ASPECTS
Use of coronary angioplasty should reduce medical expenses in the United States, where private medicine prevails and unsaturated facilities for cor onary bypass surgery abound. An American multicenter study calculated average hospital charges of $5,000 for single-vessel coronary angioplasty and $16,000 for single-vessel bypass surgery (38). A difference of $7,000 was projected, taking into account a 20% primary failure rate but not the recurrences. A more realistic attempt to calculate the annual savings by coronary angioplasty in the United States was based on the one-year history of 79 patients admitted for coronary angioplasty and 89 patients admitted for bypass surgery to a private hospital (39). The primary success rate of the patients with angioplasty was 70%, which is lower than contemporary success rates. The recurrence rate was 33%. During the year of follow up, angioplasty patients were hospitalized a total of 15 days per patient compared to 17 days per surgical patient. There was no difference in quality of life or vocational rehabilitation between the groups. The mean hospital charges were only 15% lower for angioplasty patients than for surgical patients ($11,000 versus $13,000). This was extrapolated to theo-
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MEIER
retical annual savings of 45 million dollars on a national level under the assumption that 15% of patients needing coronary revascu1arization were amenable to angioplasty. It was speculated that an increase in primary success to 95% and a reduction of recurrence to 20% would more than double the savings. The latter goal was met in a similar study on 78 patients with single-vessel coronary angioplasty and 85 patients with single-vessel bypass surgery followed Over one year (40). The success rate of angioplasty was 74% and the recurrence rate 18%. Mean total hospitalization time was 1 1 days in both groups, but mean cost was 45% less for angioplasty patients ($8,000 versus $ 14,000). The difference of results from the other study may be explained, aside from the lower recurrence rate, by the fact that there was no charge for surgical standby. The expansion of coronary angioplasty to multivessel disease was taken into account in a more recent calculation based on a one-year follow-up in 100 consecutive patients with multivessel angioplasty and 100 patients with elective bypass surgery in a private American medical center (41). The total costs were $11,000 for angioplasty (no fee for surgical standby) and $23,000 for surgery. In most other western, let alone developing countries, the situation is entirely different. Patients with single-vessel disease are frequently not considered candidates for bypass surgery because of insufficient surgical capacities. Most countries have nationalized or seminationalized health services. Sophisticated medical interventions are heavily subsidized by tax money. Patients treated by angioplasty may foreshorten the surgical waiting list but they will not decrease the number of operations actually performed. The cost of angioplasty is therefore added to the general health cost, and financial considerations are not in favor of angioplasty. Some economic benefit may be derived from patients resuming work promptly after successful angioplasty, who would have been put on permanent disability without revascularization or who would have returned to work with more delay after bypass surgery. After all, no therapy is cost-efficient in terms of tax money if it possesses even the slightest potential to prolong life in patients already retired. NATURAL COURSE OF ANGIOPLASTY CANDIDATES
With any therapeutic measure, the question is well taken "how would the patient fare without itT Not much gain in longevity should be expected from coronary angioplasty since it is directed primarily toward the subset of coronary patients with the best prognosis (42). A possible exception are
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
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patients with a very proximal stenosis in the left anterior descending coronary artery who have an increased three-year mortality if untreated (43). However, their outcome after angioplasty has not been investigated specifically. A retrospective analysis of the five-year outcome of 110 patients who were ideal candidates for coronary angioplasty before it was available, revealed excellent survival (97%), a reasonably low rate of myocardial infarction (15%), frequent clinical improvement at six months (78%), and an acceptable work status (86% at work at six months of those working before catheterization) (44). Bypass surgery became necessary in 51%. The four-year survival of patients with successful angioplasty in the American registry was identical (97%) but the rate of myocardial infarction was lower (3%); only 21% required further revascularization and 67% were asymptomatic (1). However, these data do not include patients with a failed angioplasty. Analyzing the four-year follow-up of 796 Coronary Artery Surgery Study patients (4% of all patients), retrospectively assessed as good can didates for angioplasty, reveals a survival rate of 95% (45). A total of 53% were operated upon with perioperative mortality and infarction rates of 1% and 6%, respectively. Of the operated patients, 59% were asympto matic and 58% worked compared to 34% and 61%, respectively, of the medically treated patients. We analyzed the natural history over a mean of nine months of 26 patients accepted for coronary angioplasty who did not undergo the pro cedure for nonmedical reasons. There was no death and only one myo cardial infarction had occurred two months after catheterization. Five patient� had undergone bypass surgery and 13 patients (50%) had improved symptomatically with a modified medical regimen. An increase of clinically improved patients from 50% to about 70% would have been the benefit to be expected had angioplasty actually been performed. An incidence of myocardial infarction between 2% and 10% of patients on the waiting list for angioplasty has been reported (46--48). This is comparable to the expected peri-intervcntional infarction rate. Vessel occlusions were observed more frequently, but they were mostly silent because it is the well-collateralized vessels that are prone to occlusion between diagnostic study and angioplasty. OUTCOME OF ANGIOPLASTY CANDIDATES WITH BYPASS SURGERY
A study compared the history of 198 patients with angioplasty to that of 143 patients with single-vessel bypass grafting, preferably with the internal
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mammary artery (49). The results with surgery (no death, no infarction, no recurrence of symptoms) made the results of angioplasty look rather poor: 72% primary success, 0.5% mortality, 11% emergency bypass sur gery (with no mortality but with 38% infarction), 6% total infarction, and 22% recurrence. Elective bypass surgery was carried out in 28 patients with primary failure with no mortality or perioperative infarction. Finally, the mean hospital stay was only three days longer in the surgical patients. Undoubtedly, therapy for single-vessel disease with an internal mammary artery graft accomplished with such expertise and safety is a convincing alternative to coronary angioplasty. Further comparative studies are necessary and they must be randomized. CONCLUSIONS
The long-term results of coronary angioplasty leave a lot to be desired, but they are superior to the natural course. The procedure clearly provides symptom relief, and perhaps prolongs life to a small extent. These results arc obtained with less suffering and cost than the admittedly more spec tacular results of coronary bypass surgery using the internal mammary arteries. It should however, not be forgotten that coronary angioplasty offers results as durable as those achieved surgically with internal mam mary arteries, once the initial months of the scarring process with smooth muscle cell proliferation are over. The ongoing randomized trials will show whether borderline indications for coronary angioplasty can be pursued, such as multivessel angioplasty, fraught with more complications and recurrences (50), and angioplasty for chronic total occlusions, innocuous but plagued by low primary success and high recurrence (51). Even single-vessel angioplasty will be put into perspective, especially for proximal stenoses of the left anterior descending coronary artery where an internal mammary artery graft is such a for midable competitor. It is to be expected that the current enthusiasm will be damped to some extent by the results of these trials. Yet, after a period of reflection, balloon angioplasty is likely to gain momentum again, supported one hopes by new techniques and drugs to reduce restenosis. Literature Cited
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27C-31C 2. Cowley, M. J., Block, P. C. 1985. A review of the NHLBI PTCA Registry data. In Angiaplasty, ed. G. D. Jang, pp. 368-78. New York: McGraw-Hill. 451 pp. 3. Dorros, G., Cowley, M. J., Janke, L.,
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V., LeFree, M. T., Mancini, G. B. J., et a!. 1985. Comparative long-term effects of coronary artery bypass graft surgery and percutaneous transluminal cor onary angioplasty on regional coronary flow reserve. Circulation 72: 833-39 25. Engel, H. J., Kaltenbach, M., Rafflen beul, W., Kober, G., Scherer, D., et al. 1982. Changes of coronary obstructions in the months following transluminal coronary angioplasty. In Transluminal
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30.
pp.I77-82
31. Laird-Meeler, K., Erdman, A. M., van Domburg, R., Azar, A. J., de Feyter, P. J., et a!. 1989. Probability of a return to work after either coronary balloon dilatation or coronary bypass surgery. Eur. Heart J. 10: 917-22 32. Fitzgerald, S. T., Becker, D. M., Celen tano, D. D., Swank, R., Brinker, J. 1989. Return to work after percutaneous transluminal coronary angioplasty. Am. J. Cardiol. 64: 1108-12 33. Johnson, W. D., Kayser, K. L., Pedraza, P. M., Shore, R. T. 1982. Employment patterns in males before and after myo cardial revascularization surgery. A study of 2229 consecutive male patients followed for as long as 10 years. Cir culation 65: 1086-93 34. Almeida, D., Bradford, J. M., Wenger,
N. K., King, S. B., Hurst, J. W. 1983. Return to work after coronary bypass surgery. Circulation 68(Supp!. II): 20513 35. Danchin, N., David, P., Bourassa, M. G. 1983. Coronary artery surgery as a measure of vocational rehabilitation: an analysis of the working status of patients 'Nith mild angina randomly assigned to medical or surgical treatment. Eur. Heart J. 4: 687-90 36. CASS principal investigators and their associates. 1983. Coronary Artery Sur gery Study (CASS): a randomized trial of coronary artery bypass surgery. Qual ity of life in patients randomly assigned to treatment groups. Circulation 68: 951-60 37. Smith, H. C., Hammes, L. N., Gupta, S., Vlietstra, R. E., Elveback, L. 1982. Employment status after coronary artery bypass surgery. Circulation 65 (Supp!. II): 120-25 38. Jang, G. C., Block, P. C, Cowley, M. J., Gruentzig, A. R., Dorros, G., et a!. 1984. Relative cost of coronary angioplasty and bypass surgery in a one-vessel dis ease model. Am. 1. Cardiol. 53: 52C5SC 39. Reeder, G. S., Krishan, 1., Nobrega, F. T., Naessens, J., Kelly, M., et a!. 1984. Is percutaneous transluminal coronary angioplasty less expensive than bypass surgery? N. Engl. J. Med. 311: 1157--62 40. Kelly, M. E., Taylor, G. J., Moses, H. W., Mikcll, F. L., Dove, J. T., ct a!. 1985. Comparative cost of myocardial revascularization: perculaneous lrans luminal angioplasty and coronary artery bypass surgery. 1. Am. Call. Cardiol. 5: 16-20 41. Black, A. J. R., Roubin, G. S., Sutor, c., Moe, N., Jarboe, J. M., et al. 1988. Comparative costs of percutaneous transluminal coronary angioplasty and coronary bypass grafting in multivessel coronary artery disease. Am. J. Cardiol. 62: 809-11 42. Mock, M. B., Ringqvist, 1., Fisher, L. D., Davis, K. B., Chaitman, B. R., and participants in the Coronary Artery Sur gery Study. 1982. Survival of medically treated patients in the Coronary Artery Surgery Study (CASS) Registry. Cir culation 66: 562-68 43. Klein, L. W., Weintraub, W. S., Agar wal, J. B., Schneider, R. M., Seelaus, P. A., et a!. 1986. Prognostic significance of severe narrowing of the proximal por tion of the left anterior descending cor onary artery. Am 1. Cardial. 58: 42-46 44. Hlatky, M. A., Califf, R. M., Kong, Y., Harrell, F. E., Rosati, R. A. 1983. Natu.
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
ral history of patients with single-vessel disease suitable for percutaneous trans luminal coronary angioplasty. Am. J. Cardial. 5 2: 225-29 45. Holmes, D. R. Jr., Vlietstra, R. E., Fisher, L. D., Smith, H. C., Mock, M. B., and participants in the Coronary Artery Surgery Study. 1983. Follow-up of patients from the Coronary Artery Surgery Study (CASS) suitable for per cutaneous transluminal coronary angio plasty. Am. Heart J. 106: 981-88 46. Morton, B. C, Higginson, L. A. J., Chambers, R. J., Beanlands, D. S. 1983. Progression of coronary disease in can didates for transluminal coronary angio plasty. Cathet. Cardiavasc. Diagn. 9: 497-500
47. Kober, G., Reinemer, H., Kaltenbach, M. 1984. Vorkommen und Vorherseh barkeit der Progredienz hochgradiger Koronargefiissstenosen zu Verschliiss en. Z. Kardiol. 73: 674--78
59
48. Robert, J., Bourassa, M. G., Moise, A.,
Kouz, S., Crepeau, J., et a!. 1986. Risk of preangioplasty occlusion and myo cardial infarction in one-vessel-disease patients scheduled for percutaneous transluminal coronary angioplasty. Ca thet. Cardiovasc. Diagn. 12: 292-97 49. Acinapura, A. J., Cunningham, J. N. Jr., Jacobowitz, I. 1., Rose, D. M., Kramer, M. D., et al. 1985. Efficacy of per cutaneous transluminal coronary angio plasty compared with single-vessel by pass. J. Thorae. Cardiovase. Surg. 89: 35-41
50. Vandormael, M., Deligonul, U. 1990. Multivessel coronary angiop1asty. In Interventional Cardiology, ed. B. Meier, pp. 117-43. Toronto: Hogrefe & Huber. 343 pp. 51. Meier, B. 1990. Coronary angioplasty for chronic total occlusion. See Ref. 50, pp. 145-74
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LONG-TERM RESULTS OF CORONARY BALLOON Annu. Rev. Med. 1991.42:47-59. Downloaded from www.annualreviews.org Access provided by Carnegie Mellon University on 02/01/15. For personal use only.
ANGIOPLASTY B.
Meier, M.D.
Cardiology Center, University Hospital, 1211 Geneva 4, Switzerland KEY
WORDS:
percutaneous transluminal coronary angioplasty, coronary bal loon dilatation, late results after coronary angioplasty, follow-up after coronary angioplasty
ABSTRACT
Long-term results after coronary balloon angioplasty are characterized by an eventful early period up to six months, with about a 30% recurrence rate per lesion, and by a stable situation thereafter. Myocardial infarction due to the dilated site is extremely rare during follow-up because the smooth, elastic, inner lining of a restenosis is much less prone to thrombosis than the initial plaque. A positive effect of coronary angioplasty on survival has not been documented, but there is clear functional improvement over the natural course of the untreated disorder. The improvement is com parable to that attained by bypass surgery if repeat angioplasty during the first months is considered as part of the procedure rather than as proof of failure. INTRODUCTION
All procedures are ultimately judged by their long-term results. Coronary balloon angioplasty, in contrast to bypass surgery employing venous grafts, clusters virtually all follow-up problems into the first six months and exhibits thereafter a remarkably stable and favorable course. It is thus legitimate to confine oneself to the first year when assessing long-term outcome of coronary angioplasty. Later events are almost always due to disease progression on sites other than the ones subjected to the procedure. 47 0066-4219/91/0401-0047$02.00
MEIER
48
CLINICAL OUTCOME
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Mortality Survival and infarct-free survival two years after coronary angioplasty are about 98% and 94%, respectively (1). Risk factors for late mortality after angioplasty are the same as those for coronary artery disease in general: left main stem disease, multivessel disease, previous myocardial infarction, diminished left ventricular function, smoking, and hypertension. Unstable angina pectoris before angioplasty portends a higher late mortality as well (2). Male gender proved an additional risk factor for late mortality, quite in contrast to early mortality due to acute complications, for which female gender is a risk factor (3).
Other Cardiac Events The important cardiac events during the first year of follow-up reported from different centers are summarized in Table 1. The initial 133 successful patients of Andreas Gruentzig exhibited 30% recurrences within six months. Then followed more than three years without a single problem in the pertinent artery segments, after which time six more significant stenoses in these segments were found during seven years of follow-up (14). This reflects the peculiar but welcome fact that balloon angioplasty may well have a high initial recurrence rate as a result of intimal proliferation in Table 1
Cardiac events during first year following successful coronary balloon angioplasty
Source
Number
Repeat
Bypass
Year of
of
angioplasty
surgery
Infarction
Death
report
patients
(%)
(%)
(%)
(%)
10 12 10
18 9 23 13 15 19
10 11 12 5 1 55 5 8 5 10 6
3
0 2 2 2
15
7
2
2
1982 1984 1985 1986 1986 1986 1987 1988 1989 1989 1989
Zurich NHLBI reg! Rochester Rhode Island Lille Geneva Nieuwegein Atlanta London' Rotterdam NHLBI reg." Total or average "NHLBI reg.
=
134 906 153 141 130 282 1163 338 331 710 1405 5693
nrb
22
National Heart. Lung, and Blood Institute registry.
bnr = not reported. 'Single-vessel disease only.
3 3 4
3 2 0 2
1 2
2 3
Ref.
4 5 6 7 8 9 10 11 12 13
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
49
the weeks following the intervention, but once this "scarring" process terminates, the underlying plaque appears "frozen" for several years if not for ever. The late problems in the same artery segment may well be disease progression adjacent to the dilated site rather than resurgence of the initial plaque. Cardiac events such as death, myocardial infarction, and need for further angioplasty or bypass surgery are poor indicators of what is occurring at the dilated site since they are based on a mixture of restenosis, preexisting disease in other vessels, and disease progression. Death and myocardial infarction due to restenosis are extremely rare because recur rent stenoses exhibit a markedly reduced propensity to plaque rupture and thrombotic occlusion compared to genuine atherosclerotic plaques.
Even in the absence of an angiogram, reappearance of initially elim inated symptoms can be attributed with a high degree of accuracy to true restenosis if it occurs within six months and to disease progression thereafter.
Subjective Outcome The main goal of coronary revascularization is long-term clinical improve ment. A survey indicated that 84% of patients who had a successful coronary angioplasty felt improved an average of 14 months later. This was significantly inferior to the 94% of surgical patients making the same statement a mean of 26 months after their elective bypass operation (IS). Quite in contrast, another study with at least one year of follow-up found that 96% of patients with successful angioplasty felt improved compared to 88% of patients with failed angioplasty followed by bypass surgery and 20% of patients with failed angioplasty and medical treatment serving as controls (6). Results similar to those in the latter study emerged from a multicenter report (16) but seem optimistic in light of the fact that only half of patients with successful angioplasty are free of symptoms at one year according to the American registry (1), or 86% at 6 months (7), and 74% at 24 months (5) according to other studies if the beneficial influence of additional procedures is not considered.
Objective Outcome In the first 32 patients successfully treated with coronary angioplasty by its innovator, Andreas Gruentzig, 28 (88%) were functionally improved based on their New York Heart Association class for angina (subjective and stress test data) 3 to 18 months after angioplasty. However, three had had repeat angioplasty, two coronary bypass surgery, and one medical therapy for intercurrent exacerbation of symptoms (17). A lasting salutary effect of coronary angioplasty was clearly dem onstrated by an improvement from the pre-angioplasty to the one-year
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MEIER
follow-up exercise test in the first 132 patients treated successfully by Gruentzig (18). The amelioration was maintained at four years. A sig nificant improvement of the perfusion defects after exercise thallium-201 scintigraphy was demonstrated with serial tests up to a mean of 18 months after the procedure in patients without restenosis (19). Similar results were obtained with exercise tests combined with thallium201 scintigraphy at one, three, and six months after successful coronary angioplasty (20). The correlation between thallium-201 results and control angiography was fairly good. The American registry reported on paired nuclear stress tests before and an average of eight months after angioplasty on patients with persistently successful results (21). The tests were clinically and/or electrocardiographically positive in 68% before and in 7% at follow-up. All thallium-201 studies were normal at follow-up and the nuclear left ventricular exercise ejection fraction was improved. Yet, there was still some regional dysfunction in half of the patients. This may relate to a prior subendocardial infarction in some cases. Several studies permit comparison of late functional results of coronary angioplasty and bypass surgery. The comparison favors angioplasty slightly, probably because patients selected for angioplasty have less severe initial disease. Patients with bypass surgery followed over five years exhi bited a durable increase in work capacity of about 50% that was not present in randomized controls treated medically. No patients in the study had single-vessel disease, and the results were better in patients with com plete revascularization. Graft attrition rate was 15% at five years (22). In another randomized study comparing bypass surgery with medical treatment over five years, 31 % of surgical patients had positive stress test results at five years (63% before the operation) compared to 52% of the medical controls. The difference was significant in terms of chest pain but not in terms of electrocardiographic changes. There were 18% of patients with single-vessel disease, and complete revascularization was again iden tified as a favorable factor ( 23). The only study comparing long-term exercise test results of matched patients with coronary angioplasty or bypass surgery (about 50% single vessel disease) is hampered by the fact that the surgical patients are those with a failed angioplasty attempt and that almost half of them underwent a nonelective operation (18). The long-term functional results of the surgical patients in this study still compare favorably to those of the surgical patients without prior angioplasty attempts of other reports (22, 23), who admittedly had more severe disease. The exercise test was assessed as positive in the angioplasty patients in 97% before and in 34% a mean of 30 months after the intervention. The respective figures for bypass patients were almost identical with 96% and 36%. The target heart rate was reached
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
51
without pain and with a normal electrocardiogram in I % before and in 36% at follow-up in angioplasty and in 4% and 32%, respectively, in surgical patients ( 18). Another comparative study used the regional coronary flow reserve in 50 patients (24). The study included patients with atherosclerotic coronary disease before revascularization, patients late after coronary angioplasty, patients late after bypass surgery, and normal controls. The results were expressed by a ratio of flow velocity before and during hyperemia, induced by an injection of contrast medium. The coron"!-ry flow reserve in untreated diseased arteries was abolished. In patients late after coronary angioplasty and bypass surgery, flow reserve was improved to an identical degree but was still inferior to that of normal vessels. ANGIOGRAPHIC OUTCOME Follow-up angiography was initially recommended to all patients with successful coronary angioplasty. In light of the knowledge about the angio graphic late outcome gathered over the years and the increased number of angioplasties performed, it is now considered acceptable and is in fact economically necessary to restrict follow-up angiography to those patients with recurrent symptoms or signs of ischemia. Studies on patients with early and late follow-up angiography revealed that the majority of stenoses remain unchanged during the first months after angioplasty. Deterioration of stenosis (recurrence) is next in frequency. An improvement of more than 10% of the normal vessel diam eter was found in 23% of lesions studied immediately and three months after angioplasty (25). Additional angiograms in 22 of these patients at 12 and 42 months showed no diameter changes greater than 10% in either direction (26). Together with similar results of more recent studies per forming repeat angiograms in the first months after angioplasty on sep arate patient groups (27) or serially in a single patient group (28), this again underlines the remarkable stability of coronary sites treated with balloon dilatation after the initial 3-6 months.
VOCATIONAL REHABILITATION
Return to work rates (Table 2) depend on local health and welfare systems and economic situations as well as on the type of work. A wage earner supported by an excellent disability insurance system is more likely to stay disabled than a self-employed person eager to keep his or her business going. Extremely high return-to-work rates after coronary angioplasty were
52
MEIER
Table 2
Return to work after coronary revascularization
Source
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Rochester NHLBI reg.c Frankfurt Geneva
Year of report
Number of patients·
Return to work (%)
Mean delay (days)
PTCA CABG
PTCA CABG
PTCA CABG
180
Rotterdam
1983 1984 1985 1985 1989
Baltimore
1989
82
Milwaukee
1982 1983 1983 1983
Atlanta Montreal
CASS reg.' Total or average
775
54 83 94
99b 262b
99 86 61 81 76
52b
113 125
b
52
267
148
IS
nr
31
d nr
nr
----
71
16
------
PTCA = percutaneous transluminal coronary angioplasty; CABG Surgery after failed angioplasty.
=
32 nr nr 141 nr
81 73 86
16 29 30
79
66
4896
60 73
25
81
-a
14 7
87 63
87 2229 1590 36 390
1268
97 81
Ref.
33 34 35 36
108 ------ ---
coronary artery bypass grafting.
"NHLBI reg. = National Heart, Lung, and Blood Institute registry. d nr = not reported. 'CASS reg. = Coronary Artery Surgery Study registry.
reported from private American hospitals (16). Return to work was 99% in patients with successful angioplasty, with an average delay of 14 days, and it was 97% in those with failed angioplasty followed by bypass surgery, whose average postoperative disability amounted to 60 days. The differ ence between patients with successful and failed angioplasty was more apparent in wage earners, whose return to work rates wcre 85% and 68%, respectively. Other pertinent studies unveil both coronary bypass surgery and cor onary angioplasty as rather poor means for vocational rehabilitation. Complete vocational rehabilitation, defined as return to an occupational activity equal or superior to that before the sick leave, was reported to be 43% in patients with successful angioplasty and 49% in patients with surgery (15). The American registry analyzed the return-to-work rate of patients with successful angioplasty, patients with failed angioplasty and bypass surgery, and patients with failed angioplasty and medical treatment (29). Initially, 68% of all patients were employed. They represent 100% of the following figures. A mean of 18 months after the procedure, employ ment rates were 86% in the group with successful angioplasty (mean postinterventional disability was 7 days), 81% in the group with surgery after failed angioplasty (73 days), and 83% in the group with medical
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
53
treatment after failed angioplasty (13 days). All figures being inferior to 100%, they represent a net loss in the work force, a loss that is comparable among the three groups. The delay in work resumption was significantly prolonged by bypass surgery. Two studies compared the employment status during follow-up of randomized surgical and medical coronary patients and found no difference (35, 36). The following factors were identified as hindering vocational rehabili tation: long absence from work before the intervention, persistent or recurrent chest pain, incomplete revascularization, previous infarction, large number of drugs prescribed after the intervention, and personal dissatisfaction with the intervention. Delays of several weeks before returning to work after coronary angio piasty can hardly be explained on medical grounds. A few days of recov ery granted for organizational and emotional reasons are in order, although even physical work can be resumed the day after an uneventful angioplasty providing complete revascularization. Further education of patients and referring physicians may enhance early return to work, one of the major advantages of angioplasty. Physicians, for instance, are responsible for the number of drugs prescribed, which can negatively influence return to work (15) independently from chest pain, one of the strongest factors against reintegration (29, 34, 37). ECONOMIC ASPECTS
Use of coronary angioplasty should reduce medical expenses in the United States, where private medicine prevails and unsaturated facilities for cor onary bypass surgery abound. An American multicenter study calculated average hospital charges of $5,000 for single-vessel coronary angioplasty and $16,000 for single-vessel bypass surgery (38). A difference of $7,000 was projected, taking into account a 20% primary failure rate but not the recurrences. A more realistic attempt to calculate the annual savings by coronary angioplasty in the United States was based on the one-year history of 79 patients admitted for coronary angioplasty and 89 patients admitted for bypass surgery to a private hospital (39). The primary success rate of the patients with angioplasty was 70%, which is lower than contemporary success rates. The recurrence rate was 33%. During the year of follow up, angioplasty patients were hospitalized a total of 15 days per patient compared to 17 days per surgical patient. There was no difference in quality of life or vocational rehabilitation between the groups. The mean hospital charges were only 15% lower for angioplasty patients than for surgical patients ($11,000 versus $13,000). This was extrapolated to theo-
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54
MEIER
retical annual savings of 45 million dollars on a national level under the assumption that 15% of patients needing coronary revascu1arization were amenable to angioplasty. It was speculated that an increase in primary success to 95% and a reduction of recurrence to 20% would more than double the savings. The latter goal was met in a similar study on 78 patients with single-vessel coronary angioplasty and 85 patients with single-vessel bypass surgery followed Over one year (40). The success rate of angioplasty was 74% and the recurrence rate 18%. Mean total hospitalization time was 1 1 days in both groups, but mean cost was 45% less for angioplasty patients ($8,000 versus $ 14,000). The difference of results from the other study may be explained, aside from the lower recurrence rate, by the fact that there was no charge for surgical standby. The expansion of coronary angioplasty to multivessel disease was taken into account in a more recent calculation based on a one-year follow-up in 100 consecutive patients with multivessel angioplasty and 100 patients with elective bypass surgery in a private American medical center (41). The total costs were $11,000 for angioplasty (no fee for surgical standby) and $23,000 for surgery. In most other western, let alone developing countries, the situation is entirely different. Patients with single-vessel disease are frequently not considered candidates for bypass surgery because of insufficient surgical capacities. Most countries have nationalized or seminationalized health services. Sophisticated medical interventions are heavily subsidized by tax money. Patients treated by angioplasty may foreshorten the surgical waiting list but they will not decrease the number of operations actually performed. The cost of angioplasty is therefore added to the general health cost, and financial considerations are not in favor of angioplasty. Some economic benefit may be derived from patients resuming work promptly after successful angioplasty, who would have been put on permanent disability without revascularization or who would have returned to work with more delay after bypass surgery. After all, no therapy is cost-efficient in terms of tax money if it possesses even the slightest potential to prolong life in patients already retired. NATURAL COURSE OF ANGIOPLASTY CANDIDATES
With any therapeutic measure, the question is well taken "how would the patient fare without itT Not much gain in longevity should be expected from coronary angioplasty since it is directed primarily toward the subset of coronary patients with the best prognosis (42). A possible exception are
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LONG-TERM CORONARY ANGIOPLASTY RESULTS
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patients with a very proximal stenosis in the left anterior descending coronary artery who have an increased three-year mortality if untreated (43). However, their outcome after angioplasty has not been investigated specifically. A retrospective analysis of the five-year outcome of 110 patients who were ideal candidates for coronary angioplasty before it was available, revealed excellent survival (97%), a reasonably low rate of myocardial infarction (15%), frequent clinical improvement at six months (78%), and an acceptable work status (86% at work at six months of those working before catheterization) (44). Bypass surgery became necessary in 51%. The four-year survival of patients with successful angioplasty in the American registry was identical (97%) but the rate of myocardial infarction was lower (3%); only 21% required further revascularization and 67% were asymptomatic (1). However, these data do not include patients with a failed angioplasty. Analyzing the four-year follow-up of 796 Coronary Artery Surgery Study patients (4% of all patients), retrospectively assessed as good can didates for angioplasty, reveals a survival rate of 95% (45). A total of 53% were operated upon with perioperative mortality and infarction rates of 1% and 6%, respectively. Of the operated patients, 59% were asympto matic and 58% worked compared to 34% and 61%, respectively, of the medically treated patients. We analyzed the natural history over a mean of nine months of 26 patients accepted for coronary angioplasty who did not undergo the pro cedure for nonmedical reasons. There was no death and only one myo cardial infarction had occurred two months after catheterization. Five patient� had undergone bypass surgery and 13 patients (50%) had improved symptomatically with a modified medical regimen. An increase of clinically improved patients from 50% to about 70% would have been the benefit to be expected had angioplasty actually been performed. An incidence of myocardial infarction between 2% and 10% of patients on the waiting list for angioplasty has been reported (46--48). This is comparable to the expected peri-intervcntional infarction rate. Vessel occlusions were observed more frequently, but they were mostly silent because it is the well-collateralized vessels that are prone to occlusion between diagnostic study and angioplasty. OUTCOME OF ANGIOPLASTY CANDIDATES WITH BYPASS SURGERY
A study compared the history of 198 patients with angioplasty to that of 143 patients with single-vessel bypass grafting, preferably with the internal
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mammary artery (49). The results with surgery (no death, no infarction, no recurrence of symptoms) made the results of angioplasty look rather poor: 72% primary success, 0.5% mortality, 11% emergency bypass sur gery (with no mortality but with 38% infarction), 6% total infarction, and 22% recurrence. Elective bypass surgery was carried out in 28 patients with primary failure with no mortality or perioperative infarction. Finally, the mean hospital stay was only three days longer in the surgical patients. Undoubtedly, therapy for single-vessel disease with an internal mammary artery graft accomplished with such expertise and safety is a convincing alternative to coronary angioplasty. Further comparative studies are necessary and they must be randomized. CONCLUSIONS
The long-term results of coronary angioplasty leave a lot to be desired, but they are superior to the natural course. The procedure clearly provides symptom relief, and perhaps prolongs life to a small extent. These results arc obtained with less suffering and cost than the admittedly more spec tacular results of coronary bypass surgery using the internal mammary arteries. It should however, not be forgotten that coronary angioplasty offers results as durable as those achieved surgically with internal mam mary arteries, once the initial months of the scarring process with smooth muscle cell proliferation are over. The ongoing randomized trials will show whether borderline indications for coronary angioplasty can be pursued, such as multivessel angioplasty, fraught with more complications and recurrences (50), and angioplasty for chronic total occlusions, innocuous but plagued by low primary success and high recurrence (51). Even single-vessel angioplasty will be put into perspective, especially for proximal stenoses of the left anterior descending coronary artery where an internal mammary artery graft is such a for midable competitor. It is to be expected that the current enthusiasm will be damped to some extent by the results of these trials. Yet, after a period of reflection, balloon angioplasty is likely to gain momentum again, supported one hopes by new techniques and drugs to reduce restenosis. Literature Cited
I. Kent, K. M., Bentivoglio, L. G., Block, P. C., Bourassa, M. G., Cowley, M. J.,
et al. 1984. Long-term efficacy of per cutaneous transluminal coronary angi oplasty (PTCA): report from the National Heart, Lung, and Blood Insti tute PTCA Registry. Am. J. Cardial. 53:
27C-31C 2. Cowley, M. J., Block, P. C. 1985. A review of the NHLBI PTCA Registry data. In Angiaplasty, ed. G. D. Jang, pp. 368-78. New York: McGraw-Hill. 451 pp. 3. Dorros, G., Cowley, M. J., Janke, L.,
LONG-TERM CORONARY ANGIOPLASTY RESULTS
4.
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5.
6.
7.
8. 9.
10.
II.
12.
13.
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