Saphenous Vein Bypass Grafts: Long-Term Patency and Effect on the Native Coronary Circulation
SAMUEL DAVID
B. ITSCOITZ, R. REDWOOD,
EDWARD ROBERT
B. STINSON, L. REIS,
MD,
STEPHEN
E. EPSTEIN,
Bethesda,
Maryland
MD MD MD
FACC
FACC MD,
FACC
The long-term durability of saphenous vein bypass grafts and their effect on existing intrinsic coronary artery disease remain ill defined. Therefore, sequential catheterization studies were performed in patients selected for study solely on the basis of documentation of a patent graft at an earlier study performed three to nine months postoperatively; at that time 29 patent grafts were demonstrated in 20 patients. Fifteen to 36 months postoperatively (average 22 months), 27 grafts were unchanged, 1 manifested minimal luminal irregularities and 1 was occluded. In one additional patient, studied 4 months and 4 l/2 years postoperatively, the graft was widely patent and had good distal runoff at the second study. Sequential coronary arteriograms revealed that progression of dlsease to complete occlusion occurred in 24 percent of vessels with severe lesions proximal to a patent graft, whereas progression of disease distal to a graft anastomosis was uncommon. Of 25 vessels not recelving grafts, disease progressed in 5 (20 percent). Grafts that are patent 3 months after operation appear to remain patent for at least 2 to 3 years, and their presence does not unduly accelerate the disease process involving the native coronary arteries.
The proper role of the saphenous vein aortocoronary bypass operation in the treatment of coronary artery disease remains unc1ear.l Many questions must be resolved before cardiologists and cardiac surgeons can be confident in recommending or not recommending this procedure to individual patients. The problems are formidable. For example, years will certainly pass before the effects of this operation on longevity and on the risk of subsequent myocardial infarction are fully understood. Other questions lend themselves more readily to clinical investigation. First, what is the long-term durability of patent saphenous vein bypass grafts? Do they remain patent, or do they tend to occlude with time? Second, what effects do patent vein grafts have on the underlying disease process in the recipient coronary artery? Published data pertaining to these questions are limited and, in some cases, conflicting. 2-5 In an attempt to gain some additional information, we restudied 15 to 36 months postoperatively the saphenous vein grafts and native coronary arteries of a group of patients who had patent vein grafts 3 to 9 months postoperatively. Materials
and Methods
During the 18 months from September 1970 to March 1972 a total of 40 From the Cardiology Branch and Clinic of Sur-
gery, National Heart and Lung Institute, Bethes-
da, Md. Manuscript accepted May 14, 1975. Address for Reorints: Samuel B. Itscoitz. MD. Cardiology Branch, National Heart and Lung Institute, Bldg. 10, Room 78-15, Bethesda, Md. 20014.
aortocoronar; bypass surgery at the National Heart and In each case the indication for operation was chronic severe angina pectoris. No perioperative deaths occurred. Three of these 40 patients did not have postoperative cardiac catheterization studies. The remaining 37 underwent cardiac catheterization to determine graft patency during the 1st postoperative year, with most studies being performed 3 to 9 months after operation. These initial postoperative studies revealed that 9 of the 37 papatients-underwent
Lung Institute.
November 1975
The American Journal of CARDIOLOGY
Volume 36
739
SAPHENOUS VEIN BYPASS GRAFTS-ITSCOITZ ET AL.
FIRST
PO
STUDY
3 9mm /A”‘ WIDELY
SECOND
5,
PO
STUDY
5 35 mos / AYG 22 /
PATENT
GO00
RUNOFF NO CHANGE
WIDELY SLOW
PATENT RUNOFF
TOTAL
OCCLUSlON
FIGURE 1. Analysis of graft stability. No anatomic or functional change was noted between the first and second postoperative cardiac catheterization studies in 27 of 29 patent vein grafts (93 percent). P.O. = postoperative.
tients had occlusion of all grafts; the remaining 28 had at least one patent graft with or without coexistent occluded grafts. Twenty of these 28 patients underwent late restudy 15 to 36 months after operation to evaluate long-term graft patency; the remaining 8 patients did not differ significantly from the study group with respect to age distribution, sex distribution or the presence or absence of residual symptoms. The only criterion for restudy was graft patency demonstrated during the first postoperative cardiac catheterization. Therefore, the results should not be biased by factors such as clinical deterioration or new complicating clinical events, the usual criteria for late restudy in such patients6 The data obtained from these 20 patients and from 1 additional patient form the basis of our report. The study group consisted of 18 men and 2 women ranging in age from 36 to 62 years (average 49 years). All patients were in clinically improved condition after operation, and eight were completely angina-free. Cardiac catheterization studies were performed with patients in the postabsorptive state after premeditation with intramuscularly administered pentobarbital sodium. Coronary angiograms and cineangiograms of the grafts were obtained by the Sones or Judkins technique in the left anterior oblique, right anterior oblique and lateral projections. All patients had selective coronary arteriograms preoperatively as well as selective coronary and graft angiograms during both the first and second postoperative studies. Thus in each patient three sequential coronary arteriograms and two sequential graft angiograms were available for comparison. Data
obtained
in one
additional
patient
are also re-
ported here. This patient, now aged 26 years, underwent saphenous vein aortocoronary bypass grafting 7 years ago for anomalous origin of the left coronary artery from the pulmonary artery. Sequential postoperative studies to determine graft patency were carried out 4 months and again 4 l/2 years postoperatively.
Results Analysis of Graft Stability
The data on graft stability obtained from the sequential postoperative studies are summarized in
740
November
1975
The American
Figure 1. The first postoperative study, in which patent grafts were demonstrated in all 20 patients, was performed 3 to 9 months (average 5 months) after operation. Twenty-nine patent grafts were demonstrated in the 20 patients (12 grafts to the left anterior descending coronary artery, 9 to the left circumflex coronary artery and 8 to the right coronary artery). Of these 29 patent grafts, 21 were widely patent with good distal runoff, 5 were widely patent with slow runoff, 2 had stenoses at the distal anastomosis (1 of which was severe with very poor flow) and 1 graft had minor luminal irregularities. The second postoperative study was performed 15 to 36 months (average 22 months) after operation. In each patient, the anatomic and functional appearance of the graft at the first and second postoperative studies was compared (Fig. 1). Of the 21 widely patent grafts with good runoff at the first study, 20 were unchanged at the second study whereas 1 graft had minor luminal irregularities with no apparent functional consequences. All of the five widely patent grafts with slow runoff remained unchanged. As noted, at the first postoperative study two grafts had stenoses at the coronary anastomosis. In one, the lesion was severe and there was very poor flow through the graft; this graft was the only one of the entire group studied in which occlusion occurred between the first and second studies. The other graft in this subgroup remained unchanged. One graft had minor irregularities at the initial study, and at follow-up no change was noted. Thus, of the 29 patent grafts studied 27 (93 percent) were anatomically and functionally stable. Figures 2 and 3 show examples of early and late postoperative studies in two patients aged, respectively, 45 and 55 years. As is evident from the tine frames shown in the left anterior oblique projection, the appearance of the grafts remained unchanged 16 months (Fig. 3) and 2.5 years (Fig. 2) postoperatively. Figure 4 shows the results obtained at late restudy in the patient with anomalous origin of the left coronary artery from the pulmonary artery. Four months postoperatively a widely patent graft with good distal runoff was demonstrated. The graft remained widely patent with excellent distal runoff 4 l/2 years postoperatively, indicating that a saphenous vein graft can remain stable in the aortocoronary position for at least this length of time.
Journal of CARDIOLOGY
Progression
of Native Coronary
Artery Disease
Since selective coronary arteriography was performed in each patient preoperatively and during both the early and late postoperative studies, we were able to detect changes that occurred in the native coronary arteries. Figure 5 summarizes the results of this analysis. Although the study group is small it is unique in that the sequential studies were performed not because of new complicating clinical events, the usual reason for such late restudies,6,7 but as part of a planned sequential analysis.
Volume
36
SAPHENOUS VEIN BYPASS GRAFTS-ITSCOITZ ET AL.
FIGURE 2. Sequential postoperative (P.O.) studies in a 45 year old man with angina pectoris. Six months after operation (left), the initial postoperative study revealed a widely patent graft to the left circumflex system. The appearance of the graft was unchanged at late restudy 2 112 years after operation (right).
16 Months PO.
4 Months f? 0.
FIGURE 3. Sequential postoperative studies in a 55 year old man with angina pectoris. Four months postoperatively (I&) a widely patent graft to the left anterior descending coronary artery was demonstrated. At late restudy 1 year later (rlght), the appearance of the graft was unchanged.
FIGURE 4. Late postoperative study in a 26 year old man with anomalous origin of the left coronary artery. Four and one-half years after saphenous vein grafting, a stable, widely patent graft was again demonstrated and is illustrated here in both the right anterior oblique (RAO) and left anterior oblique (LAO) projections. CORONARY
ARTERIES
RECEIVING.
SEQUENTIAL CORONARY
ARTERIOGRAMS
PATENT GRAFTS
PROGRESSION
FIGURE 5. Progression of underlying coronary artery disease. The average interval between the first and last studies was 2 years. Rates of progression of disease were similar when vessels receiving patent grafts were compared with ungrafted vessels. N.G. = no graft: O.G. = occluded graft; P.G. = patent graft.
%PROGRESSION
GR%TS
P_G 28
N_t 20
03 17
PROGRESSION
OCCLUDED GRAFTS
November 1975
The American Journal ot CARDIOLOGY
Volume 36
741
SAPHENOUS
VEIN BYPASS
GRAFTS-ITSCOITZ
ET AL,
In the 20 patients the average interval between the preoperative and late postoperative coronary arteriogram was 2 years. For purposes of analysis, each major vessel system-the left anterior descending, the left circumflex and the right coronary arterywas regarded as one vessel, giving a total of 60 vessels in the 20 patients. The left main coronary artery was considered part of the left anterior descending system. Twenty-nine of these 60 vessels had patent grafts at the first postoperative study. Of these, 21 showed no progression of the underlying coronary disease at the second study, whereas definite progression was noted in 8; in 7 of the 8, the severe narrowing proximal to the entry site of the graft had progressed to apparent total occlusion. Progression of disease, in this case a new 70 percent stenosis, was noted in only one vessel distal to the entry site of the patent graft. Twenty-five vessels did not receive vein grafts. In 20, there was no progression of disease, in 5, more advanced disease was noted, usually a change from mild to moderate stenosis. In six vessels the grafts were occluded at the first postoperative study. Five of these showed no progression of disease, whereas in one vessel severe narrowing proximal to the graft site had progressed to complete occlusion. Discussion Our data indicate that if a saphenous vein aortocoronary bypass graft remains patent for the first 3 to 5 months after operation, the likelihood of anatomic or functional deterioration during the subsequent 2 to 3 years is remote. Of the original 30 patent vein grafts, 28 were completely unchanged on late restudy, 1 had new but minor irregularities and only 1 had become occluded. When these results are cons‘idered in conjunction with those from other medical centers, an interesting picture of the temporal sequence of saphenous vein graft occlusion emerges. Several centers have reported graft patency rates of about 90 percent2,8,g; in each of these reports grafts were studied during the 1st postoperative month. However, when patients are studied 6 to 12 months after operation, most groups report patency rates of 75 to 85 percent,2~““” indicating that between I month and 1 year after operation an additional 10 to 15 percent of patent vein grafts undergo occlusion. Our data, indicating that graft occlusion is rare after the 3rd postoperative month, imply that this additional occlusion rate of 10 to 15 percent takes place between the 1st and 3rd postoperative months. This conclusion is in agreement with data from the excellent sequential study reported by Grondin et al.” In their study graft occlusion was distinctly uncommon between the 1st and 3rd postoperative years, whereas at an undetermined time between 2 weeks and 1 year postoperatively, 20 percent of the patent vein grafts became occluded. The data on graft patency after the 3rd postoperative year are limited to anecdotal reports. Our patient
lb2
November 6975
The American Journal of CARDIOLOGY
with anomalous origin of the left coronary artery has a widely patent saphenous vein graft 4 l/2 years after operation (however. he differs from the usual patient in that he does not have underlying atherosclerotic coronary disease and the anastomosis of graft to coronary artery is end to end rather than end to side). Garrett et al.‘:j reported patency of a saphenous vein aortocoronary bypass graft to the left anterior descending coronary artery 7 years after operation in a 42 year old man with angina pectoris. Obviously, further sequential studies are needed to define clearly t,he course of patent vein grafts after the 3rd postoperative year. Effect of bypass graft on natural progression of coronary artery disease: A properly designed study to evaluate the effects of vein grafts on the natural progression of coronary artery disease would involve random assignment of equivalent subsets of patients with coronary artery disease into operative and nonoperative groups with long-term follow-up studies of each group with sequential coronary arteriograms. To date, no such study has been reported. Published studies, including this report, compare the rate of progression of disease in grafted arteries with that in nongrafted arteries in the same patients. This approach has obvious shortcomings and thus it is not surprising that the available data are conflicting. Our results, indicating that severe coronary arterial stenoses proximal to the site of graft entry often appear to progress to complete occlusion after the distal establishment of a patent vein graft, are in agreement with most available published information.4~6~11~14~16 Although it is highly likely that the altered flow patterns induced by the presence of a distal patent vein graft contribute to this progression of disease proximally, there are no appropriate control data. Indeed, it is impossible to determine whether a stenosis proximal to the site of graft entry that has apparently progressed to complete occlusion is anatomically occluded, since a patent graft will transmit aortic pressure (or nearly so) just distal to the site of proximal narrowing, reducing or eliminating the pressure gradient across the stenosis and thereby reducing or eliminating flow even in the absence of anatomic occlusion. Conflicting data exist concerning the rate of progresssion of disease in vessels distal to the entry site of a patent vein graft. In our study, progression of disease distally was noted in only 1 of 29 vessels receiving patent vein grafts over an average follow-up period of nearly 2 years. This low rate of progression is in agreement with the data of Glassman et al.,” in which a 2 percent rate of progression of disease in distal vessels was found in a 9 month postoperative follow-up period. Similarly, Bourassa et aLs reported an 8 percent rate of progression in vessels distal to patent vein grafts during a 1 year follow-up period. In several other reports a considerably higher rate of progression of coronary artery disease was noted distal to patent vein grafts. 4*14 It is not clear whether these differences reflect different patient popula-
Volume 36
SAPHENOUS VEIN BYPASS GRAFTS-ITSCOITZ ET AL.
tions, variations in surgical technique or other ill defined factors. In summary, our results considered in conjunction with those of other published reports indicate that saphenous vein graft occlusion is largely confined to
the first 12 weeks after operation. Thereafter patent vein grafts enter a period of prolonged stability. During this period there is a low rate of progression of disease in the recipient coronary artery distal to the site of graft anastomosis.
References 1. Lepley D, Buckley MJ, Carlson RG, et al: Optimal resources for coronary artery surgery. Circulation 46:A-325-A-339, 1972 2. Walker JA, Frledberg HD, Flemma RJ, et al: Determinants of angiographic patency of aortocoronary vein bypass grafts. Circulation 45: Suppl 1:1-66-l-90, 1972 3. Grondln CM, Lesperance J, Bourassa MG: Serial angiographic evaluation in 60 consecutive patients with aorto-coronary artery vein grafts 2 weeks, 1 year, and 3 years after operation. J Thorat Surg 67:1-6, 1974 4. Griffith LSC, Achuff SC, Conti CR, et al: Changes in intrinsic coronary circulation and segmental ventricular motion after saphenous-vein coronary bypass graft surgery. N Engl J Med 268589-595, 1973 5. Bouraasa YG, Goulet C, Lesperance J: Progression of coronary arterial disease after aortocoronary bypass grafts. Circulation 48:Suppl lll:lll-127-111-131, 1973 6. Henderson RR, Rowe GG: The progression of coronary atherosclerotic disease as assessed by cinecoronary arteriography. Am Heart J 86:165-172, 1973 7. Genslnl GG, Esente P, Kelly A: Natural history of coronary disease in patients with and without coronary bypass graft surgery. Circulation 5O:Suppl ll:ll-98-11-102, 1974 8. Effler DB, Favaloro RG, Groves LK, et al: The simple approach to direct coronary artery surgery. J Thorac Cardiovasc Surg
62:503-510, 1971 9. Grondln CM, Meere C, Castonguay YR, et al: Blood flow through aorto-to-coronary artery bypass grafts and early postoperative patency. Ann Thorac Surg 12:574-581. 1971 10. Grondin CM, Castonguay YR, Lesperance J, et al: Attrition rate of aorto-to-coronary artery saphenous vein grafts after one year. Ann Thorac Surg 14:223-231, 1972 11. Glassman E, Spencer FC, Krauss KR, et al: Changes in the underlying coronary circulation secondary to bypass grafting. Circulation 5O:Suppl ll:ll-80-11-83, 1974 12. Sheldon WC, Rlncon G, Etfler DB, et al: Vein graft surgery for coronary artery disease. Circulation 48:Suppl lll:lll-184-111-189, 1973 13. Garrett HE, Dennis ED, DeBakey ME: Aorto-coronary bypass with saphenous vein graft. JAMA 233:792-794, 1973 14. Maurer BJ, Oberman A, Holt JH, et al: Changes in grafted and nongrafted coronary arteries following saphenous vein bypass grafting. Circulation 50:293-300, 1974 15. Yallnow MR, Kremkan EL, Kloster FE, et al: Occlusion of coronary arteries after vein bypass. Circulation 47:1211-1216, 1973 16. Bousvaros G, Chandhry MA, Plrache AR: Progression of proximal coronary arterial lesions to total occlusion after vein graft surgery and its effects (abstr). Am J Cardiol 29:255, 1972
November 1975
The American Journal of CARDIOLOGY
Volume 36
743
SAMUEL DAVID
B. ITSCOITZ, R. REDWOOD,
EDWARD ROBERT
B. STINSON, L. REIS,
MD,
STEPHEN
E. EPSTEIN,
Bethesda,
Maryland
MD MD MD
FACC
FACC MD,
FACC
The long-term durability of saphenous vein bypass grafts and their effect on existing intrinsic coronary artery disease remain ill defined. Therefore, sequential catheterization studies were performed in patients selected for study solely on the basis of documentation of a patent graft at an earlier study performed three to nine months postoperatively; at that time 29 patent grafts were demonstrated in 20 patients. Fifteen to 36 months postoperatively (average 22 months), 27 grafts were unchanged, 1 manifested minimal luminal irregularities and 1 was occluded. In one additional patient, studied 4 months and 4 l/2 years postoperatively, the graft was widely patent and had good distal runoff at the second study. Sequential coronary arteriograms revealed that progression of dlsease to complete occlusion occurred in 24 percent of vessels with severe lesions proximal to a patent graft, whereas progression of disease distal to a graft anastomosis was uncommon. Of 25 vessels not recelving grafts, disease progressed in 5 (20 percent). Grafts that are patent 3 months after operation appear to remain patent for at least 2 to 3 years, and their presence does not unduly accelerate the disease process involving the native coronary arteries.
The proper role of the saphenous vein aortocoronary bypass operation in the treatment of coronary artery disease remains unc1ear.l Many questions must be resolved before cardiologists and cardiac surgeons can be confident in recommending or not recommending this procedure to individual patients. The problems are formidable. For example, years will certainly pass before the effects of this operation on longevity and on the risk of subsequent myocardial infarction are fully understood. Other questions lend themselves more readily to clinical investigation. First, what is the long-term durability of patent saphenous vein bypass grafts? Do they remain patent, or do they tend to occlude with time? Second, what effects do patent vein grafts have on the underlying disease process in the recipient coronary artery? Published data pertaining to these questions are limited and, in some cases, conflicting. 2-5 In an attempt to gain some additional information, we restudied 15 to 36 months postoperatively the saphenous vein grafts and native coronary arteries of a group of patients who had patent vein grafts 3 to 9 months postoperatively. Materials
and Methods
During the 18 months from September 1970 to March 1972 a total of 40 From the Cardiology Branch and Clinic of Sur-
gery, National Heart and Lung Institute, Bethes-
da, Md. Manuscript accepted May 14, 1975. Address for Reorints: Samuel B. Itscoitz. MD. Cardiology Branch, National Heart and Lung Institute, Bldg. 10, Room 78-15, Bethesda, Md. 20014.
aortocoronar; bypass surgery at the National Heart and In each case the indication for operation was chronic severe angina pectoris. No perioperative deaths occurred. Three of these 40 patients did not have postoperative cardiac catheterization studies. The remaining 37 underwent cardiac catheterization to determine graft patency during the 1st postoperative year, with most studies being performed 3 to 9 months after operation. These initial postoperative studies revealed that 9 of the 37 papatients-underwent
Lung Institute.
November 1975
The American Journal of CARDIOLOGY
Volume 36
739
SAPHENOUS VEIN BYPASS GRAFTS-ITSCOITZ ET AL.
FIRST
PO
STUDY
3 9mm /A”‘ WIDELY
SECOND
5,
PO
STUDY
5 35 mos / AYG 22 /
PATENT
GO00
RUNOFF NO CHANGE
WIDELY SLOW
PATENT RUNOFF
TOTAL
OCCLUSlON
FIGURE 1. Analysis of graft stability. No anatomic or functional change was noted between the first and second postoperative cardiac catheterization studies in 27 of 29 patent vein grafts (93 percent). P.O. = postoperative.
tients had occlusion of all grafts; the remaining 28 had at least one patent graft with or without coexistent occluded grafts. Twenty of these 28 patients underwent late restudy 15 to 36 months after operation to evaluate long-term graft patency; the remaining 8 patients did not differ significantly from the study group with respect to age distribution, sex distribution or the presence or absence of residual symptoms. The only criterion for restudy was graft patency demonstrated during the first postoperative cardiac catheterization. Therefore, the results should not be biased by factors such as clinical deterioration or new complicating clinical events, the usual criteria for late restudy in such patients6 The data obtained from these 20 patients and from 1 additional patient form the basis of our report. The study group consisted of 18 men and 2 women ranging in age from 36 to 62 years (average 49 years). All patients were in clinically improved condition after operation, and eight were completely angina-free. Cardiac catheterization studies were performed with patients in the postabsorptive state after premeditation with intramuscularly administered pentobarbital sodium. Coronary angiograms and cineangiograms of the grafts were obtained by the Sones or Judkins technique in the left anterior oblique, right anterior oblique and lateral projections. All patients had selective coronary arteriograms preoperatively as well as selective coronary and graft angiograms during both the first and second postoperative studies. Thus in each patient three sequential coronary arteriograms and two sequential graft angiograms were available for comparison. Data
obtained
in one
additional
patient
are also re-
ported here. This patient, now aged 26 years, underwent saphenous vein aortocoronary bypass grafting 7 years ago for anomalous origin of the left coronary artery from the pulmonary artery. Sequential postoperative studies to determine graft patency were carried out 4 months and again 4 l/2 years postoperatively.
Results Analysis of Graft Stability
The data on graft stability obtained from the sequential postoperative studies are summarized in
740
November
1975
The American
Figure 1. The first postoperative study, in which patent grafts were demonstrated in all 20 patients, was performed 3 to 9 months (average 5 months) after operation. Twenty-nine patent grafts were demonstrated in the 20 patients (12 grafts to the left anterior descending coronary artery, 9 to the left circumflex coronary artery and 8 to the right coronary artery). Of these 29 patent grafts, 21 were widely patent with good distal runoff, 5 were widely patent with slow runoff, 2 had stenoses at the distal anastomosis (1 of which was severe with very poor flow) and 1 graft had minor luminal irregularities. The second postoperative study was performed 15 to 36 months (average 22 months) after operation. In each patient, the anatomic and functional appearance of the graft at the first and second postoperative studies was compared (Fig. 1). Of the 21 widely patent grafts with good runoff at the first study, 20 were unchanged at the second study whereas 1 graft had minor luminal irregularities with no apparent functional consequences. All of the five widely patent grafts with slow runoff remained unchanged. As noted, at the first postoperative study two grafts had stenoses at the coronary anastomosis. In one, the lesion was severe and there was very poor flow through the graft; this graft was the only one of the entire group studied in which occlusion occurred between the first and second studies. The other graft in this subgroup remained unchanged. One graft had minor irregularities at the initial study, and at follow-up no change was noted. Thus, of the 29 patent grafts studied 27 (93 percent) were anatomically and functionally stable. Figures 2 and 3 show examples of early and late postoperative studies in two patients aged, respectively, 45 and 55 years. As is evident from the tine frames shown in the left anterior oblique projection, the appearance of the grafts remained unchanged 16 months (Fig. 3) and 2.5 years (Fig. 2) postoperatively. Figure 4 shows the results obtained at late restudy in the patient with anomalous origin of the left coronary artery from the pulmonary artery. Four months postoperatively a widely patent graft with good distal runoff was demonstrated. The graft remained widely patent with excellent distal runoff 4 l/2 years postoperatively, indicating that a saphenous vein graft can remain stable in the aortocoronary position for at least this length of time.
Journal of CARDIOLOGY
Progression
of Native Coronary
Artery Disease
Since selective coronary arteriography was performed in each patient preoperatively and during both the early and late postoperative studies, we were able to detect changes that occurred in the native coronary arteries. Figure 5 summarizes the results of this analysis. Although the study group is small it is unique in that the sequential studies were performed not because of new complicating clinical events, the usual reason for such late restudies,6,7 but as part of a planned sequential analysis.
Volume
36
SAPHENOUS VEIN BYPASS GRAFTS-ITSCOITZ ET AL.
FIGURE 2. Sequential postoperative (P.O.) studies in a 45 year old man with angina pectoris. Six months after operation (left), the initial postoperative study revealed a widely patent graft to the left circumflex system. The appearance of the graft was unchanged at late restudy 2 112 years after operation (right).
16 Months PO.
4 Months f? 0.
FIGURE 3. Sequential postoperative studies in a 55 year old man with angina pectoris. Four months postoperatively (I&) a widely patent graft to the left anterior descending coronary artery was demonstrated. At late restudy 1 year later (rlght), the appearance of the graft was unchanged.
FIGURE 4. Late postoperative study in a 26 year old man with anomalous origin of the left coronary artery. Four and one-half years after saphenous vein grafting, a stable, widely patent graft was again demonstrated and is illustrated here in both the right anterior oblique (RAO) and left anterior oblique (LAO) projections. CORONARY
ARTERIES
RECEIVING.
SEQUENTIAL CORONARY
ARTERIOGRAMS
PATENT GRAFTS
PROGRESSION
FIGURE 5. Progression of underlying coronary artery disease. The average interval between the first and last studies was 2 years. Rates of progression of disease were similar when vessels receiving patent grafts were compared with ungrafted vessels. N.G. = no graft: O.G. = occluded graft; P.G. = patent graft.
%PROGRESSION
GR%TS
P_G 28
N_t 20
03 17
PROGRESSION
OCCLUDED GRAFTS
November 1975
The American Journal ot CARDIOLOGY
Volume 36
741
SAPHENOUS
VEIN BYPASS
GRAFTS-ITSCOITZ
ET AL,
In the 20 patients the average interval between the preoperative and late postoperative coronary arteriogram was 2 years. For purposes of analysis, each major vessel system-the left anterior descending, the left circumflex and the right coronary arterywas regarded as one vessel, giving a total of 60 vessels in the 20 patients. The left main coronary artery was considered part of the left anterior descending system. Twenty-nine of these 60 vessels had patent grafts at the first postoperative study. Of these, 21 showed no progression of the underlying coronary disease at the second study, whereas definite progression was noted in 8; in 7 of the 8, the severe narrowing proximal to the entry site of the graft had progressed to apparent total occlusion. Progression of disease, in this case a new 70 percent stenosis, was noted in only one vessel distal to the entry site of the patent graft. Twenty-five vessels did not receive vein grafts. In 20, there was no progression of disease, in 5, more advanced disease was noted, usually a change from mild to moderate stenosis. In six vessels the grafts were occluded at the first postoperative study. Five of these showed no progression of disease, whereas in one vessel severe narrowing proximal to the graft site had progressed to complete occlusion. Discussion Our data indicate that if a saphenous vein aortocoronary bypass graft remains patent for the first 3 to 5 months after operation, the likelihood of anatomic or functional deterioration during the subsequent 2 to 3 years is remote. Of the original 30 patent vein grafts, 28 were completely unchanged on late restudy, 1 had new but minor irregularities and only 1 had become occluded. When these results are cons‘idered in conjunction with those from other medical centers, an interesting picture of the temporal sequence of saphenous vein graft occlusion emerges. Several centers have reported graft patency rates of about 90 percent2,8,g; in each of these reports grafts were studied during the 1st postoperative month. However, when patients are studied 6 to 12 months after operation, most groups report patency rates of 75 to 85 percent,2~““” indicating that between I month and 1 year after operation an additional 10 to 15 percent of patent vein grafts undergo occlusion. Our data, indicating that graft occlusion is rare after the 3rd postoperative month, imply that this additional occlusion rate of 10 to 15 percent takes place between the 1st and 3rd postoperative months. This conclusion is in agreement with data from the excellent sequential study reported by Grondin et al.” In their study graft occlusion was distinctly uncommon between the 1st and 3rd postoperative years, whereas at an undetermined time between 2 weeks and 1 year postoperatively, 20 percent of the patent vein grafts became occluded. The data on graft patency after the 3rd postoperative year are limited to anecdotal reports. Our patient
lb2
November 6975
The American Journal of CARDIOLOGY
with anomalous origin of the left coronary artery has a widely patent saphenous vein graft 4 l/2 years after operation (however. he differs from the usual patient in that he does not have underlying atherosclerotic coronary disease and the anastomosis of graft to coronary artery is end to end rather than end to side). Garrett et al.‘:j reported patency of a saphenous vein aortocoronary bypass graft to the left anterior descending coronary artery 7 years after operation in a 42 year old man with angina pectoris. Obviously, further sequential studies are needed to define clearly t,he course of patent vein grafts after the 3rd postoperative year. Effect of bypass graft on natural progression of coronary artery disease: A properly designed study to evaluate the effects of vein grafts on the natural progression of coronary artery disease would involve random assignment of equivalent subsets of patients with coronary artery disease into operative and nonoperative groups with long-term follow-up studies of each group with sequential coronary arteriograms. To date, no such study has been reported. Published studies, including this report, compare the rate of progression of disease in grafted arteries with that in nongrafted arteries in the same patients. This approach has obvious shortcomings and thus it is not surprising that the available data are conflicting. Our results, indicating that severe coronary arterial stenoses proximal to the site of graft entry often appear to progress to complete occlusion after the distal establishment of a patent vein graft, are in agreement with most available published information.4~6~11~14~16 Although it is highly likely that the altered flow patterns induced by the presence of a distal patent vein graft contribute to this progression of disease proximally, there are no appropriate control data. Indeed, it is impossible to determine whether a stenosis proximal to the site of graft entry that has apparently progressed to complete occlusion is anatomically occluded, since a patent graft will transmit aortic pressure (or nearly so) just distal to the site of proximal narrowing, reducing or eliminating the pressure gradient across the stenosis and thereby reducing or eliminating flow even in the absence of anatomic occlusion. Conflicting data exist concerning the rate of progresssion of disease in vessels distal to the entry site of a patent vein graft. In our study, progression of disease distally was noted in only 1 of 29 vessels receiving patent vein grafts over an average follow-up period of nearly 2 years. This low rate of progression is in agreement with the data of Glassman et al.,” in which a 2 percent rate of progression of disease in distal vessels was found in a 9 month postoperative follow-up period. Similarly, Bourassa et aLs reported an 8 percent rate of progression in vessels distal to patent vein grafts during a 1 year follow-up period. In several other reports a considerably higher rate of progression of coronary artery disease was noted distal to patent vein grafts. 4*14 It is not clear whether these differences reflect different patient popula-
Volume 36
SAPHENOUS VEIN BYPASS GRAFTS-ITSCOITZ ET AL.
tions, variations in surgical technique or other ill defined factors. In summary, our results considered in conjunction with those of other published reports indicate that saphenous vein graft occlusion is largely confined to
the first 12 weeks after operation. Thereafter patent vein grafts enter a period of prolonged stability. During this period there is a low rate of progression of disease in the recipient coronary artery distal to the site of graft anastomosis.
References 1. Lepley D, Buckley MJ, Carlson RG, et al: Optimal resources for coronary artery surgery. Circulation 46:A-325-A-339, 1972 2. Walker JA, Frledberg HD, Flemma RJ, et al: Determinants of angiographic patency of aortocoronary vein bypass grafts. Circulation 45: Suppl 1:1-66-l-90, 1972 3. Grondln CM, Lesperance J, Bourassa MG: Serial angiographic evaluation in 60 consecutive patients with aorto-coronary artery vein grafts 2 weeks, 1 year, and 3 years after operation. J Thorat Surg 67:1-6, 1974 4. Griffith LSC, Achuff SC, Conti CR, et al: Changes in intrinsic coronary circulation and segmental ventricular motion after saphenous-vein coronary bypass graft surgery. N Engl J Med 268589-595, 1973 5. Bouraasa YG, Goulet C, Lesperance J: Progression of coronary arterial disease after aortocoronary bypass grafts. Circulation 48:Suppl lll:lll-127-111-131, 1973 6. Henderson RR, Rowe GG: The progression of coronary atherosclerotic disease as assessed by cinecoronary arteriography. Am Heart J 86:165-172, 1973 7. Genslnl GG, Esente P, Kelly A: Natural history of coronary disease in patients with and without coronary bypass graft surgery. Circulation 5O:Suppl ll:ll-98-11-102, 1974 8. Effler DB, Favaloro RG, Groves LK, et al: The simple approach to direct coronary artery surgery. J Thorac Cardiovasc Surg
62:503-510, 1971 9. Grondln CM, Meere C, Castonguay YR, et al: Blood flow through aorto-to-coronary artery bypass grafts and early postoperative patency. Ann Thorac Surg 12:574-581. 1971 10. Grondin CM, Castonguay YR, Lesperance J, et al: Attrition rate of aorto-to-coronary artery saphenous vein grafts after one year. Ann Thorac Surg 14:223-231, 1972 11. Glassman E, Spencer FC, Krauss KR, et al: Changes in the underlying coronary circulation secondary to bypass grafting. Circulation 5O:Suppl ll:ll-80-11-83, 1974 12. Sheldon WC, Rlncon G, Etfler DB, et al: Vein graft surgery for coronary artery disease. Circulation 48:Suppl lll:lll-184-111-189, 1973 13. Garrett HE, Dennis ED, DeBakey ME: Aorto-coronary bypass with saphenous vein graft. JAMA 233:792-794, 1973 14. Maurer BJ, Oberman A, Holt JH, et al: Changes in grafted and nongrafted coronary arteries following saphenous vein bypass grafting. Circulation 50:293-300, 1974 15. Yallnow MR, Kremkan EL, Kloster FE, et al: Occlusion of coronary arteries after vein bypass. Circulation 47:1211-1216, 1973 16. Bousvaros G, Chandhry MA, Plrache AR: Progression of proximal coronary arterial lesions to total occlusion after vein graft surgery and its effects (abstr). Am J Cardiol 29:255, 1972
November 1975
The American Journal of CARDIOLOGY
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