Importance of Identifying Left Main Coronary Artery Narrowing in Subsets of Patients with Coronary Artery Disease A N I M P O R T A N T FACT that has emerged from numerous studies conducted during the past decade is that all patients with coronary artery disease do not conveniently 308
manifest a homogenous "natural history." Subgroups of patients can be identified with more ominous prognoses, thereby raising the possibility that such subgroups might
August 1979 • Annals of Internal Medicine • Volume 91 • Number 2
Downloaded from https://annals.org by Tulane University user on 01/12/2019
benefit from prophylactic surgery. Although many factors predisposing to higher mortality have been implicated, the most powerful seem to be the functional status of the left ventricle and the number of vessels critically narrowed (1-4). Patients with left main coronary artery narrowing have a particularly poor prognosis (5-8), and in several studies patients with unstable angina also have been shown to be at increased risk (9-11). Based on these perceptions, recommendations have been made at one time or another to operate prophylactically on all patients with double- or triple-vessel coronary disease, unstable angina, or significant narrowing of the left main coronary artery. Emphasis on the word prophylactic is critical, because there is currently no debate about the wisdom of proceeding with surgery in a subject who remains severely symptomatic despite medical treatment. The vital question and great dilemma is "Should the subject with stable symptoms that are adequately controlled medically, or the subject with unstable angina who has not yet had adequate medical trial, be operated on forthwith to enhance survival?" Unfortunately, the answer to this question is still shrouded in controversy. Patients with Stable Symptoms
There are vigorous proponents of the concept that all patients with coronary artery disease who have significant narrowing of two or three vessels require operation to prolong life regardless of symptomatic status (12-16). These conclusions derive largely from comparing the long-term survival of patients operated on with either the survival of patients not operated on who were identified and treated in the 1960s and early 1970s or with the survival of nonrandomized, but computer-matched, patients. Many of the patients in these nonoperative series were severely symptomatic. However, the coronary patient with mild symptoms (17) or with good left ventricular function (17-19), identified and treated in the mid1970s, has recently been recognized to have a consistently better prognosis than that anticipated from the older natural history studies (1, 20-23) with which the operative results have been compared. The favorable natural history data of the mildly symptomatic patient (17) or the patient with good left ventricular function (17-19) seriously weakens the case for prophylactic operation, because survival in such patients treated medically, even in the presence of two- or three-vessel disease, is as good as the survival of patients who had operations (17). This concept is also supported by the data of three prospectively conducted randomized studies comparing the effects of operative-versus-medical therapy on survival, in which it was shown that operation does not prolong survival in patients with stable coronary disease (24-26) except in those patients with left main disease (5). Thus, given existing data, deferring operation in the patient with stable symptoms that are well-controlled on medical therapy is reasonable, even if two- or three-vessel disease is present. Although many authorities would disagree with this statement, few would dispute the concept that coronarybypass operation is indicated for all symptomatic patients
with left main disease (although the fact that such patients do not constitute a homogenous group and operation does not unequivocally improve survival in all subgroups must be recognized [5, 6]). Because patients with left main disease and stable symptoms constitute about 10% of mildly symptomatic patients with coronary disease (17) and comprise a group in which operative therapy seems warranted, the question arises as to whether they can be reliably identified by means short of coronary angiography (17). Does a similar dilemma relate to the patient with unstable angina, the subject of the article by Dr. Plotnick and his co-workers, that appears on pages 149-153 in this issue (27)? Patients with Unstable Angina
Is detecting left main stenosis in patients with unstable angina imperative, or does the mere presence of unstable angina identify a subgroup at high risk of imminent death that necessitates operation regardless of coronary anatomy? Early studies suggested a rather high mortality in such patients (9-11, 28). In addition, the results of one study strongly suggested that coronary-bypass surgery enhances survival in patients with one type of unstable angina, that characterized by prolonged and intense bouts of chest pain unrelated to exertion and refractory to nitrates (28). These patients have been classified as having the "intermediate syndrome." Although not entirely clear, other studies have apparently excluded this particular subgroup of patients with unstable angina from randomization, considering them medical failures and proceeding with operation. In all other types of patients classified as having unstable angina and operated on before hospital discharge, however, survival was not found to be increased by surgery. These results have been observed in several studies (28-31), including the National Cooperative Study of Unstable Angina (29) and the study showing enhanced survival after surgery in patients with the "intermediate syndrome" (28). Although many medically treated patients in the National Cooperative Study (29) eventually required operation because of recurrent severe symptoms, survival of patients was unaffected by delaying operation. Thus, because symptoms eventually are controlled medically in many patients, unnecessary surgery can be avoided if operation is deferred until it is determined which patient experiences symptoms not easily controlled on medication. These results appear to offer the physician a clear strategy of patient management: Treat the patient with unstable angina vigorously medically and proceed with catheterization and operation only if symptoms cannot be controlled satisfactorily. The potential flaw in this approach, however, is the fact that the results of the studies quoted above (with the exception of Reference 28, which showed that surgery increased survival in one clinical subgroup) excluded patients with left main coronary artery disease. Because the prevalence of left main coronary artery disease in patients with unstable angina is probably as high as 10% to 2 0 % , and because operation in patients with unstable angina and stenosis of the left main coronary Editorial
Downloaded from https://annals.org by Tulane University user on 01/12/2019
309
artery is likely to enhance survival, as it does in patients with stable angina pectoris (5), identifying such patients without undue delay is critical. The study by Dr. Plotnick and coworkers (27), although yielding negative results, provides the clinician with some important insights. It has shown that a multitude of potential noninvasive clinical indicators of left main coronary artery disease, including the baseline electrocardiogram, changes in the electrocardiogram, presence of congestive heart failure, characteristics of the anginal pain, presence or absence of arrhythmias, or identification of calcification in the area of the left main coronary artery on fluoroscopy, are of limited value in the detection of coronary artery disease because of low sensitivity, low predictive value, or both. The major deficiency of their study as it applies to more current diagnostic techniques, however, is the lack of data regarding the potential utility of exercise testing using electrocardiography, thalium scans, or radionuclide cineangiography in detecting left main disease. Preliminary studies in patients with stable coronary artery disease suggest that the radionuclide techniques will not be able to discriminate between patients with left main disease and those with multivessel coronary disease (32). There is some hope, however, that exercise electrocardiography can identify a subgroup of patients with a somewhat greater likelihood of having left main coronary disease than an unscreened population and that such testing probably will result in relatively few false-negative results (17). However, such studies have not yet been applied to patients with unstable angina. The negative results of Plotnick and associates (27), as well as their confirmation of the high prevalence of left main disease in a population of patients with unstable angina, underlines the importance of conducting further studies in patients with unstable angina to ascertain whether reliable noninvasive predictors of left main coronary disease can be developed. Until that time, the physician must act within the framework of existing studies that have shown, or strongly suggest, a high prevalence of left main disease in patients with unstable angina and a high likelihood that operation enhances survival in patients with left main disease. Although E G G exercise testing may offer a reasonable compromise as a screening test for determining which patients should have angiography (17), its precise reliability and utility in such patients are still unproved. At present, the only definitive way to rule out the possibility of significant narrowing of the left main coronary artery is coronary angiography. ( S T E P H E N E. E P S T E I N , M.D.; Cardiology
tional Heart, Lung, and Blood Institute, tutes of Health; Bethesda, Maryland)
Branch,
National
Na-
Insti-
4. BURGGRAF GW, PARKER JO. Prognosis in coronary artery disease: angiographic hemodynamic, and clinical factors. Circulation. 1975;51:14656. 5. T A K A R O T, H U L T G R E N N H , L I P T O N MJ, D E T R E K M , P A R T I C I P A N T S
IN THE STUDY G R O U P . The VA cooperative randomized study of surgery for coronary arterial occlusive disease: II. Subgroup with significant left main lesions. Circulation. 1976;54(Suppl 3): 107-17. 6. C A M P E A U L, CORBARA F, C R O C H E T D, P E T I T C L E R C R. Left main
coronary artery stenosis: the influence of aortocoronary bypass surgery on survival. Circulation. 1978;57:1111-5. 7. L I M JS, PROUDFIT WL, JONES FM J R . Left main coronary arterial obstruction: long-term follow-up of 141 nonsurgical cases. Am J Cardiol. 1957;36:131-5. 8. C O N L E Y MJ, E L Y RL, KISSLO J, L E E KL, M C N E E R J F , ROSATI RA.
The prognostic spectrum of left main stenosis. Circulation. 1978;57:94752. 9. KRAUSS KR, H U T T E R AM JR, DESANCTIS RW. Acute coronary insufficiency: course and follow-up. Circulation. 1972;45(Suppl 1):66-71. 10. G A Z E S PC, M O B L E Y EM J R , F A R I S HM J R , D U N C A N RC, H U M P H R I E S
GB. Preinfarctional (unstable) angina: a prospective study: ten year follow-up. Circulation. 1973;48:331-7. 11. LOPES MG, SPIVACK AP, H A R R I S O N DC, SCHROEDER JS. Prognosis of
non-infarction coronary care unit patients. Am J Cardiol. 1973:31:144. Abstract. 12. H U R S T JW, K I N G SB III, LOGUE RB, et al. Value of coronary bypass surgery. Controversies in cardiology: Part I. Am J Cardiol. 1978;42:30829. 13. PROUDFIT WL: Criticisms of the VA randomized study of coronary bypass surgery. Clin Res. 1978;26:236-40. 14. VISMARA LA, M I L L E R RR, P R I C E JE, K A R E M R, D E M A R I A AN, M A -
SON DT. Improved longevity due to reduction of sudden death by aortocoronary bypass in coronary atherosclerosis: prospective evaluation of medical versus surgical therapy in matched patients with multivessel disease. Am J Cardiol. 1977;39:919-24. 15. H A M M E R M E I S T E R K E , D E R O U E N TA, M U R R A Y JA, D O D G E JT. Effect
of aortocoronary saphenous vein bypass grafting on death and sudden death: comparison of nonrandomized medically and surgically treated cohorts with comparable coronary disease and left ventricular function. Am J Cardiol. 1977;39:925-34. 16. C O H N LH, BOYDEN CM, COLLINS JJ JR. Improved long-term survival after aortocoronary bypass for advanced coronary artery disease. Am J Surg. 1975;129:380-5. 17. E P S T E I N SE, K E N T KM, G O L D S T E I N RE, B O R E R JS, R O S I N G
DR.
Strategy for evaluation and surgical treatment of the asymptomatic or mildly symptomatic patient with coronary artery disease. Am J Cardiol. 1979;43:1015-25. 18. D E T R E K, M U R P H Y ML, H U L T G R E N H. Effect of coronary bypass surgery on longevity in high and low risk patients. Lancet. 1977;2:1243-5. 19. GROSS H, V A I D AK, COHEN MV. Prognosis in patients rejected for coronary revascularization surgery. Am J Med. 1978;64:9-20. 20. M C N E E R J F , S T A R M E R C F , B A R T E L AG, et al. The nature of treatment
selection in coronary artery disease: experience with medical and surgical treatment of a chronic disease. Circulation. 1974;49:606-14. 21. O B E R M A N A, H A R R E L L RR, R U S S E L L RO J R , K O U C H O U K A S
NT,
H O L T JH J R , RACKLEY CE. Surgical versus medical treatment in disease of the left main coronary artery. Lancet. 1976;2:591-4. 22. WEBSTER JS, MOBERG C, RINCON G. Natural history of severe proximal coronary artery disease as documented by coronary cineangiography. Am J Cardiol. 1974;33:195-200. 23. B R Y M E R J F , B U T E R T H , W A L T O N JA J R , W I L L I S PW III. A natural
history study of the prognostic role of coronary arteriography. Am Heart J. 1974;88:139-43. 24. M U R P H Y ML, H U L T G R E N N H , D E T R E K, T H O M S E N J, T A K A R O M, PARTICIPANTS OF T H E VA C O O P E R A T I V E STUDY. Treatment of chronic
stable angina: a preliminary report of survival data of the randomized Veterans Administration Cooperative Study. N Engl J Med. 1977;297:621-7. 25. M A T H U R VS, G U I N N GA. Long-term follow-up (4-7 years) of a prospective randomized study to evaluate surgical vs medial treatment for stable angina pectoris: clinical status, exercise performance and survival. Am J Cardiol. 1979;43:382. Abstract. 26. K L O S T E R
FE,
KREMKAU
EL,
RITZMANN
LW,
RAHMTOOLA
SH,
ROSCH J, K A N A R E K PH. Coronary bypass for stable angina: a prospective randomized study. NEnglJMed. 1979;300:149-57.
References 1. BRUNSCHKE AVG, P R O U D F I T WL, SONES J R FM. Progress study of
27. P L O T N I C K G D , G R E E N E HL, C A R L I N E R N H , B E C K E R LC, F I S H E R
590 consecutive nonsurgical cases of coronary disease followed 5-9 years: II. Ventriculographic and other correlations. Circulation. 1973;47:1154-63.
ML. Clinical indicators of left main coronary artery disease in unstable angina. Ann Intern Med. 1979;91:149-53. 28. BERTOLASI CA, T R O N G E JE, R I C C I T E L L I
of angina pectoris. Am J Cardiol. 1974;33:423-30. 3. FRIESINGER GC, PAGE EE, ROSS RS. Prognostic significance of coronary arteriography. Trans Assoc Am Physicians. 1970;83:78-92. 310
RM,
29. N A T I O N A L C O O P E R A T I V E S T U D Y Q R O U P T O C O M P A R E M E D I C A L A N D
August 1979 • Annals of Internal Medicine • Volume 91 • Number 2
Downloaded from https://annals.org by Tulane University user on 01/12/2019
MA, V I L L A M A Y O R
ZUFFARDI E. Natural history of unstable angina with medical or surgical therapy. Chest. 1976;70:596-605.
2. R E E V E S TJ, O B E R M A N A, J O N E S WB, S H E F F I E L D LT. Natural history
SURGICAL THERAPY. Unstable Angina Pectoris: II. In-Hospital experi-
ence and initial follow-up results in patients with one, two and three vessel disease. Am J Cardiol. 1978;42:839-48.
domized study of patients treated medically and surgically. Am J Cardiol 1978;41:1291-8.
30. S E L D E N R, N E I L L WA, R I T Z M A N N LW, O K I E S JE, A N D E R S O N R P .
32. BORER JS, K E N T K M , B A C H A R A C H SL, E T AL. Sensitivity, specificity
Medical versus surgical therapy for acute coronary insufficiency: a randomized study. N Engl J Med. 1975;293:1329-33. 31. P U G H B, P L A T T MR, M I L L S LJ, et al. Unstable angina pectoris: a ran-
and predictive accuracy of radionuclide cineangiography during exercise in patients with coronary artery disease: comparison with exercise electrocardiography. Circulation. 1979;60. In press.
Editorial Notes
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311
manifest a homogenous "natural history." Subgroups of patients can be identified with more ominous prognoses, thereby raising the possibility that such subgroups might
August 1979 • Annals of Internal Medicine • Volume 91 • Number 2
Downloaded from https://annals.org by Tulane University user on 01/12/2019
benefit from prophylactic surgery. Although many factors predisposing to higher mortality have been implicated, the most powerful seem to be the functional status of the left ventricle and the number of vessels critically narrowed (1-4). Patients with left main coronary artery narrowing have a particularly poor prognosis (5-8), and in several studies patients with unstable angina also have been shown to be at increased risk (9-11). Based on these perceptions, recommendations have been made at one time or another to operate prophylactically on all patients with double- or triple-vessel coronary disease, unstable angina, or significant narrowing of the left main coronary artery. Emphasis on the word prophylactic is critical, because there is currently no debate about the wisdom of proceeding with surgery in a subject who remains severely symptomatic despite medical treatment. The vital question and great dilemma is "Should the subject with stable symptoms that are adequately controlled medically, or the subject with unstable angina who has not yet had adequate medical trial, be operated on forthwith to enhance survival?" Unfortunately, the answer to this question is still shrouded in controversy. Patients with Stable Symptoms
There are vigorous proponents of the concept that all patients with coronary artery disease who have significant narrowing of two or three vessels require operation to prolong life regardless of symptomatic status (12-16). These conclusions derive largely from comparing the long-term survival of patients operated on with either the survival of patients not operated on who were identified and treated in the 1960s and early 1970s or with the survival of nonrandomized, but computer-matched, patients. Many of the patients in these nonoperative series were severely symptomatic. However, the coronary patient with mild symptoms (17) or with good left ventricular function (17-19), identified and treated in the mid1970s, has recently been recognized to have a consistently better prognosis than that anticipated from the older natural history studies (1, 20-23) with which the operative results have been compared. The favorable natural history data of the mildly symptomatic patient (17) or the patient with good left ventricular function (17-19) seriously weakens the case for prophylactic operation, because survival in such patients treated medically, even in the presence of two- or three-vessel disease, is as good as the survival of patients who had operations (17). This concept is also supported by the data of three prospectively conducted randomized studies comparing the effects of operative-versus-medical therapy on survival, in which it was shown that operation does not prolong survival in patients with stable coronary disease (24-26) except in those patients with left main disease (5). Thus, given existing data, deferring operation in the patient with stable symptoms that are well-controlled on medical therapy is reasonable, even if two- or three-vessel disease is present. Although many authorities would disagree with this statement, few would dispute the concept that coronarybypass operation is indicated for all symptomatic patients
with left main disease (although the fact that such patients do not constitute a homogenous group and operation does not unequivocally improve survival in all subgroups must be recognized [5, 6]). Because patients with left main disease and stable symptoms constitute about 10% of mildly symptomatic patients with coronary disease (17) and comprise a group in which operative therapy seems warranted, the question arises as to whether they can be reliably identified by means short of coronary angiography (17). Does a similar dilemma relate to the patient with unstable angina, the subject of the article by Dr. Plotnick and his co-workers, that appears on pages 149-153 in this issue (27)? Patients with Unstable Angina
Is detecting left main stenosis in patients with unstable angina imperative, or does the mere presence of unstable angina identify a subgroup at high risk of imminent death that necessitates operation regardless of coronary anatomy? Early studies suggested a rather high mortality in such patients (9-11, 28). In addition, the results of one study strongly suggested that coronary-bypass surgery enhances survival in patients with one type of unstable angina, that characterized by prolonged and intense bouts of chest pain unrelated to exertion and refractory to nitrates (28). These patients have been classified as having the "intermediate syndrome." Although not entirely clear, other studies have apparently excluded this particular subgroup of patients with unstable angina from randomization, considering them medical failures and proceeding with operation. In all other types of patients classified as having unstable angina and operated on before hospital discharge, however, survival was not found to be increased by surgery. These results have been observed in several studies (28-31), including the National Cooperative Study of Unstable Angina (29) and the study showing enhanced survival after surgery in patients with the "intermediate syndrome" (28). Although many medically treated patients in the National Cooperative Study (29) eventually required operation because of recurrent severe symptoms, survival of patients was unaffected by delaying operation. Thus, because symptoms eventually are controlled medically in many patients, unnecessary surgery can be avoided if operation is deferred until it is determined which patient experiences symptoms not easily controlled on medication. These results appear to offer the physician a clear strategy of patient management: Treat the patient with unstable angina vigorously medically and proceed with catheterization and operation only if symptoms cannot be controlled satisfactorily. The potential flaw in this approach, however, is the fact that the results of the studies quoted above (with the exception of Reference 28, which showed that surgery increased survival in one clinical subgroup) excluded patients with left main coronary artery disease. Because the prevalence of left main coronary artery disease in patients with unstable angina is probably as high as 10% to 2 0 % , and because operation in patients with unstable angina and stenosis of the left main coronary Editorial
Downloaded from https://annals.org by Tulane University user on 01/12/2019
309
artery is likely to enhance survival, as it does in patients with stable angina pectoris (5), identifying such patients without undue delay is critical. The study by Dr. Plotnick and coworkers (27), although yielding negative results, provides the clinician with some important insights. It has shown that a multitude of potential noninvasive clinical indicators of left main coronary artery disease, including the baseline electrocardiogram, changes in the electrocardiogram, presence of congestive heart failure, characteristics of the anginal pain, presence or absence of arrhythmias, or identification of calcification in the area of the left main coronary artery on fluoroscopy, are of limited value in the detection of coronary artery disease because of low sensitivity, low predictive value, or both. The major deficiency of their study as it applies to more current diagnostic techniques, however, is the lack of data regarding the potential utility of exercise testing using electrocardiography, thalium scans, or radionuclide cineangiography in detecting left main disease. Preliminary studies in patients with stable coronary artery disease suggest that the radionuclide techniques will not be able to discriminate between patients with left main disease and those with multivessel coronary disease (32). There is some hope, however, that exercise electrocardiography can identify a subgroup of patients with a somewhat greater likelihood of having left main coronary disease than an unscreened population and that such testing probably will result in relatively few false-negative results (17). However, such studies have not yet been applied to patients with unstable angina. The negative results of Plotnick and associates (27), as well as their confirmation of the high prevalence of left main disease in a population of patients with unstable angina, underlines the importance of conducting further studies in patients with unstable angina to ascertain whether reliable noninvasive predictors of left main coronary disease can be developed. Until that time, the physician must act within the framework of existing studies that have shown, or strongly suggest, a high prevalence of left main disease in patients with unstable angina and a high likelihood that operation enhances survival in patients with left main disease. Although E G G exercise testing may offer a reasonable compromise as a screening test for determining which patients should have angiography (17), its precise reliability and utility in such patients are still unproved. At present, the only definitive way to rule out the possibility of significant narrowing of the left main coronary artery is coronary angiography. ( S T E P H E N E. E P S T E I N , M.D.; Cardiology
tional Heart, Lung, and Blood Institute, tutes of Health; Bethesda, Maryland)
Branch,
National
Na-
Insti-
4. BURGGRAF GW, PARKER JO. Prognosis in coronary artery disease: angiographic hemodynamic, and clinical factors. Circulation. 1975;51:14656. 5. T A K A R O T, H U L T G R E N N H , L I P T O N MJ, D E T R E K M , P A R T I C I P A N T S
IN THE STUDY G R O U P . The VA cooperative randomized study of surgery for coronary arterial occlusive disease: II. Subgroup with significant left main lesions. Circulation. 1976;54(Suppl 3): 107-17. 6. C A M P E A U L, CORBARA F, C R O C H E T D, P E T I T C L E R C R. Left main
coronary artery stenosis: the influence of aortocoronary bypass surgery on survival. Circulation. 1978;57:1111-5. 7. L I M JS, PROUDFIT WL, JONES FM J R . Left main coronary arterial obstruction: long-term follow-up of 141 nonsurgical cases. Am J Cardiol. 1957;36:131-5. 8. C O N L E Y MJ, E L Y RL, KISSLO J, L E E KL, M C N E E R J F , ROSATI RA.
The prognostic spectrum of left main stenosis. Circulation. 1978;57:94752. 9. KRAUSS KR, H U T T E R AM JR, DESANCTIS RW. Acute coronary insufficiency: course and follow-up. Circulation. 1972;45(Suppl 1):66-71. 10. G A Z E S PC, M O B L E Y EM J R , F A R I S HM J R , D U N C A N RC, H U M P H R I E S
GB. Preinfarctional (unstable) angina: a prospective study: ten year follow-up. Circulation. 1973;48:331-7. 11. LOPES MG, SPIVACK AP, H A R R I S O N DC, SCHROEDER JS. Prognosis of
non-infarction coronary care unit patients. Am J Cardiol. 1973:31:144. Abstract. 12. H U R S T JW, K I N G SB III, LOGUE RB, et al. Value of coronary bypass surgery. Controversies in cardiology: Part I. Am J Cardiol. 1978;42:30829. 13. PROUDFIT WL: Criticisms of the VA randomized study of coronary bypass surgery. Clin Res. 1978;26:236-40. 14. VISMARA LA, M I L L E R RR, P R I C E JE, K A R E M R, D E M A R I A AN, M A -
SON DT. Improved longevity due to reduction of sudden death by aortocoronary bypass in coronary atherosclerosis: prospective evaluation of medical versus surgical therapy in matched patients with multivessel disease. Am J Cardiol. 1977;39:919-24. 15. H A M M E R M E I S T E R K E , D E R O U E N TA, M U R R A Y JA, D O D G E JT. Effect
of aortocoronary saphenous vein bypass grafting on death and sudden death: comparison of nonrandomized medically and surgically treated cohorts with comparable coronary disease and left ventricular function. Am J Cardiol. 1977;39:925-34. 16. C O H N LH, BOYDEN CM, COLLINS JJ JR. Improved long-term survival after aortocoronary bypass for advanced coronary artery disease. Am J Surg. 1975;129:380-5. 17. E P S T E I N SE, K E N T KM, G O L D S T E I N RE, B O R E R JS, R O S I N G
DR.
Strategy for evaluation and surgical treatment of the asymptomatic or mildly symptomatic patient with coronary artery disease. Am J Cardiol. 1979;43:1015-25. 18. D E T R E K, M U R P H Y ML, H U L T G R E N H. Effect of coronary bypass surgery on longevity in high and low risk patients. Lancet. 1977;2:1243-5. 19. GROSS H, V A I D AK, COHEN MV. Prognosis in patients rejected for coronary revascularization surgery. Am J Med. 1978;64:9-20. 20. M C N E E R J F , S T A R M E R C F , B A R T E L AG, et al. The nature of treatment
selection in coronary artery disease: experience with medical and surgical treatment of a chronic disease. Circulation. 1974;49:606-14. 21. O B E R M A N A, H A R R E L L RR, R U S S E L L RO J R , K O U C H O U K A S
NT,
H O L T JH J R , RACKLEY CE. Surgical versus medical treatment in disease of the left main coronary artery. Lancet. 1976;2:591-4. 22. WEBSTER JS, MOBERG C, RINCON G. Natural history of severe proximal coronary artery disease as documented by coronary cineangiography. Am J Cardiol. 1974;33:195-200. 23. B R Y M E R J F , B U T E R T H , W A L T O N JA J R , W I L L I S PW III. A natural
history study of the prognostic role of coronary arteriography. Am Heart J. 1974;88:139-43. 24. M U R P H Y ML, H U L T G R E N N H , D E T R E K, T H O M S E N J, T A K A R O M, PARTICIPANTS OF T H E VA C O O P E R A T I V E STUDY. Treatment of chronic
stable angina: a preliminary report of survival data of the randomized Veterans Administration Cooperative Study. N Engl J Med. 1977;297:621-7. 25. M A T H U R VS, G U I N N GA. Long-term follow-up (4-7 years) of a prospective randomized study to evaluate surgical vs medial treatment for stable angina pectoris: clinical status, exercise performance and survival. Am J Cardiol. 1979;43:382. Abstract. 26. K L O S T E R
FE,
KREMKAU
EL,
RITZMANN
LW,
RAHMTOOLA
SH,
ROSCH J, K A N A R E K PH. Coronary bypass for stable angina: a prospective randomized study. NEnglJMed. 1979;300:149-57.
References 1. BRUNSCHKE AVG, P R O U D F I T WL, SONES J R FM. Progress study of
27. P L O T N I C K G D , G R E E N E HL, C A R L I N E R N H , B E C K E R LC, F I S H E R
590 consecutive nonsurgical cases of coronary disease followed 5-9 years: II. Ventriculographic and other correlations. Circulation. 1973;47:1154-63.
ML. Clinical indicators of left main coronary artery disease in unstable angina. Ann Intern Med. 1979;91:149-53. 28. BERTOLASI CA, T R O N G E JE, R I C C I T E L L I
of angina pectoris. Am J Cardiol. 1974;33:423-30. 3. FRIESINGER GC, PAGE EE, ROSS RS. Prognostic significance of coronary arteriography. Trans Assoc Am Physicians. 1970;83:78-92. 310
RM,
29. N A T I O N A L C O O P E R A T I V E S T U D Y Q R O U P T O C O M P A R E M E D I C A L A N D
August 1979 • Annals of Internal Medicine • Volume 91 • Number 2
Downloaded from https://annals.org by Tulane University user on 01/12/2019
MA, V I L L A M A Y O R
ZUFFARDI E. Natural history of unstable angina with medical or surgical therapy. Chest. 1976;70:596-605.
2. R E E V E S TJ, O B E R M A N A, J O N E S WB, S H E F F I E L D LT. Natural history
SURGICAL THERAPY. Unstable Angina Pectoris: II. In-Hospital experi-
ence and initial follow-up results in patients with one, two and three vessel disease. Am J Cardiol. 1978;42:839-48.
domized study of patients treated medically and surgically. Am J Cardiol 1978;41:1291-8.
30. S E L D E N R, N E I L L WA, R I T Z M A N N LW, O K I E S JE, A N D E R S O N R P .
32. BORER JS, K E N T K M , B A C H A R A C H SL, E T AL. Sensitivity, specificity
Medical versus surgical therapy for acute coronary insufficiency: a randomized study. N Engl J Med. 1975;293:1329-33. 31. P U G H B, P L A T T MR, M I L L S LJ, et al. Unstable angina pectoris: a ran-
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Editorial Notes
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