- Email: [email protected]
Coronary arteriography 1976—For whom?
Coronary Arteriography STEPHEN
J. GULOTTA,
1976-For
Whom?
MD, FACC
New York, New York
The introduction of selective coronary angiography by Sones and Shireyl has brought about major advances in the evaluation and treatment of coronary artery disease. Selective coronary arteriography can precisely define the extent and distribution of coronary disease in man during life. As a result of Sones’ contributions, interest in direct coronary revascularization was renewed so that now surgical management of coronary artery disease has become routine in many large medical centers. Despite 8 years of extensive clinical experience, the indications for operative intervention remain unclear in many clinical situations. A major difficulty is determining which subjects are in need of arteriographic study, for in order to make rational decisions both the natural history of coronary artery disease and the long-term effects of surgical treatment must be known. Current Patterns of Practice In our institution, selective coronary angiography is performed for a variety of indications. Angiographic studies are performed to (1) evaluate patients with angina pectoris being considered for surgery; (2) assess the results of saphenous vein bypass graft surgery; and (3) evaluate patients with chest pain of unknown origin. Surgical management of cornary artery disease is commonly accepted practice in patients with (1)severe angina pectoris unresponsive to optimal medical management who have adequate distal runoff and reasonably good left ventricular function; and (2) severe left main coronary disease with 75 percent or greater narrowing of luminal diameter. However, indications for surgical management of patients with several other clinical conditions is less clear. This group includes (1) patients with preinfarction angina; (2) patients with nondisabling stable angina; (3) patients who, after their first or second myocardial infarction, are asymptomatic; and (4) asymptomatic patients who have had one or two angina1 episodes in the past. Although others, such as Pichard,smight take a more aggressive stance and recommend coronary angiography for all patients suspected of having coronary artery disease regardless of their symptoms, we now take exception to this approach because it presupposes that From the Department of Medicine, Division of Cardiology, North Shore University Hospital, Manhasset, N. Y. and the Department of Medicine, Cornell University Medical College, New York, N. Y. Address for reprints: Stephen J. Gulotta, MD, Division of Cardiology, North Shore University Hospital, Manhasset, N. Y. 11030.
there have been definitive studies clearly demonstrating that surgical therapy prevents myocardial infarction and promotes longevity. This is not yet the case. It is generally agreed by most cardiologists that coronary bypass surgery relieves or abolishes angina1 symptoms in 80 to 90 percent of patients. Results of longer follow-up studies from many centers suggest that 75 percent of survivors remain improved symptomatically even 4 years after surgery.3 Objective as well as subjective improvement has been noted as evidenced by increased exercise tolerance and improved hemodynamic status, both of which correlate well with graft patency.4y5 Thus, there is little question concerning the immediate value of coronary surgery. What effect coronary surgery will have on the survival of the patient with coronary artery disease remains to be seen. Several surgical groups have now reported prolonged survival for surgically treated patients by comparison with medically treated patients.6,7 However, most surgical studies are retrospective, fail to define subgroups and lack randomization. Nevertheless, some cumulative surgical experience suggests that survival is in fact prolonged and that symptoms are significantly relieved in selected subsets of patients. One such set is composed of patients with severe occlusion of the left main coronary artery. The outlook for these patients is grim when they are treated medicallys,g; surgical intervention has improved both survival rate and functional capacity-
9,lO
Another group of patients that might benefit from surgery are those with unstable or preinfarction angina. The variability in definitions and the lack of general agreement as to what constitutes preinfarction angina have made objective assessment of this group extremely difficult. Thus, reported mortality rates for such patients range from 3 to 40 percent.il The marked disparity in these figures is obviously due to differences in the rigor with which the preinfarction state is defined. Adherence to a rigid definition (severe chest pain at complete bed rest, transient reversible S-T segment depression of 2 mm or more occurring with pain and no electrocardiographic or enzyme evidence for acute myocardial infarction) permitted identification of a subset of patients truly at high risk for myocardial infarction.12 Emergency surgical therapy performed immediately after angiographic evaluation decreased the rate of infarction and improved survival rate. Conti et al.,l’ reporting on a similar group of patients, found no significant difference in morbidity and mortality be-
October 1976
The Amerkan
Journal of CARDIOLOGY
Volume 36
537
EDITORIALS
tween the surgically and medically treated groups. A more detailed study of this unstable group of patients is clearly needed. Goals and Future Directions The overwhelming consensus is that most patients with severe angina unresponsive to optimal medical management improve symptomatically after coronary bypass surgery. That the operation improves the quality of life in these patients is incontrovertible and, since it is clear that surgery does not shorten survival time, operative intervention will be the mainstay of therapy in this group and justifiably so. But what about the clinical situations previously alluded to? Should all patients with known or suspected coronary artery disease undergo coronary angiography? Does a single episode of angina pectoris dictate the need for coronary angiography? Serial angiographic studies performed in all patients with suspected coronary artery disease would unquestionably provide objective data on the natural history and progression of coronary atherosclerosis, but such a procedure is certainly not warranted. At least not until or unless prospective studies demonstrate unequivocally that coronary bypass surgery prevents myocardial infarction and increases long-term survival. Until then, we as clinicians should strive to identify patients at high risk of having an acute myocardial infarction or death. Patients with severe angina at rest or on minimal exertion associated with inordinate prolonged shortness of breath may have left main coronary disease or severe multivessel diseases,13 and should be studied. Similarly, patients satisfying the criteria cited for preinfarctian angina should undergo coronary angiographic evaluation. Other patients at high risk can be identified with noninvasive techniques. A readily available and widely used tool is the postexercise electrocardiogram, which provides information not available from coronary angiography alone. The various exercise tests, which are easily performed and relatively free of risk, attempt to test the physiologic adequacy of the myocardial blood supply. They are by no means capable of ferreting out all patients with coronary artery disease from the normal population but, when performed carefully and interpreted properly (so important!), they do identify patients who are at high risk of having a major coronary event. Several studies14l6 have shown a good correlation between the number of angiographically demonstrable diseased coronary vessels and the frequency and degree of abnormality in the postexercise electrocardiogram. Thus, 95 percent of patients with S-T segment depression of 2 mm or more had two or three had vessel coronary artery disease, and 72 percent had three vessel disease.14 Robb and Seltzer17 recently reviewed the results of the Master double two-step test administered to 3,325 male applicants for life insurance who were then followed up for an average of 9 years. They found that the degree of ischemic S-T segment depression was related to the severity of coronary artery disease and ultimately to prognosis. Thus, the mortality rate in their grade III
538
October 1976
The American Journal of CARDIOLOGY
cases (2 mm or more depression) was 6 times greater than in grade I cases (less than 1 mm depression). The observation that a severe degree of S-T depression indicates the presence of severe triple vessel diseasei4Je and a poor prognosis17 lends a quantitative capability to the exercise electrocardiogram and identifies the high risk patient. Another promising area of investigation utilizes radionucleotides in assessing the adequacy of myocardial blood flow. Along with potassium-43, cesium-129 and rubidium-81, thallium-201 is an intracellular monovalent cation that concentrates in normal myocardium in direct proportion to the coronary blood flow. Although still in the early stages of evaluation, thallium-201 appears to have the best biologic and physical characteristics of this group of isotopes. With the new high resolution gamma scintillation cameras now available, measurement of myocardial ischemia by thallium-201 imaging has become feasible. With this technique areas of ischemia or infarction appear as zones of decreased tracer uptake, that is, perfusion defects. Since physiologic studies have demonstrated that normal resting flow can occur in coronary arteries with 50 to 70 percent narrowing of the luminal diameter, it should not be surprising that myocardial perfusion images obtained at rest in this setting might well be normal.ls However, scans performed during the stress of exercise will readily identify these patients. Areas of myocardium supplied by a critically narrowed artery cannot experience a significant increase in the coronary blood flow during exercise and will therefore show up as a perfusion defect. The larger the defect the greater the area of ischemia. Zaret et al.,lg using potassium-43, have suggested that a perfusion defect noted both at rest and during exercise is indicative of myocardial scarring, whereas an abnormal scan noted only during exercise is due to transient myocardial ischemia. A normal myocardial perfusion scan during stress rules out a hemodynamically significant coronary lesion with a high degree of certainty. In our present state of knowledge, angiographic evaluation of presumed patients at low risk is not justified. However, an urgent need exists for reliable data regarding the effects of coronary artery bypass surgery in patients with ischemic heart disease at high risk of having a major coronary event. Patients in this category should be evaluated hemodynamically and angiographically, placed in several sharply defined clinical subsets and entered into a randomized prospective study comparing short- and long-term results of coronary bypass surgery with those of medical management. For such data to be meaningful the severity of the disease must be precisely defined anatomically and physiologically. The subsequent clinical course and the surgical and medical management must be meticulously defined. The data derived from patients managed operatively must be compared with the clinical course of similar patients characterized in the same fashion but treated medically. Information derived from this type of study will enable us to make individual recommendations for therapy on a more rational basis.
Volume 38
EDITORIALS
References 1. Sones FM, Shirey EK: Cine coronary arteriography. Mod Concepts Cardiovase Dis 31:735-736, 1962 2. Pichard AD: Coronary atteriography for everyone? Am J Cardiol 38:533-535, 1976 3. Alderman EL, Matlof JH, Wexler L, el al: Results of direct coronary artery surgery for the treatment of angina pectoris. N Engl J Med 288:535-539, 1973 4. Sheldon WC, Rincon G, Plchard AD, el al: Surgical treatment of coronary artery disease: pure graft operations with a study of 741 patients followed 3-7 years. Prog Cardiovasc Dis 16:237-253, 1975 5. Siegel W, Lim J, Proudflt WL, et al: The spectrum of exercise test and angiographic correlation in myocardial revascularization surgery. Circulation 51:Suppl l:l-156-l-161, 1975 6. Anderson RP, Rahlmtoola SH, Bonchek LI, et al: The prognosis of patients with coronary artery disease after coronary bypass operations. Circulation 501274-282, 1974 7. Spencer FC, lsom OW, Glassman E, el al: The long term influence of coronary bypass grafts on myocardial infarction and survival. Ann Surg 160:439-451, 1974 6. Cohen MV, Cohn PF, Herman MV, et al: Diagnosis and prognosis of main left coronary artery obstruction. Circulation 45:Suppl I:I57-l-65, 1972 9. DeMots H, Bonchek Ll, Rosch J, et al: Left main coronary disease. Risks of angiography, importance of coexisting disease of other coronary arteries and effects of revascularization. Am J Cardiol 36:136-141, 1975 10. McConahay DR, Klllen DA, McCallister BD, et al: Coronary artery bypass surgery for left main coronary artery disease. Am J Cardiol
37:885-889.1976 11. Contl RC, Brawley RK, Griffith LS, et al: Unstable angina pectoris: morbidity and mortality in 57 consecutive patients evaluated angiographically. Am J Cardiol 32:745-750, 1973 12. Berk G, Kaplitt M, Padmanabhan V, et al: Management of preinfarction angina. J Thorac Cardiovasc Surg 71: 110-l 17, 1976 13. Lavlne R, Klmblrls D, Segal BL, et al: Left main coronary artery disease. Am J Cardiol 30:791-796, 1972 14. Most MS, Kemp HG, Gorlin R: Postexercise electrocardiography in patients with arteriographically documented coronary artery disease. Ann Intern Med 71:1043-1049, 1969 15. Mason RE, Likar I, Biern RO, et al: Multiple lead electrocardiography. Experience in 107 normal subjects and 67 patients with angina pectoris and comparison with coronary angiography in 64 patients. Circulation 36:517-525, 1967 16. Cohen LS, Elliot WC, Klein MD, et al: Coronary heart disease. Clinical, cinearteriographic and metabolic correlations. Am J Cardiol 17:153-166, 1966 17. Robb GP, Seltzer F: Appraisal of the double twc-step exercise test. A long term follow-up study of 3,325 men. JAMA 234:722-727, 1975 16. Pitt B, Strauss HW: Myocardial imaging in the noninvasive evaluation of patients with suspected ischemic heart disease. Am J Cardiol 37:797-606, 1976 19. Zaret BL, Martin ND, Flamm MD: Myocardial imaging for the non-invasive evaluation of regional perfusion at rest and after exercise. In. Cardiovascular Nuclear Medicine (Strauss HW, Pitt B, James AE, ed). St Louis, CV Mosby, 1974, p 161-210
October 1976
The American Journal of CARDIOLOGY
Volume 39
539
J. GULOTTA,
1976-For
Whom?
MD, FACC
New York, New York
The introduction of selective coronary angiography by Sones and Shireyl has brought about major advances in the evaluation and treatment of coronary artery disease. Selective coronary arteriography can precisely define the extent and distribution of coronary disease in man during life. As a result of Sones’ contributions, interest in direct coronary revascularization was renewed so that now surgical management of coronary artery disease has become routine in many large medical centers. Despite 8 years of extensive clinical experience, the indications for operative intervention remain unclear in many clinical situations. A major difficulty is determining which subjects are in need of arteriographic study, for in order to make rational decisions both the natural history of coronary artery disease and the long-term effects of surgical treatment must be known. Current Patterns of Practice In our institution, selective coronary angiography is performed for a variety of indications. Angiographic studies are performed to (1) evaluate patients with angina pectoris being considered for surgery; (2) assess the results of saphenous vein bypass graft surgery; and (3) evaluate patients with chest pain of unknown origin. Surgical management of cornary artery disease is commonly accepted practice in patients with (1)severe angina pectoris unresponsive to optimal medical management who have adequate distal runoff and reasonably good left ventricular function; and (2) severe left main coronary disease with 75 percent or greater narrowing of luminal diameter. However, indications for surgical management of patients with several other clinical conditions is less clear. This group includes (1) patients with preinfarction angina; (2) patients with nondisabling stable angina; (3) patients who, after their first or second myocardial infarction, are asymptomatic; and (4) asymptomatic patients who have had one or two angina1 episodes in the past. Although others, such as Pichard,smight take a more aggressive stance and recommend coronary angiography for all patients suspected of having coronary artery disease regardless of their symptoms, we now take exception to this approach because it presupposes that From the Department of Medicine, Division of Cardiology, North Shore University Hospital, Manhasset, N. Y. and the Department of Medicine, Cornell University Medical College, New York, N. Y. Address for reprints: Stephen J. Gulotta, MD, Division of Cardiology, North Shore University Hospital, Manhasset, N. Y. 11030.
there have been definitive studies clearly demonstrating that surgical therapy prevents myocardial infarction and promotes longevity. This is not yet the case. It is generally agreed by most cardiologists that coronary bypass surgery relieves or abolishes angina1 symptoms in 80 to 90 percent of patients. Results of longer follow-up studies from many centers suggest that 75 percent of survivors remain improved symptomatically even 4 years after surgery.3 Objective as well as subjective improvement has been noted as evidenced by increased exercise tolerance and improved hemodynamic status, both of which correlate well with graft patency.4y5 Thus, there is little question concerning the immediate value of coronary surgery. What effect coronary surgery will have on the survival of the patient with coronary artery disease remains to be seen. Several surgical groups have now reported prolonged survival for surgically treated patients by comparison with medically treated patients.6,7 However, most surgical studies are retrospective, fail to define subgroups and lack randomization. Nevertheless, some cumulative surgical experience suggests that survival is in fact prolonged and that symptoms are significantly relieved in selected subsets of patients. One such set is composed of patients with severe occlusion of the left main coronary artery. The outlook for these patients is grim when they are treated medicallys,g; surgical intervention has improved both survival rate and functional capacity-
9,lO
Another group of patients that might benefit from surgery are those with unstable or preinfarction angina. The variability in definitions and the lack of general agreement as to what constitutes preinfarction angina have made objective assessment of this group extremely difficult. Thus, reported mortality rates for such patients range from 3 to 40 percent.il The marked disparity in these figures is obviously due to differences in the rigor with which the preinfarction state is defined. Adherence to a rigid definition (severe chest pain at complete bed rest, transient reversible S-T segment depression of 2 mm or more occurring with pain and no electrocardiographic or enzyme evidence for acute myocardial infarction) permitted identification of a subset of patients truly at high risk for myocardial infarction.12 Emergency surgical therapy performed immediately after angiographic evaluation decreased the rate of infarction and improved survival rate. Conti et al.,l’ reporting on a similar group of patients, found no significant difference in morbidity and mortality be-
October 1976
The Amerkan
Journal of CARDIOLOGY
Volume 36
537
EDITORIALS
tween the surgically and medically treated groups. A more detailed study of this unstable group of patients is clearly needed. Goals and Future Directions The overwhelming consensus is that most patients with severe angina unresponsive to optimal medical management improve symptomatically after coronary bypass surgery. That the operation improves the quality of life in these patients is incontrovertible and, since it is clear that surgery does not shorten survival time, operative intervention will be the mainstay of therapy in this group and justifiably so. But what about the clinical situations previously alluded to? Should all patients with known or suspected coronary artery disease undergo coronary angiography? Does a single episode of angina pectoris dictate the need for coronary angiography? Serial angiographic studies performed in all patients with suspected coronary artery disease would unquestionably provide objective data on the natural history and progression of coronary atherosclerosis, but such a procedure is certainly not warranted. At least not until or unless prospective studies demonstrate unequivocally that coronary bypass surgery prevents myocardial infarction and increases long-term survival. Until then, we as clinicians should strive to identify patients at high risk of having an acute myocardial infarction or death. Patients with severe angina at rest or on minimal exertion associated with inordinate prolonged shortness of breath may have left main coronary disease or severe multivessel diseases,13 and should be studied. Similarly, patients satisfying the criteria cited for preinfarctian angina should undergo coronary angiographic evaluation. Other patients at high risk can be identified with noninvasive techniques. A readily available and widely used tool is the postexercise electrocardiogram, which provides information not available from coronary angiography alone. The various exercise tests, which are easily performed and relatively free of risk, attempt to test the physiologic adequacy of the myocardial blood supply. They are by no means capable of ferreting out all patients with coronary artery disease from the normal population but, when performed carefully and interpreted properly (so important!), they do identify patients who are at high risk of having a major coronary event. Several studies14l6 have shown a good correlation between the number of angiographically demonstrable diseased coronary vessels and the frequency and degree of abnormality in the postexercise electrocardiogram. Thus, 95 percent of patients with S-T segment depression of 2 mm or more had two or three had vessel coronary artery disease, and 72 percent had three vessel disease.14 Robb and Seltzer17 recently reviewed the results of the Master double two-step test administered to 3,325 male applicants for life insurance who were then followed up for an average of 9 years. They found that the degree of ischemic S-T segment depression was related to the severity of coronary artery disease and ultimately to prognosis. Thus, the mortality rate in their grade III
538
October 1976
The American Journal of CARDIOLOGY
cases (2 mm or more depression) was 6 times greater than in grade I cases (less than 1 mm depression). The observation that a severe degree of S-T depression indicates the presence of severe triple vessel diseasei4Je and a poor prognosis17 lends a quantitative capability to the exercise electrocardiogram and identifies the high risk patient. Another promising area of investigation utilizes radionucleotides in assessing the adequacy of myocardial blood flow. Along with potassium-43, cesium-129 and rubidium-81, thallium-201 is an intracellular monovalent cation that concentrates in normal myocardium in direct proportion to the coronary blood flow. Although still in the early stages of evaluation, thallium-201 appears to have the best biologic and physical characteristics of this group of isotopes. With the new high resolution gamma scintillation cameras now available, measurement of myocardial ischemia by thallium-201 imaging has become feasible. With this technique areas of ischemia or infarction appear as zones of decreased tracer uptake, that is, perfusion defects. Since physiologic studies have demonstrated that normal resting flow can occur in coronary arteries with 50 to 70 percent narrowing of the luminal diameter, it should not be surprising that myocardial perfusion images obtained at rest in this setting might well be normal.ls However, scans performed during the stress of exercise will readily identify these patients. Areas of myocardium supplied by a critically narrowed artery cannot experience a significant increase in the coronary blood flow during exercise and will therefore show up as a perfusion defect. The larger the defect the greater the area of ischemia. Zaret et al.,lg using potassium-43, have suggested that a perfusion defect noted both at rest and during exercise is indicative of myocardial scarring, whereas an abnormal scan noted only during exercise is due to transient myocardial ischemia. A normal myocardial perfusion scan during stress rules out a hemodynamically significant coronary lesion with a high degree of certainty. In our present state of knowledge, angiographic evaluation of presumed patients at low risk is not justified. However, an urgent need exists for reliable data regarding the effects of coronary artery bypass surgery in patients with ischemic heart disease at high risk of having a major coronary event. Patients in this category should be evaluated hemodynamically and angiographically, placed in several sharply defined clinical subsets and entered into a randomized prospective study comparing short- and long-term results of coronary bypass surgery with those of medical management. For such data to be meaningful the severity of the disease must be precisely defined anatomically and physiologically. The subsequent clinical course and the surgical and medical management must be meticulously defined. The data derived from patients managed operatively must be compared with the clinical course of similar patients characterized in the same fashion but treated medically. Information derived from this type of study will enable us to make individual recommendations for therapy on a more rational basis.
Volume 38
EDITORIALS
References 1. Sones FM, Shirey EK: Cine coronary arteriography. Mod Concepts Cardiovase Dis 31:735-736, 1962 2. Pichard AD: Coronary atteriography for everyone? Am J Cardiol 38:533-535, 1976 3. Alderman EL, Matlof JH, Wexler L, el al: Results of direct coronary artery surgery for the treatment of angina pectoris. N Engl J Med 288:535-539, 1973 4. Sheldon WC, Rincon G, Plchard AD, el al: Surgical treatment of coronary artery disease: pure graft operations with a study of 741 patients followed 3-7 years. Prog Cardiovasc Dis 16:237-253, 1975 5. Siegel W, Lim J, Proudflt WL, et al: The spectrum of exercise test and angiographic correlation in myocardial revascularization surgery. Circulation 51:Suppl l:l-156-l-161, 1975 6. Anderson RP, Rahlmtoola SH, Bonchek LI, et al: The prognosis of patients with coronary artery disease after coronary bypass operations. Circulation 501274-282, 1974 7. Spencer FC, lsom OW, Glassman E, el al: The long term influence of coronary bypass grafts on myocardial infarction and survival. Ann Surg 160:439-451, 1974 6. Cohen MV, Cohn PF, Herman MV, et al: Diagnosis and prognosis of main left coronary artery obstruction. Circulation 45:Suppl I:I57-l-65, 1972 9. DeMots H, Bonchek Ll, Rosch J, et al: Left main coronary disease. Risks of angiography, importance of coexisting disease of other coronary arteries and effects of revascularization. Am J Cardiol 36:136-141, 1975 10. McConahay DR, Klllen DA, McCallister BD, et al: Coronary artery bypass surgery for left main coronary artery disease. Am J Cardiol
37:885-889.1976 11. Contl RC, Brawley RK, Griffith LS, et al: Unstable angina pectoris: morbidity and mortality in 57 consecutive patients evaluated angiographically. Am J Cardiol 32:745-750, 1973 12. Berk G, Kaplitt M, Padmanabhan V, et al: Management of preinfarction angina. J Thorac Cardiovasc Surg 71: 110-l 17, 1976 13. Lavlne R, Klmblrls D, Segal BL, et al: Left main coronary artery disease. Am J Cardiol 30:791-796, 1972 14. Most MS, Kemp HG, Gorlin R: Postexercise electrocardiography in patients with arteriographically documented coronary artery disease. Ann Intern Med 71:1043-1049, 1969 15. Mason RE, Likar I, Biern RO, et al: Multiple lead electrocardiography. Experience in 107 normal subjects and 67 patients with angina pectoris and comparison with coronary angiography in 64 patients. Circulation 36:517-525, 1967 16. Cohen LS, Elliot WC, Klein MD, et al: Coronary heart disease. Clinical, cinearteriographic and metabolic correlations. Am J Cardiol 17:153-166, 1966 17. Robb GP, Seltzer F: Appraisal of the double twc-step exercise test. A long term follow-up study of 3,325 men. JAMA 234:722-727, 1975 16. Pitt B, Strauss HW: Myocardial imaging in the noninvasive evaluation of patients with suspected ischemic heart disease. Am J Cardiol 37:797-606, 1976 19. Zaret BL, Martin ND, Flamm MD: Myocardial imaging for the non-invasive evaluation of regional perfusion at rest and after exercise. In. Cardiovascular Nuclear Medicine (Strauss HW, Pitt B, James AE, ed). St Louis, CV Mosby, 1974, p 161-210
October 1976
The American Journal of CARDIOLOGY
Volume 39
539