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Ischemic cardiomyopathy: Medical versus surgical treatment
Ischemic cardiomyopathy: Medical versus surgical treatment The natural history of patients with ischemic heart disease and depressed left ventricular function is dismal, and medical therapy has failed to alter its course. To assess the results of aorta-coronary bypass grafting in patients with coronary artery disease and decreased left ventricular ejection fraction (LVEF ~ 0.3), we compared 70 medically treated patients to 46 patients having aorta-coronary bypass grafting. The duration offollow-up was 6 to 72 months (mean 19 months). All patients had angina pectoris. Congestive heart failure was present in 56 percent (39/70) of the medical and 43 percent (20/46) of the surgical group. The medical group had a mean LVEF of 0.20 and a mean left ventricular end-diastolic pressure (LVEDP) of 29 mm. Hg. The surgical group had a mean LVEF of 0.21 and a mean LVEDP of 24 mm. Hg. Three vessel disease was found in 60 percent (42/70) of the medical group and 83 percent (38/46) of the surgical group. The operative mortality rate in the surgical group was 4 percent (2/46). There werefour late deaths. The 2 year actuarial survival rate for medical and surgical groups was 47 percent and 83 percent, respectively. Significant improvement in angina pectoris and/or congestive heart failure was found in 16 percent (11/70) of medically treated patients and 95 percent (38/40) of the surgically treated patients. Aorta-coronary bypass grafting can be performed in patients with poor left ventricular function with a low operative mortality rate, relief of angina pectoris, and improvement in symptoms of congestive heart failure.
Scott L. Faulkner, William S. Stoney, William C. Alford, Clarence S. Thomas, George R. Burrus, Robert A. Frist, and Harry L. Page, Nashville, Tenn.
T he natural history of patients with symptomatic
coronary artery disease and depressed left ventricular function (ischemic cardiomyopathy) is dismal, and medical treatment has uniformly failed to alter significantly its course. 1 Bruschke and associates" reported that only 12 percent of patients with three vessel coronary artery disease and poor left ventricular function secondary to diffuse scarring were alive 5 years after their initial cardiac catheterization. Excellent relief of symptoms of ischemic heart disease by aorta-coronary bypass grafting is now accomplished with a low operative mortality rate. 3- 5 The primary determinants of the mortality rate relate to left ventricular function.v" In patients with poor left ventricular function, operative mortality rates as high as 55 percent have been reported. 8 In addition, relief of angina pectoris and symptoms of heart failure in this From the Department of Cardiac and Thoracic Surgery, Vanderbilt University Hospital, and St. Thomas Hospital, Nashville, Tenn. Received for publication Jan. 3, 1977. Accepted for publication March 21, 1977. Address for reprints: W. S. Stoney, M.D., St. Thomas Medical Building, Nashville, Tenn. 37205.
subset of patients have not been documented following a variety of operative procedures. Recently aorta-coronary bypass grafting, either alone or in combination with ventricular aneurysmectomy, left ventricular plication, or mitral valve replacement, has been performed with operative mortality rates of 7 to 15 percent.P' P However, a recent study comparing operative versus nonoperative management of patients with ischemic cardiomyopathy failed to demonstrate an advantage of either form of therapy with respect to either relief of symptoms or survival. 13 It is the purpose of this report to evaluate the efficacy of aorta-coronary bypass grafting in the natural history of ischemic cardiomyopathy. Methods
We reviewed the results of cardiac catheterization of 5,500 patients evaluated for coronary artery disease at St. Thomas Hospital during the period from January, 1969, to December, 1975. All patients found to have obstructive coronary artery disease (at least 70 percent narrowing of one coronary artery) and decreased left ventricular function (ejection fraction :5 0.30) were further reviewed with respect to symptoms, past medi77
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Table I. Clinical comparison of patients with ischemic cardiomyopathy treated medically and operatively
No. of patients Age (yr.) Sex ratio (M: F) Previous myocardial infarctions None One Two or more LVEDP (mm. Hg) Mean Ejection fraction (%) Mean (%) Follow-up period (mo.) Mean
Medical
Operative
70 31-74 (56) 58: 12
46 42-76 (50) 40:06
4 (6%)* 43 (61%) 18 (26%) 8-49 29 1-30 20 1-49 14
10 (22%) 14 (30%) 22 (48%) 6-50 24 2-30
2T
1-72
19
Legend: LVEDP. Left ventricular end-diastolic pressure.
*Based on 65 patients on whom documentation was available.
Table II. Distribution of symptoms and extent of disease in 116 patients with ischemic cardiomyopathy Operative _ _ _ _I-N-:ed-&j-% No.
~
Symptoms Angina Congestive failure Angina + failure Primarily angina Primarily failure
24 II
34 16
26
57
28 7
40 10
19 I
41 2
6 22 42
9 31 60
3 5 38
6 II 83
Extent of disease Single vessel Double vessel Triple vessel
Table III. Results of medical and operative treatment in 116 patients with ischemic cardiomyopathy Medical
Patients Patients lost to follow-up Death Early Late Over-all survival Asymptomatic or improved Unimproved or dead 'Based on 44 patients with follow-up.
Operative
No.
I%
No.
70 0
0
46 2
4
7 33 30 II 59
10 47 43 16 84
2 4 38 36 8
4 9 83 82* 18*
I
%
cal history, and response to medical or operative treatment. Patients with left ventricular aneurysm or mitral insufficiency were excluded from this study. All cardiac catheterizations were performed by the percutaneous transfemoral route as previously described. 14 Left ventricular angiograms were performed in the right anterior oblique position and left ventricular ejection fractions calculated after the methods of Sandler and Dodge" and Chatterjee and associates.!" Left ventricular end-diastolic pressures were recorded before and after the injection of contrast material. Hospital records, interviews with attending physicians, and postoperative visits were utilized to evaluate these patients. A total of 116 patients satisfied the criteria for inclusion in this study. Patients were not randomized as to type of therapy. Each individual patient and his physician selected the mode of therapy. Some medically treated patients were not seen by the surgeons, and some patients treated medically were not felt to be operative candidates after surgical consultation. The actuarial survival rate in both groups is calculated according to the method of Cutler and Ederer Y
Medical group Seventy patients were treated with varying combinations of digitalis, diuretics, propranolol, long-acting nitrates, and nitroglycerin (Table I). There were 58 men and 12 women in this group with a mean age of 56 years (range 31 to 74). Eighty-seven percent of the patients had had at least one myocardial infarction documented by electrocardiographic and enzymatic changes; 18 patients (26 percent) had had two or more myocardial infarctions. Six patients manifested intraventricular conduction defects on the electrocardiograms. The symptoms and distribution of coronary arterial disease are summarized in Table II. Thirty-four percent of patients had angina pectoris alone, and 10 percent had congestive heart failure without angina pectoris. Sixty percent of patients had three vessel coronary disease. The mean left ventricular ejection fraction for the entire group was 0.20 (range 0.01 to 0.30), and the mean left ventricular end-diastolic pressure was 29 mm. Hg (range 8 to 49 mm. Hg, Table I). The mean duration of follow-up was 14 months (range 1 to 49 months).
Operative group Forty-six patients underwent aorta-coronary bypass grafting for relief of symptomatic angina pectoris (Table I). There were 40 men and 6 women in the group with a mean age of 56 years (range 42 to 76 years). Ten patients (22 percent) did not have previously
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documented myocardial infarction; however, 22 of 46 patients (48 percent) had had at lease two previous infarctions, and 14 patients (30 percent) had one previous infarction. Five patients had evidence of intraventricular conduction defects on the electrocardiogram. The symptoms and distribution of coronary artery disease are summarized in Table II. Fifty-seven percent had angina pectoris alone, and 43 percent were being treated for congestive heart failure in addition to having angina pectoris. Eighty-three percent of patients had three vessel coronary artery disease. For the group, the mean left ventricular ejection fraction was 0.21 (range 0.02 to 0.30), and the mean left ventricular enddiastolic pressure was 24 mm. Hg (range 6 to 50 mm. Hg) (Table I). The mean duration of follow-up was 19 months (range I to 72 months).
Results Medical group. Only 43 percent of patients were alive at the completion of the review (Table III). Seven patients died within 30 days of catheterization. Eleven patients (16 percent) were improved with respect to angina pectoris or symptoms of congestive heart failure. Short-lived or no improvement was found in the remaining patients. The 2 year actuarial survival rate was 47 percent (Fig. I). Operative group. Thirty-eight of 46 patients were known to be alive at the completion of the study; only two patients were lost to follow-up (Table III). The over-all survival rate in this group was 83 percent, and the 2 year actuarial survival rate was 77 percent. There were two deaths in the first 30 days postoperatively (4 percent). One patient was taken to the operating room
in cardiogenic shock and underwent triple bypass grafting plus endarterectomy of the left main coronary artery; he had a cardiac arrest in the recovery room and died 2 days later with a persistent low cardiac output. The second patient died on the ninth postoperative day following pulmonary embolectomy for a massive pulmonary embolus. There were four late deaths (9 percent) for an over-all mortality rate of 13 percent. Three patients died at home 2, 8, and 21 months postoperatively. The fourth patient died 2 months postoperatively from a ruptured abdominal aneurysm. There were no intraoperative myocardial infarctions as diagnosed by the appearance of new Q waves on electrocardiograms or elevation of cardiac enzyme values. Four patients (9 percent) required continuous infusion of inotropic agents at the termination of cardiopulmonary bypass, but only two of them required more than 18 hours of inotropic support (2 and 4 days). One patient sustained a myocardial infarction 3 years after the operation. Thirty-six (95 percent) of the survivors are asymptomatic or improved with respect to both angina and congestive heart failure.
Intraoperative management All preoperative medications were discontinued at least 8 hours prior to operation. Patients with severe three vessel or left main coronary artery disease were anesthetized after the arterial pressure monitoring lines had been placed under local anesthesia. Ketamine or morphine supplemented by small amounts of halothane were used during the procedure. Cardiopulmonary bypass with hemodilution prime was carried out at a body temperature of 30° C. with the use of a bubble
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oxygenator. The bypass flow was maintained at 2.2 L. per square meter. The mean arterial blood pressure was constantly monitored and maintained above 50 mm. Hg by increasing bypass flow or by pharmacologic means. The left ventricle was vented in each case through its apex. Distal saphenous veins or internal mammary arteries were used to bypass severe coronary arterial lesions if the area of myocardium supplied by the coronary artery did not appear to be predominately replaced by scar tissue. Distal coronary artery-vein graft anastomoses were performed with the aorta cross-clamped and after minimal dissection on the surface of the coronary artery. The anastomoses were constructed with 7-0 monofilament suture, 2 to 3.5 power optical magnification, and fiberoptic headlamp illumination. Ninety-five percent of anastomoses were performed with less than 15 minutes of ischemic arrest. Following completion of the proximal anastomoses, the heart was cardioverted with a single countershock if spontaneous sinus rhythm had not returned. The average bypass time was 110 minutes. After completion of the procedure, right ventricular and occasionally right atrial temporary pacing wires were placed. Discussion The combination of anatomic extent of obstructive lesions in the coronary arterial network and left ventricular functional abnormalities provides the best prognostic index of survival in patients with coronary artery disease. Although several natural history studies have demonstrated that patients with triple vessel disease have an over-all 5 year survival rate of only 37 to 53 percent;'- 2. 18 left ventricular dysfunction reduces this rate to 12 percent. In several series of patients undergoing coronary artery bypass, the strongest predicator of operative death was a decreased left ventricular ejection fraction. 9. 19 Operative mortality rates for patients undergoing aorta-coronary bypass grafting when the left ventricular ejection fraction is less than 30 percent range from 10 to 55 percent.P: 8, 10, 13 Over-all operative mortality rates for aorta-coronary bypass grafting range from less than 1 percent to 6.4 percent depending on the individual institutions and extent of disease.v? A variety of procedures have been utilized in the operative treatment of patients with severe and diffuse coronary artery disease and over-all poor left ventricular function. In addition to revascularization of the left ventricle, resection of aneurysms, plication and/or resection of infarcted tissue, and mitral valve replacement have also been performed in an attempt to improve the left ventricular dysfunction. Most series combine a variety of these procedures in treating pa-
The Journal of Thoracic and Cardiovascular Surgery
tients who have both angina pectoris and congestive heart failure in an effort to improve over-all survival and left ventricular function. With increasing technical skill, more complete revascularization, and preservation of viable myocardium, the number of deaths has decreased in this subset of patients from 31 to 55 percent" 8. 20 to 7 to 10 percent. 10, 12 Improvement in symptoms of angina pectoris occurs in 80 to 90 percent of survivors. 10. 12 In 1972, Burch and associates" used the term "ischemic cardiomyopathy" to describe the ventricular dysfunction resulting from diffuse fibrosis of left ventricular myocardium secondary to repeated episodes of ischemia. The natural history of ischemic cardiomyopathy recently has been reviewed by Yatteau and colleagues. 13 Their group of patients was described as having a generalized deficiency in left ventricular wall excursion, resulting in an ejection fraction not greater than 25 percent, and significant coronary artery disease. Patients with ventricular aneurysms and localized contraction abnormalities are excluded. Most of their patients had prior myocardial infarctions (95 percent) and angina pectoris (76 percent); 50 percent of these patients manifested congestive heart failure. The average left ventricular ejection fraction was 19 percent and the average left ventricular end-diastolic pressure was 21 mm. Hg. Seventy-one percent of these patients had triple vessel disease. The 2 year mortality rate of 42 medically treated patients was 38 percent. The results of operative treatment in patients with coronary artery disease and decreased left ventricular function should be critically examined by analyzing separately the patients undergoing aorta-coronary bypass grafting alone and those undergoing combined procedures. The mechanism of poor left ventricular function in patients with coronary artery disease alone is different than that in patients with coronary artery disease and ventricular aneurysms or mitral insufficiency. When examining the results of combined procedures (aorta-coronary bypass grafting plus mitral valve replacement or aneurysmectorny), we find that operative mortality rates range from 6.3 to 33 percent. 22,23 Several groups'": 23 have also noted late death in 16 to 38 percent of patients followed for 18 to 33 months. Thus it is difficult to compare our operative mortality rate of 4 percent and late death rate of 9 percent to previously published data. The only series that has utilized aorta-coronary bypass grafting alone in patients with poor left ventricular function is that of Yatteau and associates.P Their poor results with operative treatment of patients with ischemic cardiomyopathy (50 percent 2 year survival) are strongly influenced by a 33 percent operative mortality rate
Volume 74 Number 1 July, 1977
(eight of 24 patients). Whereas all patients in their series underwent operation from 1968 to 1972, 85 percent (39 of 46) of our patients underwent operation from 1972 through 1975. Increased technical skill as well as attempts to revascularize all areas of myocardium in jeopardy has undoubtedly resulted in increased survival. Whereas in 1971 Spencer and associates" reported that 60 percent of their patients had two bypass grafts and 40 percent had a single bypass graft, a report from the same institution 12 in 1975 showed 60 percent of patients receiving three or. more grafts. Procedures such as left ventricular plication, ventricular aneurysmectomy, and mitral valve replacement have been added to aortacoronary bypass grafting in these patients. Preservation of myocardial tissue and function during cardiopulmonary bypass are important in all patients with ischemic heart disease, but they are more so in patients with impaired function. Myocardial hypothermia, limitation of the time of ischemic arrest, adequate mean perfusion pressure during bypass, avoidance of prolonged ventricular fibrillation or distention, and avoidance of air in the coronary arteries all aid in preserving myocardial function. Strict attention to all these details has lowered the over-all operative mortality rates in patients with coronary artery disease to less than 2 percent. 3, 4 Long-term favorable clinical results of procedures to revascularize myocardial tissue are proportional to the amount of viable although ischemic muscle, the patency of grafts, and the completeness of the revascularization procedure. Increasing blood flow to fibrotic tissue is of no benefit. Thus patients with pure ischemic cardiomyopathy presenting solely as congestive heart failure are unlikely to be benefited by any procedure designed to increase blood flow. Symptoms of angina pectoris, on the other hand, present evidence of ischemic but potentially viable myocardial tissue. In addition, the mean length of survival is clearly prolonged. In those patients with ischemic cardiomyopathy without ventricular aneurysms and without mitral insufficiency, aorta-coronary bypass grafting results in prolonged survival (77 percent) compared to medical treatment (47 percent). In addition, the operation can be employed with a low operative mortality rate (4 percent), and symptoms of angina pectoris are relieved in 95 percent of survivors. REFERENCES Bruschke, A. V. G., Proudfit, W. L., and Jones, F. M., Jr.: Progress Study of 590 Consecutive Non-surgical Cases of Coronary Disease Followed by 5-9 Years. I. Arteriographic Correlations, Circulation 47: 1147, 1973.
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2 Bruschke, A. V. G., Proudfit, W. L., and Jones, F. M., Jr.: Progress Study of 590 Consecutive Non-surgical Cases of Coronary Disease Followed by 5-9 Years. II. Ventriculographic and Other Correlations, Circulation 47: 1154, 1973. 3 Sheldon, W. C., Rincon, G., Pichard, A. D., Razavi, M., Cheanvechai, C., and Loop, F. D.: Surgical Treatment of Coronary Artery Disease: Pure Graft Operations With a Study of 741 Patients Followed 3-7 Years, Prog. Cardiovasc. Dis. 18: 237, 1975. 4 Hutchinson, J. E., Green, G. E., Mekhjian, H. A., and Kemp, H. G.: Coronary Artery Bypass Grafting in 376 Consecutive Patients With Three Operative Deaths, 1. THoRAc. CARDIOVASC. SURG. 67: 7, 1974. 5 Mundth, E. D., and Austin, W. G.: Surgical Measures for Coronary Heart Disease, N. Engl. 1. Med. 293: 13, 1975. 6 Collins, 1. J., Jr., Cohn, C. H., Sonnenblick, E. H., Herman, M. V., Cohn, P. F., and Gorbin, R.: Determinants of Survival After Coronary Artery Bypass Surgery, Circulation 47, 48: 132, 1973 (Suppl. III). 7 Hammermeister, I. C. E., and Kennedy, 1. W.: Predictors of Surgical Mortality in Patients Undergoing Direct Myocardial Revascularization, Circulation 49, 50: 112, 1974 (Suppl. II). 8 Oldham, H. N., Kong, Y., Bartel, A. G., Morris, J. J., Jr., Behar, V. W., Peter, R. H., Rosati, R. A., Young, W. G., Jr., and Sabiston, D. c.. Jr.: Risk Factors in Coronary Artery Bypass Surgery, Arch. Surg. 105: 918, 1972. 9 Nelson, G. R., Cohn, P. F., and Gorlin, R.: Prognosis in Medically Treated Coronary Artery Disease: Influence of Ejection Fraction Compared to Other Parameters, Circulation 52: 408, 1975. 10 Mundth, E. D., Harthorne, J. W., Dinsmore, R., and Austen, W. G.: Direct Coronary Arterial Revascularization: Treatment of Cardiac Failure Associated With Coronary Artery Disease, Arch. Surg. 103: 529, 1971. II Mitchel, B. F., Jr., Alivizatos, P. A., Adam, M., Geisler, G. F., Thiele, J. P., and Lambert, C. J.: Myocardial Revascularization in Patients With Poor Left Ventricular Function, 1. THoRAc. CARDIOVASC. SURG. 69: 52, 1975. 12 Isom, O. W., Spencer, F. C., Glassman, E., Dembrow, 1. M., and Pasternack, B. S.: Long-term Survival Following Coronary Bypass Surgery in Patients With Significant Impairment of Left Ventricular Function, Circulation 51, 52: 141, 1975 (Suppl. I). 13 Yatteau, R. F., Peter, R. H., Behar, V. S., Bartel, A. G., Rosati, R. A., and Kong, Y.: Ischemic Cardiomyopathy: The Myopathy of Coronary Artery Disease, Am. J. Cardiol. 34: 520, 1974. 14 Page, H. L., and Campbell, W. B.: Percutaneous Transfemoral Coronary Arteriography: Prevention of Morbid Complications, Chest 67: 221, 1975. 15 Sandler, H., and Dodge, H. T.: The Use of Single Plane Angiocardiograms for the Calculation of Left Ventricular Volume in Man, Am. Heart J. 75: 325, 1968.
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16 Chatterjee, K., Savor, M., Sutton, G. c., and Miller, G. A. H.: Assessment of Left Ventricular Function by Single Plane Cineangiographic Volume Analysis, Br. Heart 1. 33: 565, 1971. 17 Cutler, S. 1., and Ederer, F.: Maximum Utilization of the Life-Table Method in Analyzing Survival, J. Chron. Dis. 8: 699, 1958. 18 Webster, J. S., Moberg, c., and Rincon, G.: Natural History of Severe Proximal Coronary Artery Disease as Documented by Coronary Cineangiography, Am. J. Cardiol. 33: 195, 1974. 19 Cohn, P. F., Godin, R., Cohn, L. H., and Collins, J. J., Jr.: Left Ventricular Ejection Fraction as a Prognostic Guide in Surgical Treatment of Coronary and Valvular Heart Disease, Am. 1. Cardio!. 34: 136, 1974.
The Journal of Thoracic and Cardiovascular Surgery
20 Spencer, F. c., Green, G. E., Tice, D. A., Walesh, E., Mills, N. L., and Glassman, E.: Coronary Artery Bypass Grafts for Congestive Heart Failure, J. THORAC. CARDIOVASC. SURG. 62: 529, 1971. 21 Burch, G. E., Tsui, C. Y., and Harb, 1. M.: Ischemic Cardiomyopathy, Am. Heart 1. 83: 340, 1972. 22 Assad-Morrell, J. L., Connolly, D. C., Brandenburg, R. 0., Giuliani, E. R., Schattenberg, T. T., Pluth, J. R., Barnhorst, D. A., Wallace, R. B., and Danielson, G. K.: Aorta-Coronary Artery Saphenous Vein Bypass Grafts: Isolated and Combined With Other Procedures, J. THORAC. CARDIOVASC. SURG. 69: 841,1975. 23 Berger, T. J., Karp, R. B., and Kouchoukos, N. T.: Valve Replacement and Myocardial Revascularization, Circulation 51, 52: 126, 1975 (Supp!. I).
Scott L. Faulkner, William S. Stoney, William C. Alford, Clarence S. Thomas, George R. Burrus, Robert A. Frist, and Harry L. Page, Nashville, Tenn.
T he natural history of patients with symptomatic
coronary artery disease and depressed left ventricular function (ischemic cardiomyopathy) is dismal, and medical treatment has uniformly failed to alter significantly its course. 1 Bruschke and associates" reported that only 12 percent of patients with three vessel coronary artery disease and poor left ventricular function secondary to diffuse scarring were alive 5 years after their initial cardiac catheterization. Excellent relief of symptoms of ischemic heart disease by aorta-coronary bypass grafting is now accomplished with a low operative mortality rate. 3- 5 The primary determinants of the mortality rate relate to left ventricular function.v" In patients with poor left ventricular function, operative mortality rates as high as 55 percent have been reported. 8 In addition, relief of angina pectoris and symptoms of heart failure in this From the Department of Cardiac and Thoracic Surgery, Vanderbilt University Hospital, and St. Thomas Hospital, Nashville, Tenn. Received for publication Jan. 3, 1977. Accepted for publication March 21, 1977. Address for reprints: W. S. Stoney, M.D., St. Thomas Medical Building, Nashville, Tenn. 37205.
subset of patients have not been documented following a variety of operative procedures. Recently aorta-coronary bypass grafting, either alone or in combination with ventricular aneurysmectomy, left ventricular plication, or mitral valve replacement, has been performed with operative mortality rates of 7 to 15 percent.P' P However, a recent study comparing operative versus nonoperative management of patients with ischemic cardiomyopathy failed to demonstrate an advantage of either form of therapy with respect to either relief of symptoms or survival. 13 It is the purpose of this report to evaluate the efficacy of aorta-coronary bypass grafting in the natural history of ischemic cardiomyopathy. Methods
We reviewed the results of cardiac catheterization of 5,500 patients evaluated for coronary artery disease at St. Thomas Hospital during the period from January, 1969, to December, 1975. All patients found to have obstructive coronary artery disease (at least 70 percent narrowing of one coronary artery) and decreased left ventricular function (ejection fraction :5 0.30) were further reviewed with respect to symptoms, past medi77
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Table I. Clinical comparison of patients with ischemic cardiomyopathy treated medically and operatively
No. of patients Age (yr.) Sex ratio (M: F) Previous myocardial infarctions None One Two or more LVEDP (mm. Hg) Mean Ejection fraction (%) Mean (%) Follow-up period (mo.) Mean
Medical
Operative
70 31-74 (56) 58: 12
46 42-76 (50) 40:06
4 (6%)* 43 (61%) 18 (26%) 8-49 29 1-30 20 1-49 14
10 (22%) 14 (30%) 22 (48%) 6-50 24 2-30
2T
1-72
19
Legend: LVEDP. Left ventricular end-diastolic pressure.
*Based on 65 patients on whom documentation was available.
Table II. Distribution of symptoms and extent of disease in 116 patients with ischemic cardiomyopathy Operative _ _ _ _I-N-:ed-&j-% No.
~
Symptoms Angina Congestive failure Angina + failure Primarily angina Primarily failure
24 II
34 16
26
57
28 7
40 10
19 I
41 2
6 22 42
9 31 60
3 5 38
6 II 83
Extent of disease Single vessel Double vessel Triple vessel
Table III. Results of medical and operative treatment in 116 patients with ischemic cardiomyopathy Medical
Patients Patients lost to follow-up Death Early Late Over-all survival Asymptomatic or improved Unimproved or dead 'Based on 44 patients with follow-up.
Operative
No.
I%
No.
70 0
0
46 2
4
7 33 30 II 59
10 47 43 16 84
2 4 38 36 8
4 9 83 82* 18*
I
%
cal history, and response to medical or operative treatment. Patients with left ventricular aneurysm or mitral insufficiency were excluded from this study. All cardiac catheterizations were performed by the percutaneous transfemoral route as previously described. 14 Left ventricular angiograms were performed in the right anterior oblique position and left ventricular ejection fractions calculated after the methods of Sandler and Dodge" and Chatterjee and associates.!" Left ventricular end-diastolic pressures were recorded before and after the injection of contrast material. Hospital records, interviews with attending physicians, and postoperative visits were utilized to evaluate these patients. A total of 116 patients satisfied the criteria for inclusion in this study. Patients were not randomized as to type of therapy. Each individual patient and his physician selected the mode of therapy. Some medically treated patients were not seen by the surgeons, and some patients treated medically were not felt to be operative candidates after surgical consultation. The actuarial survival rate in both groups is calculated according to the method of Cutler and Ederer Y
Medical group Seventy patients were treated with varying combinations of digitalis, diuretics, propranolol, long-acting nitrates, and nitroglycerin (Table I). There were 58 men and 12 women in this group with a mean age of 56 years (range 31 to 74). Eighty-seven percent of the patients had had at least one myocardial infarction documented by electrocardiographic and enzymatic changes; 18 patients (26 percent) had had two or more myocardial infarctions. Six patients manifested intraventricular conduction defects on the electrocardiograms. The symptoms and distribution of coronary arterial disease are summarized in Table II. Thirty-four percent of patients had angina pectoris alone, and 10 percent had congestive heart failure without angina pectoris. Sixty percent of patients had three vessel coronary disease. The mean left ventricular ejection fraction for the entire group was 0.20 (range 0.01 to 0.30), and the mean left ventricular end-diastolic pressure was 29 mm. Hg (range 8 to 49 mm. Hg, Table I). The mean duration of follow-up was 14 months (range 1 to 49 months).
Operative group Forty-six patients underwent aorta-coronary bypass grafting for relief of symptomatic angina pectoris (Table I). There were 40 men and 6 women in the group with a mean age of 56 years (range 42 to 76 years). Ten patients (22 percent) did not have previously
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documented myocardial infarction; however, 22 of 46 patients (48 percent) had had at lease two previous infarctions, and 14 patients (30 percent) had one previous infarction. Five patients had evidence of intraventricular conduction defects on the electrocardiogram. The symptoms and distribution of coronary artery disease are summarized in Table II. Fifty-seven percent had angina pectoris alone, and 43 percent were being treated for congestive heart failure in addition to having angina pectoris. Eighty-three percent of patients had three vessel coronary artery disease. For the group, the mean left ventricular ejection fraction was 0.21 (range 0.02 to 0.30), and the mean left ventricular enddiastolic pressure was 24 mm. Hg (range 6 to 50 mm. Hg) (Table I). The mean duration of follow-up was 19 months (range I to 72 months).
Results Medical group. Only 43 percent of patients were alive at the completion of the review (Table III). Seven patients died within 30 days of catheterization. Eleven patients (16 percent) were improved with respect to angina pectoris or symptoms of congestive heart failure. Short-lived or no improvement was found in the remaining patients. The 2 year actuarial survival rate was 47 percent (Fig. I). Operative group. Thirty-eight of 46 patients were known to be alive at the completion of the study; only two patients were lost to follow-up (Table III). The over-all survival rate in this group was 83 percent, and the 2 year actuarial survival rate was 77 percent. There were two deaths in the first 30 days postoperatively (4 percent). One patient was taken to the operating room
in cardiogenic shock and underwent triple bypass grafting plus endarterectomy of the left main coronary artery; he had a cardiac arrest in the recovery room and died 2 days later with a persistent low cardiac output. The second patient died on the ninth postoperative day following pulmonary embolectomy for a massive pulmonary embolus. There were four late deaths (9 percent) for an over-all mortality rate of 13 percent. Three patients died at home 2, 8, and 21 months postoperatively. The fourth patient died 2 months postoperatively from a ruptured abdominal aneurysm. There were no intraoperative myocardial infarctions as diagnosed by the appearance of new Q waves on electrocardiograms or elevation of cardiac enzyme values. Four patients (9 percent) required continuous infusion of inotropic agents at the termination of cardiopulmonary bypass, but only two of them required more than 18 hours of inotropic support (2 and 4 days). One patient sustained a myocardial infarction 3 years after the operation. Thirty-six (95 percent) of the survivors are asymptomatic or improved with respect to both angina and congestive heart failure.
Intraoperative management All preoperative medications were discontinued at least 8 hours prior to operation. Patients with severe three vessel or left main coronary artery disease were anesthetized after the arterial pressure monitoring lines had been placed under local anesthesia. Ketamine or morphine supplemented by small amounts of halothane were used during the procedure. Cardiopulmonary bypass with hemodilution prime was carried out at a body temperature of 30° C. with the use of a bubble
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oxygenator. The bypass flow was maintained at 2.2 L. per square meter. The mean arterial blood pressure was constantly monitored and maintained above 50 mm. Hg by increasing bypass flow or by pharmacologic means. The left ventricle was vented in each case through its apex. Distal saphenous veins or internal mammary arteries were used to bypass severe coronary arterial lesions if the area of myocardium supplied by the coronary artery did not appear to be predominately replaced by scar tissue. Distal coronary artery-vein graft anastomoses were performed with the aorta cross-clamped and after minimal dissection on the surface of the coronary artery. The anastomoses were constructed with 7-0 monofilament suture, 2 to 3.5 power optical magnification, and fiberoptic headlamp illumination. Ninety-five percent of anastomoses were performed with less than 15 minutes of ischemic arrest. Following completion of the proximal anastomoses, the heart was cardioverted with a single countershock if spontaneous sinus rhythm had not returned. The average bypass time was 110 minutes. After completion of the procedure, right ventricular and occasionally right atrial temporary pacing wires were placed. Discussion The combination of anatomic extent of obstructive lesions in the coronary arterial network and left ventricular functional abnormalities provides the best prognostic index of survival in patients with coronary artery disease. Although several natural history studies have demonstrated that patients with triple vessel disease have an over-all 5 year survival rate of only 37 to 53 percent;'- 2. 18 left ventricular dysfunction reduces this rate to 12 percent. In several series of patients undergoing coronary artery bypass, the strongest predicator of operative death was a decreased left ventricular ejection fraction. 9. 19 Operative mortality rates for patients undergoing aorta-coronary bypass grafting when the left ventricular ejection fraction is less than 30 percent range from 10 to 55 percent.P: 8, 10, 13 Over-all operative mortality rates for aorta-coronary bypass grafting range from less than 1 percent to 6.4 percent depending on the individual institutions and extent of disease.v? A variety of procedures have been utilized in the operative treatment of patients with severe and diffuse coronary artery disease and over-all poor left ventricular function. In addition to revascularization of the left ventricle, resection of aneurysms, plication and/or resection of infarcted tissue, and mitral valve replacement have also been performed in an attempt to improve the left ventricular dysfunction. Most series combine a variety of these procedures in treating pa-
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tients who have both angina pectoris and congestive heart failure in an effort to improve over-all survival and left ventricular function. With increasing technical skill, more complete revascularization, and preservation of viable myocardium, the number of deaths has decreased in this subset of patients from 31 to 55 percent" 8. 20 to 7 to 10 percent. 10, 12 Improvement in symptoms of angina pectoris occurs in 80 to 90 percent of survivors. 10. 12 In 1972, Burch and associates" used the term "ischemic cardiomyopathy" to describe the ventricular dysfunction resulting from diffuse fibrosis of left ventricular myocardium secondary to repeated episodes of ischemia. The natural history of ischemic cardiomyopathy recently has been reviewed by Yatteau and colleagues. 13 Their group of patients was described as having a generalized deficiency in left ventricular wall excursion, resulting in an ejection fraction not greater than 25 percent, and significant coronary artery disease. Patients with ventricular aneurysms and localized contraction abnormalities are excluded. Most of their patients had prior myocardial infarctions (95 percent) and angina pectoris (76 percent); 50 percent of these patients manifested congestive heart failure. The average left ventricular ejection fraction was 19 percent and the average left ventricular end-diastolic pressure was 21 mm. Hg. Seventy-one percent of these patients had triple vessel disease. The 2 year mortality rate of 42 medically treated patients was 38 percent. The results of operative treatment in patients with coronary artery disease and decreased left ventricular function should be critically examined by analyzing separately the patients undergoing aorta-coronary bypass grafting alone and those undergoing combined procedures. The mechanism of poor left ventricular function in patients with coronary artery disease alone is different than that in patients with coronary artery disease and ventricular aneurysms or mitral insufficiency. When examining the results of combined procedures (aorta-coronary bypass grafting plus mitral valve replacement or aneurysmectorny), we find that operative mortality rates range from 6.3 to 33 percent. 22,23 Several groups'": 23 have also noted late death in 16 to 38 percent of patients followed for 18 to 33 months. Thus it is difficult to compare our operative mortality rate of 4 percent and late death rate of 9 percent to previously published data. The only series that has utilized aorta-coronary bypass grafting alone in patients with poor left ventricular function is that of Yatteau and associates.P Their poor results with operative treatment of patients with ischemic cardiomyopathy (50 percent 2 year survival) are strongly influenced by a 33 percent operative mortality rate
Volume 74 Number 1 July, 1977
(eight of 24 patients). Whereas all patients in their series underwent operation from 1968 to 1972, 85 percent (39 of 46) of our patients underwent operation from 1972 through 1975. Increased technical skill as well as attempts to revascularize all areas of myocardium in jeopardy has undoubtedly resulted in increased survival. Whereas in 1971 Spencer and associates" reported that 60 percent of their patients had two bypass grafts and 40 percent had a single bypass graft, a report from the same institution 12 in 1975 showed 60 percent of patients receiving three or. more grafts. Procedures such as left ventricular plication, ventricular aneurysmectomy, and mitral valve replacement have been added to aortacoronary bypass grafting in these patients. Preservation of myocardial tissue and function during cardiopulmonary bypass are important in all patients with ischemic heart disease, but they are more so in patients with impaired function. Myocardial hypothermia, limitation of the time of ischemic arrest, adequate mean perfusion pressure during bypass, avoidance of prolonged ventricular fibrillation or distention, and avoidance of air in the coronary arteries all aid in preserving myocardial function. Strict attention to all these details has lowered the over-all operative mortality rates in patients with coronary artery disease to less than 2 percent. 3, 4 Long-term favorable clinical results of procedures to revascularize myocardial tissue are proportional to the amount of viable although ischemic muscle, the patency of grafts, and the completeness of the revascularization procedure. Increasing blood flow to fibrotic tissue is of no benefit. Thus patients with pure ischemic cardiomyopathy presenting solely as congestive heart failure are unlikely to be benefited by any procedure designed to increase blood flow. Symptoms of angina pectoris, on the other hand, present evidence of ischemic but potentially viable myocardial tissue. In addition, the mean length of survival is clearly prolonged. In those patients with ischemic cardiomyopathy without ventricular aneurysms and without mitral insufficiency, aorta-coronary bypass grafting results in prolonged survival (77 percent) compared to medical treatment (47 percent). In addition, the operation can be employed with a low operative mortality rate (4 percent), and symptoms of angina pectoris are relieved in 95 percent of survivors. REFERENCES Bruschke, A. V. G., Proudfit, W. L., and Jones, F. M., Jr.: Progress Study of 590 Consecutive Non-surgical Cases of Coronary Disease Followed by 5-9 Years. I. Arteriographic Correlations, Circulation 47: 1147, 1973.
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2 Bruschke, A. V. G., Proudfit, W. L., and Jones, F. M., Jr.: Progress Study of 590 Consecutive Non-surgical Cases of Coronary Disease Followed by 5-9 Years. II. Ventriculographic and Other Correlations, Circulation 47: 1154, 1973. 3 Sheldon, W. C., Rincon, G., Pichard, A. D., Razavi, M., Cheanvechai, C., and Loop, F. D.: Surgical Treatment of Coronary Artery Disease: Pure Graft Operations With a Study of 741 Patients Followed 3-7 Years, Prog. Cardiovasc. Dis. 18: 237, 1975. 4 Hutchinson, J. E., Green, G. E., Mekhjian, H. A., and Kemp, H. G.: Coronary Artery Bypass Grafting in 376 Consecutive Patients With Three Operative Deaths, 1. THoRAc. CARDIOVASC. SURG. 67: 7, 1974. 5 Mundth, E. D., and Austin, W. G.: Surgical Measures for Coronary Heart Disease, N. Engl. 1. Med. 293: 13, 1975. 6 Collins, 1. J., Jr., Cohn, C. H., Sonnenblick, E. H., Herman, M. V., Cohn, P. F., and Gorbin, R.: Determinants of Survival After Coronary Artery Bypass Surgery, Circulation 47, 48: 132, 1973 (Suppl. III). 7 Hammermeister, I. C. E., and Kennedy, 1. W.: Predictors of Surgical Mortality in Patients Undergoing Direct Myocardial Revascularization, Circulation 49, 50: 112, 1974 (Suppl. II). 8 Oldham, H. N., Kong, Y., Bartel, A. G., Morris, J. J., Jr., Behar, V. W., Peter, R. H., Rosati, R. A., Young, W. G., Jr., and Sabiston, D. c.. Jr.: Risk Factors in Coronary Artery Bypass Surgery, Arch. Surg. 105: 918, 1972. 9 Nelson, G. R., Cohn, P. F., and Gorlin, R.: Prognosis in Medically Treated Coronary Artery Disease: Influence of Ejection Fraction Compared to Other Parameters, Circulation 52: 408, 1975. 10 Mundth, E. D., Harthorne, J. W., Dinsmore, R., and Austen, W. G.: Direct Coronary Arterial Revascularization: Treatment of Cardiac Failure Associated With Coronary Artery Disease, Arch. Surg. 103: 529, 1971. II Mitchel, B. F., Jr., Alivizatos, P. A., Adam, M., Geisler, G. F., Thiele, J. P., and Lambert, C. J.: Myocardial Revascularization in Patients With Poor Left Ventricular Function, 1. THoRAc. CARDIOVASC. SURG. 69: 52, 1975. 12 Isom, O. W., Spencer, F. C., Glassman, E., Dembrow, 1. M., and Pasternack, B. S.: Long-term Survival Following Coronary Bypass Surgery in Patients With Significant Impairment of Left Ventricular Function, Circulation 51, 52: 141, 1975 (Suppl. I). 13 Yatteau, R. F., Peter, R. H., Behar, V. S., Bartel, A. G., Rosati, R. A., and Kong, Y.: Ischemic Cardiomyopathy: The Myopathy of Coronary Artery Disease, Am. J. Cardiol. 34: 520, 1974. 14 Page, H. L., and Campbell, W. B.: Percutaneous Transfemoral Coronary Arteriography: Prevention of Morbid Complications, Chest 67: 221, 1975. 15 Sandler, H., and Dodge, H. T.: The Use of Single Plane Angiocardiograms for the Calculation of Left Ventricular Volume in Man, Am. Heart J. 75: 325, 1968.
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16 Chatterjee, K., Savor, M., Sutton, G. c., and Miller, G. A. H.: Assessment of Left Ventricular Function by Single Plane Cineangiographic Volume Analysis, Br. Heart 1. 33: 565, 1971. 17 Cutler, S. 1., and Ederer, F.: Maximum Utilization of the Life-Table Method in Analyzing Survival, J. Chron. Dis. 8: 699, 1958. 18 Webster, J. S., Moberg, c., and Rincon, G.: Natural History of Severe Proximal Coronary Artery Disease as Documented by Coronary Cineangiography, Am. J. Cardiol. 33: 195, 1974. 19 Cohn, P. F., Godin, R., Cohn, L. H., and Collins, J. J., Jr.: Left Ventricular Ejection Fraction as a Prognostic Guide in Surgical Treatment of Coronary and Valvular Heart Disease, Am. 1. Cardio!. 34: 136, 1974.
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20 Spencer, F. c., Green, G. E., Tice, D. A., Walesh, E., Mills, N. L., and Glassman, E.: Coronary Artery Bypass Grafts for Congestive Heart Failure, J. THORAC. CARDIOVASC. SURG. 62: 529, 1971. 21 Burch, G. E., Tsui, C. Y., and Harb, 1. M.: Ischemic Cardiomyopathy, Am. Heart 1. 83: 340, 1972. 22 Assad-Morrell, J. L., Connolly, D. C., Brandenburg, R. 0., Giuliani, E. R., Schattenberg, T. T., Pluth, J. R., Barnhorst, D. A., Wallace, R. B., and Danielson, G. K.: Aorta-Coronary Artery Saphenous Vein Bypass Grafts: Isolated and Combined With Other Procedures, J. THORAC. CARDIOVASC. SURG. 69: 841,1975. 23 Berger, T. J., Karp, R. B., and Kouchoukos, N. T.: Valve Replacement and Myocardial Revascularization, Circulation 51, 52: 126, 1975 (Supp!. I).