Aortocoronary Bypass in the Treatment of Left Main Coronary Artery Stenosis

Transcription

1 Aortocoronary Bypass in the Treatment of Left Main Coronary Artery Stenosis W. C. Alford, Jr., M.D., I. J. Shaker, M.D., C. S. Thomas, Jr., M.D., W. S. Stoney, M.D., G. R. Burrus, M.D., and H. L. Page, M.D. ABSTRACT Because of the high risk of sudden death, coronary cineangiography should be done with caution in patients with possible left main coronary artery (LMCA) stenosis. After confirmation of LMCA stenosis, these patients should undergo careful monitoring; and aortocoronary artery bypass procedures, when technically feasible, have urgent priority. This report contains data on 104 patients with LMCA stenosis from St. Thomas Hospital in Nashville who were managed in this way. Eighty-six subsequently had coronary artery bypass grafting. There were 7 operative deaths and 2 late cardiac deaths in 38 months of follow-up observations. When compared with nonoperated patients with similar angiographic findings, the operated group showed considerably greater survival. Certain modifications of the usual operative techniques are described which tend to lessen the operative risk in patients with LMCA stenosis. S ignificant stenosis (greater than 50%) of the left main coronary artery (LMCA) is the most ominous single coronary artery lesion demonstrable by coronary arteriography. The high early mortality in unoperated patients has been well documented. This group of patients provides the most critical test of aortocoronary bypass as a procedure capable of prolonging life as well as decreasing symptoms of myocardial ischemia. The effectiveness of bypass grafting in altering survival has been partially negated in previous reports by a considerable operative mortality. The results of surgical treatment in 86 patients with LMCA stenosis operated upon at St. Thomas Hospital, Nashville, are presented. This experience demonstrates that low operative mortality is attainable and that patients treated surgically show considerably greater survival than previously reported nonoperated patients. Clinical Material and Methods Patient records covering 2,360 coronary angiograms performed at the St. Thomas Hospital between 1968 and 1973 were reviewed by one of the authors (H. L. P.). Only patients with greater than 50% stenosis of the From the Cardiac Surgical Service and the Department of Cardiology, St. Thomas Hospital, Nashville, Tenn. Supported in part by U.S. Public Health Service Grant 5T01-GM Presented at the Twentieth Annual Meeting of the Southern Thoracic Surgical Association. Louisville, Ky., Nov. 1-3, Address reprint requests to Dr. Alford, 2108 West End Ave., Nashville, Tenn VOL. 17, NO. 3, MARCH,

2 ALFORD ET AL. A B C FIG. 1. Cineangiography frames showing left main coronary artery stenosis (arrows): (A) ostial stenosis, (B) localized stenosis, and (C) diffuse stenosis. LMCA were selected for retrospective analysis (Fig. 1). Follow-up clinical information was obtained on each patient. In most instances, selective coronary cineangiography was performed by the transfemoral technique. Those patients suspected of having potential LMCA lesions-i.e., patients with severe or crescendo angina pectoris, unusually positive resting or treadmill electrocardiograms, LMCA calcification, or damping of the pressure contour as shown by monitoring during intubation of the left coronary ostium-were rotated into a moderately shallow right anterior oblique position for better visualization of the LMCA during the first left coronary injection. Since attempts at nonselective opacification are frequently suboptimal, the injection was performed selectively and the catheter was immediately withdrawn to facilitate washout of the contrast material. With this modified technique, the number of injections was minimized and a single, well-opacified view was often obtained (Fig. 2). Patients with demonstrable LMCA stenosis of greater than 50% underwent urgent aortocoronary bypass procedures. Certain modifications of the usual operative technique were utilized in these patients in order to decrease complications. The radial artery and central venous pressure monitoring catheters were inserted under local anesthesia. These provided the anesthesiologist with instant pressure measurements during and following induction of anesthesia. Hypotension prior to bypass was scrupulously avoided. After cardiopulmonary bypass was instituted and moderate hypothermia (32 C.) 248 THE ANNALS OF THORACIC SURGERY

3 Aortocoronary Byfiass in Left Main CA Stenosis A FIG. 2. Single-injection views of left and right coronary arteries of the same patient, showing: (A) localixed left main coronary artery stenosis (arrow) and (B) tight midright coronary stenosis (arrow). was achieved, prompt revascularization of the most significant left coronary artery branch (usually the left anterior descending) was performed, followed by other, less urgent grafting procedures. Results Among the 2,360 patients studied by coronary cineangiography for symptoms of angina, congestive heart failure, or arrhythmia, 104 patients (4.4y0) were found to have greater than 50y0 stenosis of the LMCA. The average age of the patients with LMCA stenosis was 55 years, with a range of 33 to 74 years. Ten patients were women and 94 were men. Their clinical signs and symptoms are presented in Table 1 and their electrocardiographic findings in Table 2. Nine patients had a normal resting ECG. Three of these 9 ECGs as well as 5 of the ECGs with nonspecific changes became positive during treadmill exercise stress testing. Fifteen patients had definite evidence of ischemia at rest, 32 had nonspecific ST-T wave abnormalities, and 48 had evidence of previous myocardial infarction. Eighty-six patients underwent urgent aortocoronary artery bypass procedures. The remaining 18 patients were not operated upon because of in- B

4 ALFORD ET AL. TABLE 1. SIGNS AND SYMPTOMS IN 104 PATIENTS WITH LEFT MAIN CORONARY ARTERY STENOSIS' Symptom No. of Patients Recent onset or crescendo angina 49 Stable angina 47 Congestive heart failure 8 Arrhythmia 2 Mitral regurgitation 3 Some patients had more than one symptom. adequacy of distal vessels or ventricular function or because they died shortly after coronary cineangiography, they refused operation, or they were advised against operation by their referring physicians. Three of these 18 patients died suddenly within four days of coronary cineangiography. A fourth patient died of dissecting thoracic aortic aneurysm l month later. An additional patient died suddenly 15 months after cardiac catheterization; thus 5 of the 18 nonoperated patients died within a year and a half of their evaluation. Of the 86 patients who had coronary artery bypass grafts (CABG) inserted, there were 8 single, 37 double, 38 triple, and 3 quadruple grafts (Fig. 3). Three patients underwent concomitant left ventricular aneurysmectomy, and 1 of these also had mitral valve replacement. In the entire op erative group, 7 hospital deaths occurred. Two patients who failed to survive the CABG procedure were in cardiogenic shock and were undergoing cardiopulmonary resuscitation at the time they arrived in the operating room. Three patients died of multiple systems failure. One of these patients had concomitant mitral valve replacement and left ventricular aneurysmectomy. A sixth patient died of pulmonary embolism and arrhythmia on the twentyeighth postoperative day. The seventh patient died of respiratory failure following laparotomy for intestinal obstruction thirty days after the procedure. Thus 5 of the 84 patients who underwent elective operations died, and no deaths have occurred since 1971 (43 patients). The 79 survivors have been followed for a period of 1 to 38 months (mean, 11 months). Only 2 late cardiac deaths have occurred. One patient died of cardiac failure following mitral valve replacement done 4 months TABLE 2. ELECTROCARDIOGRAPHIC FINDINGS IN 104 PATIENTS WITH LEFT MAIN CORONARY ARTERY STENOSIS ECG Findinn Normal Nonspecific ST-T wave changes Ischemia at rest Previous infarction No. of Patients THE ANNALS OF THORACIC SURGERY

5 Aortocoronay Bypass in Left Main CA Stenosis OPERATIVE DEATH m!!ikii% \mtock ELECTIVE CASES FIG. 3. Number of coronary artery 54 1 bypass grafting procedures and 06- eratiue deaths in 86 patients with left main coronary artery stenosis. NUMBER OF GRAFTS PERFORMED PER PATIENT after CABG, and a second patient died of myocardial infarction and ventricular fibrillation 32 months postoperatively. Two additional noncardiac deaths occurred 5 months postoperatively, 1 following an intracerebral hemorrhage and the second due to a Pancoast s tumor of the left lung. If unsuccessful operations for cardiogenic shock in 2 patients and late noncardiac deaths are excluded, the survival following aortocoronary artery bypass at this time is 91.5%. Comment The incidence of LMCA stenosis is not great. Occurrence of this lesion in reported series has varied between 2.50/, (Cohen and associates [3]) and 5.9y0 (Bruschke and colleagues [l, 21). In our series it was 4.4y0. Continued study of this potentially lethal lesion is thus desirable. Two pertinent factors associated with such a study are the predictably high risk of infarction and death after the diagnosis is established and the dangers of cineangiography in these patients. Lavine and co-workers [5] reported a 30% mortality within 1 month of coronary cineangiography. A high nonsurgical mortality was also reported by Bruschke and associates [l] in their series of 37 patients with LMCA stenosis. This increased to , within 5 years and to 74y0 if the right coronary artery was totally obliterated in association with the LMCA lesion. In the series of Cohen and colleagues [3], half of the nonoperated patients died within 25 months. The fact that our nonsurgical mortality of 5 of 18 patients who were followed for 38 months is somewhat lower is thought to be due to modifications of coronary catheterization techniques and perhaps to the smaller number of patients involved. Modified cardiac catheterization is undertaken at the discretion of the cardiologist in any patient suspected of having LMCA stenosis from the cri- VOL. 17, NO. 3, MARCH,

6 ALFORD ET AL. teria previously described. The left ventricle is first examined in the usual manner. The patient is then rotated so that a shallow right anterior oblique view can be obtained, and a left coronary injection is carefully performed. If greater than 50% LMCA stenosis is proved, no additional injections of the left coronary artery are done. The right coronary artery is then studied, and the procedure is terminated. By carefully following this protocol, serious complications from the catheterization procedure have been greatly reduced. The natural history of patients with proved LMCA stenosis of greater than 50y0 reveals that they are at greatest risk in the first few weeks following coronary cineangiography [ 1, 3, 51. For this reason, urgent myocardial revascularization is advised if this natural process is to be modified downward. However, the significant operative mortality has tended to negate this trend. Operative mortality to date in such patients has been reported to be as high as 31y0 in 1972 [6]. Three other reports contain mortality figures of 11.7%, 12%, and 12.5% for the same operation [3, 5, 81. In an effort to decrease the risk of operation in our patients with LMCA stenosis, several empirical modifications of the usual operative technique have been employed. These include: (I) insertion of arterial and venous pressure monitoring catheters under local anesthesia, (2) avoiding hypotension during and following induction of anesthesia, and (3) initial revascularization of the most important coronary artery. Since these measures were instituted in 1971, no operative deaths have occurred in 43 patients who underwent elective bypass procedures for LMCA stenosis. There has been a total of 7 operative deaths in this group of 86 patients. Among the 84 patients with LMCA disease who were not in cardiac shock when bypass procedures were carried out, only 5 patients died. This is comparable PERCENT SURVIVORS 0 SURGICAL SURVIVORS EXCLUDING CARDIOGENIC SHOCK AND NONCARDIAC DEATHS X NONSURGICAL SURVIVORS - I3 CASES 0 CLEVELAND CLINIC - 37 NONSURGICAL CASES 0 COHEN ET AL - IS NONSURGICAL CASES I I I 1 I YEARS FOLLOWING CARDIAC CATHETERIZATION FIG. 4. Suruival of operated versus nonoperated patients with left main coronary artery stenosis [#I. 252 THE ANNALS OF THORACIC SURGERY

7 Aortocoronary Bypass in Left Main CA Stenosis to the overall operative mortality of 2.7Q/, for aortocoronary bypass at our institution [7]. The 38-month follow-up on patients who survived operation for LMCA stenosis has been gratifying (Fig. 4). When compared to the nonoperated patients in our group and the results in other series, it appears that a significant improvement has been achieved. We believe that the method described for detection and treatment of this lesion offers a unique opportunity to assess the value of aortocoronary bypass grafting. When low operative mortality is attainable, surgically treated patients with LMCA stenosis are shown to have considerably greater survival than those treated by any other method. References Bruschke, A. V. G., Proudfit, W. L., and Sones, F. M., Jr. Progress study of 590 consecutive nonsurgical cases of coronary disease followed 5-9 years: Arteriographic correlations. Circulation 47: 1147, Bruschke, A. V. G., Proudfit, W. L., and Sones, F. M., Jr. Progress study of 590 consecutive nonsurgical cases of coronary disease followed 5-9 years: Ventriculographic and other correlations. Circulation 47: 1154, Cohen, M. V., Cohn, P. F., Herman, M. V., and Gorlin, R. Diagnosis and prognosis of main left coronary artery obstruction. Circulation (Suppl. I):57, Favaloro, R. G., Effler, D. B., Groves, L. K., Sheldon, W. C., Shirey, E. K., and Sones, F. M., Jr. Severe segmental obstruction of the left main coronary artery and its divisions: Surgical treatment by the saphenous vein graft technique. J. Thorac. Cardiowasc. Surg. 60:469, Lavine, P., Kimbris, D., Segal, B. L., and Linhart, J. W. Left main coronary artery disease: Clinical, arteriographic and hernodynamic appraisal. Am. J. Cardiol. 30:791, Oldham, H. N., Jr., Kong, Y., Bartel, A. G., Morris, J. J., Jr., Behar, V. S., 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, Thomas, C. S., Jr., Alford, W. C., Jr., Burrus, G. R., and Stoney, W. S. The decreasing risk of aortocoronary artery bypass. J. Tenn. Med. Assoc. 66:815, Zeft, H. J.,.Manley, J. C., Huston, J. H., Tector, A. C., and Johnson, W. D. Direct coronary surgery in patients with left main coronary artery stenosis. Circulation (Suppl. II):50, Addendum Subsequent to this report, an additional 17 patients with greater than 50% LMCA stenosis have undergone coronary artery bypass grafting at this institution with 1 hospital death.