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Ann Thorac Surg 1995;60:26
© 1995 The Society of Thoracic Surgeons
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Introduction |
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 Top Introduction |
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DR JACK J. CURTIS (Columbia, MO): I congratulate the investigators on a beautifully illustrated and well-articulated presentation. I would like to share with you a similar study done several years ago at the University of Missouri covering an operative time interval in the 1980s.
We were very interested in the influence of recency of myocardial infarction (MI) on operative mortality for coronary artery bypass grafting (CABG). Our data suggested a definite trend in operative mortality with recency of MI, going from 18% if patients were operated on within the first 24 hours after an MI down to 2.7% after 3 weeks.
We noticed, however, that the patients who were operated on with stable angina after an MI had an overall operative mortality of 0.8% compared with 7% in patients who had unstable angina. When we categorized patients by anginal syndrome, which is similar to what you have done in your more recent study, the recency of MI was eliminated as a risk predictor for mortality with CABG.
I congratulate you on the study. I am a little bit confused, however, by your final conclusion that operative mortality is related to recency of MI when you have given us very good data to show that, in patients who have elective bypass operations, it is not.
DR CRESWELL: Thank you for your comments. The relationship between the timing of operation and the recency of MI is only an apparent one, as you have indicated. We can select out a patient group, either those undergoing elective operation, as we have termed it, or patients who have their unstable angina controlled who can undergo bypass grafting early after MI with acceptable morbidity and mortality.
DR I. AYHAN OZDEMIR (Bursa, Turkey): I enjoyed this presentation very much. Since June 1994 we studied 35 patients with acute MI and treated them within 6 hours after the onset of the symptoms. After cardiac catheterization 20 patients underwent emergency CABG, 12 of them had percutaneous transluminal coronary angioplasty, and 3 had fibrinolytic therapy. Surgical intervention for acute MI was required when thrombolytic therapy or percutaneous transluminal coronary angioplasty had been unsuccessful. Patients with ongoing ischemia or hemodynamic instability also were considered as candidates. The mean age was 57.2 ± 2.2 (standard error of the mean); 14 patients were male. In 13 patients (65%) anterior, in 4 (20%) inferior, and in 3 patients (15%) lateral infarction was present. Two patients (10%) had single-, 7 (35%) had double-, 10 (50%) had triple-vessel, and 1 patient (5%) had left main coronary artery disease. Five patients (25%) had previous MI. Two patients (10%) with left ventricle aneurysm were admitted in cardiogenic shock and acute pulmonary edema. Nine patients (45%) were in cardiac arrest before the angiography or on the way to the operating room. The average reperfusion time was 5.1 ± 0.4 hours. Grafts/patient was 2.5. Left internal mammary artery to left anterior descending artery was performed in 8 patients (40%). Two patients had aneurysmectomies. One patient (5%) died of cardiac failure in the fourth day. Surviving patients were all asymptomatic and doing well.
If a patient with a deteriorating acute myocardial infarction cannot be stabilized with conventional treatment, either fibrinolytic therapy or percutaneous transluminal coronary angioplasty, we should do emergency CABG. We believe that this is a life-saving procedure; in the early phase of infarction, emergency CABG can be performed with an acceptable mortality, the complications of acute MI could be prevented, and infarct size could be restricted. Doctor Creswell, do you have such a patient group, and did you have a chance to treat those within 6 hours? I noticed that there were 9 patients; can you compare those patients with the other group regarding the cardiac function and damaged myocardium in the early and long-term period?
DR CRESWELL: Thank you for your comments. Several groups have advocated CABG in the very early period after acute MI. There are, of course, logistic difficulties with accomplishing operation within a 6-hour time frame, and this has been the case at our institution. The fact is that I have shared with you our entire experience. There were only 11 patients in 8 years' time who underwent bypass grafting within 6 hours of MI, and we had an operative mortality in that group of patients of approximately 9%. We do not have any long-term follow-up data on those patients, but we generally have been reluctant to perform operation in the very early period after acute MI.
DR JOHN E. CODD (Bridgeton, MO): During this study what was the intraoperative myocardial protection? Did changes in cardioplegia technique influence the results within study groups? Was there any influence of infarct location on outcome?
DR CRESWELL: We have not examined the issue of myocardial protection specifically. The vast majority of patients received myocardial protection in the form of intermittent antegrade cold crystalloid cardioplegia. In the most recent years we have tended to use blood cardioplegia more frequently and more patients have received retrograde cardioplegia in combination with antegrade cardioplegia. We do not know what influence the changing pattern in myocardial preservation techniques has had on our results over the time period of the study, however.
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