Clinical and angiographic prediction of myocardial infarction and recurrence of severe angina during a five-year follow-up after coronary artery bypass grafting

Abstract

In a prospective, angiographically controlled study, 339 consecutive patients were examined to evaluate the pre-, peri- and postoperative risk factors for occurrence of myocardial infarction, and recurrence of severe angina during 5 years after coronary artery bypass grafting (CABG). The incidence of myocardial infarction was 6% and the recurrence of severe angina 13%. No pre- or perioperative variable could predict the occurrence of myocardial infarction. Postoperative ejection fraction was significantly lower in patients with than without myocardial infarction (58 ±10% vs 50 ±11%; p < 0.001), and the Cox proportional-hazards method showed a low postoperative ejection fraction to be the only significant risk factor for the occurrence of myocardial infarction (p = 0.02). Patients with a recurrence of severe angina had higher blood total cholesterol concentrations (7.7 ± 1.4 vs 7.0 ± 1.3 mmol/liter; p < 0.05) and triglyceride levels (2.7 mmol/l ± 1.5 vs 2.0 ± 1.0 mmol/liter; p < 0.01) than did those without angina, and also more often had ≥1 occluded bypass graft 3 months after CABG (p < 0.05). No other pre- or postoperative variable could predict the recurrence of angina. Both total blood cholesterol concentration and triglyceride level were significant predictors of the risk of recurrent severe angina by the Cox proportional-hazards method (p = 0.01 and 0.03, respectively). Thus, reduced ejection fraction is a risk factor for subsequent myocardial infarction, whereas blood lipid abnormalities predict the recurrence of severe angina during the 5 years after CABG. The dissimilarities in risk factors between these cardiac events may be explained by differences in their pathophysiologic trigger mechanisms.