Incidence and outcomes of perioperative myocardial infarction associated with coronary artery bypass surgery

Abstract

Perioperative myocardial infarction (PMI) after CABG can contribute to in-hospital morbidity and mortality, however, its clinical significance on long-term outcome, remains inadequately addressed. We studied both 30-day mortality and long-term effects of PMI in Icelandic CABG-patients. A retrospective nationwide-study on 1446 consecutive CABG-patients operated at Landspitali in Iceland 2002-2018 without evidence of preoperative myocardial infarction. PMI was defined as a tenfold elevetion in serum-CK-MB associated with new ECG changes or diagnostic imaging consistent with ischemia. Patients with PMI were compared to a reference group with uni- and multivariate analyses. Long-term and MACCE-free survival were estimated with the Kaplan-Meier method and logistic regression used to determine factors associated with PMI. The mean follow-up time was 8.3 years. Out of 1446 patients 78 (5.4%) were diagnosed with PMI (range: 0-15.5%) with a significant annual decline in the incidence of PMI (12.7%, p<0.001). Over the same period preoperative aspirin use increased by 22.3% (p<0.018). PMI patients had a higher rate of short-term complications and a 11.5% 30-day mortality rate compared to 0.4% for non-PMI patients. PMI was found to be a predictor of 30-day mortality (OR 15.44, 95% CI: 6.89-34.67). PMI patients had worse 5-year MACCE-free survival (69.2% vs. 84.7, p=0,01), although overall survival was comparable between the groups. Although PMI after CABG is associated with significantly higher rates of short-term complications and 30-day mortality, long-term survival was similar to the reference group. Therefore, the mortality risk attributable to PMI appears to diminish after the immediate postoperative period.