Background: Recent myocardial infarction has been identified as a risk factor and is currently used as a strong predictor in different scores. The aim of our study was to determine whether the impact of myocardial infarction, especially acute myocardial infarction, is still strong enough to justify a restrictive indication for isolated CABG procedure in patients with significant coronary artery disease.
Methods: 10 272 patients underwent isolated CABG at a single institution. A 10-year follow-up was performed with a completeness of 97.2 %.
Results: 6 107 (59.5 %) of the patients had a history of myocardial infarction. A stratified Kaplan-Meier analysis demonstrates a significantly worse survival for patients with myocardial infarction (chi-square value: 36.7, P < 0.0001). At a further differentiation for no myocardial infarction (n = 4 165), myocardial infarction > 90 days (n = 4 578), myocardial infarction up to 90 days (recent myocardial infarction) (n = 1 266) and ongoing acute myocardial infarction up to 15 days (n = 263), indicated a higher mortality for the more recent infarction in the univariate analysis. However, if patients with acute myocardial infarction in the past 6 years were analyzed separately, their risk remained at the same level as patients with non-acute myocardial infarction over the total observation period. Furthermore, propensity score matching revealed no statistical significant difference in the outcome of the patients.
Conclusions: Structural myocardial damage represents a risk factor for survival after isolated CABG in univariate analysis. More appropriate statistical methods indicate a time-dependent loss of statistically relevant differences between patients with or without myocardial infarction prior to CABG. This is also true for "recent" myocardial infarction which is still part of current scores.