Preoperative anemia does not increase the risks of early surgical revascularization after myocardial infarction

Recent clinical studies suggest preoperative anemia may increase mortality and morbidity after cardiac surgery. Anemic patients are potentially even more vulnerable in the setting of a recent myocardial infarction (MI). The objective of this study was to investigate the impact of preoperative anemia on short-term outcomes after coronary bypass surgery in patients with a recent MI.

We conducted a retrospective cohort study of 655 patients who underwent an isolated coronary bypass procedure within 21 days of MI, 432 of whom were anemic preoperatively, defined as a hemoglobin less than 13 g/dL for men and less than 12 g/dL for women. The primary outcomes were in-hospital mortality and major adverse events (MAE), which included MI, stroke, and renal failure requiring dialysis.

Before risk adjustment, in-hospital mortality and the incidence of MAE were significantly higher in patients with anemia versus no anemia (mortality, 5.1% versus 1.4%, p = 0.02; MAE, 8.6% versus 3.1%, p = 0.009). After risk adjustment, the association between preoperative anemia and mortality or MAE became insignificant (mortality odds ratio 2.34, 95% confidence interval: 0.56 to 9.87, p = 0.25; MAE odds ratio 1.13, 95% confidence interval: 0.46 to 2.79, p = 0.78). Preoperative hemoglobin, treated as a continuous variable, yielded similar results.

Preoperative anemia does not directly increase risks of surgical revascularization performed within 21 days of MI.