Association between postoperative haemoglobin concentrations and composite of non-fatal myocardial infarction and all-cause mortality in noncardiac surgical patients: post hoc analysis of the POISE-2 trial

Abstract

BackgroundMyocardial infarction is the most common postoperative major vascular complication. Perioperative anaemia may contribute to cardiac supply–demand mismatch, and therefore myocardial injury. We therefore tested the hypothesis that the lowest in-hospital postoperative haemoglobin concentration is associated with a composite of non-fatal myocardial infarction and all-cause mortality within the first 30 days after noncardiac surgery. MethodsWe conducted a retrospective analysis of patients enrolled in the PeriOperative Ischemic Evaluation-2 (POISE-2) trial. We assessed the association between the lowest postoperative haemoglobin concentration during the initial hospitalisation and a composite of non-fatal myocardial infarction (Third Universal Definition) and all-cause mortality within 30 postoperative days, using a multivariable logistic regression model. ResultsWe analysed 7227 patients from POISE-2, of whom 7.8% developed myocardial infarction; 1.5% died within 30 days. The composite primary outcome of non-fatal myocardial infarction and all-cause mortality occurred in 8.9% patients overall, ranging from 16% in patients with postoperative haemoglobin concentrations <88 g L−1 to 4.1% in patients with postoperative haemoglobin >113 g L−1. After adjusting for baseline factors, in patients with a lowest postoperative haemoglobin concentration <110 g L−1, each 10 g L−1 reduction in the lowest postoperative haemoglobin concentration was associated with a 1.46 (95% confidence interval: 1.37–1.56; P<0.001) fold increase in the odds of the composite outcome. In contrast, there was no significant relationship amongst patients with lowest postoperative haemoglobin concentration >110 g L−1. ConclusionsPostoperative anaemia may be a modifiable risk factor for non-fatal myocardial infarction and all-cause mortality.