Timing of coronary artery bypass grafting after acute myocardial infarction: does it influence outcomes?

The optimal timing of coronary artery bypass grafting (CABG) operations in patients with recent acute myocardial infarction (AMI) remains unclear.

To assess the influence of timing on post-operative outcomes in patients undergoing CABG following AMI.

In this retrospective analysis 12,224 consecutive patients undergoing CABG were included. 2477 (20.5%) patients had a history of AMI. Based on timing, patients were divided into 3 groups: those operated within 7 days of AMI; those operated after 7 days but within 1 month; and a third group operated after 1 month but within 3 months. The 3 groups were compared in terms of baseline, intra-operative, and post-operative morbidity and mortality. Multivariate analysis was carried out to assess the independent influence of timing of CABG on outcomes.

There was no difference in terms of previous neurological events (p = 0.554), presence of carotid artery disease (p = 0.555), prevalence of hypertension (p = 0.119), diabetes (p = 0.144), hypothyroidism (p = 0.53), chronic obstructive pulmonary disease (p = 0.079), peripheral vascular disease (p = 0.771), and impaired left ventricular function (p = 0.072). On univariate analysis, mortality risk was highest between 1 week and 1 month (p = 0.003). Multivariate analysis showed that the closer the MI and CABG duration, the higher the mortality (co-efficient -0.517; p = 0.019; odds ratio = 0.596; 95% CI: 0.388-0.917).

The duration between MI and CABG has a direct influence on outcomes after CABG. While it is clear that the longer the duration between MI and CABG, the lower the mortality risk, it is however difficult to decide on an exact cut-off time frame.