Weigel F, Nudy M, Krakowski G, et al. - According to findings, there is a serious risk of bias, due to patient selection and confounding, in the current publications comparing timing of coronary artery bypass grafting (CABG) after myocardial infarction (MI). Also, heterogeneity exists in both study populations and intervention time intervals.

• This systematic review and meta-analysis was conducted to determine the optimal timing of CABG in patients after an acute MI.

• Studies that compared death rates in patients who had CABG at different time intervals after acute MI, were included (22 retrospective studies comprising 137,373 patients).

• When CABG was conducted within 6 hours of MI, the average proportion of patients who died was estimated to be 12.7%; these estimates were 10.9%, 9.8%, 3.0%, 5.9%, and 2.7% when CABG was performed within 6 to 24 hours of MI, within 1 day of MI, any time after 1 day of MI, within 7 days of MI, and any time after 7 days of MI, respectively.

• Within subgroups, there appeared significant heterogeneity in death rates.

• Only 1 study accounted for immortal time bias, and all other studies had a serious risk of selection bias.

• In 55% of studies, confounding was identified to be a serious risk for bias due to a lack of accounting for type of MI, MI severity, or other verified cardiac risk factors.