Elsevier

The American Journal of Cardiology

Volume 164, 1 February 2022, Pages 44-51
The American Journal of Cardiology

Meta-Analysis of Nonrandomized Studies to Assess the Optimal Timing of Coronary Artery Bypass Grafting After Acute Myocardial Infarction

https://doi.org/10.1016/j.amjcard.2021.10.033Get rights and content

The optimal timing of coronary artery bypass grafting (CABG) in patients after an acute myocardial infarction (MI) is unknown. We performed a systematic review and meta-analysis of studies comparing mortality rates in patients who underwent CABG at different time intervals after acute MI. Bias assessments were completed for each study, and summary of proportions of all-cause mortality were calculated based on CABG at various time intervals after MI. A total of 22 retrospective studies, which included a total of 137,373 patients were identified. The average proportion of patients who died when CABG was performed within 6 hours of MI was 12.7%, within 6 to 24 hours of MI was 10.9%, within 1 day of MI was 9.8%, any time after 1 day of MI was 3.0%, within 7 days of MI was 5.9%, and any time after 7 days of MI was 2.7%. Interstudy heterogeneity, assessed using I2 values, showed significant heterogeneity in death rates within subgroups. Only 1 study accounted for immortal time bias, and there was a serious risk of selection bias in all other studies. Confounding was found to be a serious risk for bias in 55% of studies because of a lack of accounting for type of MI, MI severity, or other verified cardiac risk factors. The current publications comparing timing of CABG after MI is at serious risk of bias because of patient selection and confounding, with heterogeneity in both study populations and intervention time intervals.

Section snippets

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement was followed and is detailed in Supplementary Figure 1. Studies published between 2000 and 2020 were identified using MEDLINE, the search syntax used for literature review is listed in Supplementary Table 1. This systematic review was not registered on PROSPERO.

Studies included in the systematic review were nonrandomized retrospective studies that compared mortality in patient groups who underwent CABG after acute

Results

In total 22 retrospective studies, evaluating 137,373 patients, were identified evaluating either 30-day or in-hospital mortality in patients who underwent CABG after acute MI. A total of 9 studies were multi-center registries or population-level databases, whereas 13 studies were from a single institution. A total of 12 studies evaluated CABG after MI (nonspecified), whereas 4 studied CABG after STEMI. CABG after NSTEMI was studied in 5 reports, and CABG after transmural MI was evaluated in 1

Discussion

The present study provides new information by summarizing the proportion of patients who die if they do undergo CABG within a certain period after MI. This is beneficial for prognostic purposes and to inform shared decision-making; however, we would caution that it is insufficient to compare mortality across subgroups in such a way that one might say that waiting longer improves survival as these associations are not likely causal. Although delayed CABG is associated with improved CABG-related

Disclosures

The authors have no conflicts of interest to declare.

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