Restrictive Versus Liberal Blood Transfusion Strategy in Patients with Acute Myocardial Infarction: A Meta-Analysis of Randomized Clinical Trials

Background: A meta-analysis of observational studies comparing differences in outcomes between restrictive blood transfusion (RBT) and liberal blood transfusion (LBT) in patients with acute myocardial infarction (AMI) reported that LBT is associated with higher all-cause mortality. Few randomized clinical trials (RCTs) have compared RBT to LBT in patients with AMI and anemia, but no meta-analysis of RCTs was performed to date. Aim: To assess the clinical effect of RBT compared to LBT in patients with AMI and anemia regarding was all-cause mortality, recurrent MI, revascularization, and heart failure exacerbation. Methods: The electronic databases Ovid MEDLINE, EMBASE, Cochrane Central, Scopus, and Google Scholar, were systematically searched to identify eligible studies published before June 19th, 2021. RCTs that assessed the effect of RBT compared to LBT were included. The primary endpoint was all-cause mortality. Secondary endpoints included recurrent MI, revascularization, and heart failure exacerbation. Results: Three RCTs with 821 patients were included (421 received RBT, and 400 received LBT). The mean age was 75.9 +/- 6.1 years, and 56% were male. Our meta-analysis showed that RBT was not associated with reduced all-cause mortality (RR = 1.61; 95% CI = 0.38-6.96, p = 0.52), recurrent MI (RR = 0.98; 95% CI = 0.48-1.96, p = 0.94), revas-cularization (RR = 1.18; 95% CI = 0.26-5.44, p = 0.83) and heart failure exacerbation (RR = 0.86; 95% CI = 0.23-3.22, p = 0.82) when compared to LBT. Conclusion: RBT was not associated with reduced all-cause mortality, recurrence of MI, need for revascularization, or heart failure exacerbation in patients with AMI and anemia compared to LBT. A larger RCT is required to confirm the above findings.