Restrictive versus liberal red cell transfusion strategies in patients with acute myocardial infarction: a systematic review and meta-analysis

Abstract BackgroundAnemia is frequent in patients with acute myocardial infarction(AMI), and the optimal red blood cell transfusion strategy for patients with AMI and anemia is still controversial. We aimed to compare the efficacy of restrictive and liberal red cell transfusion strategies in patients with AMI and anemia.MethodsWe systematically searched PubMed, EMBASE, Web of Science, Cochrane Library, and Clinicaltrials.gov, from their inception until March 2021. Inclusion criteria were clinical trials that compared the efficacy of restrictive and liberal transfusion strategies in patients with AMI and anemia on all-cause mortality and major adverse cardiovascular events. The primary outcome was all-cause mortality, including overall mortality, in-hospital, or follow-up mortality. Risk ratios (RR) with 95% confidence intervals (CI) were presented and pooled by random-effects models. ResultsThe search yielded a total of 6630 participants in six studies. Among the included patients, the average age ranged from 69.0 to 79.5 years and 2950 (44.5%) were men. A total of 2008 patients received restrictive red blood transfusion while 4622 patients were given liberal red blood transfusion. No difference was found in overall mortality and follow-up mortality between restrictive and liberal blood transfusion groups (RR=1.07, 95% CI=0.82–1.40, P=0.62; RR=0.89, 95% CI=0.56–1.42, P=0.62). However, restrictive transfusion was associated with a higher risk of in-hospital mortality compared with liberal transfusion (RR=1.22, 95% CI=1.00–1.50, P=0.05). No secondary outcomes, including follow-up reinfarction, stroke, and acute heart failure, differed significantly between the two groups. In addition, subgroup analysis showed no differences in overall mortality between the two groups based on sample size and design.ConclusionRestrictive and liberal red blood transfusion have a similar effect on overall mortality and follow-up mortality in patients with AMI and anemia. However, restrictive transfusion was associated with a higher risk of in-hospital mortality compared with liberal transfusion. The findings suggest that transfusion strategy should be evaluated in the more future researches.