Restrictive versus liberal transfusion for anemic patients with acute myocardial infarction: Systematic review and meta-analysis

Abstract

• Meta-analysis of RCTs comparing transfusion thresholds for patients with acute MI and anemia failed to exclude either appreciable harm or benefit. • The mechanism by which blood transfusions are thought to improve outcomes in patients with MI and anemia requires further investigation. • Additional research utilizing published results from larger randomized controlled trials is needed to understand the relative safety of liberal to restrictive blood transfusion strategies and overcome the quality limitations of current evidence. The optimal blood transfusion threshold for patients with acute myocardial infarction (MI) and anemia is unclear. This meta-analysis aimed to assess the safety of restrictive transfusion to liberal thresholds. We searched MEDLINE, EMBASE, Web of Science, and CENTRAL for randomized controlled trials comparing different transfusion strategies in patients with acute MI. Two independent reviewers screened the studies for inclusion, extracted data, evaluated methodological quality, and assessed the quality of evidence. Primary outcomes were all measured at 30-days post-randomization and included: All-cause mortality, heart failure, recurrent MI, and stroke. A random-effects model was used. Our searches yielded a total of 5980 unique results. Three studies were eligible and included in the analysis (n = 821 patients). In all studies, the restrictive and liberal thresholds were equivalent to 8g/dL and 10g/dL hemoglobin, respectively. There was no significant difference in all-cause mortality (RR = 0.63; 95% CI 0.15 to 2.66; P = 0.53; I 2 = 59%), heart failure (RR = 1.17; 95% CI 0.31 to 4.34; P = 0.82; I 2 = 70%), recurrence of MI (RR = 1.61; 95% CI 0.65 to 4.02; P = 0.30; I 2 = 0%), or stroke (RR = 1.41; 95% CI 0.27 to 7.43; P = 0.69; I 2 = 0%). Our meta-analysis found no significant difference in the primary outcomes between transfusion strategies for patients with acute MI and anemia. Results from trials with larger sample sizes is needed to clarify the dilemma between transfusion strategies in this population.