Is there any difference between blood and crystalloid cardioplegia for myocardial protection during cardiac surgery? A meta-analysis of 5576 patients from 36 randomized trials

Abstract

Objective: To compare the efficacy of blood versus crystalloid cardioplegia for myocardial protection in patients undergoing cardiac surgery. Methods: MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, LILACS, Google Scholar and reference lists of relevant articles were searched for clinical studies that reported in-hospital outcomes after blood or crystalloid cardioplegia for myocardial protection during cardiac surgery procedures from 1966 to 2011. The principal summary measures were risk ratio (RR) for blood compared to crystalloid cardioplegia with 95% Confidence Interval (CI) and P values (considered statistically significant when <0.05). The RRs were combined across studies using the DerSimonian-Laird random effects model and fixed effects model using the Mantel-Haenszel model - both models were weighted. The meta-analysis was completed using the software Comprehensive Meta-Analysis version 2 (Biostat Inc., Englewood, New Jersey). Results: Thirty-six studies (randomized trials) were identified and included a total of 5576 patients (2834 for blood and 2742 for crystalloid). There was no significant difference between the blood and crystalloid groups in the risk for death (risk ratio [RR] 0.951, 95% CI 0.598 to 1.514, P=0.828, for both effect models) or myocardial infarction (RR 0.795, 95% CI 0.547 to 1.118, P=0.164, for both effect models) or low cardiac output syndrome (RR 0.765, 95% CI 0.580 to 1.142, P=0.094, for the fixed effect model; RR 0.690, 95% CI 0.480 to 1.042, P=0.072, for the random effect model). It was observed that there was no publication bias or heterogeneity of effects about any outcome. Conclusion: We found evidence that argues against any superiority in terms of hard outcomes between blood or crystalloid cardioplegia for myocardial protection during cardiac surgery.