Mechanical Unloading of the Left Ventricle before Coronary Reperfusion in Preclinical Models of Myocardial Infarction without Cardiogenic Shock: A Meta-Analysis

Aim: to compare a conventional primary reperfusion strategy with a primary unloading approach before reperfusion in preclinical studies. Methods: we performed a meta-analysis of preclinical studies. The primary endpoint was infarct size (IS). Secondary endpoints were left ventricle end-diastolic pressure (LVEDP), mean arterial pressure (MAP), heart rate (HR), cardiac output (CO). We calculated mean differences (MDs) and associated 95% confidence intervals (CIs). Sensitivity and subgroup analyses on the primary and secondary endpoints, as well as a meta-regression on the primary endpoint using the year of publication as a covariate, were also conducted. Results: 11 studies (n = 142) were selected and entered in the meta-analysis. Primary unloading reduced IS (MD -28.82, 95% CI -35.78 to -21.86, I-2 96%, p < 0.01) and LVEDP (MD -3.88, 95% CI -5.33 to -2.44, I-2 56%, p = 0.02) and increased MAP (MD 7.26, 95% CI 1.40 to 13.12, I-2 43%, p < 0.01) and HR (MD 5.26, 95% CI 1.97 to 8.55, I-2 1%, p < 0.01), while being neutral on CO (MD -0.11, 95% CI -0.95 to 0.72, I-2 88%, p = 0.79). Sensitivity and subgroup analyses showed, overall, consistent results. The meta-regression on the primary endpoint demonstrated a significant influence of the year of publication on effect estimate. Conclusions: in animal models of myocardial infarction, a primary unloading significantly reduces IS and exerts beneficial hemodynamic effects compared to a primary reperfusion.