Morphine and P2Y12 Inhibitors in ST-Elevation Myocardial Infarction: An Updated Meta-Analysis

Morphine is used to control pain in ST-elevation myocardial infarction but reduces P2Y12 inhibition. It is not known if this modulation of platelet inhibition appreciably affects clinical outcomes. We screened 979 articles and identified seven studies that met the eligibility criteria for meta-analysis. Outcomes included 11 metrics across angiographic and clinical domains. A random effects model assessed heterogeneity between studies. The opiate group showed decreased achievement of postprocedural thrombolysis in myocardial infarction (TIMI) 2 flow relative to placebo [risk ratio (RR) 0.71, 95% confidence interval (CI) 0.52-0.97, p = 0.03, I = 0.0%]. All other metrics listed below showed no statistically significant difference between groups: infarct size, microvascular obstruction, microvascular/salvage index, absence of pre- percutaneous coronary intervention (PCI) TIMI 3 flow, postprocedural TIMI 2 flow, postprocedural TIMI 3 flow, all-cause mortality, stroke, repeat MI, unstable angina, and left ventricular ejection fraction. However, there were no statistically significant differences in infarct size [odds ratio (OR) - 0.12, 95% CI - 0.37 to 0.17, p = 0.42], microvascular obstruction [standard mean difference (SMD) = 0.02, 95% CI - 0.12 to 0.16, p = 0.82], microvascular obstruction/salvage index (SMD = - 0.05, 95% CI - 0.24 to 0.13, p = 0.57), absence of pre-PCI TIMI 3 flow (OR 0.98, 95% CI 0.79-1.22, p = 0.87), and postprocedural TIMI 3 flow (OR 1.23, 95% CI 0.84-1.79, p = 0.28) between the two groups. In STEMI, opiates correlate with worse angiographic outcomes, specifically postprocedural TIMI 2 flow. However, this observation does not appear to be clinically consequential.