Effect of metformin on outcome in patients undergoing primary percutaneous coronary intervention for st-segment elevation myocardial infarction

Methods From January 2004 until June 2013, all consecutive critically ill patients undergoing primary PCI for STEMI at the University Medical Center Groningen were included in a registry and 1-year follow-up was obtained. Our primary endpoint consisted of the composite endpoint of myocardial infarction, target vessel and target lesion revascularization, and all-cause mortality (MACE). The secondary endpoint, myocardial infarction size, was estimated using peak levels of creatine kinase (CK), the myocardial band of CK (CK-MB), troponin T, and high-sensitive troponin T (hs-troponin T). The effect of metformin on myocardial infarct size from the 2004-2010 cohort has been reported previously [1]. Therefore myocardial infarction size was reported for patients admitted from 2011 until 2013 and the combined 2004-2013 cohort. Results In total, 4776 consecutive patients underwent primary PCI for STEMI, 719 (15%) diabetic patients were included in the final analysis and 215 (30%) patients used metformin at admission. MACE and mortality rates were 21% and 12% for patients with diabetes, 23% and 19% for metformin patients, 21% and 15% for patients on sulfonylurea, and 30% and 20% for patients on insulin, respectively. Metformin was not associated with reduced risk for MACE (adjusted hazard ratio (aHR): 1.19 (95% confidence interval (95%CI) 0.78-1.81), P = 0.42) or survival benefit (aHR: 0.23 (CI95% 0.802.51), P = 0.23) compared to diabetic patients not using metformin. Insulin use was an independent predictor for MACE (aHR 1.73 (CI95% 1.13-2.65), P = 0.01) and all-cause mortality (aHR 1.81 (CI95% 1.03-3.21), P = 0.04). Baseline levels of CK, CK-MB, and hs-troponin T were comparable between both groups. Median (interquartile range) peak levels of CK, CK-MB, and hs-Troponin T were all non-significant lower in the metformin group (table 1). When both cohorts were combined, peak levels of CK, CK-MB, and troponin T were all significantly lower in patients using metformin, as depicted in table 1.