Determinants of Left Ventricular Systolic Function One Year after Primary Percutaneous Coronary Intervention for ST-elevation Myocardial Infarction in a Middle-Income Country

Background: Little is known about the predictors of left ventricular ejection fraction (LVEF) —an important predictor of mortality— after primary percutaneous coronary intervention (PCI) in low- and middle-income countries. Methods: In a prospective cohort study at Imam Ali hospital, Kermanshah, Iran, we enrolled consecutive ST-elevation myocardial infarction (STEMI) patients treated with primary PCI (2016-2018) and followed them up to one year. LVEF levels were measured by echocardiography, at baseline and one-year follow-up. Determinants of preserved/improved LVEF were assessed using multi-variable logistic regression models. Results: Of 803 patients (mean age 58.53±11.7 years, 20.5% women), baseline LVEF levels of ≤35% were reported in 44%, 35- 50% in 40%, and ≥50% in 16% of patients. The mean ± SD of LVEF increased from 38.13%±9.2% at baseline to 41.49%±9.5% at follow-up. LVEF was preserved/improved in 629 (78.3%) patients. Adjusted ORs (95% CIs) for predictors of preserved/improved LVEF showed positive associations with creatinine clearance, 1.01 (1.00-1.02) and adherence to clopidogrel, 2.01 (1.33-3.02); and inverse associations with history of myocardial infarction (MI), 0.44 (0.25-0.78); creatine kinase MB (CK-MB), 0.997 (0.996- 0.999); door-balloon time (3rd vs. 1st tertile), 0.62 (0.39-0.98); number of diseased vessels (2 and 3 vs. 1: 0.63 (0.41-0.99) and 0.58 (0.36-0.93), respectively); and baseline LVEF (35-50% and ≥50% vs. ≤35%: 0.45 (0.28-0.71) and 0.19 (0.11-0.34), respectively). Conclusion: Adherence to clopidogrel, short door-balloon time, high creatinine clearance, and lower baseline LVEF were associated with preserved/improved LVEF, while history of MI, high CK-MB, and multi-vessel disease were predictors of reduced LVEF. Long-term drug adherence should be considered for LVEF improvement in low- and middle-income countries.