Incidence, Predictors, and In-Hospital Clinical Outcomes of Significant Distal Non-Culprit Coronary Lesions in Patients with ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention for Proximal Culprit Lesions

Abstract

Objective: To determine the incidence of significant distal non-culprit coronary lesions, identify their independent clinical predictors, and evaluate their association with adverse in-hospital outcomes among ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI) for proximal culprit lesions. Methodology: This retrospective observational cohort study included consecutive adult patients with STEMI who underwent PPCI for angiographically confirmed proximal culprit lesions were identified from the institutional cardiac registry. Significant distal non-culprit lesions were defined as angiographic stenosis ≥70% or physiologically significant lesions identified by fractional flow reserve (FFR ≤0.80) or quantitative flow ratio (QFR ≤0.80), when available. Results: A total of 8,591 patients were included, of whom 1,099 (12.8%) had significant distal non-culprit lesions. Independent predictors included male sex (adjusted OR 1.42, 95% CI 1.19–1.69; p<0.001), age ≥50 years (adjusted OR 1.50, 95% CI 1.27–1.78; p<0.001), and diabetes mellitus (adjusted OR 1.55, 95% CI 1.35–1.78; p<0.001). Smoking demonstrated an inverse statistical association (adjusted OR 0.78, 95% CI 0.64–0.96; p=0.020), although this finding should not be interpreted as a protective biological effect. Patients with distal lesions experienced higher crude rates of all-cause in-hospital mortality, heart failure, and cardiogenic shock. Following multivariable adjustment, distal non-culprit lesions remained independently associated only with all-cause in-hospital mortality (adjusted OR 1.21, 95% CI 1.01–1.46; p=0.041). Conclusion: Significant distal non-culprit lesions were identified in approximately one in eight STEMI patients undergoing PPCI for proximal culprit lesions. Male sex, increasing age, and diabetes mellitus independently predicted their presence. Although distal lesions were associated with worse crude in-hospital outcomes, only mortality remained independently associated after adjustment.