Comparison of clinical outcomes between direct and indirect transfer in patients with ST-segment elevation myocardial infarction

Primary percutaneous coronary intervention (PCI) is the cornerstone of treatment for ST-segment elevation myocardial infarction (STEMI). Previous studies suggest that direct transport by ambulance to a primary PCI facility is associated with better clinical outcomes in patients with STEMI. However, those studies included seriously ill patients for whom direct transport is the only option. We included 462 patients with STEMI who were supposed to select either direct transport by ambulance or indirect transport via primary care doctor, and compared the clinical outcomes between the direct transfer group (n = 172) and the indirect transfer group (n = 290). The primary endpoint was major adverse cardiovascular events (MACE), which was defined as the composite of all-cause death, non-fatal myocardial infarction, re-admission for heart failure, and target vessel revascularization. The median follow-up duration was 540 days (86-1266 days). Age was significantly higher in the indirect transfer group [72.0 (64-80) years] than in the direct transfer group [69.5 (58.3-77) years] (p = 0.013). Onset to balloon time was significantly shorter in the direct transport group (p < 0.001). The Kaplan-Meier curves revealed that MACE were similarly observed between the two groups (31.4% vs. 27.2%; p = 0.330). After adjusting for potential confounders, indirect transfer was not associated with MACE (adjusted hazard ratio: 0.740, 95% confidence interval: 0.485-1.128, p = 0.161). In conclusion, indirect transfer was not associated with poor clinical outcomes in patients with STEMI who were supposed to select either direct transport or indirect transport.