Huang X, et al. - In this study involving patients with non-anterior ST-elevation myocardial infarction (NA-STEMI) from the HORIZONS-AMI trial, researchers investigated clinical, electrocardiographic (ECG), and angiographic characteristics that may be predictive of 3-year mortality following primary percutaneous coronary intervention (PCI). ST-segment elevation in lateral (V5, V6, I, aVL), inferior (II, III, aVF), or inferolateral (I, II, III, aVF, and V5-V6) ECG leads or posterior myocardial infarction with ST-segment depression of ≥ 1 mm in ≥ 2 contiguous anterior leads defined NA-STEMI. Independent predictors of 3-year mortality were determined by Cox regression. No prior coronary artery bypass grafting was performed on 2,578/3,602 patients in the HORIZONS-AMI trial. These individuals had single-vessel PCI, and had baseline ECG data assessed in an independent core laboratory. NA-STEMI was detected in 1,495 patients. A better prognosis was observed in association with NA-STEMI vs anterior STEMI, but high-risk patient cohorts with NA-STEMI may be identified who have substantial 3-year mortality. Older age (median: > 59.0 years of age), diabetes, reduced LVEF (≤ 50%), Killip class ≥2, post-procedure TIMI flow 0–2 vs 3, renal insufficiency, and ST-resolution < 30% at 60 minutes post-PCI were identified as independent predictors of increased 3-year mortality in NA-STEMI.