INTRODUCTION: Ventricular premature depolarizations (VPDs) in the setting of acute coronary syndrome (ACS) were associated with increased hospital mortality in the early revascularization era. OBJECTIVE: Examine the predictive value of VPDs and their morphology for hospital and post-discharge mortality in patients admitted for ACS. METHODS: We identified patients admitted with ACS across 13 Northwell Health Hospitals from 2015 to 2021 and had VPDs captured on a 12-lead ECG or full disclose telemetry. We characterized and reported descriptively the VPDs based on bundle branch block pattern (right or RBBB vs. left or LBBB), frontal (inferior vs. superior) and horizontal (leftward vs. rightward) axis, QRS width, and coupling interval (CI). Hierarchical generalized linear mixed modeling was used to assess the association between VPDs and hospital mortality, while Cox regression was used for post-discharge mortality. RESULTS: Of 18 009 patients admitted for ACS, we identified 627 patients with VPDs with complete data (65.7% RBB, 49.9% superior, and 63.4% leftward axis). Mean VPD QRS width and CI were 175 ± 30 and 523 ± 157 ms, respectively. Hospital mortality was higher in the VPD group (7.8% vs. 4.9%, p <
0.001) with most common mode of death being arrhythmic (28.1% vs. 14.5%). After adjusting for clinical covariates, only VPDs with RBBB patterns were associated with hospital mortality (OR 2.26, 95% CI 1.06-4.82). Conversely, age-adjusted post-discharge mortality was higher only for patients with superior axis VPDs (HR 1.59, 95% CI 1.13-2.24). CONCLUSION: Among patients with VPDs during an ACS admission, presence of RBBB pattern predicts hospital mortality, whereas superior axis is associated with post-discharge mortality.