Background <p>Reperfusion-induced ventricular arrhythmias (VAs) are a common yet under-recognized complication in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Their clinical impact and predictors remain incompletely understood.</p> Objectives <p>This study aimed to evaluate the incidence, distribution, risk factors, and prognostic significance of reperfusion-related VAs in a contemporary STEMI population treated with PPCI.</p> Methods <p>We retrospectively analyzed 736 STEMI patients who underwent PPCI between 2018 and 2023. Continuous telemetry monitoring was used to detect VAs, including premature ventricular contractions (PVCs), accelerated idioventricular rhythm (AIVR), non-sustained ventricular tachycardia (NSVT), sustained ventricular tachycardia (VT), and ventricular fibrillation (VF). Logistic regression models were applied to identify independent predictors of VA occurrence and assess their association with in-hospital major adverse cardiovascular events (MACE).</p> Results <p>VAs were observed in 48.8% of patients, with frequent PVCs (43.7%) and AIVR (18.9%) being the predominant subtypes. Multivariate analysis identified extensive anterior infarction and left anterior descending artery (LAD) involvement as independent predictors of VA development (<i>p</i> = 0.032). The presence of VAs was significantly associated with higher rates of in-hospital MACE, including cardiac death, recurrent myocardial infarction, and urgent target vessel revascularization.</p> Conclusions <p>Reperfusion-related VAs are common following PPCI for STEMI and carry a substantial adverse prognostic impact. Early identification of high-risk patients based on infarct characteristics and continuous arrhythmia monitoring is essential to improve clinical outcomes. Further prospective studies are warranted to refine management strategies targeting reperfusion arrhythmias.</p>