Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 21 1 2026 04 26 20 31 Rizki Hilman Department of Cardiology, Faculty of Medicine, Dr. Zainoel Abidin Hospital, Universitas Syiah Kuala, Banda Aceh, Indonesia Adi Purnawarman Department of Cardiology, Faculty of Medicine, Dr. Zainoel Abidin Hospital, Universitas Syiah Kuala, Banda Aceh, Indonesia Haris Munirwan Department of Cardiology, Faculty of Medicine, Dr. Zainoel Abidin Hospital, Universitas Syiah Kuala, Banda Aceh, Indonesia Muhammad Ridwan Department of Cardiology, Faculty of Medicine, Dr. Zainoel Abidin Hospital, Universitas Syiah Kuala, Banda Aceh, Indonesia Herlina Dimiati Department of Pediatric, Faculty of Medicine, Dr. Zainoel Abidin Hospital, Universitas Syiah Kuala, Banda Aceh, Indonesia 2025 12 26 2026 02 03 Background: Arrhythmia is a common and clinically significant complication during hospitalization for ST-segment elevation myocardial infarction (STEMI). This study aimed to identify factors associated with the occurrence of arrhythmia in the acute phase of STEMI. Methods: This single-center cross-sectional study was conducted among adult patients hospitalized with STEMI. Demographic and clinical variables, including cardiovascular risk factors and disease severity (Killip class, Thrombolysis in Myocardial Infarction [TIMI] score, and Global Registry of Acute Coronary Events [GRACE] score), were obtained from medical records. The primary outcome was in-hospital arrhythmia, defined as documented atrial or ventricular tachyarrhythmia or clinically significant bradyarrhythmia. Factors associated with arrhythmia were assessed using bivariate analyses followed by multivariable logistic regression. Results: This study involved 113 patients, with a mean age of 56.4 (11.1) years. Arrhythmia occurred in 26.5% (30 patients) during hospitalization. In bivariate analyses, arrhythmia was associated with higher Killip class (P<0.001), higher TIMI score (P=0.005), higher GRACE score (P=0.001), lower tricuspid annular plane systolic excursion (P=0.002), elevated serum potassium level (P=0.010), and impaired renal function, reflected by higher urea (P=0.005) and creatinine levels (P = 0.004). After multivariable adjustment, only Killip class remained independently associated with arrhythmia: patients presenting with Killip class I had a significantly lower risk of arrhythmia than those with higher Killip classes (adjusted OR, 0.404; 95% CI, 0.20 to 0.80; P=0.009). Conclusion: In hospitalized patients with STEMI, arrhythmic risk is chiefly driven by early clinical severity. Killip class is a simple bedside predictor of in-hospital arrhythmia and can aid early risk stratification and monitoring. https://jthc.tums.ac.ir/index.php/jthc/article/view/2417 https://jthc.tums.ac.ir/index.php/jthc/article/download/2417/1242