Frequency of in-hospital new-onset arrhythmias and conduction blocks among patients with acute coronary syndrome

Background: Acute coronary syndrome is frequently complicated by rhythm disturbances during early admission. Local data on new-onset arrhythmias and conduction blocks remain limited, particularly during the first 24 hours of hospitalization. The purpose of the study was to determine the frequency of in-hospital new-onset arrhythmias and conduction blocks among patients admitted with acute coronary syndrome at Khyber Teaching Hospital, Peshawar. Methods: A descriptive study was conducted in the Department of Cardiology, Khyber Teaching Hospital, Peshawar, from February 2026 to June 2026. Consecutive patients aged 18 to 80 years with ST-elevation myocardial infarction, non-ST-elevation myocardial infarction, or unstable angina were enrolled. Patients with previous arrhythmia or conduction block, permanent pacemaker or implantable cardioverter-defibrillator, significant electrolyte disturbance, or poor-quality ECG recordings were excluded. All patients underwent continuous cardiac monitoring for the first 24 hours. Rhythm abnormality or conduction delay was confirmed by 12-lead ECG. Data were analyzed using SPSS version 27. Results: A total of 151 patients were included. The median age was 60.0 years. Males were 55.6%, and STEMI was the main presentation, seen in 78.1%. New-onset arrhythmia was detected in 88 patients, giving a frequency of 58.3%. Conduction block was detected in 63 patients, with a frequency of 41.7%. Overall, 145 patients had at least one rhythm or conduction abnormality. Ventricular tachycardia was the most frequent arrhythmia, followed by atrial fibrillation. Third-degree atrioventricular block was the commonest conduction defect. Conclusion: Early rhythm and conduction abnormalities were common in acute coronary syndrome. Careful cardiac monitoring during the first 24 hours remains important.