Background: Although antiarrhythmic drugs are effective at preventing arrhythmias and reducing the associated symptoms, they carry a considerable risk of proarrhythmias among other toxic effects, that warrants their judicial use and careful monitoring. Clinical pharmacists play an important role in resolving and preventing drug therapy problems through their interventions. The aim of the study was to describe prescribing trends and resulting adverse effects of antiarrhythmic drugs at Sultan Qaboos University Hospital, and to analyze clinical pharmacist interventions in antiarrhythmic drug management in terms of drug therapy problems, intervention rate, physician acceptance and clinical significance. Methods: This was a retrospective observational study that was carried out by reviewing electronic patient records of adult patients (≥18 years) who received at least one dose of the available antiarrhythmic drugs (procainamide, lidocaine, flecainide, atenolol, bisoprolol, carvedilol, esmolol, propranolol, amiodarone, sotalol, diltiazem, verapamil, adenosine, digoxin and magnesium sulphate) for any arrhythmia at Sultan Qaboos University Hospital during the study period from January 2020 to December 2021. Results: A total of 400 patients were enrolled. The overall mean age of the cohort was 62.5 ± 16.6 years ranging from 19 to 96 years with 55.3% (221/400) of the patients being male. Atrial arrhythmias consisting of atrial fibrillation and atrial flutter were the most common types of arrhythmias observed (313/400, 78.3%). The majority of the prescriptions were beta-blockers (337/500, 67.4%) with bisoprolol particularly being the highest prescribed antiarrhythmic drug (262/500, 52.4%) at a dose of 5 mg once-daily (111/500, 22.2%) followed by carvedilol (64/500, 12.8%) and amiodarone (58/500, 11.6%). Class III (60/500, 12%) and the miscellaneous agents (48/500, 9.6%) were the second and third most prescribed AADs respectively. Class IV agents (18/500, 3.6%) were the least prescribed AADs. Monotherapy was prescribed for 75% (300/400) of the patients and dual therapy for 25% (100/400) of the patients. A total of 109 adverse effects were documented for 86 prescriptions in 20.5% (82/400) of the patients. Considering the adverse effects due to the patients' most recent prescriptions only, a total of 57 adverse effects were noted for 45 prescriptions in 45 patients, resulting in an overall incidence of 9% (45/500). Among the various classes of antiarrhythmic drugs, amiodarone (Class III) was responsible for the highest incidence of adverse effects (9/60, 15%), followed by miscellaneous antiarrhythmic drugs (7/48, 14.6%). Cardiovascular adverse effects comprised the majority of the reported adverse effects (41/109, 37.6%) with bradycardia being the most common complication (27/109, 24.8%) caused by beta-blockers (n=17), amiodarone (n=5) and digoxin (n=5). Risk factors associated with adverse effects included patients with coronary artery disease (18.6% vs. 31.7%; p=0.015) and those who were on antiarrhythmic drug therapy for more than 10 years (4.1% vs. 9.6%; p=0.045). A total of 122 clinical pharmacist interventions were recorded in 13% (52/400) of the patients. Beta-blockers were associated the highest number of interventions (61/122, 50%) with both bisoprolol and carvedilol being responsible for 28 prescriptions each. Patients with older age (61.84 years vs. 66.75 years; p=0.047), co-morbidities (83.6% vs. 96.2%; p=0.019), the presence of renal impairment (19.6% vs. 40.4%; p=0.001) or heart failure (11.8% vs. 28.9%; p=0.002), those vii with concomitant medications (84.5% vs. 98.1%; p=0.004), polypharmacy (51.1% vs. 69.2%; p=0.022) and those who received antiarrhythmic drug therapy for a period of less than one year (9.3% vs. 27.3%; p<0.001) were significantly associated with a greater need for intervention compared to those patients who did not have these risk factors. Conclusion: Antiarrhythmic drugs from all classes were used to treat various kinds of arrhythmias at Sultan Qaboos University Hospital. Beta-blockers (Class II) were the most commonly prescribed antiarrhythmic drugs. Amiodarone (Class III) was associated with the highest incidence of adverse effects in the utilization period. The safe and effective use of antiarrhythmic drugs was aided by clinical pharmacist interventions.