Cilostazol for heart rate increase in atrial fibrillation with slow ventricular response: an exploratory randomized controlled trial

Abstract Background Atrial fibrillation (AF) with slow ventricular response is a clinically challenging condition, particularly in elderly patients with multiple comorbidities. Current therapeutic options for the chronic pharmacological management of bradycardia remain limited. The aim of this study was to evaluate the effects of cilostazol on heart rate (HR) and ventricular arrhythmia in patients with permanent AF and a slow ventricular response. Methods This was a randomized, double-blind, placebo-controlled trial including 26 patients with permanent AF and a mean HR 65bpm on 24-hour Holter monitoring. Patients were randomized to receive cilostazol 100mg twice daily (n=14) or placebo (n=12) for 3 months. The primary endpoint was the increase in mean HR. Results After 30 days of treatment, the cilostazol group demonstrated a significant increase in minimum HR (from 34.17 to 39.14 bpm; p=0.032) and mean HR (from 55.42 to 64.43 bpm; p=0.013) compared to placebo. The total number of QRS complexes increased significantly (from 73879 to 85249 p=0.029), and the number of cardiac pauses (2.5s) was significantly reduced (mean from 56.25 to 2.57 and median from 5.5 to 0.0 p=0.018). No significant differences were observed in the incidence of ventricular arrhythmias. Adverse effects were mild and included headache and gastrointestinal symptoms, with no statistical difference between groups. Conclusion Cilostazol significantly increased HR in patients with AF and slow ventricular response without increasing ventricular arrhythmias. These findings suggest that cilostazol may represent a pharmacological alternative for selected patients when pacemaker implantation is not immediately feasible.