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Effects of Cilostazol on Heart Rate and its Variation in Patients With Atrial Fibrillation Associated With Bradycardia

Background: Heart-rate (HR) variability is an important predictor of mortality in patients with heart disease. We examined the effects of cilostazol, a quinolinone derivative, on HR and HR variability in patients with chronic atrial fibrillation associated with bradycardia episodes. Patients and Methods: Thirteen patients with chronic atrial fibrillation associated with bra dycardia episodes (minimal HR <40/min and/or pauses, ie, episodes with an RR interval > 2.5 sec) received cilostazol (100 or 200 mg/day) orally for at least 2 months and 24-hour Holter electrocardiography was performed before and after the start of cilostazol administration. Results: Minimal HR was significantly increased, by an average of 14 beats/min (bpm), at 3.3 ± 0.8 weeks (mean ± SD) after the start of cilostazol treatment. The number of pauses was significantly decreased. As a consequence, mean HR was increased by an average of 18 bpm. Maximal HR was also increased by an average of 19 bpm. The circadian variation of the HR, determined by cosine fitting, was not changed by cilostazol treatment. The time-domain HR variabilities, ie, the SD of the mean RR interval and the SD of the 5-minute mean RR intervals, were also unchanged. New York Heart Association functional class was signifi cantly improved and the plasma atrial natriuretic polypeptide level was significantly de creased after the initiation of cilostazol treatment. Conclusion: Cilostazol improves the slow HR episodes associated with chronic atrial fibril lation and maintains the HR circadian variation and time-domain variability, indicating that cilostazol has therapeutic utility for the treatment of the slow HR associated with chronic atrial fibrillation.