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.


METHODS
Thirteen patients with chronic atrial fibrillation associated with bradycardia 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 significantly improved and the plasma atrial natriuretic polypeptide level was significantly decreased after the initiation of cilostazol treatment.


CONCLUSIONS
Cilostazol improves the slow HR episodes associated with chronic atrial fibrillation 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.
Toyonaga
S
S
Departments of Internal Medicine I, Faculty of Medicine, and Medical Technology, Faculty of Health Sciences, Okayama University Medical School, Okayama, Japan.
Nakatsu
T
T
Murakami
T
T
Kusachi
S
S
Mashima
K
K
Tominaga
Y
Y
Yamane
S
S
Uesugi
T
T
Kanai
H
H
Tsuji
T
T
D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000097:blood / Q000188:drug therapy*; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000187:drug effects*; D001919:Bradycardia / Q000097:blood / Q000188:drug therapy*; D000077407:Cilostazol; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D018709:Statistics, Nonparametric; D013777:Tetrazoles / Q000494:pharmacology* / Q000627:therapeutic use
D010726:Phosphodiesterase Inhibitors; D013777:Tetrazoles; D009320:Atrial Natriuretic Factor; D000077407:Cilostazol