Effects of cilostazol in patients with bradycardiac atrial fibrillation

OBJECTIVES: Cilostazol, an antithrombotic agent, directly and indirectly increases the heart rate. This study investigated whether cilostazol increases the heart rate, and whether it has chronotropic effects on cardiac failure in patients with bradycardiac atrial fibrillation. METHODS: Twelve patients (6 males and 6 females) with bradycardiac atrial fibrillation underwent Holter monitoring (24-hour total heartbeat counts and frequency of pause), echocardiography (left ventricular end-diastolic diameter, percentage fractional shortening), chest roentgenography (cardiothoracic ratio), and measurements of brain natriuretic peptide and atrial natriuretic peptide before and 6 months after daily oral administration of 100-200 mg cilostazol. RESULTS: Cilostazol administration increased the 24-hour total heartbeat counts from 69,685 +/- 1,690 (mean +/- SE; mean heart rate: 48 beats/min) to 87,352 +/- 3,123 (60), and decreased the frequency of pause from 362.3 +/- 72.9 to 112.3 +/- 41.0. Cardiothoracic ratio decreased from 55.8 +/- 1.1% to 52.5 +/- 1.1%, left ventricular end-diastolic diameter from 56.1 +/- 0.9 to 52.9 +/- 0.8 mm, but percentage fractional shortening was not significantly changed (from 33.0 +/- 2.2% to 33.7 +/- 2.1%). Brain natriuretic peptide decreased from 97.9 +/- 20.5 to 33.5 +/- 4.8 pg/ml, and atrial natriuretic peptide from 69.5 +/- 12.1 to 46.7 +/- 8.3 pg/ml. CONCLUSIONS: Cilostazol has beneficial effects in patients with bradycardiac atrial fibrillation. The increase of heart rate may be mediated by improvement of conductivity in the atrioventricular node and increase of coronary blood supply caused by dilation of vessels.