Modulation of ventricular rate in permanent atrial fibrillation: randomized, crossover study of the effects of slow-release formulations of gallopamil, diltiazem, or verapamil.

BACKGROUND

The management of permanent atrial fibrillation (PAF) consists primarily of long-term anticoagulation with either aspirin or warfarin to prevent systemic embolization, and modulation of ventricular rate (VR) to improve cardiac function by prolonging the ventricular diastolic filling time.

HYPOTHESIS

The effects of slow-release formulations of gallopamil (100 mg b.i.d.), diltiazem (120 mg b.i.d.), or verapamil (120 mg b.i.d.) on VR were evaluated in 18 patients with PAF without organic heart disease.

METHODS

In all patients, each treatment was administered randomly, was compared with oral digoxin, and was assessed by 24-h Holter monitoring during daily life and by a 6-min walking test.

RESULTS

There were no significant differences in mean and minimum VR recorded during 24-h Holter monitoring among the four treatments. Peak heart rates recorded during the 6-min walking test with digoxin treatment was 167 +/- 12 beats/min. This was significantly reduced by gallopamil (149 +/- 23 beats/min, p = 0.01), diltiazem (142 +/- 24 beats/min, p < 0.001), and verapamil (137 +/- 30 beats/min, p < 0.001). There were no significant differences in peak VR during the walking test among the three calcium antagonists. Pauses of > 3 s were observed in 3 of 18 (17%) patients who received digoxin (max 3.4 s) and in 5 of 18 (28%) patients who received diltiazem (max 3.4 s); p = NS. Periods of bradycardia < 30 beats/min were observed in 5 of 18 (28%) patients during digoxin treatment, and in 3 of 18 (17%) patients during treatment with gallopamil, diltiazem, and verapamil; p = NS.

CONCLUSION

Gallopamil, diltiazem, or verapamil are superior to digoxin in controlling VR during mild exercise in patients with PAF without organic heart disease. The reduction of peak VR is obtainable without further slowing of resting VR. However, gallopamil appears to be the least effective calcium blocker at controlling resting and exercise VR; thus, there are no advantages over the other calcium blockers in its use in the clinical setting.