COMPARISON OF INTRAVENOUS DILTIAZEM AND VERAPAMIL FOR THE ACUTE TREATMENT OF ATRIAL-FIBRILLATION AND ATRIAL-FLUTTER

Study Objectives. To compare the efficacy and safety of intravenous di ltiazem and verapamil in controlling ventricular rate in patients with atrial fibrillation or flutter, and to evaluate the effects of these agents on left ventricular systolic function. Design. Prospective, ran domized, double-blind, crossover study. Setting. University-affiliated hospital and Veterans Administration hospital. Patients. Seventeen me n with atrial fibrillation or flutter with a ventricular rate of 120 b eats/minute or higher and a systolic blood pressure of 100 mm Hg or gr eater. Interventions. Patients received up to two intravenous boluses of either diltiazem or verapamil, followed by an 8-hour continuous inf usion if a therapeutic response was achieved (phase I). after a washou t period, patients who responded were crossed over to receive the othe r drug in a similar fashion (phase II).Measurements and Main Results. At the end of each infusion, the patient's ejection fraction was asses sed by gated angiography. Of the 17 men initially randomized, 8 succes sfully completed both phases I and II. In these patients, baseline mea n (+/- SD) ventricular rates before treatment with intravenous diltiaz em and verapamil were 138 +/- 15 and 132 +/- 9 beats/minute, respectiv ely (NS). At 2 minutes after the initial bolus dose, the mean ventricu lar rate decreased to 100 +/- 13 beats/minute in the diltiazem group c ompared with 114 +/- 17 beats/minute in those receiving verapamil (p<0 .05). Mean ventricular rates of 96 +/- 11 and 97 +/- 9 beats/minute we re maintained during the 8-hour continuous infusion of diltiazem and v erapamil, respectively (NS). On completion of the bolus dose(s) and du ring continuous infusions, there were no significant differences in bl ood pressures between the groups. Mean ejection fractions were 35.6 +/ - 13.6% and 35.5 +/- 15.4% in the diltiazem and verapamil groups, resp ectively (NS). For the 17 patients, the mean maximum percentage decrea ses in blood pressure were not significantly different between groups. However, three patients developed symptomatic hypotension, all of who m were randomized to receive verapamil initially. Conclusion. Intraven ous diltiazem and verapamil are comparable in terms of efficacy and ef fect on systolic function in patients with rapid atrial fibrillation a nd flutter. However, hypotension may limit therapy with verapamil in s ome patients.