INTRAVENOUS DILTIAZEM FOR THE TREATMENT OF PATIENTS WITH ATRIAL-FIBRILLATION OR FLUTTER AND MODERATE TO SEVERE CONGESTIVE-HEART-FAILURE

The objective of this multicenter, randomized, double-blind, placebo-c ontrolled study was to determine the! safety and efficacy of intraveno us diltiazem in the treatment of 37 patients with rapid (ventricular r ate, mean +/- SD 142 +/- 17 beats/min) atrial fibrillation or nutter a nd moderate to severe congestive heart failure (ejection fraction, mea n +/- SD 36 +/- 14%; New York Heart Association class III [23 patients ], class IV [14 patients]). During the double-blind portion of the stu dy, patients received either intravenous diltiazem, 0.25 mg/kg over 2 minutes, or placebo followed 15 minutes later by diltiazem or placebo, 0.35 mg/kg over 2 minutes, if the first dose was tolerated but ineffe ctive. Placebo nonresponders were given open-label intravenous diltiaz em in a similar fashion as in the double-blind portion of the study. I n the double-blind part of the study, 21 (18 with 0.25 mg/kg, 3 with a n additional 0.35 mg/kg) of the 22 patients (95%) responded to diltiaz em, and 0 of 15 patients (0%) responded to placebo (p <0.001). AII 15 patients (13 with 0.25 mg/kg and 2 with an additional 0.35 mg/kg) who received placebo during the double-blind period had a therapeutic resp onse to diltiazem during open-label therapy. Overall, 36 of 37 patient s (97%) had a therapeutic response to intravenous diltiazem. Heart rat e response to diltiazem after tbe 2-minute bolus infusions consisted o f a greater than or equal to 20% decrease in heart rate from baseline in 36 patients; in addition, 17 patients also had heart rates decrease d to <100 beats/min, whereas no patient had conversion to sinus rhythm . The median time to response from the beginning of the 2-minute bolus dose of diltiazem was about 5 minutes. Hypotension was the most commo n adverse event occurring in 4 of the 37 patients (11%). No patient ha d an exacerbation of congestive heart failure due to diltiazem. In con clusion, intravenous diltiazem is rapid, safe, and effective in acutel y lowering a rapid ventricular rate in patients with atrial fibrillati on or nutter and moderate to severe congestive heart failure.