title: Effects of nadolol on the spontaneous and exercise-provoked heart rate of patients with chronic atrial fibrillation receiving stable dosages of digoxin.
abstract: Nadolol, a long-acting beta-adrenergic-blocking agent, was evaluated in 20 patients with chronic atrial fibrillation by means of a randomized, double-blind, crossover study. Patients were required either to demonstrate resting heart rates in excess of 80 bpm or to show a rate of 120 bpm or an increment of greater than 50 bpm during mild treadmill exercise provocation (3 minutes, 1.75 mph, 10% grade). With placebo the group averaged a heart rate of 92 +/- 19 bpm, determined by 24 hours of ambulatory ECG recordings; this rate was significantly reduced to 73 +/- 16 bpm (p less than 0.001) with nadolol (mean dosage, 87 +/- 43 mg/day). During standardized exercise testing, heart rates increased to 153 +/- 26 bpm with placebo and to 111 +/- 24 bpm with nadolol (p less than 0.001), representing 65% and 52% increments, respectively. Digoxin blood levels averaged 0.8 +/- 0.5 ng/ml with placebo and were similar with nadolol (0.9 +/- 0.4; p = NS). Total exercise time on a modified Bruce treadmill protocol was 466 +/- 143 seconds with placebo and was significantly decreased by nadolol (380 +/- 143; p less than 0.01). During initial dose titration with nadolol, one patient was dropped from study for intolerable fatigue and one for worsened claudication. No patients were dropped from the double-blind treatment periods, although two patients receiving nadolol and one patient receiving placebo complained of moderate fatigue. We conclude that nadolol is a safe and effective agent for the control of spontaneous and exercise-provoked heart rates in patients with chronic atrial fibrillation who were already receiving digoxin treatment.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000188:drug therapy*; D002986:Clinical Trials as Topic; D004077:Digoxin / Q000627:therapeutic use*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009248:Nadolol; D005082:Physical Exertion; D011412:Propanolamines / Q000627:therapeutic use*; D011897:Random Allocation; D013997:Time Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D009248:Nadolol; D004077:Digoxin