title: Effect of sotalol on ventricular fibrillation and defibrillation in humans.
abstract: Antiarrhythmic drugs are frequently administered to patients receiving implanted cardioverter defibrillators. Some of these drugs may decrease the efficacy of defibrillation shocks from the defibrillator. Sotalol, a drug with beta-blocking and class III antiarrhythmic properties, lowers defibrillation energy requirements in experimental animals and may do so in humans. Oral sotalol 171 +/- 58 mg was administered before and after device implantation in 25 patients receiving implanted defibrillators. During sotalol therapy, the lowest energy required for successful defibrillation was 5.9 +/- 3.4 J (range 2-15J). In a concurrent nonrandomized comparison group of 23 patients, including 18 treated with amiodarone, the lowest successful energy was 16 +/- 10 J (p < 0.01). In 5 sotalol patients, ventricular fibrillation (VF) could not be induced at all (1 patient) or more than 2 or 3 times (4 patients) despite repeated 60 Hz stimulation. The induced VF had a pronounced tendency to terminate spontaneously, with the termination occurring at up to 23 seconds after the offset of 60 Hz stimulation. The cycle length of the VF was 236 +/- 34 msec, significantly greater than in patients not given drug therapy (191 +/- 21 msec, p < 0.01). In 10 patients, but none of the controls, intracardiac electrograms during surface electrocardiographic VF were regular, monoform, and without low-amplitude diastolic activity. In addition, monophasic action potentials during apparent VF showed maintenance of distinct and normal morphology. The ventricular effective refractory period increased after sotalol (249.4 +/- 19 to 278.4 +/- 24 msec; p < 0.03) and the maximum heart rate response to exercise was limited to 120 +/- 28 beats/min.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Division of Cardiology, St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Dorian
authors.forename: D
authors.initials: D
authors.lastname: Newman
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage*; D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013015:Sotalol / Q000008:administration & dosage*; D014693:Ventricular Fibrillation / Q000503:physiopathology / Q000628:therapy*
chemical_list: D000889:Anti-Arrhythmia Agents; D013015:Sotalol