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Sotalol in patients with implanted automatic defibrillators: effects on defibrillation and comparison with amiodarone
Objectives:
Although many patients receiving implanted cardioverter defibrillators receive concomitant antiarrhythmic therapy, the risks and benefits of different agents for such patients are not well understood. It was hypothesized that sotalol, a drug with beta-blocking and class II antiarrhythmic properties would be useful in these patients.
Design:
Nonrandomized prospective cohort study of the effects of sotalol versus other antiarrhythmic therapy on defibrillation energy requirements.
Setting:
Tertiary care referral centre.
Patients:
Patients referred for management of life threatening ventricular arrhythmia in whom an implanted cardioverter defibrillator was indicated on standard clinical grounds.
Interventions:
Intraoperative testing of defibrillation energy requirements, exercise testing, electrophysiological testing.
Main Results:
Fifteen patients were treated with oral sotalol (173.3 +/- 59.8 mg/day). Sotalol blunted maximal heart rate during treadmill exercise (120.9 +/- 29.9 beats/min). Mean right ventricular effective refractory period increased from 251.7 +/- 21.7 to 276.7 +/- 25.7 ms (P = 0.05). All patients received one large (28 cm2) and one small (14 cm2) epicardial electrode patch. The lowest energy to defibrillate successfully from induced ventricular fibrillation (VF) was 5.9 +/- 3.7 J (median 4.1 J), with all patients defibrillated at 15 J or less. In a concurrent comparison group of 16 similar patients not treated with sotalol (13 on amiodarone and three on beta-blockers), with identical or larger patch size, and identical placement, the lowest successful energy to defibrillate from induced VF was significantly higher (16 +/- 8.8 J) (P < 0.05). Mean cycle length of VF from intracardiac recordings was 232 +/- 37 ms, and was significantly inversely correlated with lowest successful energy (r = 0.61, P < 0.05).
Conclusions:
Oral sotalol may be useful in conjunction with an automatic defibrillator; it is associated with low defibrillation energy requirements in humans, and may alter VF.