Sotalol in patients with implanted automatic defibrillators: effects on defibrillation and comparison with amiodarone.
OBJECTIVE
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.


METHODS
Nonrandomized prospective cohort study of the effects of sotalol versus other antiarrhythmic therapy on defibrillation energy requirements.


METHODS
Tertiary care referral centre.


METHODS
Patients referred for management of life threatening ventricular arrhythmia in whom an implanted cardioverter defibrillator was indicated on standard clinical grounds.


METHODS
Intraoperative testing of defibrillation energy requirements, exercise testing, electrophysiological testing.


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.
Dorian
P
P
Department of Medicine, St Michael's Hospital, Toronto, Ontario.
Newman
D
D
Harris
L
L
Downar
E
E
D000284:Administration, Oral; D000638:Amiodarone / Q000494:pharmacology / Q000627:therapeutic use*; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D003131:Combined Modality Therapy; D017147:Defibrillators, Implantable; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D004594:Electrophysiology; D006352:Heart Ventricles; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D016343:Monitoring, Intraoperative; D011446:Prospective Studies; D013015:Sotalol / Q000494:pharmacology / Q000627:therapeutic use*
D013015:Sotalol; D000638:Amiodarone