Does an ICD with biphasic shocks reduce the defibrillation threshold compared to monophasic shocks in patients with VT or VF?
ICDs utilizing biphasic shocks significantly lower the defibrillation threshold for both ventricular tachycardia and ventricular fibrillation compared to monophasic shocks.
Clinical efficacy and safety of two new third-generation implantable cardioverter defibrillators (ICD) were studied in 38 patients with ventricular tachycardia (VT) or fibrillation (VF). There were 31 patients with coronary disease, three patients with right ventricular dysplasia, one patient with dilated cardiomyopathy, and three patients with valvular disease. Twenty-four patients (group I) received an ICD with monophasic (Ventak PRx 1700, CPI) and 14 patients (group II) with biphasic shocks (Cadence V 100, Ventritex). Intraoperatively, the mean defibrillation threshold was significantly lower in group II than in group I, both in patients with induced VT (group I 11.0 +/- 6.3 joules; group II 5.8 +/- 1.3 joules) (P < 0.01) and induced VF (group I 17.5 +/- 4.6 joules; group II 9.6 +/- 5.2 joules) (P < 0.01). During the mean follow-up of 12 +/- 7 months four patients (11%) died. 865 arrhythmia events (AE) occurred and were terminated by ATP (671 VTs, 78%). Acceleration of VTs was observed in 28 AE (3%) and ATP was unable to interrupt 58 AE (7%). ICD shocks were delivered as a first therapy in 108 AE (13%).
Trappe et al. (Fri,) studied this question.