Compatibility of a nonthoracotomy lead system with a biphasic implantable cardioverter-defibrillator

This prospective multicenter study was conducted under the Food and Drug Administration Investigational Device Exemption to evaluate the safety and efficacy of the combination of the Cadence® implantable defibrillator (Ventritex, Inc.) and 60-series Endotak®C leads (Cardiac Pacemakers, Inc.). Implantation was attempted in 148 patients with hemodynamkally compromising ventricular tachycardia or fibrillation (VF), or with pace-terminable ventricular tachycardia. The system was successfully implanted in 97% of patients, with 96% of implants in a transvenous-lead-alone configuration. At implantation, the defibrillation threshold was 455 ± 94 V (14 ± 6 J) for lead-alone patients and 532 ± 40V (19± 3J) for those requiring a subcutaneous patch. VF conversion efficacy was reconfirmed in patients who underwent a 3-month chronic induction study. The system successfully detected all 763 induced arrhythmias and terminated 99.5% of them; after system modification, successful conversion was demonstrated in the 2 patients who initially had induced episodes requiring external defibrillation (1 lead revision; 1 reprogramming). All spontaneous episodes were terminated with an implantable cardioverter defibrillator. Postshock VF redetection times were significantly shorter than initial detection times (4.5 ± 1.8 seconds detection, 2.1 ± 0.7 seconds redetection; p < 0.0001). During an 8-month mean follow-up (range 1 to 31 months), 2 unwitnessed deaths were classified as sudden cardiac deaths, and 11 patients experienced a total of 12 complications, none of which was associated with the Cadence-Endotak combination.