Comparison of frequency of aggravation of ventricular tachyarrhythmias after implantation of automatic defibrillators using epicardial versus nonthoracotomy lead systems.

The time of onset of 4,471 episodes of ventricular tachycardia (VT) or fibrillation (VF) in 40 of 65 patients with an implantable cardioverter-defibrillator (ICD) with endocardial defibrillation electrodes (group 1) and in 53 of 123 with epicardial defibrillation electrodes (group 2) was analyzed to examine whether the incidence of VT/VF immediately after surgery is greater than during further follow up and whether the site of lead placement exerts an influence on the occurrence of these arrhythmias. Actuarial survival rates free of VT/VF were 77, 65, and 54% at 1, 3 and 6 months, respectively, for group 1, and 84, 66 and 52%, respectively, for group 2. The probability of VT/VF was increased only during the first week after surgery; in that week, 12.8% of all patients had VT/VF, without significant differences between groups 1 and 2. Until the end of the first month, this percentage increased to 23%, whereas only 12 to 15% of patients had VT/VF during subsequent months. In 19 patients with third-generation devices capable of terminating tachycardias by overdrive pacing, 326 of 412 VT/VF episodes occurring in the first week after surgery were terminated by antitachycardia pacing, and only 86 had to be terminated by cardioversion or defibrillation. No postoperative exacerbation of inappropriate ICD therapies was observed in any group; 2 to 5% of patients per month received ICD therapies for atrial fibrillation or sinus tachycardia. Patients who received appropriate ICD therapies in the first week after surgery were at high risk of recurrence of VT/VF.(ABSTRACT TRUNCATED AT 250 WORDS)