Fatal and nonfatal cardiac arrest in patients with an implanted antitachycardia device for the treatment of supraventricular tachycardia

Abstract

P aroxysmal supraventricular tachycardia (SVT) is a frequent and disabling condition, sometimes unresponsive to medical therapy.l Tachycardia termination pacing is a useful alternative treatment in patients with SVT. The use of antitachycardia pacing has been shown to have acceptable long-term efficacy.2 However, in patients with ventricular tachycardia it is known to carry a risk of tachycardia acceleration3 or induction of ventricular fibrillation.4 Therefore, for the treatment of ventricular tachycardia it is recommended that such pacemakers be physician activated (a manual nonautomatic mode] or used in association with an automatic implantable defibrillator.5 The potential danger of tachycardia termination pacing for SVT is less well defined. We report 4 cases of fatal and 1 case of nonfatal cardiac arrest in patients fitted with an antitachycardia pacemaker, the Programmable Automatic Scanning Arrhythmia Reversion (PASAR) pacemaker (model 4151). The data were collected in the form of questionnaires filled out by implanting physicians and returned to the pacemaker manufacturer (Telectronics). On a worldwide basis, a total of 122 patients (139 devices] had been implanted for the control of SVT. The follow-up period was 4 to 65 months [mean 34). Most patients (55%] had accessory pathways and 36% had atrioventricular nodal reentrant tachycardia. Sixtyone percent of the patients were paced from the right ventricular apex. Four cases of sudden unexplained cardiac deaths and I case of near sudden death were identified. The PASAR model 4151 was a prototype, implantable, bipolar pulse generator that was designed to sense the occurrence of a tachycardia by programmable high rate criteria. After 4 consecutive tachycardia beats, I or 2 timed premature stimuli were deiivered in an attempt to revert the tachycardia to sinus rhythm. How this device functions in tachycardia termination is shown in Figure 2. Jf tachycardia termination failed, the initial coupling interval between the