BENEFITS OF TREATMENT WITH IMPLANTABLE CARDIOVERTER-DEFIBRILLATORS INPATIENTS WITH STABLE VENTRICULAR-TACHYCARDIA WITHOUT CARDIAC-ARREST

Background-The availability of implantable cardioverter-defibrillators (ICD) that are capable of antitachycardia pacing may lead to an incre ased use of ICDs in patients with haemodynamically tolerated ventricul ar tachycardia without a history of cardiac arrest. The frequency of p otentially life-threatening fast ventricular tachycardias (cycle lengt h < 250 ms) was investigated in patients who had a third generation IC D with endocardial leads implanted because they had haemodynamically t olerated ventricular tachycardia without a history of cardiac arrest. Methods-Between January 1990 and October 1993, 50 patients (age (mean (SD)) 60 (11); ejection fraction 39 (16)%; 82% with coronary artery di sease and 8% with dilated cardiomyopathy) with haemodynamically tolera ted ventricular tachycardia (cycle length (mean (SD)) 348 (60) ms; ran ge 250-500 ms) and without a history of cardiac arrest were treated wi th third generation ICDs that were capable of antitachycardia pacing. Fast ventricular tachycardia had been induced in 14 (28%) during basel ine electrophysiological study. The benefit of ICD treatment was estim ated as the difference between total mortality and the occurrence of f ast ventricular tachycardia that would have been fatal if it had not b een terminated. Results-During follow up of 17 (12) months, 33 patient s (66%) had a total of 3861 episodes of ventricular tachycardia. 91% o f these episodes were terminated by antitachycardia pacing. 11 patient s (22%) had episodes of potentially life-threatening fast ventricular tachycardia and 3 of these also had inducible fast ventricular tachyca rdia. One patient died suddenly 27 months after implantation. The diff erence between survival without fast ventricular tachycardia and total mortality was 9%, 12%, 27%, and 27% at 6, 12, 18, and 24 months, resp ectively. Conclusions-About a fifth of patients who had been given an ICD to treat haemodynamically tolerated ventricular tachycardia and wh o had no history of cardiac arrest experienced fast ventricular tachyc ardia during follow up requiring immediate cardioversion. Prospective studies are needed to investigate whether the prognosis of patients wi th a history of haemodynamically tolerated ventricular tachycardia wit hout cardiac arrest is improved by ICD therapy.