POTENTIAL BENEFIT FROM IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR THERAPYIN PATIENTS WITH AND WITHOUT HEART-FAILURE

Background-Whether patients with heart failure derive a benefit from t herapy with implantable cardioverter-defibrillators (ICDs) has been qu estioned. The purpose of this study was to investigate whether New Yor k Heart Association (NYHA) functional class had an impact on the poten tial benefit from ICD therapy as assessed from data stored in the memo ry of ICDs. Methods and Results-Between 1989 and 1996, 603 patients (7 7% men; 59% with coronary artery disease and 16% with dilated cardiomy opathy; age, 57+/-13 years; ejection fraction, 44+/-18%) were treated with an ICD with extended memory function (storage of electrograms and /or RR intervals from treated episodes) in combination with endocardia l lead systems. The stages of heart failure (NYHA functional class I t hrough III) at implantation were correlated with overall mortality and the recurrence of fast ventricular tachyarrhythmias (>240 bpm) during follow-up. The potential benefit of the device was estimated as the d ifference between overall mortality and the hypothetical death rate ha d the device not been implanted. The latter was based on the recurrenc e of fast and, without termination by the devices, presumably fatal ve ntricular tachyarrhythmias. In the overall group, a significant differ ence between hypothetical death rate and overall mortality was observe d (13.9%, 23.5%, and 26.6% at 1, 3, and 5 years, respectively) that su ggested a benefit from ICD implantation. In patients in NYHA class I, the estimated benefit, which increased over time, was 15.2%, 29.2%, an d 35.6% after 1, 3, and 5 years, respectively. Tn patients in NYHA cla ss II or III, the estimated benefit increased until the third year (21 .8% and 21.9%, respectively) and then remained constant until the fift h year (22.9% and 23.8%, respectively). Even those patients in NYHA cl ass III with a history of decompensated heart failure benefited from I CD implantation. Conclusions-Analysis of stored ECG data suggests that in patients with a history of ventricular tachycardia or ventricular fibrillation, ICD therapy may lead to a prolongation of life in NYHA c lasses I through III. The initial benefit is greatest in patients in N YHA class II and class III, but the estimated benefit might persist lo ngest for patients in NYHA class I.