Single-chamber versus dual-chamber implantable cardioverter defibrillators: Indications and clinical results

The clinical benefit of standard (single-chamber) implantable cardioverter defibrillator (ICD) therapy in elderly patients or in subjects with moderat e or severe heart failure who had ventricular tachyarrhythmias has been deb ated. We studied the follow-up of 450 patients who underwent standard ICD i mplantation at our institution in relation to the functional status of hear t failure (New York Heart Association Class) or patient's age. During a mea n follow-up of 24+/-28 months (range, <1-114 months), 90 patients (23%) die d: 9 patients (2%) from sudden arrhythmic death and 5 patients (1%) suddenl y, bur probably not from arrhythmic causes; 55 patients (14%) died from con gestive heart failure and/or myocardial reinfarction and 21 patients (5%) f rom noncardiac causes. We could clearly demonstrate that ICD therapy was ab le to prevent sudden cardiac death, both in patients with severely depresse d left ventricular function and in patients aged greater than or equal to 6 5 years. An important step forward in ICD technology was the introduction o f dual-chamber pacing possibilities to improve left ventricular dysfunction and to allow a more individualized ICD therapy, At our institution, we hav e implanted a dual-chamber ICD in 15 patients. Preliminary results showed t hat heart failure improved in 5 patients (33%) and remained unchanged in 10 patients (67%, p = not significant). There were no patients who had a less er degree of heart failure after implant. Based on our experience so far, i n addition to the hemodynamic benefits of dual-chamber ICDs, dual-chamber s ensing and waveform storage capabilities are very helpful and promising dia gnostic tools for the detection and handling of inappropriate ICD therapies . (C) 1999 by Excerpta Medica, Inc.