[The implantable cardioverter-defibrillator: the Portuguese experience]

The aim of this study was to review the Portuguese experience with implantable cardioverter-defibrillator therapy (ICD), in order to evaluate the increase in the number of ICD implanted, the main indications for this kind of therapy, the technical evolution of the procedure and the results of the follow-up of these patients during the last five years.

The study group consists of 58 patients, 53 male and 5 female, mean age 54 +/- 14 years with ICD implanted in our country since 1992. The ICDs were implanted in 4 Hospitals, namely, Santa Cruz Hospital with 36 patients, Santa Maria Hospital with 11, Santa Marta Hospital with 8 and Coimbra University Hospital with 3 patients. Twenty six patients were resuscitated from cardiac arrest and the other 32 had ventricular tachycardia (VT) not tolerated haemodynamically and refractory to therapy. The diagnosis was coronary artery disease in 31 patients, dilated cardiomyopathy in 8, valvular disease in 4, congenital cardiopathy in 3, right ventricular dysplasia in 2, congenital long QT syndrome in 1, hypertrophic cardiomyopathy in one. Seven patients had idiopathic ventricular fibrillation without structural heart disease and one patient had isolated right ventricular dilatation.

All patients underwent electrophysiological study before ICD implantation. In 2 patients epicardial leads were used and in the remaining 56 patients a transvenous approach was used. The device was implanted in an abdominal position in 36 patients and in a pectoral position in 22. Defibrillation and pacing thresholds were measured during the implantation procedure and whenever necessary. Patients were followed up on an outpatient basis with evaluation of the number of arrhythmic episodes, therapy efficacy with reprogramming of the device when required.

The number of implantations has increased, from 4 devices implanted in 1992, to 32 in 1996. The implantation was successful and without mortality or complications in all patients. Defibrillation threshold was 16 +/- 3 J, with an electrode impedance of 48 +/- 9 Ohms. During a mean follow-up time of 18 +/- 15 months (1 to 56) 5 patients died, one of sudden death and 4 of non cardiac deaths, 15 patients were re-admitted to hospital and in 8 patients the device was replaced due to exhaustion. In this period, 37 patients (64%) had arrhythmic episodes detected by the device, 32 patients (55%) had shocks and 9 (16%) were treated with anti-tachycardia pacing. Inappropriate shocks were observed in 10 patients (17%). The ICD were reprogrammed in 11 patients.

Portuguese experience with IC implantation is increasing and has shown to be a safe procedure with no operative mortality or morbidity. The incidence of appropriate shocks was high with a good efficacy in sudden death reduction.