PATIENTS WITH STRUCTURAL HEART-DISEASE, S YNCOPE OF UNKNOWN ORIGIN AND INDUCIBLE VENTRICULAR ARRHYTHMIAS TREATED WITH AN IMPLANTABLE DEFIBRILLATOR

Objectives. This study evaluates the hypothesis that in patients with syncope of unknown origin and heart anomalies, inducible ventricular a rrhythmias are specific arrhythmias and therefore should be treated as such. Background. Although syncope is a frequent clinical entity, the evaluation and treatment of patients with syncope without a clear eti ology still remains undefined. Many patients with syncope of undetermi ned origin undergo invasive electrophysiologic evaluation. Abnormaliti es of the sinus node, prolongation of conduction times or inducible ar rhythmias found during these evaluations are usually assumed to be the cause of syncope, and are consequently treated. However, whether tach yarrhythmias are truly the cause of syncope, and whether treatment of these tachyarrhythmias can prevent recurrent syncope and arrhythmic de ath, is unknown. Patients and methods. An electrophysiological study w as performed on 160 patients with structural heart disease and syncope of unknown origin. In 23 out of the 160 patients (16%), programmed el ectrical stimulation induced sustained ventricular arrhythmias. In 18 out of the 23 patients an automatic defibrillator was implanted and th ey form the study group. Results. In these 18 patients, programmed ven tricular stimulation induced sustained monomorphic ventricular tachyca rdia in 12, sustained polymorphic ventricular tachycardia in 2 and ven tricular fibrillation in 4. During a mean follow-up of 14 months, 9 pa tients received 81 appropriate therapies from the device (53 because o f ventricular tachycardia and 23 because of ventricular fibrillation). The probability of appropriate therapy was 100% at 1 year follow-up. There were no episodes of sudden death and 1 patient died of congestiv e heart failure. Conclusions. In patients with syncope of undetermined origin, heart disease and inducible ventricular tachyarrhythmias trea ted with a implantable cardioverter defibrillator, there is a high inc idence of appropriate therapies. Our results support the practice of u sing implantable cardioverter defibrillators in patients with syncope of unknown origin, heart disease and inducible ventricular arrhythmias .