216-46: Inherited cardiac channelopathies: the role of implantable cardioverter–defibrillator in a real world population

Abstract

Purpose: Sudden cardiac death is an important cause of mortality. Fifteen percent of cases occur without structural heart disease, and most of these events are attributed to inherited cardiac channelopathies (ICCh). Despite the increasing prevalence of this entity, the ideal treatment is not yet defined and the current guidelines are mainly based on expert consensus. Our aim was to evaluate the rate of appropriate (shock and antitachycardia pacing (ATP)) and inappropriate therapy in ICCh patients with implantable cardioverter-defibrillator (ICD) in order to access the value of its implantation in a real world population. Methods: Retrospective study of 37 ICCh patients (46 + 15 years old, 73% male gender) with ICD (54% Brugada syndrome [BrS], 30% idiopathic ventricular fibrillation [IFV], 11% catecholaminergic ventricular tachycardia [CTV] and 5% long QT syndrome [LQTS]). Structural heart disease was excluded in all patients. Patients were under optimized antiarrhythmic treatment and ICD implantation was decided according to the current international guidelines. A clinical follow-up concerning the rate of appropriate/ inappropriate ICD therapies and mortality was done (49 months [1-198]). Results: History of syncope was present in most of the patients (73%) and 14% had a documented episode of ventricular tachycardia (3% sustained and 11% nonsustained). Thirty-one percent of patients had family history of sudden cardiac death and the genetic study was performed in 30% of them (82% BrS and 18% CTV), with pathogenic mutation identification in only one patient (SCN5A). In 51% of patients (84% BrS, 11% CVT, 5% LQTS) the ICD was implanted in primary prevention (42% history of syncope, 42% induction of ventricular arrhythmia in the electrophysiology study and 16% family history of sudden cardiac death in patients with LQTS and CVT). In the remaining 49% patients (61% IVF, 22% BrS, 11% CVT, 6% LQTS) the ICD was implanted in secondary prevention (all of them resuscitated of sudden cardiac death). Ventricular dysrhythmia was identified in 43% of individuals during follow-up (19% nonsustained VT, 19% sustained VT and 5% ventricular fibrillation); appropriated ICD therapies were detected in 22% of patients (11% appropriated shock [5.5% 3 or more shocks; 2.7% BrS, 2.7% CVT, 2.7% LQTS and 2.7% IVF]; 19% ATP). In 38% of patients with appropriated therapies, the ICD have been implanted in primary prevention. Two inappropriate shocks were observed (one due to atrial flutter and the other due to supraventricular paroxysmal tachycardia). There was no mortality during follow-up. Conclusions: This study reflects a high-risk population, with ICD implantation in secondary prevention in about half of the patients. There was a high incidence of ventricular arrhythmias during follow-up, requiring ICD therapy. There was a high number of therapies in patients that implanted the ICD in primary prevention. Thus, the authors conclude that ICD implantation according to current recommendations (even though based just in expert consensus) might prevent many life-threatening dysrhythmic events in patient with ICCh.