Antitachycardia Pacing for Shock Prevention in Patients with Hypertrophic Cardiomyopathy and Ventricular Tachycardia

Background Hypertrophic cardiomyopathy (HCM) carries an increased risk of sudden death due to ventricular arrhythmias (VA). The implantable defibrillator (ICD) is a well-established therapy to treat VA. Monomorphic ventricular tachycardias (MVT) are frequent in HCM patients and suitable for antitachycardia pacing (ATP) termination. Objective to describe VT characteristics in a population of HCM patients with ICD and to study effectiveness and safety of ATP for monomorphic VT. Methods Data proceeded from the multicentre prospective observational UMBRELLA trial including all patients with HCM and ICD followed by the CareLink Monitoring System. All the episodes of VA were collected and analyzed. ATP effectiveness and safety were described; factors related to ATP effectiveness were studied with generalized estimating equations models (GEE). Results 251 patients followed during 47 months, 67 (26.7%) were implanted in secondary prevention. Fifty-six patients presented 326 episodes of VA, 286(87%) were MVT. Mean cycle length 312±64ms. Among 264 MVT receiving ICD therapy 202 (76.5%) were ATP terminated. The 1st ATP burst was effective in 169 episodes (68.4%), overall effectiveness of the first or second ATP burst was 73.8%. Multivariate GEE-adjusted analysis showed 2 variables related to ATP effectiveness: programming FVT zone ONvs.OFF (OR2.4, CI95%1.5-5.2, p=0.03) and programming 2 or more ATP bursts vs. 1 burst only (OR1.6, CI95%1.2-3.4, p=0.04 and OR2.9,CI95%1.8-6.3,p=0.02 respectively). Conclusions MVT is the predominant VA in HCM patients with ICD. ATP is highly effective in terminating the majority of MVT and its proved effectiveness should guide device selection and programming in order to avoid unnecessary high energy shocks.