Benefits of cardiac pacing in ICD recipients with hypertrophic cardiomyopathy.

Purpose: Implantable cardiac defibrillator (ICD) is the only definitive therapy for prevention of sudden cardiac death in hypertrophic cardiomyopathy (HCM). Conventional transvenous ICDs can provide cardiac pacing unlike new subcutaneous ICD, but the usefulness of cardiac pacing in HCM patients is not well defined. We sought to assess the usefulness of ICD pacing in HCM.

Methods: We retrospectively analyzed 93 HCM patients who had undergone ICD implantation at our center. Usefulness of pacing was defined as follows: 1) need of pacing due to bradycardia or AV conduction disturbances, 2) improvement of LV outflow tract obstruction by sequential AV pacing, 3) need for CRT pacing, or 4) successful antitachycardia pacing without a subsequent shock. Independent predictors of useful pacing were investigated by multivariable analysis.

Results: During a mean follow-up of 91.3 ± 5.5 months, 43 patients (46.2%) reached the composite endpoint. Independent predictors of pacing usefulness were older age (HR 1.36; 95%CI: 1.088-1.709; p=0.007) and NYHA functional class ≥ II (HR 2.15; 95%CI: 1.083-4.301; p=0.029). Twenty-eight (30.1%) patients had appropriate ICD interventions, triggered by a monomorphic ventricular tachycardia (MVT) in 22 of them (78.5%). In 17 individuals with MVT (77%), antitachycardia pacing successfully treated MVT.

Conclusions: In our HCM series of patients with ICD, 46% of individuals benefitted from cardiac pacing. MVT were documented in nearly 80% of the patients with ventricular arrhythmias and antitachycardia pacing successfully treated them in 77% of cases.