Cardiac Resynchronization Therapy for End-Stage Hypertrophic Cardiomyopathy: The Need for Disease-Specific Criteria

Cardiac resynchronization therapy (CRT) is a wellestablished treatment for patients with heart failure (HF) with reduced left ventricular ejection fraction (LVEF), whereas its role in patients with preserved LVEF is controversial at best (1). Hypertrophic cardiomyopathy (HCM) is characterized by normal or enhanced LVEF, even in patients with severe FIGURE 1 Cardiac Amyloid in Aortic Stenosis An 88-year-old woman with severe aortic stenosis. (A) DPD scintigraphy fused single-photon emission tomography/computed tomography illustrating cardiac tracer retention suggestive of cardiac amyloid, with large bilateral pleural effusions. (B) Fluoroscopy demonstrating the 26-mm Edwards Sapien 3 valve (Edwards Lifesciences, Irvine, California) in situ during the transcatheter aortic valve replacement. Note the pre-existing dual-chamber pacemaker leads. Letters JACC VOL. 71, NO. 4, 2018 JANUARY 30, 2018:463 – 7 3 464 congestive symptoms. About 5% to 7% of patients with HCM, however, develop systolic dysfunction with LVEF values <50% and as low as 25% to 30%, subtended by extensive myocardial fibrosis (“endstage”) (2). In this subset, CRT appears a reasonable option, but the limited data available show conflicting results (1,3), possibly because eligibility criteria are undefined and variably extrapolated from systolic HF. Whether dilated cardiomyopathy (DCM) criteria apply to HCM is unresolved. Therefore, we aimed to evaluate the effects CRT on symptomatic status and outcome in end-stage HCM in a tertiary referral center. We evaluated patients with HCM consecutively seen from 2000 to 2016; patients with storage or metabolic disease were excluded. We identified 61 patients with end-stage HCM, of whom 13 (21%) received CRT (7 females, age at diagnosis 29 10 years). Patients with CRT were <1% of the total cohort. At CRT implantation (age 49 12 years), 8 patients were in New York Heart Association (NYHA) functional class II and 5 patients in class III/IV. Cardiopulmonary exercise testing was performed in 8 patients, showing marked VO2 reduction (average 52% of predicted). Left bundle branch block (LBBB) was present in 12 of 13 patients with average QRS duration of 173 27 ms, and LVEF was 42 12% (2 patients were implanted despite EF >50% due to refractory HF and marked intraventricular dyssynchrony). Nine patients had paroxysmal atrial fibrillation, evolving into permanent in 6; 4 required ablate-and-pace. The CRT group showed a higher proportion of LBBB compared with end-stage patients without CRT (12 of 13 vs. 9 of 48; p < 0.01); no difference was seen in NYHA functional class, age, LVEF, and diuretics dose. At 1 year, 7 patients (54%) improved $1 NYHA functional class, 3 reported no change, and 2 worsened $1 class. No differences were observed in LVEF and left ventricular (LV) volumes. At end of follow-up (5.2 3.1 years after implantation), 6 patients died (46%) due to HF (n ¼ 3), cerebral hemorrhage, cardiorenal complications, and heart transplant complications. Two patients were alive after heart transplantation. In the 7 CRT responders, symptomatic improvement lasted 2.7 2.5 years. At final evaluation, however, there was no sustained symptomatic improvement compared with baseline. No difference in survival was evident between CRT and no-CRT end-stage patients during comparable follow-up (p ¼ 0.46). Time from onset of NYHA functional class III/IV symptoms to listing in transplant candidates was also