Non-obstructive HCM had 18.6% 10-year SCD event incidence and 15.7% progression to burned-out phase, the worst among phenotypes, requiring careful risk management.
Does the non-obstructive hypertrophic cardiomyopathy (NOCM) phenotype have a worse prognosis for sudden cardiac death events and progression to the burned-out phase compared to other HCM phenotypes?
Contrary to the belief that non-obstructive hypertrophic cardiomyopathy has a stable clinical course, patients with NOCM have the highest risk of progression to the burned-out phase and a high risk of sudden cardiac death events among HCM phenotypes.
Absolute Event Rate: 0% vs 0%
Abstract Background In patients with hypertrophic cardiomyopathy (HCM), sudden cardiac death (SCD), mainly due to arrhythmias, is a major concern from childhood through early adulthood. In middle age and beyond, progression to the end-stage or burned-out phase becomes the primary issue, leading to recurrent heart failure and the need for left ventricular assist device (LVAD) implantation or heart transplantation. Patients with non-obstructive hypertrophic cardiomyopathy (NOCM) are often considered to have a relatively stable clinical course without a significant risk of SCD or progression to the burned-out phase. Purpose This study aimed to evaluate the prognosis of SCD events and progression to the burned-out phase in NOCM compared to other phenotypes. Methods This was a multicenter, retrospective cohort study involving 23 institutions with expertise in HCM. Patients aged ≥16 years who were diagnosed with HCM between 2006 and 2018 were identified and classified into four phenotypes: left ventricular outflow tract obstruction (LVOTO), mid-ventricular obstruction (MVO), apical HCM, and NOCM. Patient characteristics and the prognosis for SCD events and progression to the burned-out phase were compared among the four phenotypes. SCD events were defined as SCD, successfully resuscitated ventricular fibrillation and sustained ventricular tachycardia, and appropriate implantable cardioverter defibrillator (ICD) therapy. Results Among 3,335 patients, 838 (25.1%) had LVOTO, 206 (6.2%) had MVO, 892 (26.7%) had apical HCM, and 1,399 (41.9%) had NOCM. Regarding SCD risk assessment, the rate of ICD eligibility was comparable among LVOTO, MVO and NOCM, but significantly lower in apical HCM (23.7% vs. 24.3% vs. 12.3% vs. 24.4%, P0.001) (Figure A). However, the actual ICD implantation rate among eligible patients was lower in NOCM than in LVOTO and MVO (23.3% vs. 34.1% vs. 14.4% vs. 16.0%, P=0.009) (Figure B). The 10-year cumulative incidence of SCD events was the highest in MVO, followed by NOCM, LVOTO, and apical HCM (7.5% vs. 18.6% vs. 4.9% vs. 11.6%, P0.001) (Figure C). The 10-year cumulative incidence of progression to the burned-out phase was the highest in NOCM among all phenotypes (4.0% vs. 10.0% vs. 1.7% vs. 15.7%, P0.001) (Figure D). Notably, all five patients who required LVAD implantation and all two patients who underwent heart transplantation had NOCM. Conclusions Among HCM phenotypes, NOCM had the second worst prognosis for SCD events and the worst prognosis for progression to the burned-out phase. These findings suggest that patients with NOCM should be managed with careful recognition of their risk for life-threatening conditions from the time of diagnosis, regardless of the absence of obstruction.
Kimura et al. (Sat,) reported a other. Non-obstructive HCM had 18.6% 10-year SCD event incidence and 15.7% progression to burned-out phase, the worst among phenotypes, requiring careful risk management.