Long-term outcomes of hypertrophic cardiomyopathy patients undergoing septal reduction therapies: Results from the NHLBI HCMR registry
M Desai, P Kolm, J DiMarco, C Ho, R Kwong, S Dolman, P Desvigne Nickens, N Geller, D Kim, H Watkins, W Weintraub, C Kramer, S NeubauerAbstract
Background[MD1]
Current methods to predict risk of adverse events in hypertrophic cardiomyopathy (HCM) are based on retrospective studies from select tertiary centers. The HCM Registry (HCMR) is a prospective registry, funded by the NHLBI, USA to aid in development of clinical and imaging markers that could improve event prediction. Septal reduction therapies (SRT) are highly effective in improving symptoms and quality of life in symptomatic patients with obstructive HCM. We report long-term outcomes of patients in the HCMR registry who underwent SRT during follow-up.
Methods
Patients enrolled from 44 sites in North America and Europe between 2014-17, received a questionnaire, blood-based biomarker and genetic analysis, and a contrast-enhanced cardiac magnetic resonance imaging (CMR). The composite primary endpoint included: 1. HCM-related cardiovascular deaths including sudden cardiac (SCD), heart failure (HF), stroke, and procedural deaths; 2. Non-fatal ventricular tachyarrhythmias (VT, >200 beats/minute) that required intervention (appropriate internal cardioverter defibrillator [ICD] therapy or external cardioversion/defibrillation); 3. Left ventricular (LV) assist device insertion or heart transplantation. Secondary events included non-cardiac death, HF hospitalization, clinically relevant atrial fibrillation (AF) and non-fatal stroke. All events were adjudicated by a blinded clinical events committee.
Results
Of the 2698 patients included in the final analysis, 423 (15.7%) underwent SRT (340 (80.4% myectomy, 68 (16.1% alcohol ablation and 15 (3.5%) both) at a mean of 2.6±2.2 years from initial enrollment. Baseline characteristics are shown in Table. Patients undergoing SRT were more likely to be women, with a higher symptom burden and history of HF, more frequently have basal septal hypertrophy, greater degree of mitral regurgitation, higher LV mass and N-terminal brain natriuretic peptide. At a mean of 6.9±2.1 years, out of 117 (4.3%) first primary composite events, 18 (4.3%) occurred in the SRT group (12 [2.8%] were SCD/VT). Of 590 (21.9%) secondary events (59 [2.6%] HF hospitalizations and 245 [10.8%] AF), 194 (45.8%) occurred in the SRT group (HF hospitalization occurred in 23 [5.4%] and AF in 154 [36.4%] patients). In the SRT group, 55.6% of primary events occurred preoperatively, while 11.1% occurred within 30-days postoperatively. Similarly, 4.2% of secondary events occurred preoperatively, while 37.2% occurred within 30-days postoperatively. Event-free curves for the primary composite events and primary SCD/VT events of the SRT patients are shown in Figure 1A and Figure 1B.
Conclusions
In HCMR registry, 1 in 6 patients, with a higher baseline symptom burden and evidence of more advanced disease phenotype, underwent SRT during follow-up. The long-term primary event rates in the SRT group were low and similar to the overall study population.