Outcomes in Patients With Hypertrophic Cardiomyopathy and Left Ventricular Systolic Dysfunction

Background: End-stage (ES) hypertrophic cardiomyopathy (HCM) has been considered a particularly grim and unfavorable disease complication, associated with substantial morbidity and mortality, frequently requiring heart transplant. Previous reports have included small numbers of patients with relatively short follow-up, predominantly in prior treatment eras.

Objectives: The purpose of this study was to re-evaluate clinical profile and prognosis for end-stage heart failure in a large HCM cohort with contemporary management strategies.

Methods: Patients at Tufts HCM Institute, from 2004 to 2017, were identified with ES and systolic dysfunction (ejection fraction [EF] <50%), followed for 5.8 ± 4.7 years (up to 18 years).

Results: Of the 2,447 patients, 118 (4.8%) had ES-HCM (EF 39 ± 9%; range 12% to 49%) at age 48 ± 15 years. Notably, over follow-up, 57 patients (48%) achieved clinical stability in New York Heart Association functional classes I/II with medical treatment (or cardiac resynchronization therapy), including 6 patients ≥10 years from ES diagnosis (up to 14 years). In total, 61 other patients (52%) developed refractory heart failure to disabling New York Heart Association functional classes III/IV (5.2%/year); 67% have survived, including 31 with heart transplant. Of the 118 ES patients, 21 had appropriate implantable cardioverter-defibrillator (ICD) therapy terminating potentially lethal tachyarrhythmias, with no difference in frequency of events in patients with EF 35% to 49% versus EF <35% (17% vs. 19%; p = 0.80). With all available treatment modalities, ES-related mortality was 1.9%/year, with 10-year survival of 85% (95% confidence interval: 77% to 94%). Mortality was 4-fold lower than previously reported for ES (8.0%/year), but exceeded 10-fold HCM with preserved EF (0.2%/year; p < 0.001).

Conclusions: Although ES remains an important complication of HCM, contemporary treatment strategies, including ICDs and heart transplant, are associated with significantly lower mortality than previously considered. Primary prevention ICDs should be considered when EF is <50% in HCM. Rapid heart failure progression is not an inevitable consequence of ES, and some patients experience extended periods of clinical stability.