Author + information
- Iraklis Pozios, MD, PhD and
- Theodore P. Abraham, MD∗ ()
- ↵∗Johns Hopkins Hypertrophic Cardiomyopathy Center of Excellence, 600 North Wolfe Street, Carnegie 568, Baltimore, Maryland 21287
We congratulate Maron et al. (1) on their recent report regarding the natural history of nonobstructive hypertrophic cardiomyopathy (HCM). The paper and the accompanying editorial (2) are noteworthy and thought-provoking. Maron followed 573 patients with HCM, 249 nonobstructive, for a median of 6.5 years and reported 5- and 10-year survival rates of 99% and 97%, respectively, similar to expected all-cause mortality in an age- and sex-matched U.S. population. They conclude that “nonobstructive HCM patients appear to experience a relatively benign clinical course, associated with a low risk for advanced heart failure symptoms, other disease complications, and HCM-related mortality, and largely without the requirement for major treatment interventions.” Similar mortality data were also reported in a separate cohort (3). Although the low mortality rate in nonobstructive HCM is reassuring, we share the observations astutely put forth in the editorial, that “oversimplification, which, if interpreted uncritically in clinical practice, might result in a failure to monitor and treat patients whose disease is progressive and potentially life-threatening.”
Data from our recent publication (4) somewhat complement the paper and provide evidentiary support of the editorial view that clinicians be more judicious while assessing nonobstructive HCM. In 293 patients with HCM (96 nonobstructive), we found that nonobstructive hemodynamics was an independent predictor of ventricular arrhythmias even after adjusting for age, sex, and current sudden cardiac death risk factors. Appropriate defibrillator discharges were more frequent in nonobstructive HCM. These adverse outcomes may be related to worse pathology in nonobstructive patients; in our paper more nonobstructive patients had a large scar burden (late gadolinium enhancement ≥20% of myocardial mass) and microvascular ischemia by positron emission tomography. Our HCM cohort was generally similar to the Maron study. As noted in the editorial, some findings in the Maron paper warrant attention: 34 of 249 nonobstructive patients (13.7%) died suddenly, had an appropriate defibrillator discharge, or developed progressive heart failure. Furthermore, 19% had atrial fibrillation/stroke. Therefore, the cumulative disease-related morbidity is not trivial.
We agree that nonobstructive patients, like HCM in general, experience a low mortality rate. However, a focus on mortality rate alone underappreciates the considerable morbidity burden in a subset of nonobstructive patients. We submit that emerging data support a thoughtful characterization of nonobstructive patients to identify those at risk and appropriate for early intervention.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation