Author + information
- Martin S. Maron, MD and
- Barry J. Maron, MD∗ ()
- ↵∗Department of Cardiology, Tufts Medical Center, #70, 800 Washington Street, Boston, Massachusetts 02111
We appreciate the comments from Dr. Pozios and colleagues regarding our recent paper on the contemporary management and natural history of patients with nonobstructive hypertrophic cardiomyopathy (HCM) (1). The authors, and the accompanying editorial (2), have suggested that we may have “oversimplified” the adverse disease-related events associated with this subgroup of patients with HCM. Given the importance attributed to these suggestions, we wish to clarify our data and clinical message.
In our report, we observed that the risk for progression to debilitating symptoms is very low among nonobstructed patients (1.6% per year), with most (90%) experiencing a remarkably stable clinical course remaining asymptomatic, or only mildly symptomatic, over long-term follow-up. In contrast, patients with HCM with outflow tract obstruction were much more likely (by 5-fold) to progress to debilitating symptoms (7.4% per year), often requiring invasive treatments, such as surgical myectomy for relief of heart failure symptoms. We also observed that other disease-related complications, such as arrhythmic sudden death, embolic stroke, and atrial fibrillation, occur relatively uncommonly among the overall nonobstructive patient subset and with the application of contemporary management options, including the current risk stratification strategy, implantable cardioverter-defibrillators for prevention of sudden death, and anticoagulation therapies, disease-related mortality in patients with nonobstructive HCM is low (0.5% per year), with 5-year and 10-year survival rates comparable with the overall HCM patient population.
However, we have indeed emphasized the exception to this otherwise stable clinical course, in which a small number (4% of our cohort) of nonobstructive patients may develop drug-refractory end-stage heart failure symptoms requiring (or were considered for) heart transplant to restore acceptable quality of life (1). For this reason, longitudinal follow-up for patients with nonobstructed HCM for earlier detection of progressive symptoms is certainly required and consideration to advanced heart failure strategies for those who develop progression-limiting symptoms despite drug therapy.
We agree with the sentiments of the authors that, for the first time in more than 50 years, the nonobstructive form of HCM is now gaining traction in the published data as its significance within the overall disease spectrum is now better understood. These data contribute to this understanding by helping close a significant gap in the natural history of HCM in which nonobstructive patients seem as a group to represent the most benign element of the broad HCM spectrum, harboring a relatively low risk for progressive severe heart failure and other disease-related adverse events, although nevertheless with a small but important risk for heart transplant. These perspectives afford many patients with an important measure of reassurance regarding their disease.
Please note: Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation