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- ↵⁎Address for correspondence:
Dr. Martin S. Maron, Tufts Medical Center, #70, 800 Washington Street, Boston, Massachusetts 02111
recent reports have demonstrated that some patients with hypertrophic cardiomyopathy (HCM) who carry a pathogenic sarcomere mutation without left ventricular (LV) hypertrophy (genotype positive–phenotype negative [G+P−]) may nevertheless show morphological abnormalities, including: myocardial crypts, elongated mitral valve leaflets, biomarkers of fibrosis, or diastolic dysfunction (1). In the present paper (Figs. 1, 2, 3, and 4⇓⇓), we present another structural abnormality in G+P− HCM patients, in whom cardiac magnetic resonance (CMR) identified substantial late gadolinium enhancement (LGE) indicative of myocardial fibrosis (2). The precise pathophysiological mechanism responsible for LGE in HCM remains uncertain, but may be related to repetitive bouts of small vessel ischemia leading to myocyte cell death and ultimately repair in the form of replacement fibrosis.
In these 4 unrelated G+P− HCM patients (Figs. 1, 3, and 4), LGE represents a potential CMR-marker of gene-positive status, with potential implications on management strategies. In HCM family members who can undergo definitive genetic testing, identification of LGE by CMR underscores the importance of pursuing genotyping to achieve definitive HCM diagnosis. In addition, if genetic testing cannot be performed or is ambiguous, the identification of LGE in an HCM relative without LV hypertrophy should prompt close surveillance with imaging to detect development of the phenotype. At present, it is uncertain whether LGE in G+P− HCM patients is a marker of increased risk for adverse disease-related complications, including sudden death and heart failure. Nevertheless, these observations underscore the emerging principle that even nonhypertrophied LV myocardium in HCM may be structurally abnormal and suggest the need for longitudinal studies to determine the prognostic significance of such findings.
These cases stand as examples of the power of complimentary imaging with CMR in the evaluation of HCM patients. In particular, our observations underscore the potential value of routine CMR imaging as part of screening assessments in HCM family members, in conjunction with echocardiography (and 12-lead electrocardiogram).
All authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation