PREPHENOTYPIC MYOCARDIAL CRYPT MORPHOLOGY IN HYPERTROPHIC CARDIOMYOPATHY

Abstract

SESSION TITLE: Cardiovascular Disease 2 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Hypertrophic cardiomyopathy (HCM) is a genetic heart disease first described over 50 years ago. More recently, cardiovascular magnetic resonance imaging has advanced our understanding of the phenotypic heterogeneity of the disease. CASE PRESENTATION: A 21-year-old man presented after a syncopal episode while playing soccer. He reported two prior similar events that occurred ten years ago. Family history further revealed a father who was diagnosed with non-obstructive hypertrophic cardiomyopathy at a young age. Electrocardiogram showed normal sinus rhythm. Transthoracic echocardiogram identified mild concentric left ventricular hypertrophy with preserved left ventricular ejection fraction and an interventricular septal end diastolic diameter estimated at 11-millimeters. Cardiac magnetic resonance imaging (CMR) was done, which revealed a maximal wall thickness of 13-millimeters in the basal septum. There was no systolic motion of the mitral valve or evidence of flow acceleration of left ventricular outflow tract. However, myocardial crypts were noted in the basal inferior wall. These findings represent a distinctive, but unclear morphology of hypertrophic cardiomyopathy currently thought to be more prevalent in phenotype-negative patients. A four generation family pedigree of the patient was obtained. His paternal family history was notable for ischemic cardiac disease in several members but only his father had an established diagnosis of hypertrophic cardiomyopathy. Maternal family history was unremarkable for any cardiovascular disease. Father underwent genetic testing, which revealed that he was heterozygous for the p.R502W pathogenic mutation in the myosin binding protein gene (MYBPC3). Patient was then discharged home on a Life Vest with a plan for genetic testing as outpatient. Genetic testing was also offered to the other family members. DISCUSSION: HCM is an autosomal dominant genetic cardiomyopathy with most mutations having a high penetrance. In HCM, the common phenotypes encountered on Echo or Cardiac MRI are unexplained left ventricular hypertrophy, especially asymmetric, involving the septum/anterolateral wall, increased LV outflow tract gradient and systolic anterior motion of the mitral valve leaflets. Left ventricular myocardial crypts found on cardiac MRI can serve as a good ‘pre-phenotypic’ imaging marker of HCM that can help identify family members of HCM affected families to undergo genetic testing. They occur with variable frequency, but represent a distinctive morphological expression of HCM. CONCLUSIONS: Myocardial crypt identification by cardiac magnetic resonance is emerging as a potential marker for earlier recognition of genotype positive patients at risk of developing clinical hypertrophic cardiomyopathy. This case emphasizes this clinical implication and reinforces the importance of careful history taking in diagnostic decision making. Reference #1: Maron MS, Rowin EJ, Lin D et al. Prevalence and clinical profile of myocardial crypts in hypertrophic cardiomyopathy. Circ Cardiovasc Imaging 2012;5:441-7. Reference #2: Rowin EJ, Maron MS. Myocardial crypts in hypertrophic cardiomyopathy: the new gang in town. Eur Heart J Cardiovasc Imaging 2012;13:281-3. DISCLOSURES: no disclosure on file for Shantal Gupta; No relevant relationships by Sharana Hegde, source=Web Response No relevant relationships by Jae Kim, source=Web Response No relevant relationships by Anupama Rao, source=Web Response