Hypertrophic Cardiomyopathy: A

Hypertrophic Cardiomyopathy: A "more" common cause of an uncommon event

Brandon Smith, MD

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Introduction

? Sudden cardiac death (SCD) in the young athlete is rare

? Incidence 1:40,000-1:80,0001

? Hypertrophy cardiomyopathy (HCM) is a "more" common cause of SCD

? Past studies suggested that is was the most common cause of SCD in the young (incidence of 30-40%)

? More recent studies have found an incidence of 5-15%2

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What is Hypertrophic Cardiomyopathy?

? Previously known as idiopathic hypertrophic subaortic stenosis (IHSS) or hypertrophic obstructive cardiomyopathy (HOCM)

? Now all known as hypertrophic cardiomyopathy (HCM)

? Progressive hypertrophy of cardiac myocytes, typically in disorganized fashion

? Myocardial fibrosis ? Diastolic and systolic ventricular dysfunction ? Left ventricular outflow tract obstruction ? Atrial and ventricular dysrhythmia

? Reported incidence of 1:200-1:5003

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Pathogenesis and Inheritance

? HCM results in mutations in sarcomere proteins

? Sarcomeres are the contractile units in muscle

? About 50% of cases have identifiable abnormal genetic testing ? Most common gene mutations are in MYBPC3 and MYH7 genes

? Together account for 80% of cases ? Mutations can develop spontaneously but are inherited in autosomal dominant

fashion ? There are many factors that regulate HCM expression so a positive genotype

can yield different phenotypes

? Syndromes with associated phenotype

? Anderson-Fabry, Pompe disease, Danon disease, Noonan syndrome, Costello syndrome, Friedreich ataxia, Leopard syndrome

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Presentation

? Signs and symptoms

? Asymptomatic, dyspnea, chest pain, palpitations, dizziness, syncope, sudden death

? Examination

? Murmur

? Systolic ejection murmur (left ventricular outflow tract obstruction) that increases in intensity with Valsalva maneuvers or change in position from squatting to standing

? Systolic regurgitant (holosystolic) murmur of mitral regurgitation

? Increased left ventricular apical impulse ? S3 or S4 heart sound

? ECG

? Normal ECG occurs in ................
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