Research Day

Arrhythmogenic Right Ventricular Cardiomyopathy Associated With Pediatric Cardiac Arrest

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Introduction: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is one of the leading causes of arrhythmic cardiac arrest in young people and athletes; accounting for 4-22% of sudden cardiac arrest. This progressive, familial cardiac disorder is characterized by replacement of ventricular myocytes with fibrofatty tissue. Mutations in genes encoding cardiac desmosomal proteins located in the intercalated disks are responsible for eletromechanical uncoupling and histopathological changes. These modifications to the cardiac myocytes affect activation and repolarization of the myocardium resulting in ventricular dysfunction and ventricular arrhythmias. This case highlights the importance for genetic testing when there is an inability to meet the criteria for diagnosis. Patient Description: Previously healthy 17yo male who had a witnessed cardiac arrest event while at school. Patient had completed a work out consisting of running and weight lifting when he collapsed and was found to be pulseless by a teacher. An automatic external defibrillator was applied and one shock was delivered. Patient regained consciousness. Troponin, compete blood count, comprehensive metabolic panel, Magnesium, Phosphorus, blood gas, computerized tomography of the brain and chest radiograph were normal. Electrocardiogram revealed a normal sinus rhythm with a QTc of 398 milliseconds. Initial echocardiogram revealed a thin right ventricular myocardium with mild right ventricular enlargement, but normal systolic function. Patient was started on beta-blockade and admitted to the pediatric intensive care unit. During this admission the patient had multiple episodes of supraventricular tachycardia, which resolved spontaneously. Cardiac magnetic resonance imaging met the criteria for arrhythmogenic right ventricular cardiomyopathy, but no myocardial fibrofatty infiltration was noted. The patient underwent placement of a dual chamber implantable cardioverter defibrillator. Genetic testing revealed that he was heterozygous for two variants in the DSP gene. This gene encodes desmoplakin, a component of the desmosomal complex that makes up intracellular junctions. This variant has been identified in conjunction with additional cardiogenetic variants in individuals referred for cardiomyopathy / arrhythmia genetic testing. Conclusion: Arrhythomogenic right ventricular cardiomyopathy has been estimated to account for up to 22% of sudden cardiac arrests in young people and adolescents. Sports activity increases the risk of sudden cardiac death among adolescents and young adults with ARVC. The subtle clinical manifestations of ARVC make the diagnosis challenging and often unrecognizable. This further supports the importance of genetic testing and follow-up when all aspects of the diagnostic criteria are not attained.

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