Beyond the RV: Recurrent Myocarditis Unravelled as an Arrhythmogenic Cardiomyopathy

Date: Thursday, 23 Jan 2025 Speaker: Dr. Ryan Sless, PGY 5, Univeristy of Toronto Objectives: 1. Highlight a case of recurrent myocarditis and when to consider other etiologies. 2. Review guidelines for imaging of the RV and its importance in arrhythmogenic cardiomyopathy. 3. Discuss exercise restrictions in arrythmogenic cardiomyopathies. Key points: Recurrent myocarditis can sometimes be misdiagnosed when it is actually an arrhythmogenic cardiomyopathy, highlighting the importance of thorough diagnostic evaluations. Desmoplakin cardiomyopathy is a unique subtype of arrhythmogenic cardiomyopathy that often presents with episodic myocardial inflammation and requires specific diagnostic criteria and genetic testing for accurate identification. Echocardiographic assessment of the right ventricle, including careful measurement of the RVOT, is critical in diagnosing arrhythmogenic right ventricular cardiomyopathy and monitoring disease progression. Questions and Answers: 1. What is the hallmark of desmoplakin cardiomyopathy? a) Persistent chest pain without troponin elevation b) Episodic myocardial injury leading to fibrosis c) Constant myocardial edema d) Predominant right ventricular dysfunction Answer: b) Episodic myocardial injury leading to fibrosis Desmoplakin cardiomyopathy is characterized by episodic myocardial injury that results in progressive fibrosis. This fibrosis precedes the development of left ventricular dysfunction, which is opposite to most other cardiomyopathies where dysfunction typically precedes fibrosis. 2. Which diagnostic tool is most useful for early identification of desmoplakin cardiomyopathy? a) Echocardiography b) Electrocardiogram (ECG) c) Genetic testing d) Chest X-ray Answer: c) Genetic testing Genetic testing is crucial for early identification of desmoplakin cardiomyopathy. While echocardiography and ECG can reveal structural and functional abnormalities, they often do so later in the disease process. Genetic testing can identify the presence of mutations in the desmoplakin gene, allowing for earlier diagnosis and management. 3. According to the 2020 Padua criteria, which finding is considered a major criterion for right ventricular involvement in arrhythmogenic cardiomyopathy? a) Presence of a complete right bundle branch block b) PVC burden less than 500 in 24 hours c) Regional RV akinesia, dyskinesia, or bulging plus RV dilation or decreased RV systolic function d) Normal right ventricular dimensions Answer: c) Regional RV akinesia, dyskinesia, or bulging plus RV dilation or decreased RV systolic function The 2020 Padua criteria for diagnosing arrhythmogenic cardiomyopathy include the presence of regional RV akinesia, dyskinesia, or bulging, along with RV dilation or decreased RV systolic function, as a major criterion. This combination of structural and functional abnormalities is critical for confirming right ventricular involvement in the disease.