One Patient, Two Cardiomyopathies

Arrhythmogenic Right Ventricular Dysplasia; Cardiomyopathy, Hypertrophic; Tachycardia, Ventricular; Exercise; Syncope; Electric Countershock; Mutagenesis

A 50-year-old male patient, with history of well-controlled hypertension and no known personal or family history of cardiac disease, presented with chest pain followed by syncope during strenuous physical activity. The electrocardiogram showed sustained monomorphic ventricular tachycardia. Electrical cardioversion was performed, with conversion to sinus rhythm with Q waves on leads V2-5 and III-aVF (Figure 1). Transthoracic echocardiography (TTE) showed asymmetric left ventricular (LV) hypertrophy, preserved ejection fraction (EF) with apical akinesia, and hypertrabeculated right ventricle (RV). Coronary angiography showed no significant lesions. Cardiac MRI confirmed the TTE findings, showing a maximum LV wall thickness of 17 mm at the interventricular septum (Figure S1 — supplementary material), apical LV aneurysm and abnormal insertion of papillary muscles. The right side was remarkable for hypertrabeculated and hypokinetic free and inferior walls, and mildly dilated RV with reduced EF (33%). Besides having transmural delayed enhancement (DE) on the LV apex, there was also nodular DE on the LV/RV junction and on the free and inferior basal walls of the RV (Figure 2; Videos 1–2; Figure S2 of supplementary material). Genetic analysis found a heterozygous mutation on the PKP2 gene (p.Thr50Serfs*61), a pathogenic variant associated with arrhythmogenic RV cardiomyopathy.¹ However, no known mutation on genes related to hypertrophic cardiomyopathy (HCM) were found on a panel of 204 genes, 118 related to HCM. No association has been firmly made between mutations on the PKP2 gene and HCM.² The overlap between genetics and cardiomyopathy phenotypes is a well-known phenomenon.³ We hypothesize that this patient either had an additional unknown HCM gene mutation or, less likely, a phenotypic expression of two different cardiomyopathies in the context a PKP2 gene mutation.

Figure 1
– The electrocardiogram after electrical cardioversion.

Figure 2
– Cardiac magnetic resonance imaging — delayed enhancement on the left ventricular apex and free wall of the right ventricle.

Vídeo 1
– Cardiac MRI 4-chamber view (left) and 3-chamber view (right). URL: http://abccardiol.org/supplementary-material/2020/11503/2019-0853_video01.mp4

Vídeo 2
– Cardiac MRI — right ventricle inflow and outflow view (left) and right ventricle outflow tract long axis view (right). URL: http://abccardiol.org/supplementary-material/2020/11503/2019-0853_video02.mp4

Referências

• ¹
  Wang W, James CA, Calkins H. Diagnostic and therapeutic strategies for arrhythmogenic right ventricular dysplasia/cardiomyopathy patient. Europace. 2019; 21 (1): 9-21.
• ²
  Bainbridge MN, Li L, Tan Y, Cheong BY, Marian AJ. Identification of established arrhythmogenic right ventricular cardiomyopathy mutation in a patient with the contrasting phenotype of hypertrophic cardiomyopathy. BMC Med Genet. 2017; 18 (1): 24.
• ³
  Hershberger RE, Givertz MM, Ho CY, Judge DP, Kantor PF, McBride KL, et al. Genetic Evaluation of Cardiomyopathy – A Heart Failure Society of America Practice Guideline. J Card Fail. 2018; 24 (5): 281-302.

• Study Association
  This study is not associated with any thesis or dissertation work.
• Ethics Approval And Consent To Participate
  This article does not contain any studies with human participants or animals performed by any of the authors.
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  Supplemental Materials
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• Sources of Funding
  There were no external funding sources for this study.

Publication Dates

• Publication in this collection
  28 Sept 2020
• Date of issue
  Sept 2020

History

• Received
  01 Dec 2019
• Reviewed
  03 Feb 2020
• Accepted
  08 Apr 2020