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Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy, which is associated with life-threatening ventricular arrhythmias. Approximately 60% of patients carry a putative disease-causing genetic variant, but interpretation of genetic test results can be challenging. The aims of this study were to systematically reclassify genetic variants in patients with ARVC and to assess the impact on ARVC diagnosis. Methods: This study included patients from the Multicenter Zurich ARVC Registry who hosted a genetic variant deemed to be associated with the disease. Reclassification of pathogenicity was performed according to the modified 2015 American College of Medical Genetics criteria. ARVC diagnosis (categories: definite, borderline, possible) based on the 2010 Task Force Criteria was reclassified after genetic readjudication. Results: In 79 patients bearing 80 unique genetic variants, n=47 (58.8%) genetic variants were reclassified, and reclassification was judged to be clinically relevant in n=33 (41.3%). Variants in plakophilin-2 ( PKP2 ) were shown to reclassify less frequently as compared with other genes ( PKP2 , n=1, 8.3%; desmosomal non- PKP2 , n=20, 66.7%; nondesmosomal, n=26, 68.4%; P =0.001for overall comparison; PKP2 versus desmosomal non- PKP2, P =0.001; PKP2 versus nondesmosomal, P Conclusions: Given that approximately half of genetic variants were reclassified, with 10.1% of patients losing their definite disease status, accurate determination of variant pathogenicity is of utmost importance in the diagnosis of ARVC.

CME ECG 66/Answers: Torsade de Pointes: The Danger of a Rotating Heart Axis

CME ECG 66/Answers: Torsade de Pointes: The Danger of a Rotating Heart Axis Abstract. Torsade de pointes tachycardia is a potentially life-threatening heart rhythm disorder, caused by prolongation of the QT interval resulting in triggered activity. This QT prolongation can be congenital or acquired. If acquired, it is mainly caused by pharmacological therapy. The hallmark of torsade de pointes is an undulating QRS axis with a twist of the QRS complex around the ECG's baseline. Often, this polymorphic ventricular tachycardia is self-limiting, but degeneration into ventricular fibrillation is possible, which makes torsade de pointes tachycardia dangerous. This article aims to provide insights into etiology, diagnostics, prevention and management of this heart rhythm disorder.