Arrhythmogenic Right Ventricular Cardiomyopathy — Epsilon Wave

A 26-year-old man is resuscitated from out-of-hospital ventricular fibrillation during a football match. His 12-lead ECG shows sinus rhythm with T-wave inversions in V1–V3, prolonged terminal activation duration (>55 ms) in V1, and a low-amplitude notch at the end of the QRS complex immediately before the T-wave onset, best seen in leads V1 and V2. Cardiac MRI demonstrates right ventricular dilatation with fibrofatty replacement of the RV free wall. Genetic testing reveals a pathogenic PKP2 mutation. The structure marked **A** in the diagram represents the distinctive ECG finding described above. This finding reflects which of the following pathophysiological processes?