Ventricular arrhythmia post-concealed myocarditis

Male, 67 y/o, Caucasian, hypertensive, with history of long-standing ventricular arrhythmia (20 years).
Family background irrelevant. Negative Chagas disease serology.
He described that it all started more or less 20 years ago, in a trip to São Paulo. On the occasion, after being exposed to cold weather, he presented symptoms of flu with palpitations after some days.