A 52-year-old male presents with paroxysmal palpitations for 6 months, occasional chest tightness, dyspnea when climbing 2 floors for 3 months, and lower extremity edema for 3 days. ECG shows sinus rhythm, heart rate 64 bpm, PR interval 0.24 sec with complete right bundle branch block. Diagnosed with dilated cardiomyopathy and HF. Treated with digitalis, diuretics, and vasodilators. On day 4, sudden loss of consciousness and convulsions occurred, with absent heart sounds and BP 0 kPa. After resuscitation, consciousness returned, heart rate was 45 bpm with frequent premature beats. The loss of consciousness and convulsions should be considered as: