My 29 year old brother had a pacemaker placed three years ago after survival from a sudden cardiac arrest. Doctors found the cause of the cardiac arrest to be a ventricular fibrillation. Last week was the first time he received a shock from his pacemaker, that is, exactly three years after his first episode. My question is, whether we can find the root cause of his ventricular fibrillation. What is the best treatment for his case?