A 54-year-old man without significant medical history presented with sudden-onset chest discomfort and multiple episodes of ventricular fibrillation requiring external defibrillation and cardiopulmonary resuscitation. Coronary angiography ruled out significant artery stenosis. Both ventriculography and echocardiography revealed decreased left ventricular ejection fraction (25%). On examination, he was haemodynamically stable. The lungs were clear to auscultation and there was no jugular venous dilation. The cardiac examination revealed a regular rate and rhythm without murmur. Cardiac magnetic resonance (CMR) and 18F-2-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) images were shown (figure 1).Question
Which of the following would be the next best step?