Participants will be invited to be in a research study called MODULAR ATP because your doctor believes you are a candidate to receive a Boston Scientific EMBLEM™ subcutaneous implantable cardioverter defibrillator (S-ICD) to treat abnormal heart rhythms, or you may already have an EMBLEM S-ICD implanted. This study tests the combination of the EMBLEM S-ICD and a leadless pacemaker (EMPOWER™) for the treatment of rapid, life-threatening heartbeats called ventricular arrhythmias (VA). This combined system, called the “Coordinated System”, is investigational, and is different from having only a S-ICD or a conventional pacemaker implanted, as it uses the communication between the two devices to determine how best to treat those rapid heartbeats. The purpose of this study is to test how safe and effective is the investigational Coordinated System.