Primary prevention implantable cardioverter defibrillator in patients with reduced ejection fraction: for ischemic or non-ischemic cardiomyopathy or both?

The European Society of Cardiology (ESC) and the American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death in patients with heart failure and reduced left ventricular ejection fraction (1,2). These recommendations have been primarily based on clinical trials that mainly included patients with ischemic heart disease as the etiology for heart failure (3-6). In contrast, the body of evidence for primary prevention ICD in those with non-ischemic cardiomyopathy has been less robust. While a meta-analysis of randomized clinical trials conducted more than a decade ago confirmed the mortality benefit of ICD in this population (7), the recently published Danish Study to Assess the Efficacy of ICDs in Patients with Non-ischaemic Systolic Heart Failure on Mortality (DANISH) showed no survival benefit for ICD implantation in this setting (8). These conflicting results generated debate amongst cardiologists regarding the utility of primary prevention ICD in the modern era of guideline directed medical therapy, and particularly in the absence of ischemic heart disease. Since ICD implantation is not without risk (e.g., short- and long-term device related infections, and inappropriate device therapies), as well as the considerable cost related to the device, it is important to identify those who will gain the most benefit