Implantable cardioverter defibrillator outcome: beyond ejection fraction?

Abstract

This editorial refers to ‘Clinical markers of organ dysfunction associated with increased 1-year mortality post-implantable cardioverter defibrillator implantation’ by D. Chong et al ., on page 508 Over three decades of clinical experience have brought evidence that implantable cardioverter defibrillators (ICDs) should be considered as ‘gold standard’ therapy in prevention of sudden cardiac death. Implantable cardioverter defibrillators are currently indicated for secondary prevention in patients after cardiac arrest and life-threatening ventricular tachyarrhythmias or for primary prevention in patients considered at high risk of sudden arrhythmic death. The vast majority of ICDs for primary prevention are implanted in patients with significantly reduced left ventricular ejection fraction (LVEF) due to ischaemic or non-ischaemic cardiomyopathy. Although current eligibility for primary prevention ICD implantation is based merely on poor LVEF, we still experience an ongoing debate on how to identify patients who will benefit from ICD implantation. Furthermore, according to current guidelines, patients qualified for device implantation should have reasonable expectation of survival with a ‘good functional status’ for at least 1 year.1,2 Therefore, attempts are made to identify not only the ‘appropriate ICD candidate’, but also the one who may be ‘too sick’ to benefit from ICD therapy. The amount of benefit from an ICD is not uniform across the population eligible for ICD implantation, and may be limited due to early death from other than arrhythmic causes. Lack of survival benefit observed within the first year after implantation may be attributed to a higher risk of non-sudden death. Data from the MADIT II (Multicenter Automatic Defibrillator Implantation Trial), SCD-HeFT (Sudden Cardiac Death in heart Failure Trial), and DINAMIT (Defibrillation in Acute Myocardial Infarction Trial) studies demonstrated no separation of the Kaplan–Meier curves within the first 10–18 months after ICD implantation, suggesting that early mortality remains unaffected by ICD therapy. This …