Current heart failure guidelines recommend insertion of implantable cardiac defibrillators (ICD) for primary prevention of sudden cardiac death (SCD) in patients whose left ventricular ejection fraction is (LVEF) ≤ 35% on maximally tolerated medical therapy. However, the majority of sudden cardiac death (SCD) in patients with heart failure occurs in those with mild-moderate systolic heart failure (LVEF 36%-50%) who currently do not qualify for an ICD. At present, our tools to reliably risk stratify patients with mild-moderate heart failure to predict the likelihood of SCD are limited.
Recent data however suggest that ventricular scar and/or replacement fibrosis, reliably identified on Cardiac Magnetic Resonance Imaging (CMR), forms a substrate for malignant arrhythmia, thus potentially identifying a group at increased risk of SCD.
The primary aim of the C ardiovascular M agnetic R esonance GUIDE d management of mild-moderate left ventricular systolic H eart F ailure ( CMR GUIDE HF) trial is to test the hypothesis that among patients with mild-moderate heart failure, a routine CMR guided management strategy of implantable defibrillator (ICD) insertion is superior to a conservative strategy of standard care.