Cardiac Magnetic Resonance GUIDEd Management of Mild-moderate Left Ventricular Systolic Dysfunction.

Overview

Contemporary heart failure (HF) guidelines recommend insertion of a primary prevention implantable defibrillator (ICD) in patients with left ventricular ejection fraction less than 35% (LVEF \< 35%) on maximally tolerated medical therapy. Nevertheless, there are a substantial number of HF patients who have LVEF\>35% and hence do not qualify for ICD, who succumb to sudden cardiac death (SCD). At present our tools to reliably risk stratify these patients with mild-moderate systolic dysfunction (LVEF 36-50%) are poor. It is likely that these patients have ventricular scar and/or replacement fibrosis as a substrate for their malignant arrhythmia. Cardiovascular magnetic resonance imaging (CMR) can reliably identify and quantify both ventricular scar (seen in Ischaemic cardiomyopathy, ICM) and replacement myocardial fibrosis (seen in Non-Ischemic Cardiomyopathy, NICM). Methods/Design: A multi-centre randomised controlled trial in which 428 patients with mild-moderate left-ventricular systolic dysfunction (either ICM or NICM) and ventricular scar/fibrosis on cardiovascular magnetic resonance are randomized to either ICD or implantable loop recorder (ILR) insertion and are followed up until the last patient recruited has been in the study for 3 years. Potentially eligible patients will have a screening CMR and will be enrolled into the device arm of study based on the presence of any ventricular scar/fibrosis (CMR +). Patients who do not have ventricular scar/fibrosis will be followed up in an observational registry, and will not be randomised. In both the device and registry arms, we aim to enrol 700 patients in Australia and 355 in Europe. The primary hypothesis is that among patients with mild-moderate left ventricular systolic dysfunction, a routine CMR guided management strategy of ICD insertion is superior to a conservative strategy of standard care.