RCT of Implantable Defibrillators in Patients With Non Ischemic Cardiomyopathy, Scar and Severe Systolic Heart Failure

Inclusion Criteria: 1. A diagnosis of NICM on contrast-enhanced cardiovascular magnetic resonance imaging 2. LV scar on routine CMR (patient without scar can enter the registry) 3. New York Heart Association (NYHA) Heart Failure (HF) functional class I-III and severely impaired left ventricular function (LVEF ≤ 35% on any imaging modality) after a minimum of 3 months of treatment with optimal medical therapy (OMT) as recommended by National Institute for Health and Care Excellence (NICE) 4. Able and willing to provide informed consent Exclusion Criteria: 1. New York Heart Association (NYHA) HF functional class IV after 3 months of optimal medical therapy (OMT) 2. Acute decompensated heart failure 3. Previous implantable device in situ (PPM, Cardiac Resynchronisation Therapy (CRT) or ICD) 4. Ischemic cardiomyopathy (ICM) is defined as segmental wall motion abnormalities or wall thinning in a particular coronary territory with subendocardial or transmural late gadolinium enhancement (LGE). Patients with an LVEF ≤35% and a small amount of ischemic LGE (i.e. an infarct out of keeping with the amount of LV dysfunction) will not be excluded (so-called dual pathology patients) 5. Known diagnosis of amyloidosis, sarcoidosis, arrhythmogenic right ventricular cardiomyopathy, or hypertrophic cardiomyopathy (diseases in which there are specific guidelines regarding defibrillator therapy) 6. Known Lamin gene mutation or a positive family history of a Lamin gene mutation 7. Valve disease is considered likely to require surgery during the 3 years follow-up period 8. Complex congenital heart disease 9. Any secondary prevention ICD indication 10. Heart transplant recipient or admitted for cardiac transplantation/ left ventricular assist device 11. Clinically apparent myocardial ischemia which requires revascularization 12. Intracardiac mass which requires surgery 13. Active endocarditis 14. Active Septicaemia 15. Pregnancy 16. Life expectancy \<2 years secondary to any other cause (i.e. malignancy) 17. Active treatment with chemotherapy 18. Severe renal failure (GFR \<30) 19. Actively participating in another study without prior agreement between both Chief Investigators