The PREPARE study will test the hypothesis that prolonged monitoring with an implantable loop recorder (ILR) will provide evidence of progressive electrical disease in gene positive ARVC patients with a non-diagnostic phenotype (negative or mild) who do not receive an implantable cardioverter defibrillator (ICD). Detection of non-sustained ventricular tachycardia will have incremental value over routine periodic clinical follow-up and standard short term monitoring (24-48 hour Holter).