PROSe-ICD is a multicenter prospective cohort study of patients who undergo ICD implantation for primary prevention of SCD, designed to compare patients who sustain SCD (as measured by an appropriate ICD firing for rapid VT or VF) to those who do not. The cohort for this observational study consists of patients with cardiomyopathy who have an ICD implanted for primary SCD prevention according to recent trials (MADIT II, SCD-HeFT, DEFINITE) and practice guidelines.