Based on these findings, the investigators hypothesize that elevated levels of inflammatory biomarkers are associated with abnormal sympathetic innervation as measured by MIBG imaging. The investigators aim to establish the strength of this association. This proposal will leverage unique access to the largest, most extensively phenotyped cohort of patients who have undergone ICD implantation for primary prevention of SCD, the PRospective Observational Study of the ICD in SCD, (PROSE-ICD).