Inflammation, Cardiac Sympathetic Innervation, and Arrhythmic Sudden Death

The primary aim is as follows: Primary Aim 1: Determine if inflammation is associated with abnormal cardiac sympathetic innervation in patients enrolled in the PROSE-ICD study. Rationale/Hypothesis: The investigators hypothesize that patients with increased biomarkers of systemic inflammation have abnormal cardiac sympathetic innervation as measured by MIBG imaging. Specifically the investigators will: Image 100 patients from the PROSE-ICD cohort, 50 each from the highest and lowest quartiles of hsCRP levels and determine whether patients with biomarker evidence of increased inflammation also have abnormal sympathetic innervation. In addition, the investigators will pursue the following secondary aims: 1. Determine if inflammation, measured by IL-6, is associated with abnormal cardiac sympathetic innervation, measured by MIBG imaging, in patients enrolled in the PROSE-ICD study. 2. Examine the association of CRP and MIBG with ICD therapies in PROSE-ICD. 3. Compare several MIBG imaging metrics of sympathetic innervation, in addition to the late H/M ratio, including the early H/M ratio and the MIBG washout rate. 4. Compare MIBG imaging to ECG metrics of sympathetic innervation. 5. Examine the relationship between inflammation and regional myocardial innervation and rest myocardial perfusion using quantitative and qualitative SPECT imaging. Specifically, the investigators will aim to determine if inflammation is associated with perfusion/innervation mismatch.