At the genome level, the investigator has focused on the role of SCN5A gene mutations in arrhythmogenesis. Lymphocyte SCN5A mRNA processing may serve as a surrogate marker to assess SCN5A function at the cardiac level and may correlated with arrhythmic risk in high risk populations. This study will determine if SCN5A variant levels are predictive of appropriate ICD therapies in patients with a newly implanted ICD.