The objective of this study was to determine the prevalence and incidence of externalized conductors and other visual lead anomalies (as evidenced by imaging) and the risk of progression to electrical dysfunction in subjects with one or more of the following St. Jude Medical (SJM) cardiac leads: Riata leads, Riata ST leads, Durata and/or QuickSite/QuickFlex Cardiac Resynchronization Therapy (CRT) leads.