Lead Failure
Lead failure was defined as per the Heart Rhythm Society consensus (8). High-voltage leads were considered to have failed if they exhibited: persistent oversensing of non-physiological rapid signals, abnormal impedance in the pace/sense or the shock component, an increase in right-ventricular lead threshold and/or decrease in sensing sufficient to make the lead unreliable (8). All leads that met these criteria were extracted and replaced; all were inspected carefully before and after extraction. Lead extraction for infection and lead revision for displacement were considered separately. Radiological images from the time of implantation were inspected for all leads that subsequently failed.