Insulation defects of thin high-voltage ICD leads: an underestimated problem?

Long-term lead failure is a known complication of ICD therapy. The precise incidence and sequelae of insulation defects at the tricuspid level, however, are not well characterized. This study determined the risk of lead failure, with particular emphasis on insulation defects at the level of the tricuspid valve, in a large series of consecutive ICD recipients. Data from 357 consecutive patients, who had received transvenous 7 and 8 French ICD-leads (St. Jude Medical, Riata family) and were followed at our center, formed the basis of this study. During a mean follow-up of 42 ± 24 months, 30 of 357 (8%) patients required surgical intervention due to lead failure. For overall lead defects, lead access via the subclavian vein and subpectoral device placement were independent predictors of overall lead failure (OR 3.47, 95% CI 1.38-8.72, P = 0.013 and OR 3.83, 95% CI 1.77-8.27, P = 0.001, respectively). Lead insulation defects at the level of the tricuspid valve accounted for 20% of all lead failures. Diagnosis of this specific insulation defect could only be established by fluoroscopy, while electrical parameters were within normal limits in all of these patients. On univariate but not on multivariate analysis the presence of nonischemic cardiomyopathy was a predictor of this lead complication (OR 8.2, CI 1.5-46.1, P = 0.02). Insulation defects of 7 and 8 French ICD leads at the tricuspid level represent an important complication of device therapy. Even moderate changes in lead impedance within the normal limits at follow-up should prompt careful fluoroscopic evaluation to avoid spurious shocks.