Prospective postmarket device studies versus returned product analysis as a predictor of system survival

Monitoring and reporting mechanisms are vital tools for clinicians to assess ICD system performance over time for optimal patient care. This article explores the various reporting mechanisms available to the clinician, both historical and current, and compares and contrasts two such methods. The lead survival rates obtained by return product analysis (RPA) are compared with those from an ongoing prospective chronic study that actively follows patients for clinical ICD system failures (Tachyarrhythmia Chronic Systems Study [TCSS]). Examination of available data shows that a prospective study such as the TCSS is capable of detecting clinically significant adverse events in 2.2% of the 3,958 leads followed. By comparison, RPA-based monitoring of the same leads detects "out of specification" events in 0.5% of the 78,571 leads followed. Statistical analyses of two separate families of leads (RV leads and SQ Patch leads) show that survival rates obtained by the two methods begin to differ at approximately 2 years of implant experience, with 95% confidence intervals no longer overlapping at 3 years. The authors conclude that prospective chronic device studies are a superior tool for the ongoing monitoring of implanted device performance compared to RPA-based reports.