INCIDENCE OF LEAD SYSTEM MALFUNCTION DETECTED DURING IMPLANTABLE DEFIBRILLATOR GENERATOR REPLACEMENT

Implantable cardioverter-defibrillator (ICD) generator replacement due to a depleted battery is a frequently performed procedure. The freque ncy with which sensing and defibrillation system failures are identifi ed during device replacement procedures has not been previously descri bed. Therefore, the purpose of this study was to prospectively determi ne the frequency of lead system malfunction detected at the time of de vice replacement in 55 consecutive patients undergoing ICD generator r eplacement. The mean age of the patients was 63 +/- 10 years and 40 of them were men. Forty-nine patients had an epicardial lead system, and six patients had a nonthoracotomy lead system. Four (7%) of these 55 patients were noted to have previously undetected lead system failure, either sensing (n = 3) or defibrillation (n = 1), necessitating syste m revision. The lead systems that failed were 40 +/- 6 months old (33- 49 months). In summary, during ICD generator replacement, previously u ndetected problems with sensing or defibrillation may be identified in approximately 10% of patients. Therefore, a comprehensive evaluation of the sensing and the defibrillation functions should be an essential component of the ICD generator replacement procedure.