Implantable cardioverter-defibrillator elective generator replacement: a procedure for all?

Abstract

Six risk stratification scores have been developed to estimate mortality risk in patients receiving an implantable cardioverter-defibrillator (ICD). This study aims at validating and comparing these risk scores in patients having elective ICD generator replacement (GR) and assessing the outcome of patients submitted to this procedure. Two hundred twenty three consecutive patients with ischaemic or non-ischaemic dilated cardiomyopathy submitted to elective ICD GR and followed-up for 44 ± 19 months were included. We evaluated which of six previously developed risk scores could predict post-discharge all-cause mortality risk in this context with the highest efficacy. Comparisons between these scores were made using receiver-operating characteristic curves and the integrated discrimination improvement (IDI) index. We further assessed risk of appropriate ICD therapies and all-cause mortality following ICD GR. The prognostic utility of the six scores was assessed by calculating the AUC for follow-up all-cause mortality prediction: Goldenberg - 0.758 ± 0.042, p < 0.001; Parkash - 0.754 ± 0.042, p < 0.001; Bilchick - 0.813 ± 0.038, p < 0.001; Kraaier - 0.721 ± 0.043, p < 0.001; REPLACE DARE - 0.746 ± 0.048, p < 0.001; Providencia - 0.739 ± 0.043, p < 0.001. Through measures of risk reclassification (IDI and relative IDI), the score by Bilchick et al. was shown to outperform all other scores. Binary logistic regression identified pre-GR-appropriate ICD therapy as an independent predictor of post-GR ICD therapy (OR 6.2, CI 95% 3.0-12.7, p < 0.001), along with male gender (OR 6.6, CI 95% 0.8-55, p = 0.082) and history of atrial fibrillation (OR 2.28, CI 95% 1.1-4.5, p = 0.019). Current prediction scores are useful in predicting mortality risk of patients considered for ICD generator replacement and can potentially help identify patients who may not benefit from continuous ICD treatment due to high mortality rates regardless of the ICD.