The impact of changes in LVEF and renal function on the prognosis of ICD patients after elective device replacement

Background: A proportion of patients with an implantable cardioverter-defibrillator (ICD) in prevention of sudden cardiac death will only receive their first appropriate ICD therapy (AT) after device replacement. Clinical reassessment at the time of replacement could be helpful to guide the decision to replace or not in the future.

Methods: All patients with an ICD for primary or secondary prevention in ischemic (ICM) or nonischemic cardiomyopathy were included in a single-center retrospective registry. The association of changes in left ventricular ejection fraction (LVEF; cut-off at 35%), worsening renal function (decrease in estimated glomerular filtration rate > 15 mL/min), and worsening New York Heart Association class at elective device replacement with mortality and AT was analyzed using adjusted Cox regression analysis.

Results: A total of 238 (33%) out of 727 patients received elective device replacement (86.1% male, 74.4% ICM, 42.9% primary prevention). During this replacement 20.2% received a device upgrade. The mean time to replacement was 6.4 ± 2.0 years and mean follow-up after replacement was 3.4 ± 3.0 years. Of patients who did not receive AT before replacement 23.1% received their first AT after replacement. Worsening renal function (hazard ratio [HR] 2.79, 95% confidence interval [CI] 1.50-5.18) and a consistently LVEF ≤35% compared to a consistently LVEF >35% (HR 2.15, 95% CI 1.10-4.19) at the time of replacement were independent predictors of mortality. Independent predictors of first AT after replacement could not be identified.

Conclusion: Although reassessment of LVEF and renal function at replacement can be helpful in predicting total mortality, the clinical utility to guide reimplantation seemed limited. Our experience indicates that approximately 25% of patients received their first AT only after replacement.