Predictors of mortality in patients with chronic kidney disease and an implantable defibrillator: an EPGEN substudy.

AIMS: Chronic kidney disease (CKD) is increasingly prevalent, and is an independent risk factor for cardiovascular mortality. Clinical trials of the implantable cardioverter-defibrillator (ICD) have demonstrated a survival benefit over medical therapy for the prevention of sudden cardiac death, but its benefit in patients with concomitant CKD is unclear.

METHODS AND RESULTS: We studied 199 subjects with CKD, defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2), who underwent ICD implantation in the Duke Electrophysiology Genetic and Genomic Studies (EPGEN) biorepository. The mean age of the cohort was 67.8 ± 9.3 years, and the mean eGFR was 41.1 ± 13.2 mL/min/1.73 m(2). There were 63 deaths over a mean follow-up of 31.1 ± 18.8 months, corresponding to an annual mortality rate of 12.2%. Additionally, there was a 7% annual rate of appropriate ICD therapy. Using Cox regression analysis, older age, lower ejection fraction, and lower eGFR were found to be significant predictors of mortality. There was a gradient of risk associated with lower renal function: a 10 mL/min reduction in eGFR conferred a 48% increase in the risk of death (P < 0.001). Further adjustment for appropriate ICD therapy did not modify these associations.

CONCLUSION: In patients with CKD treated with a defibrillator, more advanced renal dysfunction is associated with reduced survival despite appropriate defibrillator therapy. This may be due to competing mortality risks in this population that attenuate the benefit of the ICD in reducing arrhythmic death. Age, ejection fraction, and kidney disease severity can be used to risk stratify patients before device implantation.