Abstract 2852: Cystatin C is an Independent Predictor of Sudden Cardiac Death among Elderly Persons
Background - Cystatin C is a novel measure of kidney function that is superior to estimated glomerular filtration rate in predicting cardiovascular disease.
Objective - We evaluated whether kidney function was an independent predictor of sudden cardiac death (SCD) risk.
Methods - Subjects were participants in the Cardiovascular Health Study. Measures of kidney function were cystatin C and creatinine-based estimated glomerular filtration rate (eGFR). SCD was defined as a sudden pulseless condition from a cardiac origin in a previously stable individual occurring out of the hospital or in the emergency room.
Results - Among the 5157 participants, there were 156 adjudicated SCD events over a median follow-up of 11.2 years. The incidence of SCD events increased across cystatin C quintiles: 0.15% per year in quintile 1, 0.27% per year in quintile 2, 0.32% per year in quintile 3, 0.42% per year in quintile 4, and 0.53% per year in quintile 5. In addition, the rate of SCD events increased as eGFR decreased (0.28% per year among those with eGFR ≥ 60 ml/min/1.73m2 and 0.49% per year among those with eGFR < 60 ml/min/1.73m2. SCD risk increased across cystatin C quintiles after multivariate adjustment with a greater than two fold odds of risk in the highest quintiles compared to the lowest [HR = 1.62, 95% CI (0.86 –3.07) in quintile 2; HR = 1.81, 95% CI (0.96 –3.39) in quintile 3; HR = 2.29, 95% CI (1.24 – 4.22) in quintile 4; HR = 2.28, 95% CI (1.21– 4.30)] in quintile 5]. Low eGFR was predictive of SCD risk in unadjusted analysis [HR = 1.72, 95% CI (1.20 –2.47)] but did not achieve statistical significance after multivariate analysis [1.33, 95% CI (0.91–1.92)]. High cystatin C concentrations remained predictive of SCD risk even among participants without chronic kidney disease after multivariate analysis [HR = 1.84, 95% CI (1.18 –2.86)]. Finally, we noted excess SCD risk occurred in the 1633 participants with prevalent or incident MI or CHF; although, elevated cystatin C concentrations still remained predictive of SCD events in those without prevalent or incident cardiovascular disease (p for interaction = 0.05).
Conclusions - Cystatin C is a sensitive measure of kidney function that is an independent predictor of SCD risk among elderly persons.