Abstract 15770: Cystatin C is Superior to Creatinine for Predicting Sudden Cardiac Arrest in Ischemic Cardiomyopathy
Background: We have recently shown that creatinine is an independent predictor of sudden cardiac arrest (SCA) in patients with ischemic cardiomyopathy. Since estimated glomerular filtration rate (eGFR) and cystatin C (CysC) predict total mortality in heart failure, and are purported to provide even better assessments of renal function, we hypothesized that they might be superior to creatinine for predicting SCA.
Methods: The NIH sponsored PAREPET study (Prediction of ARrhythmic Events with Positron Emission Tomography) enrolled 204 subjects with ischemic cardiomyopathy (EF ≤ 35%) who were eligible for an ICD for primary prevention. The primary endpoint was SCA (arrhythmic death or ICD discharge for ventricular fibrillation or ventricular tachycardia >240 bpm). eGFR was calculated with Cockroft-Gault, Modification of Diet in Renal Disease-4, and Chronic Kidney Disease Epidemiology Collaboration equations and compared with creatinine and CysC levels.
Results: Average age was 67 ± 11 years with an ejection fraction of 27 ± 9%, and 90% were male. Mean creatinine was 1.4 ± 0.8 mg/dL, CysC was 0.62 ± 0.26 mg/L, and eGFR averaged 63 ± 26 ml/min/1.73 m2, with no differences between equations. During a median follow up of 4.1 years, there were 69 cardiac deaths of which 33 were SCAs. As continuous variables using Cox models, creatinine (hazard ratio, HR = 1.63, p = 0.0001), all three eGFR equations (all HR = 0.98, p = 0.001) and CysC (HR = 7.0, p = 0.0001) predicted time to cardiac death. However, for cause specific mortality from SCA, only creatinine (HR = 1.53, p = 0.001) and CysC (HR = 11.0, p = 0.0001) were predictive (all eGFR HR = 0.99, p = 0.14 - 0.24). When CysC was added to the multivariate analysis, it replaced creatinine as a significant, independent predictor of SCA (along with volume of denervated myocardium, LV end-diastolic volume index, and no angiotensin inhibition therapy).
Conclusion: In patients with ischemic cardiomyopathy, CysC is a very potent predictor of cause specific mortality from SCA as well as total cardiac mortality. The predictive capacity of creatinine was not improved by estimation of eGFR; however, CysC was superior and replaced creatinine as an independent predictor of SCA in PAREPET.
- © 2013 by American Heart Association, Inc.