Initial treatment of heart failure is empiric and requires frequent monitoring and medication adjustment. Predicting which patients require more intensive treatment may improve outcomes and decrease hospital length of stay. Cystatin C, a novel marker for renal function, has been studied for its prognostic value in heart failure but not in predicting treatment response. Our study examinec whether the level of cystatin C at hospital admission and age are associated with successful attenuation of N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP), a biomarker of ventricular distention and overload.
Data were analyzed from a cohort of 165 consecutive patients ≥ 25 years with a baseline creatinine ≤ 1.5 mg/dL who were admitted to an urban tertiary‐care hospital from June 2006 to April 2007 with a primary diagnosis of heart failure and received intravenous furosemide. Creatinine, cystatin C, and NT‐proBNP levels were measured at admission. NT‐proBNP was also measured at discharge. Demographic information was collected. We prospectively defined the primary outcome as odds of successful attenuation of NT‐proBNP levels, defined by a decline ≥ 50% from admission. We have previously shown that improvement in NT‐proBNP of < 50% during an acute hospitalization is associated with an increased hazard of readmission/death. Logistic regression adjusted for potential confounders, and log‐likelihood ratio testing examined interactions between cystatin C and the other covariates.
After excluding patients with incomplete medical records (n = 5), our study sample was 44% male and 69% nonwhite, with a mean age ± SD of 63 ± 15 years, median admission creatinine of 1.1 mg/dL (IQR, 0.9, 1.3 mg/L), median admission cystatin C of 1.08 mg/L (0.82, 1.38 mg/L), median admission NT‐proBNP of 4270 pg/mL (1140, 8180 pg/mL), and median discharge NT‐proBNP of 1626 pg/mL (498, 5221 pg/mL). Seventy‐two patients (45%) and 88 patients (55%) had a decline ≥ 50% or < 50% in NT‐proBNP, respectively. After adjustment for age, sex, race, and admission creatinine level, the odds of successful attenuation of NT‐proBNP decreased by 55% for each 1 mg/L increase in admission cystatin C (OR, 0.45; 95% CI, 0.20‐1.00; P = 0.05). For patients ≥ 50 years, odds of successful attenuation decreased by 4% per additional year of age, independent of sex, race, creatinine, and cystatin C (OR, 0.96; 95% CI, 0.93‐0.99; P = 0.01). Race, sex, admission creatinine, and age < 50 years were not significantly associated with odds of attenuation. No significant interaction between cystatin C and age, race, sex, or creatinine level was found.
In heart failure patients with normal admission creatinine, increasing admission cystatin C and advanced age are associated with a decrease in attenuation of NT‐proBNP. Admission cystatin C level may be an independent predictor for successful attenuation of hormonal activation and useful in identifying heart failure patients requiring more intensive treatment, monitoring, and follow‐up.
H. Michtalik‐ none; H. Yeh ‐ none; C. Campbell ‐ none; N. Haq ‐ none; H. Park ‐ none; W. Clarke ‐ none; D. Brotman ‐ Siemens Healthcare Diagnostics, research funding