Cardiac biomarkers and survival in haemodialysis patients

Abstract

Background: In dialysis patients, cardiac troponin T (cTNT) is often elevated despite the absence of acute myocardial ischaemia, and amino-terminal pro-B-natriuretic peptide (NT-proBNP) is markedly higher compared to non-haemodialysis patients. In a longitudinal observation, we evaluated the association of cTNT and NT-proBNP on cardiovascular morbidity and mortality in haemodialysis patients with and without fluid overload.

Materials and methods: Plasma cTNT levels of 134 haemodialysis patients were measured before and after a dialysis session by 3rd generation electro-chemoluminiscence immunoassay. NT-proBNP was determined using a polyclonal antibody recognizing the N-terminal fragment of BNP (Elecsys autoanalyzer 2010, Roche Diagnostics, Mannheim, Germany). Volume status was determined by a clinical score system. Cardiovascular morbidity and mortality were assessed over a follow-up period of 36 months.

Results: Plasma cTNT > 0.03 ng mL(-1) was found in 39.6% of all patients. Patients with hypervolaemia had significantly higher cTNT levels compared to euvolaemic patients (median 0.054 ng mL(-1), interquartile range 0.019-0.153 vs. 0.005 ng mL(-1), < 0.001-0.034; P < 0.001). All haemodialysis patients had excessively high levels of NT-proBNP (median 4524; interquartile range 2000-10 250 pg mL(-1)), and NT-proBNP was significantly higher in hypervolaemic haemodialysis patients (11 988, 5307-19 242) compared to euvolaemic haemodialysis patients (3247, 1619-5574); P < 0.001. Receiver operator curves showed a threshold of cTNT > 0.026 ng mL(-1) and NT-proBNP > 5300 pg mL(-1) as predictors of hypervolaemia. Asymptomatic chronic haemodialysis patients with cTNT > 0.026 ng mL(-1) and NT-proBNP > 5300 pg mL(-1) were more likely to die due to cardiac events in the follow-up period. Multivariate analysis documented that elevated cTNT and NT-proBNP levels were highly predictive for cardiovascular events.

Conclusions: Plasma levels of cTNT are elevated in approximately 40% and NT-proBNP levels in 100% of asymptomatic chronic haemodialysis patients. Both parameters depend on volume status. Increased NT-proBNP and cTNT are strongly associated with adverse outcome in end-stage renal disease patients undergoing haemodialysis, and are a useful tool for risk stratification in chronic haemodialysis patients.