Variation in and prognostic importance of troponin T measured using a high-sensitivity assay in clinically stable haemodialysis patients.
BACKGROUND
A recently introduced high-sensitivity assay can measure troponin T (hsT) at low levels with greater precision than the fourth generation troponin T assay. As most patients with end-stage renal failure (ESRF) may have elevated hsT levels, data on biological variability and the impact of haemodialysis are needed for clinical interpretation of results.


METHODS
This is a prospective observational cohort study aiming to identify baseline levels of hsT in stable haemodialysis patients in addition to examining variation in levels over time. Cardiovascular (CV) mortality was analysed at 6 months after the baseline hsT measurement. hsT was measured prior to the haemodialysis using the high-sensitivity Roche troponin T assay in 239 prevalent haemodialysis patients. In a subset of 78 patients, repeat measurements were made 1 month later, both before and after haemodialysis.


RESULTS
hsT was above the 99th centile for the normal healthy population (14 ng/mL) in 98% of patients with a median level of 63 ng/L [Interquartile range (IQR) 37-108]. Higher hsT levels were associated with diabetes and left ventricular ejection fraction <50%. hsT was higher in patients who died from CV causes (median 418, IQR 109-776) compared with alive patients (median 59.5, IQR 36-96 P = 0.0027), and this association remained significant after adjustment for other predictors of mortality. In 95% of stable patients, variation in hsT over 1 month was <54%. In three patients with unstable coronary artery disease, hsT varied by >100% and >100 ng/L. Haemodialysis reduced hsT by a median of 24% (IQR 6-22, P = 0.0001).


CONCLUSIONS
hsT levels are elevated in almost all patients with ESRF. Variation in hsT over 1 month was <50% in most patients. Greater variation may indicate an acute coronary syndrome or worsening cardiac disease.
Department of Renal Medicine , Auckland City Hospital , Auckland , New Zealand.
Martin
M
Wolley
Department of Cardiology , Auckland City Hospital , Auckland , New Zealand.
Ralph
R
Stewart
Department of Renal Medicine , Auckland City Hospital , Auckland , New Zealand.
Elizabeth
E
Curry
Department of Chemical Pathology , Auckland City Hospital , Auckland , New Zealand.
James
J
Davidson
Department of Cardiology , Auckland City Hospital , Auckland , New Zealand.
Harvey
H
White
Department of Renal Medicine , Auckland City Hospital , Auckland , New Zealand.
Helen
H
Pilmore
cardiovascular risk; end-stage renal failure; haemodialysis; high-sensitivity troponin T