Relationships of N-terminal pro-B-natriuretic peptide and cardiac troponin T to left ventricular mass and function and mortality in asymptomatic hemodialysis patients

Abstract

Background: Although the cardiac biomarker troponin T (cTnT) is related strongly to mortality in patients with end-stage renal disease, the independent association of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and cTnT levels in predicting outcomes is unknown. The objective of this study is to determine factors associated with NT-pro-BNP and cTnT and determine whether these levels are associated with mortality.

Study design: Cohort study.

Setting & participants: Asymptomatic hemodialysis patients (n = 150) in 4 university-affiliated hemodialysis units. EXPOSURE & OUTCOMES: For cross-sectional analysis, echocardiographic variables as exposures and NT-pro-BNP and cTnT levels as outcomes; for longitudinal analysis, association of NT-pro-BNP and cTnT levels as exposures to all-cause and cardiovascular disease mortality as outcomes.

Results: In a multivariate regression analysis, low midwall fractional shortening, a measure of poor systolic function, was an independent correlate of log NT-pro-BNP level (P < 0.01), whereas left ventricular mass index was an independent correlate of cTnT level (P < 0.01). During a median follow-up of 24 months, 46 patients died, 26 of cardiovascular causes. NT-pro-BNP levels had a strong graded relationship with all-cause (hazard ratios [HRs], 1.54, 4.78, and 4.03 for increasing quartiles; P < 0.001) and cardiovascular mortality (HRs, 2.99, 10.95, and 8.54; P < 0.01), whereas cTnT level had a weaker relationship with all-cause (HRs, 1.57, 2.32, and 3.39; P < 0.01) and cardiovascular mortality (HRs, 0.81, 2.12, and 2.14; P = 0.1). The combination of the 2 biomarker levels did not improve the association with all-cause or cardiovascular mortality compared with NT-pro-BNP level alone. NT-pro-BNP level was a marker of mortality even after adjusting for left ventricular mass index and midwall fractional shortening.

Limitations: Our cohort was predominantly black and of limited sample size.

Conclusion: NT-pro-BNP level strongly correlates with left ventricular systolic dysfunction and is associated more strongly with mortality than cTnT level in asymptomatic hemodialysis patients.

Figure 1

Bivariate relationship between cardiac troponin t (cTnT) and n-terminal pro-B-type natriuretic peptide. The Spearman's correlation coefficient was 0.34 (p<0.001).

Figure 2

Figure 2a - Adjusted cumulative hazard curves for quartiles of NT-proBNP for all-cause and cardiovascular mortality. Covariates adjusted for were age, race, gender, serum albumin, and ESRD etiology (diabetes vs non-diabetes) plotted at their mean values. NT-proBNP had a strong graded relationship with all-cause and cardiovascular mortality. Figure 2b - Adjusted cumulative hazard curves for quartiles of cTnT for all-cause and cardiovascular mortality. Covariates adjusted for were age, race, gender, serum albumin, and ESRD etiology (diabetes vs non-diabetes) plotted at their mean values. cTnT had a strong graded relationship with all-cause mortality, but a weaker relationship with cardiovascular mortality.