Prognostic role of highly sensitive cardiac troponin I in patients with systolic heart failure.

BACKGROUND: Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are useful biomarkers in patients with chronic heart failure (CHF). However, the clinical use has limitations due to the low sensitivity of a conventional commercial assay system. Recently, a high sensitive-cTnI (hs-cTnI) commercial assay has become available.

METHODS: To compare the prognostic value of cTnT and hs-cTnI, we measured hemodynamic parameters and serum levels of cTnT, hs-cTnI and N-terminal pro-brain natriuretic peptide (NT-proBNP)in 258 consecutive CHF patients and then followed these patients for a mean period of 2.6 years. In both assays of cTnT and hs-cTnI, the lowest concentration at which the coeffi cient of variation was < or =10% were 0.03 ng/mL, respectively. Therefore, in the present study, an elevated cTnT or cTnI test was defined as a level of > or =0.03 ng/mL.

RESULTS: During long-term follow up, there were 20 cardiac deaths. In 258 CHF patients, serum cTnT were elevated (> or =0.03 ng/mL) in 32 patients (12%) and serum hs-cTnI was elevated (> or =0.03 ng/mL) in 112 patients (43%). On stepwise multivariate analyses, high plasma NT-proBNP (> or =627 pg/mL, P = .0063) and hs-cTnI (> or =0.03 ng/mL) (P = .016) were independent significant prognostic predictors but cTnT (> or =0.03 ng/mL) was not. The hazard ratio for mortality of patients with high plasma NT-proBNP (> or =627 pg/mL) and hs-cTnI (> or =0.03 ng/mL) was 5.74 (95% CI, 2.33-14.28, P < .0001) compared to that of those with low NT-proBNP (<627 pg/mL) or hs-cTnI (<0.03 ng/mL).

CONCLUSIONS: These findings indicate that a high plasma concentration of hs-cTnI is an independent and useful prognostic predictor in patients with CHF.