Biological variation of high sensitive Troponin T in stable heart failure patients with ischemic or dilated cardiomyopathy.

INTRODUCTION: High sensitive Troponin (hsTn) assays enable detection of minimal marker elevation in heart failure patients previously deemed Troponin negative. Biovariability, reference change values (RCV), and index of individuality (II) have not been previously described for hsTnT although serial testing is important in interpreting low concentrations. For these values, a difference between ischemic heart disease (IHD) and dilated cardiomyopathy (dCMP) appears conceivable.
METHODS: Change in hsTnT was determined alongside with clinical variables in 41 patients with stable chronic systolic dysfunction at 2-week-, 1-month-, 2-month-, and 3-month-intervals (IHD n = 17; dCMP n = 24).
RESULTS: HsTnT was detectable in all patients. Individual hsTnT-variations at 2-week, 1-month, 2-month, and 3-month follow-up were 7.2, 22.6, 28.9, and 15.7%, respectively, corresponding to RCVs of 20.1, 62.5, 80.0, and 43.3%, respectively, for crude values. For log-normalised values, individual variations were 3.2, 2.8, 2.7, and 3.5%, respectively, corresponding to RCVs of 8.8, 7.9, 7.6, and 9.7%, respectively. The II was 0.03 to 0.33 according to interval. Aetiology of heart failure was not a consistent determinant of variation (p = 0.28; p = 0.07; p = 0.98; p = 0.03 for 2-week, 1-month, 2-month, and 3-month follow-up, respectively).
CONCLUSION: While short-term biological variation of hsTnT is low, it becomes relatively more important for intermediate follow-up. It is not related to aetiology of heart failure. The corresponding indices of individuality indicate high individuality of values.