Coronary microvascular dysfunction and diastolic load correlate with cardiac troponin T release measured by a highly sensitive assay in patients with nonischemic heart failure.

OBJECTIVES: This study investigated factors associated with cardiac troponin T (cTnT) release from failing myocardium.
BACKGROUND: Persistent and modest elevation of serum cTnT is frequently observed in heart failure (HF) patients free of coronary artery disease, although the mechanisms underlying this finding remain unclear.
METHODS: We evaluated serum cTnT levels in the aortic root (Ao) and coronary sinus (CS) using a highly sensitive assay in 90 nonischemic HF patients and 47 non-HF patients. Transcardiac cTnT and plasma B-type natriuretic peptide (BNP) release were described as the differences between CS and Ao cTnT levels [ΔcTnT (CS-Ao)] and BNP levels [ΔBNP (CS-Ao)], respectively. Coronary flow reserve (CFR) was measured in 68 HF patients using an intracoronary Doppler guidewire.
RESULTS: ΔcTnT (CS-Ao) levels were available in 76 HF patients and 28 non-HF patients (84% vs. 60%; p = 0.001), and higher in HF patients than non-HF patients (p < 0.001). Among HF patients, log[ΔcTnT (CS-Ao)] correlated with log[ΔBNP (CS-Ao)] (r = 0.368, p = 0.001), pulmonary capillary wedge pressure (r = 0.253, p = 0.03) and left ventricular end-diastolic pressure (LVEDP) (r = 0.321, p = 0.005). Multivariate regression analysis identified LVEDP as an independent parameter that correlated with ΔcTnT (CS-Ao). ΔcTnT (CS-Ao) levels were available in 58 HF patients who were evaluated for CFR. Coronary microvascular dysfunction, diagnosed by CFR <2.0, was observed in 18 HF patients. ΔcTnT (CS-Ao) was higher in patients with coronary microvascular dysfunction (4.8 [2.0 to 8.1] ng/l) than those without (2.0 [1.2 to 4.6] ng/l; p = 0.04).
CONCLUSIONS: cTnT release from failing myocardium correlated with diastolic load and coronary microvascular dysfunction in nonischemic HF patients.