Association of Baseline and Serial High-Sensitivity Cardiac Troponin T with In-Hospital Mortality Across Clinical Presentation, LVEF and Diabetes Status in Decompensated Heart Failure

Background/Objectives: High-sensitivity cardiac troponin T (hs-cTnT) is frequently elevated in decompensated heart failure (DHF), but its prognostic association may vary according to clinical context. We evaluated baseline and serial hs-cTnT in relation to in-hospital mortality across clinical presentation, left ventricular ejection fraction (LVEF) and diabetes status. Methods: A total of 653 patients hospitalized with DHF were prospectively analyzed. Baseline hs-cTnT was assessed globally and across clinical presentation, LVEF and diabetes status. Among 334 patients with repeated measurements, serial hs-cTnT was evaluated using continuous measures and threshold-based trajectories. Results: In-hospital mortality was 9.0%. Baseline hs-cTnT showed moderate discrimination for mortality (AUC 0.658). The internally derived 38.4 pg/mL threshold identified higher mortality above versus below the threshold (14.8% vs. 5.1%, p < 0.001) but showed limited bootstrap stability. Clinical presentation significantly modified the association between hs-cTnT and mortality (global interaction p = 0.022), driven by a stronger association in decompensated right-sided versus left-sided HF (ratio of ORs 2.77, 95% CI 1.26–6.07). No significant modification effect was observed by LVEF or diabetes status. In a serial subgroup, repeated hs-cTnT remained associated with mortality after multivariable adjustment (OR 1.59 per doubling, 95% CI 1.14–2.21), although the increase in discrimination over the baseline model was not significant (AUC 0.750 vs. 0.777, p = 0.205). The above-above trajectory remained associated with mortality in Firth regression (adjusted OR 2.32, 95% CI 1.02–5.61). Conclusions: hs-cTnT was associated with in-hospital mortality in DHF, with heterogeneity by clinical presentation. Serial measurements were associated with outcome, but their incremental discrimination value was limited. Threshold-based trajectories should be considered exploratory pending external validation.