Novel insights into short-term troponin remeasurement and long-term cardiac function and structure following fulminant myocarditis.

Background: Elevated serum high-sensitivity cardiac troponin (hs-cTn) levels are commonly observed in patients with fulminant myocarditis (FM) after the acute phase. This study aims to evaluate the relationship between elevated hs-cTnI levels at 30-day post-discharge and long-term cardiac structure and function. Methods: This study is a retrospective cohort study that selected FM patients hospitalized at Tongji Hospital in Wuhan from April 2016 to December 2022. All patients underwent serial monitoring of hs-cTnI levels. Patients were stratified into two groups based on hs-cTnI levels at 30 days post-discharge: the normal hs-cTnI (N-cTnI) group and the high hs-cTnI (H-cTnI) group. Left ventricular (LV) function and structure were assessed using 2-dimensional volume and speckle tracking strain echocardiography. Measurements were obtained at admission, discharge, and 6 months, 12 months, and annually thereafter post-discharge. Results: Among 95 patients with analysable echocardiographic data (median age: 33 years; 42.11 % male), the N-cTnI group demonstrated significantly higher proportions of patients meeting cardiac function criteria during follow-up compared to the H-cTnI group: LV ejection fraction (LVEF) > 50 % (95 % vs. 72 %; P = 0.003), global longitudinal strain (GLS) > 16 % (68 % vs. 36 %; P = 0.002), and LV end-diastolic dimension < 5 cm (86 % vs. 65 %; P = 0.020). Given that the primary composite endpoint occurred in only 5 patients, statistical analyses focused on secondary composite endpoints. The incidence of secondary composite endpoints was significantly higher in the H-cTnI group than in the N-cTnI group (61.91 % vs. 16.98 %; P < 0.001). Multivariable Cox regression identified elevated hs-cTnI at 30 days post-discharge (HR: 5.365; 95 % CI: 1.876-15.344; P = 0.002) and LV-GLS at discharge (HR: 0.844; 95 % CI: 0.732-0.974; P = 0.021) as independent predictors of secondary composite endpoints. Conclusion: Delayed normalization of hs-cTnI after 30 days post-discharge may predict long-term deterioration of cardiac function and structural remodeling in patients with FM.