Using serum cTnT/CK combined with anti-Ro52 antibodies to screen for myocardial involvement and assess prognosis in idiopathic inflammatory myopathy.

Abstract

Objective: Myocardial involvement in idiopathic inflammatory myopathy (IIM) indicates poor prognosis. This study aimed to identify risk factors for myocardial involvement and assess their prognostic value.

Methods: We analysed 92 IIM patients with abnormal cardiac troponin T (cTnT). Myocardial involvement was diagnosed by late gadolinium enhancement on cardiovascular magnetic resonance. All-cause mortality was recorded during follow-up.

Results: Among 92 patients, myocardial involvement was observed in 68.5%, who showed increased cTnT/CK ratios and anti-Ro52 antibody positivity rates. Anti-Ro52 positive patients exhibited higher rates of LGE and increased E/e'. Both cTnT/CK (OR = 1.030, p = 0.024) and anti-Ro52 (OR = 5.629, p = 0.003) independently predicted myocardial involvement. A cTnT/CK cut-off > 19.3% predicted myocardial involvement (AUC = 0.660), rising to 0.780 when combined with anti-Ro52. Subgroup analysis showed cTnT/CK was discriminative only in anti-Ro52 negative individuals. During a 36-month follow-up, 18 deaths occurred. Adjusted Cox regression identified cTnI positivity (HR = 7.395, p = 0.001) and cTnT/CK (HR = 1.012, p = 0.037) as independent mortality predictors. Time-dependent ROC at 3 years showed AUCs of 0.68 (cTnI) and 0.64 (cTnT/CK). Kaplan-Meier analysis confirmed worse survival with positive cTnI or high cTnT/CK.

Conclusion: The cTnT/CK ratio identifies myocardial involvement and predicts mortality in IIM patients with abnormal cardiac troponin T. Combining it with anti-Ro52 antibodies improves detection of myocardial involvement.