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

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. 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. 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. 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.