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

Abstract Objectives To identify risk factors for myocardial involvement in idiopathic inflammatory myopathy (IIM) and evaluate 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 Myocardial involvement occurred in 68.5% and was associated with higher cTnT/creatine kinase (CK) ratios and anti-Ro52 positivity. Anti-Ro52-positive patients exhibited higher rates of late gadolinium enhancement and increased E/e′. Both cTnT/CK [odds ratio (OR) = 1.030, P = .024] and anti-Ro52 (OR = 5.629, P = .003) independently predicted myocardial involvement. A cTnT/CK cutoff > 19.3% predicted myocardial involvement [area under the curve (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 [hazard ratio (HR) = 7.395, P = .001] and cTnT/CK (HR = 1.012, P = .037) as independent mortality predictors. Time-dependent receiver operating characteristic at 3 years showed AUCs of 0.68 (cTnI) and 0.64 (cTnT/CK). Kaplan–Meier analysis confirmed worse survival with positive cTnI or a high cTnT/CK. Conclusions The cTnT/CK ratio identifies myocardial involvement and predicts mortality in IIM patients with abnormal cTnT. Combining it with anti-Ro52 antibodies improves the detection of myocardial involvement.