Association of diastolic dysfunction with myocardial tissue characteristics assessed by multi-parameter cardiac magnetic resonance in patients with idiopathic inflammatory myopathy

OBJECTIVES: This study aimed to investigate associations between left ventricular (LV) diastolic dysfunction and myocardial tissue characteristics in idiopathic inflammatory myopathy (IIM) using multi-parameter cardiac magnetic resonance. METHODS: A total of 82 IIM patients [56 late gadolinium enhancement (LGE)-negative, 26 LGE-positive] and 37 controls were included. Patients were stratified: group 1 (active myocardial inflammation + necrosis/fibrosis: elevated T2, native T1 values + LGE-positive, n = 24), group 2 (active myocardial inflammation only: elevated T2, native T1 values, LGE-negative, n = 35) and group 3 (chronic myocardial fibrosis: normal T2, elevated native T1 value/LGE-positive, n = 12). LV volume-time indices, LV/left atrial (LA) strain, and myocardial tissue parameters [T1/T2 mapping values, extracellular volume (ECV)] were analysed via linear regression. RESULTS: IIM patients showed prolonged time-to-peak filling rate and reduced peak filling rate (PFR) vs controls (P < 0.05), with group 1 having the lowest PFR. Group 1 exhibited significantly impaired LV/LA strain, elevated T2/native T1 value and higher ECV compared with Groups 2 and 3 (all P < 0.05). Multivariable analysis revealed inverse correlations between PFR and T2 value (β = -0.245, P = 0.042), while LV global circumferential and longitudinal peak strains positively correlated with T2 value (β = 0.288 and 0.276, respectively; P < 0.05). Group 1 demonstrated the most severe diastolic dysfunction (P < 0.05 vs other groups). CONCLUSION: LV diastolic dysfunction in IIM is closely linked to myocardial tissue characteristics, particularly in patients with concurrent active myocarditis and necrosis/fibrosis. Both active myocarditis and chronic myocardial fibrosis contribute to diastolic impairment.