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

Abstract 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.