Cardiac involvement in established idiopathic inflammatory myopathy assessed by cardiac magnetic resonance mapping

OBJECTIVES: To investigate the prevalence of subclinical, myocardial involvement in patients with established idiopathic inflammatory myopathies (IIM) compared to healthy controls using T1 and T2 mapping by cardiac magnetic resonance imaging (CMRI).

METHOD: Fifty-five patients with established, stable IIM without overt cardiac involvement were consecutively enrolled in this cross-sectional study. All patients completed questionnaires, underwent clinical examination, blood tests including antibody profiling, electrocardiography, and CMRI with T1 and T2 mapping. Concurrently, CMRI was conducted on 19 healthy controls. Abnormal T1 and T2 values were defined as values exceeding the 95th percentile in the control group. Potential associations between abnormal T1 and T2 values and various cardiac- and IIM-related outcomes were assessed in exploratory analyses.

RESULTS: Abnormal T1 values were observed in 9% of all IIM patients, displaying significantly higher T1 values compared to healthy controls (p = 0.02). T2 values were elevated in 18% of IIM patients, particularly among patients with non-inclusion body myositis (IBM) IIM compared to healthy controls (p = 0.03). No significant associations between T1 or T2 values and cardiac or disease-related measures were found in the present cohort of IIM patients.

CONCLUSIONS: Our study demonstrates that subclinical cardiac involvement may be present in established, stable IIM patients, with abnormal T1 and T2 mapping observed in up to 18% of the cohort. These findings underscore the importance of ongoing cardiac monitoring, even during stable phases of the disease. However, prospective studies are needed to determine the prognostic value of T1 and T2 mapping in this disease entity. Key Points • T1 and T2 mapping on cardiac MRI identify subclinical myocardial involvement in patients with IIM. • Subclinical myocardial involvement is present in up to 18% of patients with established, stable IIM. • Cardiac T1 and T2 abnormalities are rare in patients with IBM.