Diffuse Myocardial Fibrosis and Inflammation in Rheumatoid Arthritis: Insights From CMR T1 Mapping.

The goal of this study was to assess the diffuse myocardial fibrosis and edema in rheumatoid arthritis (RA) using multiparametric cardiac magnetic resonance (CMR) and the association of myocardial T1 and extracellular volume (ECV) with disease activity, duration, and cardiac function. RA is a connective tissue disorder, with frequent cardiovascular disease. Myocardial inflammation and diffuse fibrosis can be detected noninvasively by using native T1 mapping and ECV quantification on CMR. Thirty-nine RA patients (28 women; mean age 50 ± 12 years) and 39 matched control subjects (28 women; mean age 49 ± 12 years) underwent CMR at 1.5-T, including cine, tagging, T2-weighted, native T1 mapping (shortened modified Look-Locker inversion recovery), late gadolinium enhancement (LGE), and ECV imaging. Focal fibrosis on LGE was found in 46% of RA patients compared with none of the control subjects. Patients with RA had larger areas of focal myocardial edema (10% vs. 0%), higher native T1 values (973 ± 27 ms vs. 961 ± 18 ms; p = 0.03), larger areas of involvement as detected by native T1 >990 ms (35% vs. 2%; p < 0.001), and expansion of ECV (30.3 ± 3.4% vs. 27.9 ± 2.0%; p < 0.001) compared with control subjects. Left ventricular volumes, mass, and ejection fraction were similar between RA patients and control subjects. Peak systolic circumferential strain (-16.9 ± 1.3 vs. -18.7 ± 1.2; p < 0.001) and peak diastolic circumferential strain rate (83 ± 21 s(-1) vs. 112 ± 20 s(-1); p < 0.001) were impaired in RA patients. Myocardial T1 and ECV were correlated with myocardial strain and RA disease activity. Subclinical cardiovascular disease is frequent in RA, including focal and diffuse myocardial fibrosis and inflammation, which are associated with impaired strain and RA disease activity. CMR T1 mapping provides potential added value as a biomarker for disease monitoring and study of therapies aimed at reducing diffuse myocardial fibrosis in RA.