Myocardial Inflammation, Measured Using 18-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (FDG PET-CT) is Associated with Disease Activity in Rheumatoid Arthritis.

OBJECTIVES: To determine the prevalence and correlates of subclinical myocardial inflammation in rheumatoid arthritis (RA).

METHODS: RA patients (n=119) without known cardiovascular disease (CVD) underwent cardiac 18-fluorodeoxyglucose positron emission tomography with computed tomography (FDG PET-CT). Myocardial FDG uptake was assessed visually and quantitatively by standardized uptake values (SUV). Multivariable linear regression was used to assess the associations of patient characteristics with myocardial SUV. A subset of RA patients escalating disease modifying anti-rheumatic drug (DMARD) therapy (n=8) had a second FDG PET-CT scan after 6 months to assess treatment-associated changes in myocardial FDG uptake.

RESULTS: Visually assessed FDG uptake was observed in 46 (37%) of RA patients, and 21 (18%) had abnormal quantitatively assessed myocardial FDG uptake [i.e. SUVmean≥3.10 units (two standard deviations above the SUVmean of a reference non-RA group (n=27)]. Average SUVmean was 31% higher for those with a clinical disease activity index (CDAI) ≥10 vs. those with lower scores (p=0.005) after adjusting for potential confounders. The average adjusted SUVmean was 26% lower among those treated with non-TNF targeted biologics vs. those treated with conventional (non-biologic) DMARDs (p=0.029). In the longitudinal sub-study, myocardial SUVmean decreased from 4.50 to 2.30 units over 6 months, which paralleled the decrease in average CDAI from 23 to 12 units.

CONCLUSIONS: Subclinical myocardial inflammation is frequent in RA, is associated with RA disease activity, and may decrease with RA therapy. Future longitudinal studies will be required to assess whether reduction in myocardial inflammation will reduce heart failure risk in RA. This article is protected by copyright. All rights reserved.