Myocardial Microvascular Dysfunction in Rheumatoid Arthritis_{Quantitation by ¹³N-Ammonia Positron Emission Tomography/Computed Tomography}

BACKGROUND: The goal of this study was to assess the prevalence of myocardial microvascular dysfunction in rheumatoid arthritis (RA) patients without clinical cardiovascular disease and its association with RA characteristics and measures of cardiac structure and function. METHODS: Participants with RA underwent rest and vasodilator stress N-13 ammonia positron emission tomography and echocardiography. Global myocardial blood flow was quantified at rest and during peak hyperemia. Myocardial flow reserve (MFR) was calculated as peak stress myocardial blood flow/rest myocardial blood flow. A small number of asymptomatic and symptomatic non-RA controls were also evaluated. RESULTS: In RA patients, mean±SD MFR was 2.9±0.8, with 29% having reduced MFR (<2.5). Male sex and higher interleukin-6 were significantly associated with lower MFR, while the use of tumor necrosis factor inhibitors was associated with higher MFR. Lower MFR was associated with higher left ventricle mass index and higher left ventricle volumes but not with ejection fraction or diastolic dysfunction. RA and symptomatic controls had comparable MFR (mean±SD: 2.9±0.8 versus 2.55±0.6; P=0.48). In contrast, MFR was higher in the asymptomatic controls (mean±SD: 3.25±0.7) although not statistically different. CONCLUSIONS: Reduced MFR was observed in a third of RA patients without clinical cardiovascular disease and was associated with a measure of inflammation and with higher left ventricle mass and volumes. MFR in RA patients was similar to controls referred for clinical scans (symptomatic controls). Whether reduced MFR contributes to the increased risk for heart failure in RA remains unknown.