The two main goals of this study are to demonstrate the heightened cardiovascular risk in RA by comparing platelet activity, inflammation and endothelial function in baseline rheumatoid arthritis versus age- and sex-matched patients with osteoarthritis; and 2) to demonstrate the effect of ticagrelor in rheumatoid arthritis by the pre- and post- measures of clinical RA severity, platelet activity, inflammation and endothelial function in rheumatoid arthritis before and after ticagrelor therapy.