Effects of treatment with janus kinase inhibitors on coronary microvascular perfusion in patients with rheumatoid arthritis: an observational prospective cohort study.

Despite their increasing use and their proven efficacy in the treatment of rheumatoid arthritis (RA), Janus kinase (JAK) inhibitors have been questioned by credible cardiovascular safety concerns. To date, mechanistic links of cardiovascular complications to JAK inhibitors remain largely unexplored. We aimed to investigate the effect of JAK inhibition on coronary microvascular blood flow in a previously published cohort of treated patients with RA. We prospectively enrolled RA patients initiating treatment with JAK inhibitors. Study procedures were performed at baseline and repeated 3 months after treatment. Patients underwent applanation tonometry in the radial artery to assess subendocardial viability ratio (SEVR) otherwise known as Buckberg index, a noninvasive marker of myocardial perfusion. Thirteen patients with RA were enrolled, of whom 11 completed the study. All patients presented with at least one cardiovascular risk factor (e.g., age ≥ 65 years, history of current or past smoking, obesity, hypertension). No change in other than antirheumatic treatment was performed during the study, and no significant changes were observed in baseline characteristics other than triglyceride levels. Compared to baseline, three months treatment with JAK inhibitors did not significantly alter SEVR values [126 (102-144) % vs. 134 (106-251) %, p = 0.083]. Three months treatment with JAK inhibitors did not seem to significantly affect myocardial perfusion in a small RA cohort with cardiovascular risk factors, who would be presumably more vulnerable to adverse treatment-related cardiovascular effects. Larger studies with longer follow-up are needed to document the effects of JAK inhibitors on the myocardium.