Treatment with tocilizumab led to a notable normalization of corrected QT intervals in patients with rheumatoid arthritis (RA), according to a study published in The Journal of Rheumatology.
Researchers compared corrected QT between patients who had RA (n=94) with matched participants (n=42) and examined the change in corrected QT after tocilizumab treatment. The study group received tocilizumab, either 8 mg/kg once a month or 162 mg biweekly, for 24 weeks. Clinical evaluations, electrocardiograms, physician exams, health questionnaires, and blood serum and plasma assays were completed at baseline and 24 weeks.
At baseline, 81% of patients with RA were taking disease-modifying antirheumatic drugs, 6% had hyperlipidemia, 1 patient had diabetes, and inflammation markers were above normal in most patients. The extended QT interval of patients with RA was associated with anticyclic citrullinated peptide antibodies. Patients who were seropositive for anticyclic citrullinated peptide antibodies had an 8.3 ms longer QT interval compared with patients who were seronegative (P =.021). Higher levels of C-reactive protein (CRP), increased matrix metalloproteinase 3, more articular swelling, and increased anticyclic citrullinated peptide antibodies accounted for 26% of the QT interval variability. Patients with increased levels in at least 3 of these risk categories had a mean QT interval that was 24 ms longer than patients with fewer risk categories. After 24 weeks of treatment, all disease measurements, inflammatory markers, and health questionnaire answers improved. The improvement in CRP levels had a significant association with the normalization of QT intervals (P <.001). Patients who started with the highest CRP levels saw a decrease in the QT interval by an average of 26 ms.
Future studies need to include an untreated control group to validate the improvement through tocilizumab and the potential effects of other medications on QT intervals.
Researchers concluded that patients with RA have an increased QT interval compared with matched controls, and tocilizumab treatment reduced the QT interval toward the normal level of the control group in 24 weeks.
Kobayashi H, Kobayashi Y, Yokoe I, et al. Heart rate–corrected QT interval duration in rheumatoid arthritis and its reduction with treatment with the interleukin 6 inhibitor tocilizumab [published online September 1, 2018]. J Rheumatol. doi:10.3899/jrheum.180065