Effect of infliximab treatment on QT intervals in patients with ankylosing spondylitis

Cardiovascular complications are one of the most common and the most serious extraskeletal manifestations of ankylosing spondylitis (AS). Infliximab, a monoclonal antibody against tumor necrosis factor, is widely used in the treatment of AS. QT dispersion (QTd), which relates to left ventricular function and is used as an index of cardiac dysrhythmia, may be useful as a prognostic guide. Early detection of possible cardiac involvement may not be clinically evident, whereas it may be detected by electrocardiography.

The aim of this prospective study was to assess the effect of infliximab treatment on QT intervals in patients with AS.

Twenty-one patients (17 females and 4 males) with AS who were in the active phase of disease (Bath Ankylosing Spondylitis Disease Activity Index score >4) were enrolled in the study. Infliximab was administered intravenously at a dosage of 5 mg/kg at weeks 0, 2, and 6 and every 6 weeks thereafter. QT intervals were recorded before and after 6 months of treatment.

QT corrected (QTc) for heart rate was significantly reduced in the patients with AS after 6 months of infliximab therapy (406 ± 5.5 vs 388 ± 6.6 milliseconds; P = 0.029). There was no difference in the QTc dispersion (34.3 ± 11.1 vs 34.1 ± 8.6; P = 0.171). Body mass index and lipid profile were slightly increased after the treatment, but the difference was statistically insignificant.

Inflammation can affect the ventricles with an unknown mechanism, and QTc may be slightly prolonged as a result in the active phase of AS. In our study, QTc was shortened under infliximab therapy by suppressing inflammation. Therefore, this effect may protect patients with AS from fatal arrhythmias and sudden cardiac death.