To define the prevalence of prolonged QT interval and QT dispersion (QTd) in rheumatoid arthritis (RA) patients and in a control population.
QT interval corrected by Bazett's formula (QTc) was calculated from standard 12-lead ECGs in 963 subjects free of previous cardiovascular events (646 RA patients and 317 controls strictly matched for age, sex and cardiovascular risk factors).
RA patients (59.6±9.6 years, 68.1% females) had a long mean disease duration (10.6 years) and moderate disease activity (DAS28=3.68±1.23). QTc was 5 msec longer in RA patients than in controls (412±9 vs. 407±28 msec, p=0.013). However, the prevalence of QTc prolongation in RA patients and controls was not significantly different (5.3% vs. 6.3%, p=0.50). On the contrary, RA patients had a significantly greater QTd (42±26 vs. 35±18 msec, p<0.001) and a higher prevalence of increased QTd (33.3% vs. 18.3%, p<0.001) than controls. Furthermore, RA was independently associated to increased QTd [OR(95%CI)= 2.21(1.58-3.08), p=0.0001]. In the RA population, male gender and older age were independently associated with a higher prevalence of prolonged QTd.
In this cohort of long-standing and moderately active RA patients, RA showed longer QTc but similar prevalence of prolonged QTc and an increased QTd with a 1.8-fold higher prevalence of increased QTd than the control population. Further studies in larger prospective cohorts are warranted to investigate whether QTd prolongation predicts sudden cardiac death and other adverse cardiovascular outcomes in RA.