QT-interval parameters are increased in systemic lupus erythematosus patients

Abstract

Systemic lupus erythematosus (SLE) patients have increased cardiovascular morbidity and mortality. QT-interval parameters are presumed markers of cardiovascular risk and have not been previously evaluated in SLE. Standard 12-lead ECGs were obtained from 140 female SLE outpatients and 37 age and body mass index-matched controls. QT interval was measured in each lead and heart rate-corrected maximum QT-interval duration (QTcmax) and QT-interval dispersion (QTd) were calculated. Risk factors for cardiovascular disease and lupus clinical features, disease treatment, disease activity and damage index were recorded. SLE patients have increased QT-interval parameters when compared to controls (QTcmax: 427.91 31.53 ms1/2 versus 410.05 15.45 ms1/2, P 0.001; QTd: 52.38 22.21 ms versus 37.12 12.88 ms, P 0.001). These differences persisted after excluding those patients with arterial hypertension, diabetes and with ECG abnormalities (QTcmax: 419.90 28.78 ms1/2 versus 409.15 15.85 ms1/2, P 0.041; QTd: 54.74 26.00 ms versus 37.96 13.05 ms, P 0.001). Multivariate linear regression for factors associated with QTcmaxselected the presence of electrocardiographic left ventricular hypertrophy (ECG-LVH) ( P 0.003), nonspecific ST-T-wave abnormalities ( P 0.022) and left atrial enlargement ( P 0.044). Multivariate associates with QTd were age ( P 0.018), ECG-LVH ( P 0.022) and ST-T abnormalities ( P 0.031). In conclusion, SLE patients have increased QT interval parameters when compared to controls. This prolongation may lead to an increased cardiovascular risk. This finding might be due to subclinical atherosclerotic cardiovascular disease.