Relationship between QT Interval Length and Arterial Stiffness in Systemic Lupus Erythematosus (SLE): A Cross-Sectional Case-Control Study

INTRODUCTION AND OBJECTIVES The QT interval on the electrocardiogram has been shown to be longer in patients with systemic lupus erythematosus (SLE) compared to that of the general population. The clinical significance of this finding is unknown. The aim of this study was to assess the relationship between QT interval and subclinical atherosclerosis, measured by carotid-femoral pulse-wave velocity. MATERIAL AND METHODS 93 patients with SLE and 109 healthy women with similar basal characteristics were studied. All patients underwent a 12- lead electrocardiogram, and corrected QT interval (QTc) was measured using the Bazett's formula. The presence of atherosclerosis was evaluated by carotid-femoral pulse-wave velocity. RESULTS Clinical basal characteristics were similar in both groups. QTc interval was 415 ± 21.4 milliseconds in all patients, and 407 ± 19.1 milliseconds in the control group (p = 0.007). There was a positive correlation between QTc interval and carotid-femoral pulse-wave velocity (r = 0.235; p = 0.02) in patients with SLE. This association was independent of hypertension and age in a multivariate analysis. CONCLUSION QTc interval measured by electrocardiogram is prolonged in SLE patients; it is related to subclinical atherosclerosis, measured by carotid-femoral pulse-wave velocity. This measure may help stratify risk in routine clinical practice and select the patients that might benefit from a more aggressive therapy in the prevention of cardiovascular events.