QT Dispersion in Patients With Systemic Lupus Erythematosus (SLE)

Objective: Patients with systemic lupus erythematosus (SLE) have increased cardiovascular morbidity and mortality. Although autopsy studies have documented that the heart is affected in most SLE patients, clinical manifestations occur in less than 10%. QT dispersion is a new parameter that can be used to assess homogeneity of cardiac repolarization and autonomic function. We compared the increase in QT dispersion in SLE patients with high disease activity and mild or moderate disease activity.

Methods: One hundred twenty-four patients with SLE were enrolled in the study. Complete history and physical exam, ECG, echocardiography, exercise test and SLE disease activity index (SLEDAI) were recorded. Twenty patients were excluded on the basis of our exclusion criteria. The patients were divided to two groups based on SLEDAI: 54 in the high-score group (SLEDAI >10) and 50 in the low-score group (SLEDAI <10).

Inclusion criteria

• no administration of drugs that would potentially influence QT duration except hydroxychloroquine
• no history of ischemic heart disease, congestive heart failure, atrial fibrillation, bundle branch block or abnormal serum electrolytes
• normal resting ECG and a good-quality ECG recording to measure the QT interval.

Exclusion criteria

• moderate or severe valve disease
• atrial fibrillation and other ECG abnormalities
• systolic left ventricular dysfunction (ejection fraction <50% or left ventricular end diastolic dimension >5.5 mm
• unreliable identification of the end of the T wave in the ECG and
• known presence of cardiac disease including hypertension, diabetes or coronary artery disease.