Dispersion of ventricular repolarization in relation to cardiovascular risk factors in hypertension

Rationale: Hypertension associates with sudden cardiac death, its relationship with ventricular arrhythmias being demonstrated by multiple studies, an increased dispersion of repolarization being an important arrhythmogenesis mechanism. Only a small percentage of hypertensive patients presents increased blood pressure values exclusively as risk factor, most of them presenting additional risk factors that reinforce each other leading to increased total cardiovascular risk. Aim: to analyze the dispersion of repolarization parameters (QT interval, QT dispersion, Tpeak-Tend interval (Tpe), Tpe/QT, Tpe dispersion) in relation to cardiovascular risk factors, as well as total cardiovascular risk estimated by SCORE model, in mild to moderate essential hypertension. Method: 62 consecutive patients, mean age 55±11 years, were evaluated by 24 hours Holter electrocardiography monitoring. Manual measurement of dispersion of repolarization parameters was performed. Results: Based on SCORE model, 33.9% patients presented low risk, 40.3% moderate risk, 16.1% high risk and 9.1% very high risk. Age had a positive correlation with QT and reverse correlations with QT dispersion, Tpe and Tpe/QT in lead V1. Tpe/QT showed significantly higher values in men versus women. Glucose metabolism disorders associated with higher values of QT and Tpe dispersion were present. However, dispersion of repolarization parameters was similar between risk categories assessed by SCORE model, Tpe in lead V3 correlated significantly with SCORE score. Conclusions: In mild to moderate hypertension, the dispersion of repolarization parameters is influenced by age, gender and glucose metabolism disorders. Among these, Tpe in lead V3 correlates with total cardiovascular risk assessed by SCORE model. Abbreviations: dTpe = T peak – T end interval dispersion, ECG = electrocardiography, Tpe = T peak - T end interval, Tpe/QT = T peak – T end / QT ratio, QTd = QT dispersion