Background

Two electrocardiographic markers of ventricular repolarization abnormalities have been recently proposed: spatial T-wave axis deviation and T_peak–T_end-interval duration. The aim of this study was to evaluate these markers in patients with resistant hypertension, particularly their relationships with left ventricular mass (LVM) and geometric patterns, in comparison with the more traditional marker, the QTc interval.

Methods

In a cross-sectional study, 810 resistant hypertensive patients were evaluated. Clinical, laboratory, electrocardiographic, 24-h blood pressures and echocardiographic variables were obtained. Maximum T_peak–T_end-interval duration (Tpe_max) was considered prolonged if it was beyond the upper quartile value (120 ms), and the spatial T-wave axis on the frontal plane was considered abnormally deviated if >105° or < 15°. Statistical analysis involved bivariate tests, multivariate logistic regression and analysis of covariance.

Results

Tpe_max-interval prolongation, like QTc-interval prolongation, was found to be associated with body mass index, 24-h systolic blood pressure (SBP), indexed LVM, serum potassium, and heart rate. Abnormal T-axis deviation was associated with male gender, presence of coronary heart disease, serum creatinine, 24-h SBP, LVM, and serum potassium. All three repolarization parameters were shown to be associated with increased LVM, after adjustment for possible confounders. However, when included together into the same model, only abnormal T-axis and QTc-interval prolongation remained independently associated with LVM. All three parameters were also increased in patients with concentric hypertrophy geometric pattern.

Conclusions

Both the recently proposed repolarization parameters are associated with increased LVM and hypertrophy in patients with resistant hypertension, but only abnormal T-wave axis deviation appears to have distinct and additive relationships to the more classic marker, the QTc interval. Their prognostic values should be addressed in prospective studies.

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