Recent ventricular repolarization markers in resistant hypertension: are they different from the traditional QT interval?
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 degrees or < 15 degrees . 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 .
Salles
Gil F
GF
Department of Internal Medicine, University Hospital Clementino Fraga Filho, Medical School, Federal University of Rio de Janeiro, Brazil. gilsalles@hucff.ufrj.br
Cardoso
Claudia R L
CR
Leocadio
Sharon M
SM
Muxfeldt
Elizabeth S
ES
D000200:Action Potentials; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000503:physiopathology; D001794:Blood Pressure; D003430:Cross-Sectional Studies; D004351:Drug Resistance; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D017379:Hypertrophy, Left Ventricular / Q000209:etiology* / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D013599:Systole; D013997:Time Factors
D000959:Antihypertensive Agents