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The relation between QT interval and T-wave variables in hypertensive patients
1Department of Pathophysiology, "Victor Babes" University of Medicine and Pharmacy, Timisoara, Romania.
Background:
The standard 12-lead ECG (electrocardiogram) continues to be the most frequently recorded noninvasive test in medicine. A prolonged ECG QT interval and Tpeak-Tend (Tpe) interval are predictors of ventricular arrhythmia and sudden cardiac death.
Aim:
The aim of this study is to analyze the relation between QT interval and T-wave variables in hypertensive patients, with and without left ventricular hypertrophy (LVH).
Materials And Methods:
Fifty-nine consecutive patients with grade 2 essential hypertension were included in the study. They underwent standard 12-lead ECG, and QT intervals: QTmax (the maximal duration of the QT interval in the 12 ECG leads), QTc (heart rate corrected QTmax), QTm (mean QT interval), QTII (the QT interval in lead DII), QTcII (heart rate corrected QTII), and QTd (QT dispersion); and T-wave variables: T0e (T wave duration), T0em (mean T0e), Tpe, Tpem (mean Tpem), Ta (T wave amplitude), and Tam (mean Ta) were manually assessed. LVH was diagnosed using both echocardiography and the ECG criteria.
Results:
QTc was prolonged in 41 patients (69%). Multiple regression analysis revealed a significant association between QT intervals and T-wave variables: QTmax and Tpe (P = 0.015), QTd and Tpe (P = 0.022) and Ta (P = 0.004), and Tpe with QTd and T0e (P < 0.05). A moderate but significant correlation was found between Tpe and QTmax, Tpe and QTII, and Ta and QTd. A prolonged QTc was more prevalent in hypertensive patients with LVH (85%), compared to hypertensive patients without LVH (50%). QTm, QTd, QTII, Tpe, Tpem were significantly elevated (P < 0.05) in patients with LVH.
Conclusions:
Hypertension is associated with an increased prevalence of prolonged QT intervals. QT intervals and T-wave variables are closely connected in hypertensive patients. QTm, T0em, Tpem, and Tam, do not provide significant additional information compared to QTmax, T0e, Tpe, and Ta. Left ventricular hypertrophy is associated with prolonged QT interval and Tpeak-Tend interval in hypertensive patients.
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