QT intervals and QT dispersion as measures of left ventricular hypertrophy in an unselected hypertensive population

Area of Science:

• Cardiology
• Clinical Electrophysiology
• Hypertension Research

Background:

• Electrocardiographic (ECG) QT intervals and dispersion have shown correlations with left ventricular mass index (LVMI) in select hypertensive populations.
• Assessing left ventricular hypertrophy (LVH) is crucial in managing hypertension.
• The utility of QT parameters as a simple screening tool for LVH in unselected hypertensive patients requires further investigation.

Purpose of the Study:

• To evaluate the strength of the relationship between ECG-derived QT parameters (QT interval and dispersion) and echocardiographic LVMI in a large cohort of unselected hypertensive subjects.
• To determine if QT measurements could serve as a practical, simple screening test for LVH in clinical practice.
• To compare the predictive value of QT parameters against traditional ECG voltage criteria for detecting LVH.

Main Methods:

• A cross-sectional study involving 386 unselected hypertensive individuals.
• Measurement of maximal QT intervals (QTmax), QT dispersion (QTdisp), and standard ECG voltage criteria (Sokolow-Lyon and Cornell) from 12-lead ECGs.
• Statistical analyses including linear regression, correlation, and receiver operating characteristic (ROC) curve analysis, with adjustments for confounding factors.

Main Results:

• LVMI demonstrated the strongest correlation with Cornell voltage (r = 0.44, P < .001).
• The strongest association between LVMI and QT parameters was with QTmax (r = 0.25, P < .001), which weakened with heart rate correction.
• QTdisp showed weak correlations with LVMI, regardless of heart rate correction. Sokolow-Lyon voltages, Cornell voltage, and QTmax were independently predictive of LVMI, but QTdisp was not.
• ROC curve analysis indicated that no QT parameter outperformed simple ECG voltage criteria for LVH detection.

Conclusions:

• QTmax, while associated with LVMI, was independently predictive after adjusting for standard ECG voltage criteria.
• However, QTmax, when used alone, did not offer superior performance compared to simple ECG voltage criteria for screening LVH in clinical settings.
• Traditional ECG voltage criteria remain a more effective tool for screening LVH in hypertensive patients than QT interval or dispersion measurements.