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QT dispersion in essential hypertension
P B Clarkson1, A A Naas, A McMahon
1University Department of Clinical Pharmacology, Ninewells Hospital and Medical School, Dundee, UK.
Insights
Increased QT dispersion, a measure from ECGs, is linked to sudden cardiac death risk in hypertensive patients. This finding holds true even without electrocardiographic left ventricular hypertrophy, suggesting a simple screening tool.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- Increased QT dispersion is a known risk factor for sudden cardiac death (SCD) in various cardiovascular conditions.
- Hypertension, especially with left ventricular hypertrophy (LVH), elevates SCD risk.
Purpose of the Study:
- To investigate the correlation between QT dispersion and echocardiographic left ventricular hypertrophy (echo LVH) in untreated essential hypertensive patients.
- To assess if QT dispersion can serve as a non-invasive marker for identifying hypertensive individuals at high risk of SCD.
Main Methods:
- Sixty-nine untreated essential hypertensive patients underwent ECG for QT dispersion measurement and echocardiography for LVH assessment.
- Office and 24-hour ambulatory blood pressure monitoring were performed.
- Multivariate analysis was used to determine relationships between QT dispersion and clinical parameters.
Main Results:
- Significant relationships were found between QT dispersion and office systolic blood pressure, and left ventricular mass index.
- These correlations persisted even after correcting for heart rate (QTc dispersion).
- The association between QT dispersion and hypertension risk factors remained significant even when excluding patients with electrocardiographic LVH.
Conclusions:
- Increased QT dispersion is present in essential hypertensive patients at higher risk of sudden death.
- QT dispersion measurement offers a simple, non-invasive method for screening high-risk hypertensive patients, independent of electrocardiographic LVH.
Abstract:
Increased QT dispersion is associated with sudden cardiac death in congestive heart failure, hypertrophic cardiomyopathy, and following acute myocardial infarction. Patients with hypertension, in particular those with left ventricular hypertrophy, are also at greater risk of sudden cardiac death. We examined whether QT dispersion, which is easily obtained from a routine ECG, correlates with echo LVH. Sixty-nine untreated patients with essential hypertension had QT dispersion measured from a surface 12-lead electrocardiogram, and two-dimensional echocardiography performed to measure interventricular septal thickness, posterior wall thickness, and left ventricular internal diameter. Office blood pressure was recorded, and in 56 patients, 24 h ambulatory blood pressure monitoring was also done. Multivariate analysis demonstrated significant relationships between QT dispersion and office systolic blood pressure, and left ventricular mass index. Similar findings were obtained when QT dispersion was corrected for heart rate (QTc dispersion). After patients with electrocardiographic left ventricular hypertrophy (n = 5) were excluded from the analysis, the above relationships persisted. Increased QT dispersion is thus found in those essential hypertensives at greatest risk of sudden death. Since this relationship persists even in the absence of electrocardiographic left ventricular hypertrophy, measurement of QT dispersion might be a simple, non-invasive screening procedure to identify those hypertensives at greatest risk of sudden death.