Serial electrocardiographic changes in treated hypertensive patients with reference to voltage criteria, mean QRS vectors, and the QRS-T angle

The Value of Frontal Planar QRS-T Angle in Patients without Angiographically Apparent Atherosclerosis

OBJECTIVE

The present study was undertaken to investigate the prognostic value of the frontal planar QRS-T angle in patients without angiographically apparent coronary atherosclerosis.

SUBJECTS AND METHODS

Three hundred and seven patients with normal coronary arteries on coronary angiography were included. The absolute difference between the frontal QRS- and T-wave axes was defined as the frontal planar QRS-T angle, and patients were divided into 3 subgroups based on the frontal planar QRS-T angle (<45, 45-90, and >90°). Demographic, clinical, laboratory, and angiographic data were compared between groups. Based on the regression analysis results, patients were recategorized into 4 groups according to their luminal calibers of left main coronary artery (LMCA) and history of hypertension (HT) (nonhypertensive LMCA ≤4.13 mm, nonhypertensive LMCA >4.13 mm, hypertensive LMCA ≤4.13 mm, and hypertensive LMCA >4.13 mm).

RESULTS

The median value of the frontal planar QRS-T angle of all participants was 38°. Subjects with the widest frontal planar QRS-T angle were older (p = 0.027), were hypertensive (p = 0.001), and had higher corrected QT values (p = 0.001). Patients with the widest frontal planar QRS-T angle had larger LMCA and left anterior descending coronary artery diameters compared to subjects with a normal and borderline frontal QRS-T angle (p = 0.004 and p = 0.028, respectively). Corrected QT, HT, and LMCA diameter were found as independent predictors of the frontal planar QRS-T angle. Subjects with HT and a larger luminal caliber of LMCA had the widest frontal planar QRS-T angle.

CONCLUSION

Patients with a history of HT and a larger luminal caliber of LMCA had the widest frontal planar QRS-T angle. Since HT-induced electrophysiological changes are still not well established and we observed that changes in the luminal caliber of coronary arteries are associated with an abnormal frontal QRS-T angle, the frontal QRS-T angle could serve as a marker of ventricular repolarization heterogeneity in hypertensive patients in addition to keeping track of arrhythmic events, even before overt disease.

Spatial/Frontal QRS-T Angle Predicts All-Cause Mortality and Cardiac Mortality: A Meta-Analysis

BACKGROUND

A number of studies have assessed the predictive effect of QRS-T angles in various populations since the last decade. The objective of this meta-analysis was to evaluate the prognostic value of spatial/frontal QRS-T angle on all-cause death and cardiac death.

METHODS

PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched from their inception until June 5, 2014. Studies reporting the predictive effect of spatial/frontal QRS-T angle on all-cause/cardiac death in all populations were included. Relative risk (RR) was used as a measure of effect.

RESULTS

Twenty-two studies enrolling 164,171 individuals were included. In the combined analysis in all populations, a wide spatial QRS-T angle was associated with an increase in all-cause death (maximum-adjusted RR: 1.40; 95% confidence interval [CI]: 1.32 to 1.48) and cardiac death (maximum-adjusted RR: 1.71; 95% CI: 1.54 to 1.90), a wide frontal QRS-T angle also predicted a higher rate of all-cause death (maximum-adjusted RR: 1.71; 95% CI: 1.54 to 1.90). Largely similar results were found using different methods of categorizing for QRS-T angles, and similar in subgroup populations such as general population, populations with suspected coronary heart disease or heart failure. Other stratified analyses and meta-analyses using unadjusted data also generated consistent findings.

CONCLUSIONS

Spatial QRS-T angle held promising prognostic value on all-cause death and cardiac death. Frontal QRS-T angle was also a promising predictor of all-cause death. Given the good predictive value of QRS-T angle, a combined stratification strategy in which QRS-T angle is of vital importance might be expected.

The spatial QRS-T angle: implications in clinical practice

The ventricular gradient (VG) as a concept was conceived in the 1930s and its calculation yielded information that was not otherwise obtainable. The VG was not utilized by clinicians at large because it was not easy to understand and its computation time-consuming. The contemporary spatial QRS-T angle is based on the concept of the VG and defined as its mathematical and physiological integral. Its current major clinical use is to assess the cardiac primary repolarization abnormalities in 3-dimensional spatial vectorial plans which are normally untraced in the presence of secondary electrophysiological activity in a 2-dimensional routine electrocardiogram (ECG). Currently the calculation of the spatial QRS-T angle can be easily computed on the basis of a classical ECG and contributes to localization of arrhythmogenic areas in the heart by assessing overall and local heterogeneity of the myocardial ventricular action potention duration. Recent population-based studies suggest that the spatial QRS-T angle is a dominant ECG predictor of future cardiovascular events and death and it is superior to more conventional ECG parameters. Its assessment warrants consideration for intensified primary and secondary cardiovascular prevention efforts and should be included in everyday clinical practice. This review addresses the nature and diagnostic potential of the spatial QRS-T angle. The main focus is its role in ECG assessment of dispersion of repolarization, a key factor in arrythmogeneity.

Assessment of the Spatial QRS-T Angle by Vectorcardiography: Current Data and Perspectives

The concept of the ventricular gradient (VG) was conceived in the 1930s and its calculation yielded information that was not otherwise obtainable. The VG was not utilized by clinicians at large because it was not easy to understand and its computation time-consuming. Spatial vectorcardiography is based on the concept of the VG. Its current major clinical use is to identify primary [heterogeneity of ventricular action potential (VAP) morphology] in the presence of secondary [heterogeneity in ventricular depolarization instants] T-wave abnormalities in an ECG. Nowadays, the calculation of the spatial VG can be computed on the basis of a regular routine ECG and contributes to localization of arrhythmogenic areas in the heart by assessing overall and local VAP duration heterogeneity. Recent population-based studies suggest that the spatial VG is a dominant ECG predictor of future cardiovascular events and death and it is superior to more conventional ECG parameters. Its assessment warrants consideration for intensified primary and secondary prevention efforts and can be included in everyday clinical practice. This review addresses the nature and diagnostic potential of the spatial VG. The main focus is the role of the spatial VG in ECG assessment of dispersion of repolarization, a key factor in arrhythmogeneity.

Carteolol, an antihypertensive beta-blocker with intrinsic sympathomimetic activity, reduces ECG evidence of left ventricular hypertrophy

Effective treatment of chronic hypertension may be accompanied by a decrease, increase, or no change in the extent of LVH, depending on the pharmacologic properties of the antihypertensive agents employed. Unlike beta-adrenoceptor blockers without ISA, beta-adrenoceptor blockers with ISA have been reported to increase left ventricular mass despite favorable reductions in blood pressure. To assess further the potential effect of ISA on LVH, we retrospectively evaluated the effect of carteolol, a nonspecific beta-adrenoceptor antagonist with strong ISA, upon ECG evidence of LVH. In 12 patients with LVH, carteolol treatment for one year reduced mean arterial blood pressures from 120 +/- 2 mm Hg to 100 +/- 2 mm Hg and mean hypertrophy scores from 5.2 +/- 0.6 to 2.6 +/- 0.8. Therefore, ISA does not preclude the regression of ECG evidence of LVH during the treatment of hypertension.

Electrocardiographic diagnosis of chamber enlargement

The purpose of this article is to review the changing role of the electrocardiogram in the diagnosis of cardiac chamber enlargement. Electrocardiographic criteria for the diagnosis of ventricular hypertrophy and atrial enlargement are reviewed in relation to autopsy, angiographic, echocardiographic and imaging findings. The electrocardiographic theory underlying the recognition of hypertropphy or dilation incorporates a number of sound physical principles that may lead to meaningful correlations with the tissue mass, chamber diameter and intracardiac blood volume. However, there are limiting factors related to the variable orientation of the heart in the chest, variable extracardiac factors and nonspecificity of each depolarization and repolarization abnormality used in the diagnosis of hypertrophy or dilation. This explains the superiority of the new noninvasive methods, in particular echocardiography, in the diagnosis of hypertrophy. Echocardiography is superior to electrocardiography in the detection of mild hypertrophy, and is more useful in the serial follow-up of changes during progression or regression of chamber enlargement.

Direct evidence of hypertension and the possible role of post-menopause oestrogen deficiency in the pathogenesis of berry aneurysms

To determine the significance of hypertension in the pathogenesis of berry aneurysms, 113 patients with subarachnoid haemorrhage (SAH) and verified aneurysm and 63 patients with SAH without aneurysm were compared. Of those patients with angiographically verified aneurysms, 61.9% were found to have elevated blood pressure (greater than 160/95 mmHg) and 19.5% showed electrocardiographic signs of left ventricular hypertrophy (SV1 + RV5 (6) greater than 3.5 mV). The percentages for patients without aneurysm were 36.5% and 6.4% respectively. A significant correlation was found between anterior aneurysms and left ventricular hypertrophy (P less than 0.01). The mean Sokolow index values were also significantly elevated in cases of aneurysm (P less than 0.01). There was a complementary relationship between the extent of left ventricular hypertrophy and the percentage of females with regard to localization of an aneurysm and age group. The predominance of females in the total aneurysm population, in the 50- to 59-year-old age group, and among patients with internal carotid aneurysms indicates that a sex-specific hormonal factor may also play a role in the pathogenesis of aneurysms in addition to hypertension. The collagen wasting commonly observed in bone and skin in the post-menopausal period due to decreased oestrogen levels could possibly be responsible for the formation of aneurysms in the proximal segments of the cerebral arteries, as occurs in various connective tissue diseases.