Diagnostic utility of the spatial versus individual planar QRS-T angles in cardiac disease detection

Spatial QRS-T angle can indicate presence of myocardial fibrosis in pediatric and young adult patients with hypertrophic cardiomyopathy

BACKGROUND

Myocardial fibrosis, expressed as late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR), is an important risk factor for malignant cardiac events in hypertrophic cardiomyopathy (HCM). However, CMR is not easily available, expensive, also needing intravenous access and contrast.

OBJECTIVE

To determine if derived vectorcardiographic spatial QRS-T angles, an aspect of advanced ECG (A-ECG), can indicate LGE to appropriately prioritize young HCM-patients for CMR.

METHODS

Young patients (age 7-31 years) with clinical HCM (N = 19) or genotype-positive but phenotype-negative (G+ P-) results (N = 6) and nine healthy volunteers were evaluated for LGE by CMR at a single centre between 2011 and 2018. A-ECG was performed within 4 months before and 6 months after CMR and evaluated for spatial mean and peaks QRS-T angles. ECG Risk-score and frontal, two-dimensional QRS-T angle were also calculated from the 12‑lead ECG.

RESULTS

All QRS-T angles were significantly higher in the HCM group with LGE as compared to the HCM group without LGE, and the G+ P- and Healthy groups. Only HCM-patients showed LGE (11/19). The optimal cut-offs for indicating LGE were > 50° for the spatial peaks (AUC = 0.98 [95 %CI 0.95-1.00], sensitivity 100 %, specificity 93 %; p < 0.001), >80° for the spatial mean (AUC = 0.91; p < 0.001), and > 60° for the frontal QRS-T angles (AUC = 0.85; p < 0.001), and > 2 points for an established ECG risk-score (AUC = 0.90, p < 0.001).

CONCLUSION

A spatial peaks QRS-T angle >50° has excellent sensitivity and specificity as a marker of myocardial fibrosis in a young patients with HCM, and can be useful for management and follow-up of such patients.

The association between frontal QRS-T angle and reverse dipper status in newly diagnosed hypertensive patients

The frontal QRS-T angle (fQRS-T angle) in ECG is a new measure of myocardial repolarization, in which a higher fQRS-T angle is linked with worse cardiac outcomes. Reverse dipper hypertension is also linked to poor cardiac outcomes. The purpose of this study was to investigate the association between the fQRS-T angle and reverse dipper status in individuals newly diagnosed with hypertension who did not have left ventricular hypertrophy (LVH). The investigation recruited 171 hypertensive individuals without LVH who underwent 24-h ambulatory blood pressure monitoring (ABPM). On the basis of the findings of 24-h ABPM, the study population was categorized into the following three groups: patients with dipper hypertension, non-dipper hypertension, and reverse dipper hypertension. LVH was defined by echocardiography. The fQRS-T angle was measured using the 12-lead ECG. The fQRS-T angle in individuals with reverse dipper hypertension was substantially greater than in patients with and without dipper hypertension (51° ± 28° vs. 28° ± 22° vs. 39° ± 25°, respectively, P < 0.001). The fQRS-T angle (odds ratio: 1.040, 95% confidence interval: 1.016-1.066; P = 0.001) was independently associated with reverse dipper hypertension according to multivariate analysis. In receiver operating characteristic curve analysis, the fQRS-T angle to predict reverse dipper hypertension was 33.5° with 76% sensitivity and 71% specificity. This study showed that an increased fQRS-T angle was associated with reverse dipper hypertension in newly diagnosed hypertensive patients without LVH.

Electrocardiographic parameters associated with pacemaker induced cardiomyopathy

BACKGROUND

Chronic right ventricular (RV) pacing can induce left ventricular (LV) dyssynchrony and cause pacemaker induced cardiomyopathy (PiCM). Identifying which patients are at risk for PiCM is limited.

METHODS

Patients receiving RV-only permanent pacemakers (PPMs) at Duke University Medical Center between 2011 and 2017 who had normal baseline ejection fractions (EFs) were identified. Patients who developed a subsequent decrease in EF, died, or underwent cardiac resynchronization therapy, left ventricular assist device, or heart transplant without a competing cause were considered as the primary endpoint. Pre-PPM and post-PPM electrocardiograms (ECGs) were analyzed to extract scalar measurements including the lead one ratio (LOR) as well as advanced-ECG (A-ECG) features to identify predictors of PiCM. Traditional and penalized Cox regression were used to identify variables predictive of the primary endpoint.

RESULTS

Pre-PPM ECGs were evaluated for 404 patients of whom 140 (35%) experienced the primary endpoint. Predictors included female sex (hazard ratio [HR] 1.14), a T' wave in V6 (HR 1.31), a P' wave in aVL (HR 0.88), and estimated glomerular filtration rate (HR 0.88). Post-PPM ECGs were evaluated for 228 patients for whom 94 (41%) experienced the primary endpoint. Predictors included female sex (HR 0.50), age (HR 1.06), and a history of congestive heart failure (HR 1.63). Neither LOR nor A-ECG parameters were strong predictors of the primary endpoint.

CONCLUSIONS

Baseline and paced ECG data provide limited insight into which patients are at high risk for developing PiCM.

Frontal QRS - T angle is associated with severity and prognosis of acute pulmonary embolism

INTRODUCTION

The pathological effects of acute pulmonary embolism (APE) on the right ventricle are one of the most important determinants of mortality in patients with APE. Frontal QRS-T angle (fQRSTa) predicts ventricular pathology and poor prognosis in many different cardiovascular diseases. In this study, we investigated whether there is a significant relationship between fQRSTa and APE severity.

MATERIAL AND METHODS

A total of 309 patients were included in this retrospective study. The severity of APE was classified as massive (high risk), submassive (intermediate risk), or nonmassive (low risk). fQRSTa calculated from standard ECGs.

RESULTS

fQRSTa was significantly higher in massive APE patients (p < 0.001). fQRSTa was also found to be significantly higher in the in-hospital mortality group (p < 0.001). fQRSTa was an independent risk factor for the development of massive APE (odds ratio:1.033; 95% CI: 1.012-1.052; p < 0.001).

CONCLUSION

Our study showed that increased fQRSTa predicts high-risk APE patients and mortality in APE patients.

The impact of midazolam used in cataract surgery sedation on frontal QRS-T angle

WHAT IS KNOWN AND OBJECTIVE

Midazolam is one of the most commonly used drugs in procedures requiring sedoanalgesia. It affects the myocardium's ventricular depolarization and repolarization. Previous studies examining the arrhythmogenic effects of midazolam yielded conclusive results. These studies are based on QT and Tp -e distances. The frontal QRS-T angle (f-[QRS-T]a) is a new electro cardiac parameter that shows the heterogeneity of ventricular electrical activity. This study aims to examine the effect of midazolam on f-(QRS- T)a and other depolarization-repolarization parameters in patients who have had cataract surgery.

METHODS

The study included 177 patients administered midazolam as a sedoanalgesia during cataract surgery. The sedative effect was evaluated 2-3 minutes after a 0.05 mg/kg dose of midazolam was given. Sedation was assessed again by giving 0.5 mg every 2-3 minutes until the desired level of sedation was achieved. 12-lead electrocardiogram (ECG) recordings of all patients were taken just before and immediately after surgery. ECGs were used to calculate the QT interval, QTc interval, Tp -e interval, Tp -e/QT, Tp -e/ QTc ratios and f-(QRS-T)a.

RESULTS AND DISCUSSION

After cataract surgery, f-(QRS-T)a was unchanged compared to presurgery (29.14 ± 4.52 vs. 29.18 ± 5.39, p = 0.852). In addition, no significant change in QT(351.32 ± 21.98 vs. 351.94 ± 22.44, p = 0.091), QTc (384.05 ± 24.52 vs. 385.19 ± 26.12, p = 0.819), Tp -e interval (93.12 ± 9.60 vs. 94.44 ± 8.82, p = 0.179) and Tp -e/QT (0.27 ± 0.02 vs. 0.28 ± 0.03, p = 0.664), Tp -e/ QTc ratios (0.28 ± 0.02 vs. 0.29 ± 0.03, p = 0.655) was observed after surgery when compared to presurgery values. Significant ventricular and supraventricular arrhythmias were not observed in any patient during the operation.

WHAT IS NEW AND CONCLUSION

Midazolam did not affect f -(QRS-T) with classical repolarization parameters in patients who underwent cataract surgery, according to this study. Midazolam has been found to be safe for the heart in sedoanalgesia. These results show that sedation with midazolam can be performed without electrocardiogram monitoring.

ECG Localization Method Based on Volume Conductor Model and Kalman Filtering

The 12-lead electrocardiogram was invented more than 100 years ago and is still used as an essential tool in the early detection of heart disease. By estimating the time-varying source of the electrical activity from the potential changes, several types of heart disease can be noninvasively identified. However, most previous studies are based on signal processing, and thus an approach that includes physics modeling would be helpful for source localization problems. This study proposes a localization method for cardiac sources by combining an electrical analysis with a volume conductor model of the human body as a forward problem and a sparse reconstruction method as an inverse problem. Our formulation estimates not only the current source location but also the current direction. For a 12-lead electrocardiogram system, a sensitivity analysis of the localization to cardiac volume, tilted angle, and model inhomogeneity was evaluated. Finally, the estimated source location is corrected by Kalman filter, considering the estimated electrocardiogram source as time-sequence data. For a high signal-to-noise ratio (greater than 20 dB), the dominant error sources were the model inhomogeneity, which is mainly attributable to the high conductivity of the blood in the heart. The average localization error of the electric dipole sources in the heart was 12.6 mm, which is comparable to that in previous studies, where a less detailed anatomical structure was considered. A time-series source localization with Kalman filtering indicated that source mislocalization could be compensated, suggesting the effectiveness of the source estimation using the current direction and location simultaneously. For the electrocardiogram R-wave, the mean distance error was reduced to less than 7.3 mm using the proposed method. Considering the physical properties of the human body with Kalman filtering enables highly accurate estimation of the cardiac electric signal source location and direction. This proposal is also applicable to electrode configuration, such as ECG sensing systems.

Impaired repolarization parameters may predict fatal ventricular arrhythmias in patients with hypertrophic cardiomyopathy (from the CILICIA Registry)

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is significantly associated with high risk of fatal ventricular arrhythmias (VAs). Increased frontal QRST angle (fQRSTa), Tpe interval, and Tp-e/QTc ratio are described as ventricular repolarization parameters which are related to arrhythmias. In this study, we aimed to investigate the predictive value of these repolarization parameters for fatal VAs in patients with HCM.

METHODS

A total of 127 HCM patients (mean age: 47.9 ± 12.6 years; male:79) were enrolled in this retrospective study. All patients underwent transthoracic echocardiography. Moreover, the last electrocardiograms within 3 months prior to the fatal VA documentation were assessed. The primary outcome was the occurrence of fatal VAs including sustained ventricular tachycardia and ventricular fibrillation which were documented from implantable cardioverter defibrillator records.

RESULTS

There were documented fatal VAs in 37 (29.1%) patients during a mean follow-up time of 70.1 ± 22.6 months. The prevalence of fatal VAs was significantly higher in patients with fQRSTa ≥140 degrees (67.4 vs. 7.4%; p < 0.001) and in patients with Tp-e/QTc ratio ≥ 0.19 (61.5 vs. 6.7%; p < 0.001) as compared to others. High Tp-e/QTc ratio (hazard ratio: 1.564; 95% confidence interval: 1.086-4.796; p = 0.032) and high fQRSTa (hazard ratio: 1.864; 95% confidence interval: 1.106-8.745; p = 0.002) were found to be independent predictors of fatal VAs in HCM patients.

CONCLUSIONS

Wider fQRSTa, prolonged Tp-e interval, and increased Tp-e/QTc ratio may be associated with fatal VAs in HCM patients. In addition to traditional risk factors, these simple ECG parameters may provide valuable information during evaluation of sudden cardiac death risk in HCM patients.

Evaluation of thrombolytic treatment effect on frontal plane QRS-T angle in patients with acute pulmonary embolism : A novel marker of successful thrombolysis

BACKGROUND

Acute pulmonary embolism (APE) patients with hypotension and/or shock should be evaluated for thrombolytic therapy, and hemodynamics often improves after thrombolytic therapy. Frontal plane QRS‑T (f[QRS-T]) angle, which is between the directions QRS axis and T axis, was described as a novel marker of ventricular repolarization heterogeneity. With right ventricular pressure overload, axis of heart may be affected and thrombolytic treatment may have an effect on this situation. This study aimed to investigate thrombolytic efficiency and effect on axis of heart by using f(QRS-T) angle.

METHOD

A total of 61 APE patients treated with thrombolytics and 71 APE patients treated without thrombolytics were included. Clinical findings and electrocardiogram (ECG) at diagnosis were collected. Second ECGs were included for patients with thrombolytics after 24 h, without thrombolytics after 72 h on average.

RESULTS

No significant differences were observed with regard to gender, age, hypertension, diabetes and cardiovascular disease. In patients with thrombolytics, respiratory rate, heart rate and pulmonary artery systolic pressure were significantly higher; oxygen saturation (Sat O₂) as well as systolic and diastolic pressure were significantly lower. f(QRS-T) was markedly higher in APE with right ventricular pressure overload and changed significantly after thrombolytic therapy.

CONCLUSION

Right ventricular pressure overload in APE has an effect on f(QRS-T). In thrombolytic treatment, the change of f(QRS-T) angle may be a marker of successful thrombolysis.

Prognostic value of frontal QRS-T angle in patients undergoing myocardial revascularization or cardiac valve surgery

BACKGROUND

An abnormal frontal QRS-T angle (fQRSTa) is associated with increased risk of death in primary and secondary cardiovascular prevention. The aim of this study was to evaluate the fQRSTa prognostic role in patients undergoing myocardial revascularization and/or cardiac valve surgery.

METHODS

We enrolled and prospectively followed for 48 ± 26 months 939 subjects with available QRS and T axis data; mean age was 68 ± 12 years, 449 patients (48%) underwent myocardial revascularization, 333 (35%) cardiac valve surgery, 94 (10%) valve plus bypass graft surgery and 63 (7%) cardiac surgery for other cardiovascular (CV) diseases. The ECG variables were collected at the end of the cardiac rehabilitation program and fQRSTa was considered normal if <60°, abnormal if >120°, borderline otherwise. Endpoints were overall and CV mortality.

RESULTS

The fQRSTa was normal in 333 patients (36%), borderline in 285 (30%) and abnormal in 321 (34%). Overall (p = 0.012) and cardiovascular (p = 0.007) mortality were significantly higher in patients with abnormal fQRSTa even after adjusting separately for gender, PR-, QTc- intervals, presence of right or left bundle branch block and left atrial volume index. The predictive value was confirmed in patients with stable coronary artery disease (SCAD), not in patients with acute coronary syndrome or valve disease. SCAD patients with abnormal both fQRSTa and QRS axis had higher risk of overall (hazard ratio = 2.9, p < 0.0001) and CV (hazard ratio = 4.4, p < 0.0001) mortality compared with SCAD patients with normal fQRSTa, even after multivariate adjustment for age, gender, ECG intervals, left-ventricle ejection fraction and mass index.

CONCLUSIONS

In SCAD patients undergoing myocardial revascularization, abnormal fQRSTa is independent predictor of overall and CV mortality.

The prognostic value of the frontal QRS-T angle is comparable to cardiovascular autonomic neuropathy regarding long-term mortality in people with diabetes. A population based study

Cardiovascular autonomic neuropathy (CAN) is a well known prognostic marker in diabetes. A large angle between the QRS- and the T-wave vector (QRS-T angle) in the electrocardiogram (ECG) has recently been introduced as another marker of poor prognosis.

AIM

To assess and compare the long-term predictive power of the frontal plane QRS-T angle with CAN in people with diabetes.

METHODS

In 1992-93 people with diabetes in the municipality of Horsens, Denmark, were identified by the prescription method andan age and gender stratified sample of 240 individuals with diabetes were randomly selected. The presence of CAN was defined using the heart rate response to Valsalva manoeuvre. The QRS-T angle was read using the method described by Gandhi. In July 2015 vital statistics were obtained fromthe Danish Civil Registration System.

RESULTS

178 individuals accepted to participate in the study, of which 153 (86%) completed the Valsalva manoeuvre and had sinus rhythm. Total observation time was 21.5 (0.18) years, in which 99 (65%) individuals died. An elevated QRS-T angle and the presence of cardiovascular autonomic neuropathy were both found to be significant predictors of death. In Cox regression analyses, adjusting for the effect of gender, age, duration of diabetes, BMI, total-cholesterol, diabetes type, haemoglobin A1c, smoking status, hypertension and previous MI, an independent prognostic value was found for the QRS-T angle as well as the Valsalva ratio.

CONCLUSION

A large QRS-T angle and the presence of cardiovascular autonomic neuropathy are both strong and independent long-term predictors of all-cause mortality in people with diabetes.

ECG-derived spatial QRS-T angle is associated with ICD implantation, mortality and heart failure admissions in patients with LV systolic dysfunction

Background

Increased spatial QRS-T angle has been shown to predict appropriate implantable cardioverter defibrilIator (ICD) therapy in patients with left ventricular systolic dysfunction (LVSD). We performed a retrospective cohort study in patients with left ventricular ejection fraction (LVEF) 31–40% to assess the relationship between the spatial QRS-T angle and other advanced ECG (A-ECG) as well as echocardiographic metadata, with all-cause mortality or ICD implantation for secondary prevention.

Methods

534 patients ≤75 years of age with LVEF 31–40% were identified through an echocardiography reporting database. Digital 12-lead ECGs were retrospectively matched to 295 of these patients, for whom echocardiographic and A-ECG metadata were then generated. Data mining was applied to discover novel ECG and echocardiographic markers of risk. Machine learning was used to develop a model to predict possible outcomes.

Results

49 patients (17%) had events, defined as either mortality (n = 16) or ICD implantation for secondary prevention (n = 33). 72 parameters (58 A-ECG, 14 echocardiographic) were univariately different (p<0.05) in those with vs. without events. After adjustment for multiplicity, 24 A-ECG parameters and 3 echocardiographic parameters remained different (p<2x10^-3). These included the posterior-to-leftward QRS loop ratio from the derived vectorcardiographic horizontal plane (previously associated with pulmonary artery pressure, p = 2x10^-6); spatial mean QRS-T angle (134 vs. 112°, p = 1.6x10^-4); various repolarisation vectors; and a previously described 5-parameter A-ECG score for LVSD (p = 4x10^-6) that also correlated with echocardiographic global longitudinal strain (R² = - 0.51, P < 0.0001). A spatial QRS-T angle >110° had an adjusted HR of 3.4 (95% CI 1.6 to 7.4) for secondary ICD implantation or all-cause death and adjusted HR of 4.1 (95% CI 1.2 to 13.9) for future heart failure admission. There was a loss of complexity between A-ECG and echocardiographic variables with an increasing degree of disease.

Conclusion

Spatial QRS-T angle >110° was strongly associated with arrhythmic events and all-cause death. Deep analysis of global ECG and echocardiographic metadata revealed underlying relationships, which otherwise would not have been appreciated. Delivered at scale such techniques may prove useful in clinical decision making in the future.

A large frontal QRS-T angle is a strong predictor of the long-term risk of myocardial infarction and all-cause mortality in the diabetic population

BACKGROUND

A large angle between the QRS vector and the T-wave vector (QRS-T angle) in electrocardiograms (ECGs) has recently been introduced as a marker of poor prognosis. The prognostic value in diabetes is unknown. We assessed the long-term predictive power of the frontal plane QRS-T angle in the diabetic population.

METHODS

In 1992-93, the diabetic population of the municipality of Horsens, Denmark, was delineated by the prescription method, and an age- and gender-stratified sample of 240 diabetic persons was randomly selected. In 2015, 12-lead ECGs taken in 1993-94 were analyzed. Vital statistics were obtained from the Danish Civil Registration System and data regarding hospitalizations taken from The National Patient Registry in July 2015.

RESULTS

In total, 178 people agreed to participate (74%) in the study, with the mean (sd) age being 58.9 (10.2) years and 56% being male. The total observation time was 21.5 (0.18) years, during which time 122 (69%) persons died, 32 (18%) suffered a myocardial infarction (MI) and 126 (71%) reached the composite endpoint of non-fatal MI or all-cause death. In Cox regression multivariate analysis a QRS-T angle above 90° was found to be an independent predictor of all-cause death (HR=2.2 (95% CI: 1.3-3.8)), MI (HR=2.95 (95% CI: 1.1-7.7)) and MI or all-cause death (HR=2.0 (95% CI: 1.2-3.5)) (all p<0.05), when adjusting for the effects of co-variates (gender, age, length of diabetes, BMI, total cholesterol, diabetes type, hemoglobin A1c, smoking, hypertension and previous MI).

CONCLUSION

A large QRS-T angle is a strong, independent long-term predictor of all-cause mortality, MI and MI or all-cause death in the diabetic population.

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.

Value of the Qrs-T angle in predicting the induction of ventricular tachyarrhythmias in patients with Chagas disease

Background

The QRS-T angle correlates with prognosis in patients with heart failure and coronary artery disease, reflected by an increase in mortality proportional to an increase in the difference between the axes of the QRS complex and T wave in the frontal plane. The value of this correlation in patients with Chagas heart disease is currently unknown.

Objective

Determine the correlation of the QRS-T angle and the risk of induction of ventricular tachycardia / ventricular fibrillation (VT / VF) during electrophysiological study (EPS) in patients with Chagas disease.

Methods

Case-control study at a tertiary center. Patients without induction of VT / VF on EPS were used as controls. The QRS-T angle was categorized as normal (0-105º), borderline (105-135º) or abnormal (135-180º). Differences between groups for continuous variables were analyzed with the t test or Mann-Whitney test, and for categorical variables with Fisher's exact test. P values < 0.05 were considered significant.

Results

Of 116 patients undergoing EPS, 37.9% were excluded due to incomplete information / inactive records or due to the impossibility to correctly calculate the QRS-T angle (presence of left bundle branch block and atrial fibrillation). Of 72 patients included in the study, 31 induced VT / VF on EPS. Of these, the QRS-T angle was normal in 41.9%, borderline in 12.9% and abnormal in 45.2%. Among patients without induction of VT / VF on EPS, the QRS-T angle was normal in 63.4%, borderline in 14.6% and abnormal in 17.1% (p = 0.04). When compared with patients with normal QRS-T angle, those with abnormal angle had a fourfold higher risk of inducing ventricular tachycardia / ventricular fibrillation on EPS [odds ratio (OR) 4; confidence interval (CI) 1.298-12.325; p = 0.028]. After adjustment for other variables such as age, ejection fraction (EF) and QRS size, there was a trend for the abnormal QRS-T angle to identify patients with increased risk of inducing VT / VF during EPS (OR 3.95; CI 0.99-15.82; p = 0.052). The EF also emerged as a predictor of induction of VT / VF: for each point increase in EF, there was a 4% reduction in the rate of sustained ventricular arrhythmia on EPS.

Conclusions

Changes in the QRS-T angle and decreases in EF were associated with an increased risk of induction of VT / VF on EPS.

QRS-T angle: a review

For proper distribution of preventative resources, a more robust method of cardiac risk stratification should be encouraged in addition to merely reduced ejection fraction. To this end, the QRS-T angle, an electrocardiogram-derived measure of the difference in mean vectors of depolarization and repolarization, has been found associated with sudden cardiac death and other mortal and morbid outcomes in multiple observational studies over the past decade. The use of both frontal and spatial QRS-T angle in the prediction of future cardiac events including sudden cardiac death, all-cause mortality, and further cardiac morbidity is reviewed here.

Usefulness of the QRS-T angle to improve long-term risk stratification of patients with acute myocardial infarction and depressed left ventricular ejection fraction

In light of the low cost, the widespread availability of the electrocardiogram, and the increasing economic burden of the health-related problems, we aimed to analyze the prognostic value of automatic frontal QRS-T angle to predict mortality in patients with left ventricular (LV) systolic dysfunction after acute myocardial infarction (AMI). About 467 consecutive patients discharged with diagnosis of AMI and with LV ejection fraction ≤40% were followed during 3.9 years (2.1 to 5.9). From them, 217 patients (47.5%) died. The frontal QRS-T angle was higher in patients who died (116.6±52.8 vs 77.9±55.1, respectively, p<0.001). The QRS-T angle value of 90° was the most accurate to predict all-cause cardiac death. After multivariate analysis, frontal QRS-T angle remained as an excellent predictor of all-cause and cardiac deaths, increasing the mortality 6% per each 10°. For the global mortality, the hazard ratio for a QRS-T angle>90° was 2.180 (1.558 to 3.050), and for the combined end point of cardiac death and appropriate implantable cardioverter defribrillator therapy, it was 2.385 (1.570 to 3.623). This independent predictive value was maintained even after adjusting by bundle brunch block, ST-elevation AMI, and its localization. In conclusion, a wide automatic frontal QRS-T angle (>90°) is a good discriminator of long-term mortality in patients with LV systolic dysfunction after an AMI. The ability to easily measure it from a standard 12-lead electrocardiogram together with its prognostic value makes the frontal QRS-T angle an attractive tool to help clinicians to improve risk stratification of those patients.

Relations between QRS|T angle, cardiac risk factors, and mortality in the third National Health and Nutrition Examination Survey (NHANES III)

On the surface electrocardiogram, an abnormally wide QRS|T angle reflects changes in the regional action potential duration profiles and in the direction of the repolarization sequence, which is thought to increase the risk of ventricular arrhythmia. We investigated the relation between an abnormal QRS|T angle and mortality in a nationally representative sample of subjects without clinically evident heart disease. We studied 7,052 participants ≥40 years old in the third National Health and Nutrition Examination Survey with 12-lead electrocardiograms. Those with self-reported or electrocardiographic evidence of a previous myocardial infarction, QRS duration of ≥120 ms, or history of heart failure were excluded. Borderline and abnormal spatial QRS|T angles were defined according to gender-specific 75th and 95th percentiles of frequency distributions. All-cause (1,093 women and 1,191 men) and cardiovascular (462 women and 455 men) mortality during the 14-year period was assessed through linkage with the National Death Index. On multivariate analyses, an abnormal spatial QRS|T angle was associated with an increased hazard ratio (HR) for cardiovascular mortality in women (HR 1.82, 95% confidence interval 1.05 to 3.14) and men (HR 2.21, 95% confidence interval 1.32 to 3.68). Also, the multivariate adjusted HR for all-cause mortality associated with an abnormal QRS|T angle was 1.30 (95% confidence interval 0.95 to 1.78) for women and 1.87 (95% confidence interval 1.29 to 2.7) for men. A borderline QRS|T angle was not associated with an increased risk of all-cause or cardiovascular mortality. In conclusion, an abnormal QRS|T angle, as measured on a 12-lead electrocardiogram, was associated with an increased risk of cardiovascular and all-cause mortality in this population-based sample without known heart disease.