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Until the mid-1980s, it was believed that the vectorcardiogram (VCG) presented a greater specificity, sensitivity and accuracy in comparison to the 12-lead electrocardiogram (ECG), in the cardiology diagnosis. Currently, the VCG still is superior to the ECG in specific situations, such as in the evaluation of myocardial infarctions when associated with intraventricular conduction disturbances, in the identification and location of accessory pathways in ventricular preexcitation, in the differential diagnosis of patterns varying from normal of electrical axis deviation, in the evaluation of particular aspects of Brugada syndrome, Brugada phenocopies, concealed form of arrhythmogenic right ventricular cardiomyopathy and zonal or fascicular blocks of the right bundle branch on right ventricular free wall.VCG allows us to analyze the presence of left septal fascicular block more accurately than ECG and in the diagnosis of the interatrial blocks and severity of some chambers enlargements. The three-dimensional spatial orientation of both the atrial and the ventricular activity provides a far more complete observation tool than the linear ECG. We believe that the ECG/VCG binomial simultaneously obtained by the technique called electro-vectorcardiography (ECG/VCG) brought a significant gain for the differential diagnosis of several pathologies. Finally, in the field of education and research, VCG provided a better and more rational tridimensional insight into the electrical phenomena that occurs spatially, and represented an important impact on the progress of electrocardiography.

The angle between theQRSandTvectors reflects the consistency or inconsistency of the processes of de- and repolarization of the ventricles of the heart and is considered one of the indicators of global electrical heterogeneity of myocardium. In recent years, the prognostic value of theQRS-Tangle has been demonstrated in relation to total and cardiovascular mortality, both in the population and in various groups of patients. The mechanisms of this phenomenon are not completely clear. The review analyses studies published over the past five years on the relationship between theQRS-Tangle and mortality, as well as coronary heart disease and heart failure. Possible mechanisms for increasing theQRS-Tangle are discussed. Data are given on the use of theQRS-Tangle in diagnostic and prognostic scales, including in combination with other indicators of global electrical heterogeneity of myocardium.Угол между векторамиQRSиTотражает согласованность или же рассогласованность процессов де- и реполяризации желудочков сердца и считается одним из показателей глобальной электрической гетерогенности миокарда. В последние годы продемонстрировано прогностическое значение углаQRS-Tв отношении общей и сердечно-сосудистой смертности как в популяции, так и в различных группах пациентов. Механизмы этого явления остаются не до конца ясными. В обзоре анализируются опубликованные за последние 5 лет исследования, посвященные связи углаQRS-Tсо смертностью, а также с ишемической болезнью сердца и сердечной недостаточностью. Обсуждаются возможные механизмы увеличения углаQRS-T. Приводятся данные об использовании углаQRS-Tв диагностических и прогностических шкалах, в том числе в комплексе с другими показателями глобальной электрической гетерогенности миокарда.

Myocardial infarction (MI) occurs due to the decrease in the blood flow into one part of the heart, and it further causes damage to the heart muscle. The 12-channel electrocardiogram (ECG) has been widely used to detect and localize MI pathology in clinical studies. The vectorcardiogram (VCG) is a 3-channel recording system used to measure the heart’s electrical activity in sagittal, transverse, and frontal planes. The VCG signals have advantages over the 12-channel ECG to localize posterior MI pathology. Detection and localization of MI using VCG signals are vital in clinical practice. This paper proposes a multi-channel multi-scale two-stage deep-learning-based approach to detect and localize MI using VCG signals. In the first stage, the multivariate variational mode decomposition (MVMD) decomposes the three-channel-based VCG signal beat into five components along each channel. The multi-channel multi-scale VCG tensor is formulated using the modes of each channel of VCG data, and it is used as the input to the deep convolutional neural network (CNN) to classify MI and normal sinus rhythm (NSR) classes. In the second stage, the multi-class deep CNN is used for the categorization of anterior MI (AMI), anterior-lateral MI (ALMI), anterior-septal MI (ASMI), inferior MI (IMI), inferior-lateral MI (ILMI), inferior-posterior-lateral (IPLMI) classes using MI detected multi-channel multi-scale VCG instances from the first stage. The proposed approach is developed using the VCG data obtained from a public database. The results reveal that the approach has obtained the accuracy, sensitivity, and specificity values of 99.58%, 99.18%, and 99.87%, respectively, for MI detection. Moreover, for MI localization, we have obtained the overall accuracy value of 99.86% in the second stage for our proposed network. The proposed approach has demonstrated superior classification performance compared to the existing VCG signal-based MI detection and localization techniques.

The aim of the work is to compare vectorcardiographic (VCG) variables - spatial QRS-T angle and electrocardiographic ventricular gradient (VG) with echocardiography (EchoCG) data in patients with idiopathic pulmonary hypertension (IPH) and chronic thromboembolic pulmonary hypertension (CTEPH). Materials and methods. In 40 patients with IPH and 40 patients with CTEPH at the age of 45±12 years, systolic pulmonary artery pressure (SPAP); the sizes of heart chambers, parameters of RV systolic and diastolic function were evaluated with EchoCG. The QRS-T and VG angles were calculated on the VCG, derived from 12-lead digital ECG. Results. In all patients SPAP was greater than 40 mm Hg (mean 83±18 mm Hg), EchoCG data indicated hypertrophy and dilatation of RV, its systolic and diastolic function; dilatation of the right atrium (RA). Prognostically unfavorable changes in EchoCG were observed: the presence of pericardial effusion in 35 (44%) patients, RA area greater than 26 cm2 in 18 (23%) patients; TAPSE less than 1.5 cm in 37 (46%) patients. EchoCG and VCG variables had statistically significant differences in patients with III-IV functional class in comparison with I-II functional class. Statistically significant moderate correlations between VCG and EchoCG variables were revealed. VCG variables allowed to separate patient groups with the presence and absence of prognostically unfavorable changes in EchoCG with sensitivity from 54 to 78% and specificity from 66 to 87%. Conclusion. In patients with IPH and CTEPH, changes of QRS-T angle and VG correlate with SPAP, the size of RV and RA, parameters of RV systolic and diastolic function. The possibility of the use of QRS-T angle and VG for the detection of patients with prognostically unfavorable echocardiographic changes in the general group of patients with IPH and CTEPH has been shown.

Patients with Brugada syndrome (BrS) can show a leftward deviation of the frontal QRS-axis upon provocation with sodium channel blockers. The cause of this axis change is unclear. In this study, we aimed to determine (1) the prevalence of this left axis deviation and (2) to evaluate its cause, using the insights that could be derived from vectorcardiograms. Hence, from a large cohort of patients who underwent ajmaline provocation testing (n = 1430), we selected patients in whom a type-1 BrS-ECG was evoked (n = 345). Depolarization and repolarization parameters were analyzed for reconstructed vectorcardiograms and were compared between patients with and without a &gt, 30&deg, leftward axis shift. We found (1) that the prevalence of a left axis deviation during provocation testing was 18% and (2) that this left axis deviation was not explained by terminal conduction slowing in the right ventricular outflow tract (4th QRS-loop quartile: +17 &plusmn, 14 ms versus +13 &plusmn, 15 ms, nonsignificant) but was associated with a more proximal conduction slowing (1st QRS-loop quartile: +12[8, 18] ms versus +8[4, 12] ms, p &lt, 0.001 and 3rd QRS-loop quartile: +12 &plusmn, 10 ms versus +5 &plusmn, 7 ms, p &lt, 0.001). There was no important heterogeneity of the action potential morphology (no difference in the ventricular gradient), but a left axis deviation did result in a discordant repolarization (spatial QRS-T angle: 122[59, 147]&deg, versus 44[25, 91]&deg, p &lt, 0.001). Thus, although the development of the type-1 BrS-ECG is characterized by a terminal conduction delay in the right ventricle, BrS-patients with a left axis deviation upon sodium channel blocker provocation have an additional proximal conduction slowing, which is associated with a subsequent discordant repolarization. Whether this has implications for risk stratification is still undetermined.

This study sought to determine factors associated with cardiac memory (CM) in patients with implantable cardioverter-defibrillators (ICDs). Patients with structural heart disease [n = 20; mean age: 72.6 ± 11.6 years; 80% male; mean left ventricular ejection fraction (LVEF): 31.7 ± 7.6%; history of myocardial infarction in 75% and nonsustained ventricular tachycardia (NSVT) in 85%] and preserved atrioventricular conduction received dual-chamber ICDs for primary (80%) or secondary (20%) prevention. Standard 12-lead electrocardiograms were recorded in AAI and DDD modes before and after seven days of right ventricular (RV) pacing in DDD mode with a short atrioventricular delay. The direction (azimuth and elevation) and magnitude of spatial QRS, T, and spatial ventricular gradient vectors were measured before and after seven days of RV pacing. CM was quantified as the degree of alignment between QRSDDD-7 and TAAI-7 vectors (QRSDDD-7 -TAAI-7 angle). Circular statistics and mixed models with a random slope and intercept were adjusted for changes in cardiac activation, LVEF, known risk factors, and the use of medications known to affect CM occurring on days 1 through 7. The QRSDDD-7-TAAI-7 angle strongly correlated (circular r = -0.972; p < 0.0001) with a TAAI-7-TDDD-7 angle. In the mixed models, CM-T azimuth changes [+132° (95% confidence interval (CI): 80°-184°); p < 0.0001] were counteracted by the history of MI [-180° (95% CI: -320° to -40°); p = 0.011] and female sex [-162° (95% CI: -268° to -55°); p = 0.003]. A CM-T area increase [+15 (95% CI: 6-24) mV*ms; p < 0.0001] was amplified by NSVT history [+27 (95% CI: 4-46) mV*ms; p = 0.007]. These findings suggest that preexistent electrical remodeling affects CM in response to RV pacing, that CM exhibits saturation behavior, and that women reach CM saturation more easily than men.

Background In the prehospital triage of patients presenting with symptoms suggestive of acute myocardial ischemia, reliable myocardial ischemia detection in the electrocardiogram (ECG) is pivotal. Due to large interindividual variability and overlap between ischemic and nonischemic ECG‐patterns, incorporation of a previous elective (reference) ECG may improve accuracy. The aim of the current study was to explore the potential value of serial ECG analysis using subtraction electrocardiography. Methods SUBTRACT is a multicenter retrospective observational study, including patients who were prehospitally evaluated for acute myocardial ischemia. For each patient, an elective previously recorded reference ECG was subtracted from the ambulance ECG. Patients were classified as myocardial ischemia cases or controls, based on the in‐hospital diagnosis. The diagnostic performance of subtraction electrocardiography was tested using logistic regression of 28 variables describing the differences between the reference and ambulance ECGs. The Uni‐G ECG Analysis Program was used for state‐of‐the‐art single‐ECG interpretation of the ambulance ECG. Results In 1,229 patients, the mean area‐under‐the‐curve of subtraction electrocardiography was 0.80 (95%CI: 0.77–0.82). The performance of our new method was comparable to single‐ECG analysis using the Uni‐G algorithm: sensitivities were 66% versus 67% (p‐value > .05), respectively; specificities were 80% versus 81% (p‐value > .05), respectively. Conclusions In our initial exploration, the diagnostic performance of subtraction electrocardiography for the detection of acute myocardial ischemia proved equal to that of state‐of‐the‐art automated single‐ECG analysis by the Uni‐G algorithm. Possibly, refinement of both algorithms, or even integration of the two, could surpass current electrocardiographic myocardial ischemia detection.

Patients with scar-associated fibrotic tissue remodelling are at greater risk of ventricular arrhythmic events, but current methods to detect the presence of such remodelling require invasive procedures. We present here a potential method to detect the presence, location and dimensions of scar using pacing-dependent changes in the vectorcardiogram (VCG). Using a clinically-derived whole-torso computational model, simulations were conducted at both slow and rapid pacing for a variety of scar patterns within the myocardium, with various VCG-derived metrics being calculated, with changes in these metrics being assessed for their ability to discern the presence and size of scar. Our results indicate that differences in the dipole angle at the end of the QRS complex and differences in the QRS area and duration may be used to predict scar properties. Using machine learning techniques, we were also able to predict the location of the scar to high accuracy, using only these VCG-derived rate-dependent changes as input. Such a non-invasive predictive tool for the presence of scar represents a potentially useful clinical tool for identifying patients at arrhythmic risk., Graphical abstract, Highlights • Non-invasive assessment of scar arrhythmic risk remains a significant challenge. • Rate-dependent changes in vectorcardiograms convey the functional presence of scar. • Random forest machine-learning allows high accuracy for determining scar location.

Background. Evaluating the reliability of vectorcardiography (VCG) of the heart in patients with acute myocardial infarction (MI) compared to electrocardiography (ECG) is relevant. The purpose of the research is to determine the prognostic significance of vectorcardiography in patients with acute myocardial infarction. Material and methods. We examined 396 patients with acute left ventricular myocardial infarction (ave- rage age was 61.2 ± 5.1 years, male patients — 54.55 %). In addition to ECG, we used VCG on the advanced cardiodiagnostic multifunctional complex MTM-SKM. We constructed a so-called four-field table to calculate the correlation between the results of this VCG test and the diagnostic standard (ECG). Results. The sensitivity of VCG, determined by the ratio а/(а + с) – 395/(395 + 1), was 99.7 %. That is, with a proba-bility of 99.7 %, VCG will show a positive result in patients with myocardial infarction. The specificity of VCG, calculated by the ratio d/(d + b) – 30/(30 + 2), was 93.8 %. That is, with a probability of 93.8 %, VCG will give a negative result in a patient who does not have MI. The prognostic value of a method depends on its sensitivity and specificity. The prognostic significance of a positive result, i.e. the probability of having MI with its VCG signs, was 99.6 % (а/(а + b) – 395/(395 + 2)). The prognostic significance of a negative result, that is, the proba- bility of the absence of MI without its VCG signs, was 96.8 % (d/(c + d) – 30/(1 + 30)). Conclusions. The sensitivity of VCG was 99.7 %, specificity — 93.8 %. The positive prognostic significance of VCG was 99.6 %, the negative prognostic significance — 96.8 %., Актуальность. Актуальной является оценка достоверности векторкардиографического (ВКГ) исследования сердца у больных с острым периодом инфаркта миокарда (ИМ) по сравнению с электрокардиографическим (ЭКГ) методом. Цель исследования: определить предсказательную ценность векторкардиографического исследования у больных с острым периодом инфаркта миокарда. Материалы и методы. Обследованы 396 больных с острым ИМ левого желудочка (180 больных с ИМ и 216 больных с сочетанным течением ИМ и стеатоза печени). Возраст больных составил в среднем 61,2 ± 5,1 года. Преобладали лица мужского пола — 54,55 %. Для получения более обширной и глубокой информации о состоянии электрической активности сердца дополнительно к ЭКГ использовалась ВКГ-методика на усовершенствованном кардиодиагностическом многофункциональном комплексе МТМ-СКМ. Для вычисления соотношений между результатами ВКГ-теста и стандартом диагностики (ЭКГ) строилась так называемая четырехпольная таблица. Результаты. Соотношение правильно диагностированных пациентов с помощью ВКГ-исследования позволяет определять его чувствительность и специфичность. Так, чувствительность ВКГ, определяемая отношением a/(a + c) – 395/(395 + 1), составила 99,7 %, т.е. с вероятностью 99,7 % ВКГ покажет положительный результат у больных с ИМ. Специфичность ВКГ, вычисляемая отношением d/(d + b) – 30/(30 + 2), составила 93,8 %, т.е. с вероятностью 93,8 % ВКГ даст отрицательный результат у больного, не имеющего ИМ. Прогностическая ценность метода зависит от его чувствительности и специфичности. Прогностическая ценность положительного результата, т.е. вероятность наличия ИМ при его ВКГ-признаках, составила 99,6 % (a/(a + b) – 395/(395 + 2)). Прогностическая ценность отрицательного результата, т.е. вероятность отсутствия ИМ без его ВКГ-признаков, составила 96,8 % (d/(c + d) – 30/(1 + 30)). Выводы. Чувствительность ВКГ-метода — 99,7 %, специфичность — 93,8 %. Положительная прогностическая значимость ВКГ составила 99,6 %, отрицательная прогностическая значимость ВКГ — 96,8 %., Актуальність. Актуальною є оцінка вірогідності векторкардіографічного (ВКГ) дослідження серця хворих із гострим періодом інфаркту міокарда (ІМ) порівняно з електрокардіографічним (ЕКГ) методом. Мета дослідження: визначити передбачувану цінність векторкардіографічного дослідження у хворих із гострим періодом інфаркту міокарда. Матеріали та методи. Обстежено 396 хворих з гострим ІМ лівого шлуночка (180 хворих з ІМ та 216 хворих із поєднаним перебігом ІМ і стеатозу печінки). Вік хворих становив у середньому 61,2 ± 5,1 року. Переважали особи чоловічої статі — 54,55 %. Для отримання більш широкої та глибокої інформації про стан електричної активності серця додатково до ЕКГ використовувалась ЕКГ-методика на удосконаленому кардіодіагностичному багатофункціональному комплексі МТМ-СКМ. Для обчислення співвідношень між результатами даного ВКТ-тесту і стандартом діагностики (ЕКГ) будувалась так звана чотирьохпільна таблиця. Результати. Співвідношення правильно діагностованих пацієнтів за допомогою ВКГ-дослідження дозволяє визначити його чутливість та специфічність. Так, чутливість ВКГ, що визначається відношенням а/(а + с) – 395/(395 + 1), становила 99,7 %, тобто з імовірністю 99,7 % ВКГ покаже позитивний результат у хворих з ІМ. Специфічність ВКГ, що обчислена відношенням d/(d + b) – 30/(30 + 2), дорівнювала 93,8 %, тобто з імовірністю 93,8 % ВКГ дасть негативний результат у хворого, який не має ІМ. Прогностична цінність методу залежить від його чутливості та специфічності. Прогностична цінність позитивного результату, тобто ймовірність наявності ІМ при його ВКГ-ознаках, становила 99,6 % (а/(а + b) – 395/(395 + 2)). Прогностична цінність негативного результату, тобто ймовірність відсутності ІМ без його ВКГ-ознак, становила 96,8 % (d/(с + d) – 30/(1 + 30)). Висновки. Чутливість ВКГ-методу — 99,7 %, специфічність — 93,8 %. Позитивна прогностична значущість ВКГ — 99,6 %, негативна прогностична значущість ВКГ — 96,8 %.

Background: The combination of left bundle branch block (LBBB) morphology and QRS duration is currently used to select patients for cardiac resynchronization therapy (CRT). These parameters, however, have limitations. This study evaluates the value of QRS area compared with that of QRS duration and morphology in the association with clinical and echocardiographic outcomes in a large cohort of CRT patients. Methods: A retrospective multicentre study was conducted in 1492 CRT patients. LBBB morphology, QRS duration, and QRS area in the baseline 12-lead ECG were evaluated for their association with the occurrence of the combined primary end point of all-cause mortality, cardiac transplantation, and left ventricular assist device implantation. Secondary end points were heart failure hospitalization within the first year after implantation and echocardiographic reduction in left ventricular end-systolic volume. Results: During a mean follow-up period of 3.4 years, 32% of patients reached the primary end point. The association of QRS area with all outcomes was stronger than that of LBBB morphology and QRS duration separately and at least as strong as their combination. QRS area identified patients who did not experience the primary end point better than QRS morphology and QRS duration (area under the curve, 0.61 versus 0.55 and 0.51, respectively; P P Conclusions: QRS area has a strong association to clinical and echocardiographic response to CRT, at least as strong as current patient selection parameters. QRS area may be particularly useful to predict CRT response in patients without a wide LBBB.

Aims Increased spatial angle between QRS complex and T wave loop orientations has repeatedly been shown to predict cardiac risk. However, there is no consensus on the methods for the calculation of the angle. This study compared the reproducibility and predictive power of three most common ways of QRS-T angle assessment. Methods and results Electrocardiograms of 352 healthy subjects, 941 survivors of acute myocardial infarction (MI), and 605 patients recorded prior to the implantation of automatic defibrillator [implantable cardioverter defibrillator (ICD)] were used to obtain QRS-T angle measurements by the maximum R to T (MRT), area R to T (ART), and total cosine R to T (TCRT) methods. The results were compared in terms of physiologic reproducibility and power to predict mortality in the cardiac patients during 5-year follow-up. Maximum R to T results were significantly less reproducible compared to the other two methods. Among both survivors of acute MI and ICD recipients, TCRT method was statistically significantly more powerful in predicting mortality during follow-up. Among the acute MI survivors, increased spatial QRS-T angle (TCRT assessment) was particularly powerful in predicting sudden cardiac death with the area under the receiver operator characteristic of 78% (90% confidence interval 63–90%). Among the ICD recipients, TCRT also predicted mortality significantly among patients with prolonged QRS complex duration when the spatial orientation of the QRS complex is poorly defined. Conclusion The TCRT method for the assessment of spatial QRS-T angle appears to offer important advantages in comparison to other methods of measurement. This approach should be included in future clinical studies of the QRS-T angle. The TCRT method might also be a reasonable candidate for the standardization of the QRS-T angle assessment.

Introduction: To establish an up-to-date and comprehensive set of normal values for the clinically current measurements in the adult ECG, covering all ages for both sexes.Methods: The study population included 13,354 individuals, taken from four population studies in The Netherlands, ranging in age from 16 to 90 years (55% men) and cardiologically healthy by commonly accepted criteria. Standard 12-lead ECGs were available for all participants. The ECGs were processed by a well-validated computer program. Normal limits were taken as the 2nd and 98th percentiles of the measurement distribution per age group.Results: Our study corroborates many findings of previous studies, but also provides more differentiated results, in particular for the older age groups. Age trends were apparent for the QTc interval, QRS axis, and indices of left ventricular hypertrophy. Amplitudes in the left precordial leads showed a substantial increase in the older age groups for women, but not for men. Sex-dependent differences were apparent for most ECG parameters. All results are available on the Website www.normalecg.org, both in tabular and in graphical format.Conclusions: We determined age- and sex-dependent normal values of the adult ECG. Our study distinguishes itself from other studies by the large size of the study population, comprising both sexes, the broad range of ages, and the exhaustive set of measurements. Our results emphasize that most diagnostic ECG criteria should be age- and sex-specific. (C) 2014 Elsevier Inc. All rights reserved.

Background Intra-abdominal hypertension (IAH) impairs cardiovascular function, however an effect of IAH on cardiac electrophysiology has been poorly documented. The aim of this study was to evaluate the effect of IAH following pneumoperitoneum on vectorcardiographic variables reflecting cardiac repolarisation and depolarisation. Methods Otherwise healthy women undergoing elective gynaecological laparoscopy were studied. Intra-abdominal pressure (IAP), spatial QRS-T angle and ST-segment J-point (STJ) were observed during surgery and the early postoperative period. Results Forty women, ages 22 to 43 were examined. Induction of IAH to 15 mmHg significantly widened the spatial QRS-T angle, whereas the Trendelenburg position subsequently reduced this widening. IAH also increased STJ voltage in leads III, aVF, V2 and V3 during surgery, with increased STJ voltage persisting in several leads through the morning of postoperative day 1. Conclusion Induction of IAH impacts the relationship between cardiac depolarisation and repolarisation and increases spatial QRS-T angle and STJ voltage.

Introduction Current criteria for electrocardiographic (ECG) diagnosis of left ventricular hypertrophy (LVH) have a low diagnostic accuracy. Addition of demographic, anthropomorphic, and additional ECG variables may improve accuracy. As hypertrophy affects action potential morphology and intraventricular conduction, QRS prolongation and T-wave morphology may occur and become manifest in the vectorcardiographic variables spatial QRS-T angle (SA) and spatial ventricular gradient. In this study, we attempted to improve the diagnostic accuracy for LVH by using a combination of demographic, anthropomorphic, ECG, and vectorcardiographic variables. Methods The study group (n = 196) was divided in 4 subgroups with, on one hand, echocardiographically diagnosed LVH or a normal echocardiogram and, on the other hand, with any of the conventional ECG signs for LVH or with normal ECGs. Each subgroup was randomly split into halves, yielding 2 equally-sized (n = 98) data sets A and B. Age, sex, height, weight, body mass index, body surface area (BSA), frontal QRS axis, QRS duration, QT duration, maximal QRS vector magnitude, SA, and ventricular gradient magnitude and orientation were univariate studied by receiver operating characteristic analysis and were used to build a stepwise linear discriminant model using P P > .10 as removal criterion. The discriminant model was built in set A (model A) and tested on set B. Stability checks were done by building a discriminant model on set B and testing on set A and by cross-validation analysis in the complete study group. Results The discriminant model equation was D = 5.130 × BSA − 0.014 × SA − 8.74, wherein D greater than or equal to 0 predicts a normal echocardiogram and D less than 0 predicts LVH. The diagnostic accuracy (79%) was better than the diagnostic accuracy of conventional ECG criteria for LVH (57%). Conclusion The combination of BSA and SA yields a diagnostic accuracy of LVH that is superior to that of the conventional ECG criteria.

Serial analysis could improve ECG diagnosis of myocardial ischemia caused by acute coronary occlusion.We analyzed ECG pairs of 84 cases and 398 controls. In case-patients, who underwent elective percutaneous coronary intervention, ischemic ECGs during balloon occlusion were compared with preceding non-ischemic ECGs. In control-patients, two elective non-ischemic ECGs were compared. In each ECG the ST vector at the J point and the ventricular gradient (VG) vector was computed, after which difference vectors ΔST and ΔVG were computed within patients. Finally, receiver operating characteristic analysis was done.Areas under the curve were 0.906 (P0.001; CI 0.862-0.949; SE 0.022) for ΔST and 0.880 (P0.001; CI 0.833-0.926; SE 0.024) for ΔVG. Sensitivity and specificity of conventional ST-elevation myocardial infarction (STEMI) criteria were 70.2% and 89.1%, respectively. At matched serial analysis specificity and STEMI specificity, serial analysis sensitivity was 78.6% for ΔST and 71.4% for ΔVG (not significantly different from STEMI sensitivity). At matched serial analysis sensitivity and STEMI sensitivity, serial analysis specificity was 96.5% for ΔST and 89.3% for ΔVG; ΔST and STEMI specificities differed significantly (P0.001).Detection of acute myocardial ischemia by serial ECG analysis of ST and VG vectors has equal or even superior performance than the STEMI criteria. This concept should be further evaluated in triage ECGs of patients suspected from having acute myocardial ischemia.

Background: The ECG is important in the diagnosis and triage of the acute coronary syndrome (ACS), especially in the hyperacute phase, the "golden hours," during which myocardial salvage possibilities are largest. An important triaging decision to be taken is whether or not a patient requires primary PCI, for which, as mentioned in the guidelines, the presence of an ST elevation (STE) pattern in the ECG is a major criterion. However, preexisting non-zero ST amplitudes (diagnostic, but also non-diagnostic) can obscure or even preclude this diagnosis. Methods: In this study, we investigated the potential diagnostic possibilities of ischemia detection by means of changes in the ST vector, Delta ST, and changes in the VG (QRST integral) vector, Delta VG. We studied the vectorcardiograms (VCGs) synthesized of the ECGs of 84 patients who underwent elective PTCA. Mean +/- SD balloon occlusion times were 260 +/- 76 s. The ECG ischemia diagnosis (ST elevation, STE, or non-ST-elevation, NSTE), magnitudes and orientations of the ST and VG vectors, and the differences Delta ST and Delta VG with the baseline ECG were measured after 3 min of balloon occlusion. Results: Planar angles between the Delta ST and Delta VG vectors were 14.9 +/- 14.0 degrees. Linear regression of Delta VG on Delta ST yielded Delta VG = 324. Delta ST (r = 0.85; P 0.05 mV, and the corresponding Delta VG > 16.2 mV.ms as ischemia thresholds. The classical criteria characterized the ECGs of 46/84 (55%) patients after 3 min of occlusion as STE ECGs. Combined application of the Delta ST and Delta VG criteria identified 73/84 (87%) of the patients as ischemic. Conclusion: Differential diagnosis by Delta ST and Delta VG (requiring an earlier made non-ischemic baseline ECG) could dramatically improve ECG guided detection of patients who urgently require catheter intervention. (C) 2013 Elsevier Inc. All rights reserved. (Less)

Background and Purpose Several studies have demonstrated that the spatial mean QRS-T angle (SA) predicts cardiac events and mortality. Spatial mean QRS-T angle is a vectorcardiographic variable. Because in clinical practice, 12-lead standard electrocardiograms (ECGs) are recorded rather than vectorcardiograms (VCGs) according to Frank, VCGs are commonly obtained by synthesizing them from 12-lead ECGs, by using a VCG synthesis matrix. Hence, the thus computed SA is an estimate of the real SA measured in the Frank VCG. Recent studies have shown that Kors VCG synthesis matrix yields better estimates of SA than the inverse Dower VCG synthesis matrix. Our current study aims to compare the predictive power of these SA variants for the occurrence of potentially lethal arrhythmias. Methods The study group consisted of patients with ischemic heart disease and left ventricular systolic dysfunction who received an implantable cardioverter-defibrillator (ICD) for primary prevention. During follow-up, the occurrence of appropriate device therapy (occurrence of ventricular arrhythmia) was noted. Alternative SAs were computed in VCGs synthesized from standard 12-lead ECGs by using either the inverse Dower matrix (SA-Dower) or the Kors matrix (SA-Kors). Comparison of the predictive power of SA-Dower and SA- Kors was performed by receiver operating characteristic analysis, by Kaplan-Meier analysis, and by univariate and multivariate Cox regression analysis, using every 10th percentile of SA as a cutoff value. Results The study group consisted of 412 patients (361 men; mean ± SD age 63 ± 11 years), in which 56 patients had appropriate ICD therapy during follow-up. Receiver operating characteristic analysis revealed that the area under the curve of SA-Kors was significantly larger than area under the curve of SA-Dower (0.646 vs 0.607, P = .043). The discriminative power of SA-Kors for the absence/presence of appropriate ICD therapy in patients during follow-up was generally superior to SA-Dower over a wide range of cutoff values in the Kaplan-Meier analysis and generally yielded stronger hazard ratios in the univariate and multivariate Cox regression analyses. Conclusion If there is no specific reason to use the inverse Dower matrix, VCG synthesis from standard 12-lead ECGs should preferably be done by using the Kors matrix. It is likely to assume that already published studies in which the predictive value of SA-Dower was demonstrated would yield stronger results if the SA-Dower angles were substituted by SA-Kors angles.

Highlights • Inaccuracies of QRS and T-wave markers significantly impact QRS-Ta estimation. • These errors influence the classification of clinically relevant abnormal values. • Our algorithm provides robust measurements in the presence of inaccurate VCG markers. • We present for the first time, the distribution of the QRS-Ta in a large cohort., The spatial QRS-T angle (QRS-Ta) derived from the vectorcardiogram (VCG) is a strong risk predictor for ventricular arrhythmia and sudden cardiac death with potential use for mass screening. Accurate QRS-Ta estimation in the presence of ECG delineation errors is crucial for its deployment as a prognostic test. Our study assessed the effect of inaccurate QRS and T-wave marker placement on QRS-Ta estimation and proposes a robust method for its calculation. Reference QRS-Ta measurements were derived from 1,512 VCGs manually annotated by three expert reviewers. We systematically changed onset and offset timings of QRS and T-wave markers to simulate inaccurate placement. The QRS-Ta was recalculated using a standard approach and our proposed algorithm, which limits the impact of VCG marker inaccuracies by defining the vector origin as an interval preceding QRS-onset and redefines the beginning and end of QRS and T-wave loops. Using the standard approach, mean absolute errors (MAE) in peak QRS-Ta were >40% and sensitivity and precision in the detection of abnormality (>105°) were 15 ms. Using our proposed algorithm, MAE for peak QRS-Ta were reduced to 94% for inaccuracies up to ±15 ms. Similar results were obtained for mean QRS-Ta. In conclusion, inaccuracies of QRS and T-wave markers can significantly influence the QRS-Ta. Our proposed algorithm provides robust QRS-Ta measurements in the presence of inaccurate VCG annotation, enabling its use in large datasets.