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The Ear-ECG provides a continuous Lead I like electrocardiogram (ECG) by measuring the potential difference related to heart activity by electrodes which are embedded within earphones. However, the significant increase in wearability and comfort enabled by Ear-ECG is often accompanied by a degradation in signal quality - an obstacle that is shared by the majority of wearable technologies. We aim to resolve this issue by introducing a Deep Matched Filter (Deep-MF) for the highly accurate detection of R-peaks in wearable ECG, thus enhancing the utility of Ear-ECG in real-world scenarios. The Deep-MF consists of an encoder stage, partially initialised with an ECG template, and an R-peak classifier stage. Through its operation as a Matched Filter, the encoder searches for matches with an ECG template in the input signal, prior to filtering these matches with the subsequent convolutional layers and selecting peaks corresponding to the ground-truth ECG. The latent representation of R-peak information is then fed into a R-peak classifier, of which the output provides precise R-peak locations. The proposed Deep Matched Filter is evaluated using leave-one-subject-out cross-validation over 36 subjects with an age range of 18-75, with the Deep-MF outperforming existing algorithms for R-peak detection in noisy ECG. The Deep-MF achieves a median R-peak recall of 94.9% and a median precision of 91.2% across subjects when evaluated with leave-one-subject-out cross validation. Overall, this Deep-Match framework serves as a valuable step forward for the real-world functionality of Ear-ECG and, through its interpretable operation, the acceptance of deep learning models in e-Health.

Background: The effect of left ventricular septal myocardial pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and left ventricular (LV) hemodynamic status is poorly understood., Objectives: The aim of this study was to investigate the impact of LVSP and LBBP vs biventricular pacing (BVP) on ventricular electrical synchrony and hemodynamic status in cardiac resynchronization therapy patients., Methods: In cardiac resynchronization therapy candidates with LV conduction disease, ventricular synchrony was assessed by measuring QRS duration (QRSd) and using ultra-high-frequency electrocardiography. LV electrical dyssynchrony was assessed as the difference between the first activation in leads V 1 to V 8 to the last from leads V 4 to V 8 . LV hemodynamic status was estimated using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and BVP., Results: A total of 35 patients with a mean LV ejection fraction of 29% and a mean QRSd of 168 ± 24 ms were included. Thirteen had ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LV electrical dyssynchrony than BVP (-10 ms; 95% CI: -16 to -4 ms; P = 0.001); the difference between LVSP and BVP was not significant (-5 ms; 95% CI: -12 to 1 ms; P = 0.10). LBBP was associated with higher systolic blood pressure than BVP (4%; 95% CI: 2%-5%; P < 0.001), whereas LVSP was not (1%; 95% CI: 0%-2%; P = 0.10). Hemodynamic differences during LBBP and LVSP vs BVP were more pronounced in nonischemic than ischemic patients., Conclusions: Ultra-high-frequency electrocardiography allowed the documentation of differences in LV synchrony between LBBP, LVSP, and BVP, which were not observed by measuring QRSd. LVSP provided the same LV synchrony and hemodynamic status as BVP, while LBBP was better than BVP in both., Competing Interests: Funding Support and Author Disclosures This work was supported by the Charles University Research Program Cooperation-Cardiovascular Science (Dr Curila), the Ministry of Health of the Czech Republic (grant NU21-02-00584 to Dr Curila), and National Institute for Metabolic and Cardiovascular Research “CarDia” (Programme EXCELES, ID Project No. LX22NPO5104), funded by the European Union – Next Generation EU (Dr Curila). Authors from the Cardiocenter, Third Faculty of Medicine, Charles University and University Hospital Kralovske Vinohrady, from Institute of Scientific Instruments, the Czech Academy of Sciences, have filed U.S. patent 11,517,243 B2, “Method of Electrocardiographic Signal Processing and Apparatus for Performing the Method” and are shareholders of VDI Technologies. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Heart rate is under constant autonomic influence but the development of the influence in children is not fully understood. Continuous electrocardiograms were obtained in 1045 healthy school-age children (550 females) during postural provocations with body position changes between supine, sitting, standing, supine, standing, sitting and supine (in this order), 10 min in each position with position changes within 20 s. Heart rate was measured in each position and speed of heart rate changes between positions were assessed by regressions of rates versus timing of individual cardiac cycles. Supine heart rate was gradually decreasing with age: 82.32 ± 9.92, 74.33 ± 9.79, 67.43 ± 9.45 beats per minute (bpm) in tertile age groups < 11, 11-15, > 15 years, respectively (p < 0.0001), with no significant sex difference. Averaged speed of heart rate changes differed little between sexes and age groups but was significantly faster during rate deceleration than acceleration (e.g., supine ↔ standing: 2.99 ± 1.02 vs. 2.57 ± 0.68 bpm/s, p < 0.0001). The study suggests that in children, vagal heart rate control does not noticeably change between ages of approximately 6-19 years. The gradual resting heart rate decrease during childhood and adolescence is likely caused by lowering of cardiac sympathetic influence from sympathetic overdrive in small children to adult-like sympatho-vagal balance in older adolescents., (© 2024. The Author(s).)

Since the introduction of left bundle branch pacing (LBBP), a search for precise parameters confirming successful capture of conduction system was conducted. Most of the proposed electrocardiographic criteria refer to patients with narrow QRS complexes. We present a patient with heart failure in whom cardiac resynchronization was achieved using conduction system pacing. While measuring left ventricular activation time, an isoelectric interval of 74 ms between stimulus and R-wave appeared resulting in prolongation of V6 RWPT to 124 ms. Considering the immediate narrowing of QRS complexes following LBBP, the observed latency most probably reflects prolonged conduction time through the His-Purkinje system., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Inc.)

Continuous, real-time monitoring of occupational health and safety in high-risk workplaces such as construction sites can substantially improve the safety of workers. However, introducing such systems in practice is associated with a number of challenges, such as scaling up the solution while keeping its cost low. In this context, this work investigates the use of an off-the-shelf, low-cost smartwatch to detect health issues based on heart rate monitoring in a privacy-preserving manner. To improve the smartwatch's low measurement quality, a novel, frugal machine learning method is proposed that corrects measurement errors, along with a new dataset for this task. This method's integration with the smartwatch and the remaining parts of the health and safety monitoring system (built on the ASSIST-IoT reference architecture) are presented. This method was evaluated in a laboratory environment in terms of its accuracy, computational requirements, and frugality. With an experimentally established mean absolute error of 8.19 BPM, only 880 bytes of required memory, and a negligible impact on the performance of the device, this method meets all relevant requirements and is expected to be field-tested in the coming months. To support reproducibility and to encourage alternative approaches, the dataset, the trained model, and its implementation on the smartwatch were published under free licenses.

Aims: Fragmented QRS complex with visible notching on standard 12-lead electrocardiogram (ECG) is understood to represent depolarization abnormalities and to signify risk of cardiac events. Depolarization abnormalities with similar prognostic implications likely exist beyond visual recognition but no technology is presently suitable for quantification of such invisible ECG abnormalities. We present such a technology., Methods and Results: A signal processing method projects all ECG leads of the QRS complex into optimized three perpendicular dimensions, reconstructs the ECG back from this three-dimensional projection, and quantifies the difference (QRS 'micro'-fragmentation, QRS-μf) between the original and reconstructed signals. QRS 'micro'-fragmentation was assessed in three different populations: cardiac patients with automatic implantable cardioverter-defibrillators, cardiac patients with severe abnormalities, and general public. The predictive value of QRS-μf for mortality was investigated both univariably and in multivariable comparisons with other risk factors including visible QRS 'macro'-fragmentation, QRS-Mf. The analysis was made in a total of 7779 subjects of whom 504 have not survived the first 5 years of follow-up. In all three populations, QRS-μf was strongly predictive of survival (P < 0.001 univariably, and P < 0.001 to P = 0.024 in multivariable regression analyses). A similar strong association with outcome was found when dichotomizing QRS-μf prospectively at 3.5%. When QRS-μf was used in multivariable analyses, QRS-Mf and QRS duration lost their predictive value., Conclusion: In three populations with different clinical characteristics, QRS-μf was a powerful mortality risk factor independent of several previously established risk indices. Electrophysiologic abnormalities that contribute to increased QRS-μf values are likely responsible for the predictive power of visible QRS-Mf., Competing Interests: Conflict of interest: Dr Hnatkova reports support from European Community’s Seventh Framework Programme, during the study, and from British Heart Foundation, during the study, and personal royalties from St Paul’s Cardiac Electrophysiology; Dr Andršová reports personal consulting fees from St Paul’s Cardiac Electrophysiology, and personal lecture honoraria from Servier Laboratories; Dr Novotný reports support from European Community’s Seventh Framework Programme, during the study, and personal consulting fees from St Paul’s Cardiac Electrophysiology; Dr Britton reports no conflict of interest; Dr Shipley reports no conflict of interest; Dr Vandenberk reports fellowship funding from Frans Van de Werf Fund for Clinical Cardiovascular Research; Dr Sprenkeler reports no conflict of interest; Dr Junttila reports no conflict of interest; Dr Reichlin reports institutional consultation fees from Biosense Webster, Boston Scientific, Biotronik, Farapulse, Bayer, BMS-Pfizer, and Medtronic, institutional lecture honoraria from Biosense Webster, Bayer, BMS-Pfizer, and Medtronic, and institutional meeting support from Bayer, BMS-Pfizer, and Biotronik; Dr Schlögl reports from European Community’s Seventh Framework Programme, during the study, and private investor income from Johnson and Johnson, and Bayer AG; Dr Vos reports a grant from the Horizon 2020 programme; Dr Friede reports support from European Community’s Seventh Framework Programme, during the study, personal consultation fees from Bayer, CSL Behring, Galapagos, Minoryx, Vifor, Novartis, and LivaNova, lecture fees from Fresenius Kabi, and personal fees for Advisory and Data Safety Monitoring boards from Bayer, Biosense Webster, Janssen, Novartis, Roche, and BSM; Dr Bauer reports grant from Medtronic Bakken Research Center, and lecture fees from Medtronic; Dr Huikuri reports no conflict of interest; Dr Willems reports support from European Community’s Seventh Framework Programme, during the study, post-doctoral clinical researcher support by the Fund for Scientific Research Flanders, during the study, institutional research grants from Abbott, Biotronik, Boston Scientific, and Medtronic, institutional lecture fees from Abbott, Biotronik, Boston Scientific, Medtronic, Daichi Sankyo, and Boehringer Ingelheim, meeting support from Daichi Sankyo, and unpaid Secretary position at the Belgian Heart Rhythm Society; Dr Schmidt reports his Chair positions of the Association of Medical Ethics Committees in the Federal Republic of Germany; Dr Franz reports no conflict of interest; Dr Sticherling reports support from European Community’s Seventh Framework Programme, during the study, consulting fees from Abbott, Biotronik, Boston Scientific, and Medtronic, and lecture honoraria from Abbott, Biotronik, Boston Scientific, and Medtronic; Dr Zabel reports support from European Community’s Seventh Framework Programme, during the study; Dr Malik reports support from European Community’s Seventh Framework Programme, during the study, and from British Heart Foundation, during the study, personal royalties from St Paul’s Cardiac Electrophysiology, personal royalties from Elsevier Academic Press, and institutional consultation fees from Sosei Heptares, BioCryst Pharmaceuticals, and Helsinn Healthcare., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Cardiology.)

Fragmented QRS (fQRS) is an electrocardiographic (ECG) marker of myocardial conduction abnormality, characterized by additional notches in the QRS complex. The presence of fQRS has been associated with an increased risk of all-cause mortality and arrhythmia in patients with cardiovascular disease. However, current binary visual analysis is prone to intra- and inter-observer variability and different definitions are problematic in clinical practice. Therefore, objective quantification of fQRS is needed and could further improve risk stratification of these patients. We present an automated method for fQRS detection and quantification. First, a novel robust QRS complex segmentation strategy is proposed, which combines multi-lead information and excludes abnormal heartbeats automatically. Afterwards extracted features, based on variational mode decomposition (VMD), phase-rectified signal averaging (PRSA) and the number of baseline-crossings of the ECG, were used to train a machine learning classifier (Support Vector Machine) to discriminate fragmented from non-fragmented ECG-traces using multi-center data and combining different fQRS criteria used in clinical settings. The best model was trained on the combination of two independent previously annotated datasets and, compared to these visual fQRS annotations, achieved Kappa scores of 0.68 and 0.44, respectively. We also show that the algorithm might be used in both regular sinus rhythm and irregular beats during atrial fibrillation. These results demonstrate that the proposed approach could be relevant for clinical practice by objectively assessing and quantifying fQRS. The study sets the path for further clinical application of the developed automated fQRS algorithm., (© 2022. The Author(s).)

Background: Cardiac sarcoidosis (CS) with right ventricular (RV) involvement can mimic arrhythmogenic right ventricular cardiomyopathy (ARVC). Histopathological differences may result in disease-specific RV activation patterns detectable on the 12-lead electrocardiogram. Dominant subepicardial scar in ARVC leads to delayed activation of areas with reduced voltages, translating into terminal activation delay and occasionally (epsilon) waves with a small amplitude. Conversely, patchy transmural RV scar in CS may lead to conduction block and therefore late activated areas with preserved voltages reflected as preserved R' waves., Objective: The purpose of this study was to evaluate the distinct terminal activation patterns in precordial leads V 1 through V 3 as a discriminator between CS and ARVC., Methods: Thirteen patients with CS affecting the RV and 23 patients with gene-positive ARVC referred for ventricular tachycardia ablation were retrospectively included in a multicenter approach. A non-ventricular-paced 12-lead surface electrocardiogram was analyzed for the presence and the surface area of the R' wave (any positive deflection from baseline after an S wave) in leads V 1 through V 3 ., Results: An R' wave in leads V 1 through V 3 was present in all patients with CS compared to 11 (48%) patients with ARVC (P = .002). An algorithm including a PR interval of ≥220 ms, the presence of an R' wave, and the surface area of the maximum R' wave in leads V 1 through V 3 of ≥1.65 mm 2 had 85% sensitivity and 96% specificity for diagnosing CS, validated in a second cohort (18 CS and 40 ARVC) with 83% sensitivity and 88% specificity., Conclusion: An easily applicable algorithm including PR prolongation and the surface area of the maximum R' wave in leads V 1 through V 3 of ≥1.65 mm 2 distinguishes CS from ARVC. This QRS terminal activation in precordial leads V 1 through V 3 may reflect disease-specific scar patterns., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Nonselective His-bundle pacing (nsHBp), nonselective left bundle branch pacing (nsLBBp), and left ventricular septal myocardial pacing (LVSP) are recognized as physiological pacing techniques., Objective: The purpose of this study was to compare differences in ventricular depolarization between these techniques using ultra-high-frequency electrocardiography (UHF-ECG)., Methods: In patients with bradycardia, nsHBp, nsLBBp (confirmed concomitant left bundle branch [LBB] and myocardial capture), and LVSP (pacing in left ventricular [LV] septal position without proven LBB capture) were performed. Timings of ventricular activations in precordial leads were displayed using UHF-ECG, and electrical dyssynchrony (e-DYS) was calculated as the difference between the first and last activation. Duration of local depolarization (Vd) was determined as width of the UHF-QRS complex at 50% of its amplitude., Results: In 68 patients, data were collected during nsLBBp (35), LVSP (96), and nsHBp (55). nsLBBp resulted in larger e-DYS than did LVSP and nsHBp [- 24 ms (-28;-19) vs -12 ms (-16;-9) vs 10 ms (7;14), respectively; P <.001]. nsLBBp produced similar values of Vd in leads V 5 -V 8 (36-43 ms vs 38-43 ms; P = NS in all leads) but longer Vd in leads V 1 -V 4 (47-59 ms vs 41-44 ms; P <.05) as nsHBp. LVSP caused prolonged Vd in leads V 1 -V 8 compared to nsHBp and longer Vd in leads V 5 -V 8 compared to nsLBBp (44-51 ms vs 36-43 ms; P <.05) regardless of R-wave peak time in lead V 5 or QRS morphology in lead V 1 present during LVSP., Conclusion: nslbbp preserves physiological LV depolarization but increases interventricular electrical dyssynchrony. LV lateral wall depolarization during LVSP is prolonged, but interventricular synchrony is preserved., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Monitoring of QTc interval is mandated in different clinical conditions. Nevertheless, intra-subject variability of QTc intervals reduces the clinical utility of QTc monitoring strategies. Since this variability is partly related to QT heart rate correction, 10 different heart rate corrections (Bazett, Fridericia, Dmitrienko, Framingham, Schlamowitz, Hodges, Ashman, Rautaharju, Sarma, and Rabkin) were applied to 452,440 ECG measurements made in 539 healthy volunteers (259 females, mean age 33.3 ± 8.4 years). For each correction formula, the short term (5-min time-points) and long-term (day-time hours) variability of rate corrected QT values (QTc) was investigated together with the comparisons of the QTc values with individually corrected QTcI values obtained by subject-specific modelling of the QT/RR relationship and hysteresis. The results showed that (a) both in terms of short-term and long-term QTc variability, Bazett correction led to QTc values that were more variable than the results of other corrections (p < 0.00001 for all), (b) the QTc variability by Fridericia and Framingham corrections were not systematically different from each other but were lower than the results of other corrections (p-value between 0.033 and < 0.00001), and (c) on average, Bazett QTc values departed from QTcI intervals more than the QTc values of other corrections. The study concludes that (a) previous suggestions that Bazett correction should no longer be used in clinical practice are fully justified, (b) replacing Bazett correction with Fridericia and/or Framingham corrections would improve clinical QTc monitoring, (c) heart rate stability is needed for valid QTc assessment, and (d) development of further QTc corrections for day-to-day use is not warranted., (© 2021. The Author(s).)

Background: During left bundle branch (LBB) area pacing, it is important to confirm that capture of the LBB, and not just capture of only adjacent left ventricular (LV) myocardium, has been achieved., Objective: The purpose of this study was to establish electrocardiographic (ECG) criteria for LBB capture. We hypothesized that because LBB pacing results in physiological depolarization of the LV, then the native QRS can serve as a reference for diagnosis of LBB capture in the same patient., Methods: Only patients with evidence of LBB capture (QRS morphology transition) were included. Several QRS characteristics were compared between the native rhythm and different types of LBB area capture., Results: A total of 357 ECGs (124 patients) were analyzed: 118 with native rhythm, 124 with nonselective LBB capture, 69 with selective LBB capture, and 46 with LV septal capture. Our hypotheses that during LBB capture the paced V6 R-wave peak time (RWPT; measured from QRS onset) equals the native V6 RWPT and that the paced V6 RWPT (measured from the stimulus) equals the LBB potential to V6 R-wave peak interval were positively validated. Criteria based on these rules had sensitivity and specificity of 88.2%-98.0% and 85.7%-95.4%, respectively. Moreover, 100% specific V6 RWPT cutoff for LBB capture diagnosis in patients with narrow QRS/right bundle branch block was determined to be 74 ms., Conclusion: We showed equivalency of LV activation times on ECG during native and paced LBB conduction. Therefore, if V6 RWPT is longer during pacing, this finding is indicative of lack of LBB capture., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: One of the challenges of left bundle branch (LBB) pacing is placing the pacing lead deep enough in the septum to reach the LBB area, yet not too deep to avoid perforation., Objective: The purpose of this study was to investigate whether the occurrence of the ectopic beats with qR/rsR' morphology in lead V 1 (fixation beats) during lead fixation would predict whether the desired intraseptal lead depth had been reached, whereas the lack of fixation beats would indicate a too-shallow position and the need for more lead rotations., Methods: Consecutive patients during LBB pacing device implantation were analyzed retrospectively and then prospectively with respect to the occurrence of fixation beats during each episode of lead rotation. We compared the presence of fixation beats during the lead rotation event directly before the LBB area depth was reached vs during the events before intermediate/unsuccessful positions., Results: A total of 339 patients and 1278 lead rotation events were analyzed. In the retrospective phase, fixation beats were observed in 327 of 339 final lead positions and in 9 of 939 intermediate lead positions (P <.001). Sensitivity, specificity, and positive and negative predictive values of the fixation beats as a marker for reaching the LBB area were 96.4%, 97.3%, 97.3%, and 96.5%, respectively. In the prospective, fixation beats-guided implantation phase, fixation beats were observed in all patients and only at the LBB capture depth., Conclusion: Monitoring fixation beats during deep septal lead deployment can facilitate the procedure and possibly increase the safety of lead implantation., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

The normal physiologic range of QRS complex duration spans between 80 and 125 ms with known differences between females and males which cannot be explained by the anatomical variations of heart sizes. To investigate the reasons for the sex differences as well as for the wide range of normal values, a technology is proposed based on the singular value decomposition and on the separation of different orthogonal components of the QRS complex. This allows classification of the proportions of different components representing the 3-dimensional representation of the electrocardiographic signal as well as classification of components that go beyond the 3-dimensional representation and that correspond to the degree of intricate convolutions of the depolarisation sequence. The technology was applied to 382,019 individual 10-s ECG samples recorded in 639 healthy subjects (311 females and 328 males) aged 33.8 ± 9.4 years. The analyses showed that QRS duration was mainly influenced by the proportions of the first two orthogonal components of the QRS complex. The first component demonstrated statistically significantly larger proportion of the total QRS power (expressed by the absolute area of the complex in all independent ECG leads) in females than in males (64.2 ± 11.6% vs 59.7 ± 11.9%, p < 0.00001-measured at resting heart rate of 60 beats per minute) while the second component demonstrated larger proportion of the QRS power in males compared to females (33.1 ± 11.9% vs 29.6 ± 11.4%, p < 0.001). The analysis also showed that the components attributable to localised depolarisation sequence abnormalities were significantly larger in males compared to females (2.85 ± 1.08% vs 2.42 ± 0.87%, p < 0.00001). In addition to the demonstration of the technology, the study concludes that the detailed convolution of the depolarisation waveform is individual, and that smoother and less intricate depolarisation propagation is the mechanism likely responsible for shorter QRS duration in females.

Aims: The 2017 European Society of Cardiology guidelines for the management of ST-elevation myocardial infarction recommended assessing quality of care to establish measurable quality indicators in order to ensure that every ST-elevation myocardial infarction patient receives the best possible care. We investigated the quality indicators of healthcare services in Poland provided to ST-elevation myocardial infarction patients., Methods and Results: The Polish Registry of Acute Coronary Syndromes is a nationwide, multicentre, prospective study of acute coronary syndrome patients in Poland. For the purpose of assessing quality indicators, we included 8279 patients from the Polish Registry of Acute Coronary Syndromes hospitalised with ST-elevation myocardial infarction in 2018. Four hundred and eight of 8279 patients (4.9%) arrived at percutaneous coronary intervention centre by self-transport, 4791 (57.9%) arrived at percutaneous coronary intervention centre by direct emergency medical system transport, and 2900 (37.2%) were transferred from non-percutaneous coronary intervention facilities. Whilst 95.1% of ST-elevation myocardial infarction patients arriving in the first 12 h received reperfusion therapy, the rates of timely reperfusion were much lower (ranging from 39.4% to 55.0% for various ST-elevation myocardial infarction pathways). The median left ventricular ejection fraction was 46% and was assessed before discharge in 86.0% of patients. Four hundred and eighty-nine of 8279 patients (5.9%) died during hospital stay. Optimal medical therapy is prescribed in 50-85% of patients depending on various clinical settings. Only one in two ST-elevation myocardial infarction patients is enrolled in a cardiac rehabilitation program at discharge. No patient-reported outcomes were recorded in the Polish Registry of Acute Coronary Syndromes., Conclusions: The results of this study identified areas of healthcare system that require solid improvement. These include direct transport to percutaneous coronary intervention centre, timely reperfusion, guidelines-based medical therapy (in particular in patients with heart failure), referral to cardiac rehabilitation/secondary prevention programs. Also, there is a need for recording quality indicators associated with patient-reported outcomes.

Background: Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The Selvester QRS score has been developed to estimate myocardial scar from the 12-lead electrocardiogram., Objective: We aimed to assess the value of an automated version of the Selvester QRS score for the prediction of implantable cardioverter-defibrillator (ICD) therapy and death in patients undergoing primary prevention ICD implantation., Methods: Unselected patients undergoing primary prevention ICD implantation were included in this retrospective, observational, multicenter study. The QRS score was calculated automatically from a digital standard preimplantation 12-lead electrocardiogram and was correlated to the occurrence of death and appropriate and inappropriate shocks during follow-up. Analyses were performed in groups defined by QRS duration < 130 ms vs ≥ 130 ms., Results: Overall, 1047 patients (872 [83%] men; median age 64 years IQR [55-71]) with ischemic (648, 62%) or nonischemic (399, 38%) cardiomyopathy were included. The median QRS duration was 123 ms (interquartile range [IQR] 111-157 ms), and the median QRS score was 5 (IQR 2-8). The QRS duration was <130 ms in 59% and ≥130 ms in 41%. During a median follow-up of 45 months (IQR 24-72 months), a QRS score of ≥5 was independently associated with a significantly higher risk of mortality (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.05-2.66; P = .031) and appropriate (HR 1.83; 95% CI 1.07-3.14; P = .028) and inappropriate (HR 2.32; 95% CI 1.04-5.17; P = .039) shocks in patients with QRS duration ≥ 130 ms. No association of the QRS score and outcome was observed in patients with QRS duration < 130 ms (P > .05)., Conclusion: The automatically calculated Selvester QRS score, an indicator of myocardial scar burden, predicts mortality and appropriate and inappropriate shocks in patients undergoing primary prevention ICD implantation with a prolonged QRS duration., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Right ventricular myocardial pacing leads to nonphysiological activation of heart ventricles. Contrary to this, His bundle pacing preserves their fast activation. Ultra-high-frequency electrocardiography (UHF-ECG) is a novel tool for ventricular depolarization assessment., Objective: The purpose of this study was to describe UHF-ECG depolarization patterns during myocardial and His bundle pacing., Methods: Forty-six patients undergoing His bundle pacing to treat bradycardia and spontaneous QRS complexes without bundle branch block were included. UHF-ECG recordings were performed during spontaneous rhythm, pure myocardial para-Hisian capture, and His bundle capture. QRS duration, QRS area, depolarization time in specific leads, and the UHF-ECG-derived ventricular dyssynchrony index were calculated., Results: One hundred thirty-three UHF-ECG recordings were performed in 46 patients (44 spontaneous rhythm, 28 selective His bundle, 43 nonselective His bundle, and 18 myocardial capture). The mean QRS duration was 117 ms for spontaneous rhythm, 118 ms for selective, 135 ms for nonselective, and 166 ms for myocardial capture (P < .001 for nonselective and myocardial capture compared to each of the other types of ventricular activation). The calculated dyssynchrony index was shortest during spontaneous rhythm (12 ms; P = .02 compared to selective and P = .09 compared to nonselective), and it did not differ between selective and nonselective His bundle capture (16 vs 15 ms; P > .99) and was longest during myocardial capture of the para-Hisian area (37 ms; P < .001 compared to each of the other types of ventricular activation)., Conclusion: In patients without bundle branch block, both types of His bundle, but not myocardial, capture preserve ventricular electrical synchrony as measured using UHF-ECG., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Pharmaceuticals that prolong ventricular repolarization may be proarrhythmic in susceptible patients. While this fact is well recognized, schemes for sequential QTc interval monitoring in patients receiving QT-prolonging drugs are frequently overlooked or, if implemented, underutilized in clinical practice. There are several reasons for this gap in day-to-day clinical practice. One of these is the perception that serially measured QTc intervals are subject to substantial variability that hampers the distinction between potential proarrhythmic signs and other sources of QTc variability. This review shows that substantial part of the QTc variability can be avoided if more accurate methodology for electrocardiogram collection, measurement, and interpretation is used. Four aspects of such a methodology are discussed. First, advanced methods for QT interval measurement are proposed including suggestion of multilead measurements in problematic recordings such as those in atrial fibrillation patients. Second, serial comparisons of T-wave morphologies are advocated instead of simple acceptance of historical QTc measurements. Third, the necessity of understanding the pitfalls of heart rate correction is stressed including the necessity of avoiding the Bazett correction in cases of using QTc values for clinical decisions. Finally, the frequently overlooked problem of QT-heart rate hysteresis is discussed including the possibility of gross QTc errors when correcting the QT interval for simultaneously measured short-term heart rate., (© 2019 The Authors. Annals of Noninvasive Electrocardiology published by Wiley Periodicals, Inc.)

To facilitate the precision of clinical electrocardiographic studies of J-to-Tpeak (JTp) and Tpeak-to-Tend (Tpe) intervals, the study investigated their differences between healthy females and males, and between subjects of African and Caucasian origin. In 523 healthy subjects (254 females; 236 subjects of African origin), repeated Holter recordings were used to measure QT, JT, JTp, and Tpe intervals preceded by both stable and variable heart rates. Subject-specific curvilinear regression models were used to obtain individual QTc, JTc, JTpc and Tpec intervals. Rate hysteresis, i.e., the speed with which the intervals adapted after heart rate changes, was also investigated. In all sex-race groups, Tpe intervals were not systematically heart rate dependent. Similar to QTc intervals, women had JTc, and JTpc intervals longer than males (difference 20-30 ms, p < 0.001). However, women had Tpec intervals (and rate uncorrected Tpe intervals) shorter by approximately 10 ms compared to males (p < 0.001). Subjects of African origin had significantly shorter QTc intervals than Caucasians (p < 0.001). Gradually diminishing race-difference was found for JTc, JTpc and Tpec intervals. JTc and JTpc were moderately increasing with age but Tpe/Tpec were not. Rate hysteresis of JTp was approximately 10% longer compared to that of JT (p < 0.001). In future clinical studies, Tpe interval should not be systematically corrected for heart rate and similar to the QT interval, the differences in JT, JTp and Tpe intervals should be corrected for sex. The differences in QT and JT, and JTp intervals should also be corrected for race.

Background: Strength-duration curves for permanent His bundle (HB) pacing are potentially important for pacemaker programming., Objectives: We aimed to calculate strength-duration curves and chronaxies of the HB and of the adjacent right ventricular (RV) working myocardium and to analyze zones of selective HB capture and battery current drain when pacing at different pulse durations (PDs)., Methods: Consecutive patients with permanent HB pacing were studied. The RV and HB capture thresholds were assessed at several PDs. Battery current drain and zones of selective HB capture at PDs of 0.1, 0.2, 0.4, and 1.0 ms were determined., Results: In the whole group (N = 127), the HB chronaxie was shorter than the RV chronaxie. This difference was driven by patients with selective HB pacing (HB chronaxie 0.47 ms vs RV chronaxie 0.79 ms). The strength-duration curve for the HB had a lower rheobase and its steep portion started at shorter PDs, thus creating wider distance-zone of programmable selective HB pacing-between the HB and RV strength-duration curves at shorter PDs. The battery current drain was lower with pacing at PDs of 0.1-0.4 ms vs 1.0 ms. Chronaxie-adjusted PDs offered the lowest current drain., Conclusion: For the first time, the strength-duration curves for permanent selective and nonselective HB pacing were determined. Selective HB capture and battery longevity can be promoted by shorter PDs (0.2 ms). Longer PDs (1.0 ms) offer greater safety margin for RV capture and may be preferable if simultaneous RV capture during HB pacing is desired., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: Permanent His-bundle (HB) pacing is usually accompanied by simultaneous capture of the adjacent right ventricular (RV) myocardium-this is described as a non-selective (ns)-HB pacing. It is of clinical importance to confirm HB capture using standard electrocardiogram (ECG). Our aim was to identify ECG criteria for loss of HB capture during ns-HB pacing., Methods and Results: Patients with permanent HB pacing were recruited. Electrocardiograms during ns-HB pacing and loss of HB capture (RV-only capture) were obtained. Electrocardiogram criteria for loss/presence of HB capture were identified. In the validation phase, these criteria and the 'HB ECG algorithm' were tested using a separate, sizable set of ECGs. A total of 353 ECG (226 ns-HB and 128 RV-only) were obtained from 226 patients with permanent HB pacing devices. QRS notch/slur in left ventricular leads and R-wave peak time (RWPT) in lead V6 were identified as the best features for differentiation. The 'HB ECG algorithm' based on these features correctly classified 87.1% of cases with sensitivity and specificity of 93.2% and 83.9%, respectively. The criteria for definitive diagnosis of ns-HB capture (no QRS slur/notch in Leads I, V1, V4-V6, and the V6 RWPT ≤ 100 ms) presented 100% specificity., Conclusion: A novel ECG algorithm for the diagnosis of loss of HB capture and criteria for definitive confirmation of HB capture were formulated and validated. The algorithm might be useful during follow-up and the criteria for definitive confirmation of ns-HB capture offer a simple and reliable ancillary procedural endpoint during HB device implantation., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Cardiovascular mortality is very high in chronic and end-stage kidney disease (ESKD). However, risk stratification data are lacking. Sudden cardiac deaths are among the most common cardiovascular causes of death in these populations. As a result, many studies have assessed the prognostic potential of various electrocardiographic parameters in the renal population. Recent data from studies of implantable loop recordings in haemodialysis patients from five different countries have shed light on a pre-eminent bradyarrhythmic risk of mortality. Importantly, heart block addressed by permanent pacing system was detected in a proportion of patients during the prolonged recording periods. Standard electrocardiogram is inexpensive, non-invasive and easily accessible. Hence, risk prediction models using this simple investigation tool could easily translate into clinical practice. We believe that electrocardiographic assessment is currently under-valued in renal populations. For this review, we identified studies from the preceding 10 years that assessed the use of conventional and novel electrocardiographic biomarkers as risk predictors in chronic and ESKD. The review indicates that conventional electrocardiographic markers are not reliable for risk stratification in the renal populations. Novel parameters have shown promising results in smaller studies, but further validation in larger populations is required., (© The Author(s) 2018. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Introduction: Universal QT correction formulas are potentially problematic in corrected QT (QTc) interval comparisons at different heart rates. Instead of individual-specific corrections, population-specific corrections are occasionally used based on QT/RR data pooled from all study subjects., Objective: To investigate the performance of individual-specific and population-specific corrections, a statistical modeling study was performed using QT/RR data of 523 healthy subjects., Methods: In each subject, full drug-free QT/RR profiles were available, characterized using non-linear regression models. In each subject, 50 baseline QT/RR readings represented baseline data of standard QT studies. Using these data, linear and log-linear heart rate corrections were optimized for each subject and for different groups of ten and 50 subjects. These corrections were applied in random combinations of heart rate changes between - 10 and + 25 beats per minute (bpm) and known QTc interval changes between - 25 and + 25 ms., Results: Both the subject-specific and population-specific corrections based on the 50 baseline QT/RR readings tended to underestimate/overestimate the QTc interval changes when heart rate was increasing/decreasing, respectively. The result spread was much wider with population-specific corrections, making the estimates of QTc interval changes practically unpredictable., Conclusion: Subject-specific heart rate corrections based on limited baseline drug-free data may lead to inconsistent results and, in the presence of underlying heart rate changes, may potentially underestimate or overestimate QTc interval changes. The population-specific corrections lead to results that are much more influenced by the combination of individual QT/RR patterns than by the actual QTc interval changes. Subject-specific heart rate corrections based on full profiles derived from drug-free baseline recordings with wide QT/RR distribution should be used when studying drugs expected to cause heart rate changes.

Introduction: In studies of drug-induced corrected QT (QTc) changes, fixed universal heart rate (HR) corrections (e.g., the Fridericia correction) are potentially misleading when assessing the effects of drugs that change HR. When data-specific corrections are designed, tests of their validity are needed. The proposed tests include zero correlations between QTc and corresponding RR values in the complete study data (pooling on-treatment and off-treatment interval measurements)., Objective: To document that this approach is potentially highly misleading, a statistical modeling study was conducted based on the full profiles of QT/RR data of 523 healthy subjects-254 females, mean age 33.5 years., Methods: In each of the subjects, 50 baseline QT/RR readings were selected to model baseline data. In repeated experiments, groups of ten and 50 subjects were randomly selected and drug-induced HR increases between 0 and 25 beats per minute combined with QTc changes between - 20 and + 20 ms were modeled. In each experiment, subject-specific as well as population-specific HR corrections were designed so that the QTc interval data were uncorrelated to the corresponding RR interval data., Results: The simulation experiments showed that when zero correlations of QTc data with RR data are combined with more than trivial HR increases, the HR corrections are substantially biased and underestimate or fully eliminate any drug-induced QTc interval changes. This result is in full agreement with theoretical considerations of HR correction principles., Conclusions: The lack of correlation of QTc versus RR durations including on-treatment data does not prove any validity of HR corrections. Correlations of QTc versus RR in study data pooling on- and off-drug measurements should not be used to prove the appropriateness of HR corrections.

Objective: Prolonged monitoring times (72 hours) are recommended to detect paroxysmal atrial fibrillation (pAF) after ischemic stroke but this is not yet clinical practice; therefore, an individual patient selection for prolonged ECG monitoring might increase the diagnostic yield of pAF in a resource-saving manner., Methods: We used individual patient data from 3 prospective studies (n total = 1,556) performing prolonged Holter-ECG monitoring (at least 72 hours) and centralized data evaluation after TIA or stroke in patients with sinus rhythm. Based on the TRIPOD (Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis) guideline, a clinical score was developed on one cohort, internally validated by bootstrapping, and externally validated on 2 other studies., Results: pAF was detected in 77 of 1,556 patients (4.9%) during 72 hours of Holter monitoring. After logistic regression analysis with variable selection, age and the qualifying stroke event (categorized as stroke severity with NIH Stroke Scale [NIHSS] score ≤5 [odds ratio 2.4 vs TIA; 95% confidence interval 0.8-6.9, p = 0.112] or stroke with NIHSS score >5 [odds ratio 7.2 vs TIA; 95% confidence interval 2.4-21.8, p < 0.001]) were found to be predictive for the detection of pAF within 72 hours of Holter monitoring and included in the final score (Age: 0.76 points/year, Stroke Severity NIHSS ≤5 = 9 points, NIHSS >5 = 21 points; to Find AF [AS5F]). The high-risk group defined by AS5F is characterized by a predicted risk between 5.2% and 40.8% for detection of pAF with a number needed to screen of 3 for the highest observed AS5F points within the study population. Regarding the low number of outcomes before generalization of AS5F, the results need replication., Conclusion: The AS5F score can select patients for prolonged ECG monitoring after ischemic stroke to detect pAF., Classification of Evidence: This study provides Class I evidence that the AS5F score accurately identifies patients with ischemic stroke at a higher risk of pAF., (© 2018 American Academy of Neurology.)

Introduction: Interpretation of the 12‑lead Electrocardiogram (ECG) is normally assisted with an automated diagnosis (AD), which can facilitate an 'automation bias' where interpreters can be anchored. In this paper, we studied, 1) the effect of an incorrect AD on interpretation accuracy and interpreter confidence (a proxy for uncertainty), and 2) whether confidence and other interpreter features can predict interpretation accuracy using machine learning., Methods: This study analysed 9000 ECG interpretations from cardiology and non-cardiology fellows (CFs and non-CFs). One third of the ECGs involved no ADs, one third with ADs (half as incorrect) and one third had multiple ADs. Interpretations were scored and interpreter confidence was recorded for each interpretation and subsequently standardised using sigma scaling. Spearman coefficients were used for correlation analysis and C5.0 decision trees were used for predicting interpretation accuracy using basic interpreter features such as confidence, age, experience and designation., Results: Interpretation accuracies achieved by CFs and non-CFs dropped by 43.20% and 58.95% respectively when an incorrect AD was presented (p < 0.001). Overall correlation between scaled confidence and interpretation accuracy was higher amongst CFs. However, correlation between confidence and interpretation accuracy decreased for both groups when an incorrect AD was presented. We found that an incorrect AD disturbs the reliability of interpreter confidence in predicting accuracy. An incorrect AD has a greater effect on the confidence of non-CFs (although this is not statistically significant it is close to the threshold, p = 0.065). The best C5.0 decision tree achieved an accuracy rate of 64.67% (p < 0.001), however this is only 6.56% greater than the no-information-rate., Conclusion: Incorrect ADs reduce the interpreter's diagnostic accuracy indicating an automation bias. Non-CFs tend to agree more with the ADs in comparison to CFs, hence less expert physicians are more effected by automation bias. Incorrect ADs reduce the interpreter's confidence and also reduces the predictive power of confidence for predicting accuracy (even more so for non-CFs). Whilst a statistically significant model was developed, it is difficult to predict interpretation accuracy using machine learning on basic features such as interpreter confidence, age, reader experience and designation., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Left bundle branch block (LBBB) is considered an important prognostic parameter in cardiac resynchronization therapy (CRT). We aimed to evaluate, in a sizeable cohort of patients with CRT, long-term mortality, and morbidity according to four different electrocardiographic definitions of LBBB., Methods: This longitudinal cohort study included consecutive patients who underwent CRT device implantation in our institution in years 2006-2014. Two endpoints were assessed: (a) death from any cause or urgent heart transplantation, and (b) death from any cause or heart failure admission. All preimplantation ECGs were analyzed by three physicians blinded to outcome and categorized as LBBB or non-LBBB according to four definitions., Results: A total of 552 CRT patients entered survival analysis. According to the conventional definition, 350 (63.4%) patients had LBBB, and the Marriott, WHO/AHA, and Strauss definitions identified LBBB in 254 (46.0%), 218 (39.5%) and 226 (40.9%) patients, respectively. During the 9 years of observation, 232 patients died, the combined endpoint was met by 292 patients. The Strauss LBBB definition was significantly better to the other definitions in predicting survival (Kaplan-Meier analysis with comparison of C-statistics). Multivariate Cox regression model showed that LBBB was the major determinant of all-cause mortality with the Strauss definition having the lowest hazard ratio (0.51) of the four studied definitions., Conclusions: Criteria included in various definitions of LBBB result in a diagnosis of LBBB in divergent groups of patients. Differences in LBBB definitions have clinical consequences, as patients without 'complete/true' LBBB probably get no mortality benefit from CRT., (© 2018 Wiley Periodicals, Inc.)

Background: The most common aetiology of cardiogenic shock (CS) is acute coronary syndrome (ACS), but even up to 20%-50% of CS is caused by other disorders. ST-segment deviations in the electrocardiogram (ECG) have been investigated in patients with ACS-related CS, but not in those with other CS aetiologies. We set out to explore the prevalence of different ST-segment patterns and their associations with the CS aetiology, clinical findings and 90-day mortality., Methods: We analysed the baseline ECG of 196 patients who were included in a multinational prospective study of CS. The patients were divided into 3 groups: (a) ST-segment elevation (STE). (b) ST-segment depression (STDEP). (c) No ST-segment deviation or ST-segment impossible to analyse (NSTD). A subgroup analysis of the ACS patients was conducted., Results: ST-segment deviations were present in 80% of the patients: 52% had STE and 29% had STDEP. STE was associated with the ACS aetiology, but one-fourth of the STDEP patients had aetiology other than ACS. The overall 90-day mortality was 41%: in STE 47%, STDEP 36% and NSTD 33%. In the multivariate mortality analysis, only STE predicted mortality (HR 1.74, CI 95 1.07-2.84). In the ACS subgroup, the patients were equally effectively revascularized, and no differences in the survival were noted between the study groups., Conclusion: ST-segment elevation is associated with the ACS aetiology and high mortality in the unselected CS population. If STE is not present, other aetiologies must be considered. When effectively revascularized, the prognosis is similar regardless of the ST-segment pattern in ACS-related CS., (© 2018 Wiley Periodicals, Inc.)

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.

Changes in QRS duration and pattern are regarded to reflect severe ischemia in acute coronary syndromes (ACS), and ventricular conduction blocks (VCBs) are recognized high-risk markers in both ACS and acute heart failure. Our aim was to evaluate the prevalence, temporal evolution, association with clinical and angiographic parameters, and impact on mortality of VCBs in ACS-related cardiogenic shock (CS). Data of 199 patients with ACS-related CS from a prospective multinational cohort were evaluated with electrocardiogram data from baseline and day 3. VCBs including left or right bundle branch block, right bundle branch block and hemiblock, isolated hemiblocks, and unspecified intraventricular conduction delay were assessed. Fifty percent of patients had a VCB at baseline; these patients were older, had poorer left ventricular function and had more often left main disease compared with those without VCB. One-year mortality was over 2-fold in patients with VCB compared with those without VCB (68% vs 32%, p<0.001). All types of VCBs at baseline were associated with increased mortality, and the predictive value of a VCB was independent of baseline variables and coronary angiography findings. Interestingly, 37% of the VCBs were transient, i.e., disappeared before day 3. However, 1-year mortality was much higher in these patients (69%) compared to patients with persistent (38%) or no VCB (15%, p<0.001). Indeed, a transient VCB was a strong independent predictor of 1-year mortality. In conclusion, our findings propose that any VCB in baseline electrocardiogram, even if transient, identifies very early patients at particularly high mortality risk in ACS-related CS., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The effective discrimination between patients at risk of Arrhythmic Mortality (AM) and Non-Arrhythmic Mortality (NAM) constitutes one of the important unmet clinical needs. Successful risk assessment based on Electrocardiography (ECG) records is greatly improved by the combination of different indices reflecting not only the pathological substrate but also the autonomic regulation of cardiac electrophysiology. This study assesses the cardiac risk stratification capacity of two new Heart Rate Variability (HRV) parameters, Breath Concurrence 6 (BC6) -sinusoidal RR variability of 6 heart beats per breath cycle- and Primary Ectopia (PE) -presence of early ventricular contractions of any etiology- together with the Deceleration Capacity (DC). While BC6 characterizes the response to physiological and pathophysiological stimuli, PE qualifies autonomic cardiac electrophysiology. The analysis of the European Myocardial Infarct Amiodarone Trial (EMIAT) database indicates that BC6 is related with the risk of Arrhythmic Mortality (AM) and PE with the risk of Non-Arrhythmic Mortality. BC6 is the only single parameter that significantly discriminates between AM and NAM. While the combination of BC6 and DC contributes to the identification of AM risk, PE together with DC improves the prediction of NAM in patients with severe ischemic heart disease.

We investigated prognostic value of four recently proposed ECG markers in patients with cardiac resynchronization therapy (CRT): 1./ pathological preimplantation QRS axis, 2./ increase in QRS amplitude in V3 during biventricular pacing, 3./ negative QRS in V1/V2 during left ventricular (LV)-only pacing, 4./ longer QRS duration during LV-only pacing. A longitudinal cohort study was performed (n = 552)., Results: During the 9-year observation period the primary endpoint (death from any cause or urgent heart transplantation) was met in 232 patients. The secondary endpoint of survival free of heart failure hospitalization was met in 292 patients. Long LV-paced QRS and pathological axis predicted unfavorable prognosis in Kaplan-Meier analysis. In multivariable Cox model (functional class, LV ejection fraction, LV end-diastolic dimension, permanent atrial fibrillation, age, gender, heart failure etiology, creatinine level, diabetes mellitus), LV-paced QRS duration remained a significant determinant of both endpoints. The other studied ECG markers lacked independent prognostic value., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Despite substantial progress in the field of differentiation between ventricular tachycardia (VT) and supraventricular tachycardia (SVT) with wide QRS complexes, differentiation between VT and preexcited SVT remains largely unresolved due to significant overlap in QRS morphology. Our aim was to assess the specificities of various single ECG criteria and sets of criteria (Brugada algorithm, aVR algorithm, Steurer algorithm, and the VT score) for diagnosis of VT in a sizable cohort of patients with preexcitation., Methods: We performed a retrospective study of consecutive accessory pathway ablation procedures to identify preexcited tachycardias. Among 670 accessory pathway ablation procedures, 329 cases with good quality ECG with either bona fide preexcited SVT (n = 30) or a surrogate preexcited SVT (fast paced atrial rhythm with full preexcitation, n = 299) were identified. ECGs were analyzed with the use of wide QRS complex algorithms/criteria to determine specificities of these methods., Results: The Steurer algorithm and VT score (≥3 points), with specificities of 97.6% and 96.1%, respectively, were significantly (p < .01) more specific for the diagnosis of VT than Brugada algorithm, aVR algorithm, and Pava criterion with specificities of 31%, 11.6%, and 57.1%, respectively. The first step of the Brugada algorithm and the first step of the aVR algorithm had also high specificities of 93.3% and 96.0%, respectively., Conclusion: There are sufficient electrocardiographical differences between VT and preexcited SVT to allow electrocardiographic differentiation. VT score, Steurer algorithm, and some single criteria do not overdiagnose VT in patients with preexcitation., (© 2017 Wiley Periodicals, Inc.)

Objectives: Left ventricular (LV) septal hypertrophy in aortic stenosis raises diagnostic and therapeutic questions. However, the etiology and clinical consequences of this finding have not been well studied. The aim of this study was to perform a morphologic evaluation of the LV in aortic stenosis and to investigate the contributing factors and consequences of septal hypertrophy., Methods: Patients with moderate or severe aortic stenosis were prospectively enrolled. Patients with previous myocardial infarction, wall motion abnormalities, at least moderate valvular regurgitation, known cardiomyopathy, an LV ejection fraction of less than 50%, and age younger than 65 years were excluded., Results: Forty-one patients underwent a final analysis. Septal hypertrophy (LV septal wall thickness ≥15 mm) was confirmed in 21 of 41 patients. The septal hypertrophy group had higher peak aortic valve velocity, a higher diabetes mellitus rate, and a higher rate and longer duration of hypertension than those without septal hypertrophy. The peak aortic valve velocity (odds ratio, 7.1; 95% confidence interval, 1.4-37.1) and diabetes mellitus (odds ratio, 7.4; 95% confidence interval, 1.2-46.2) were the significant factors associated with septal hypertrophy by multivariate analysis. Intraventricular conduction disturbance on electrocardiography was more frequent in the septal hypertrophy group (P = .021)., Conclusions: Left ventricular septal hypertrophy was commonly observed in elderly patients with aortic stenosis, and a higher aortic valve velocity, hypertension, and diabetes mellitus were associated factors. Intraventricular conduction disturbance occurred more often in patients with septal hypertrophy than those without, which implies the pathophysiologic consequence. Further studies are needed to determine the impact of septal hypertrophy and intraventricular conduction disturbance on the prognosis of patients after aortic valve interventions., (© 2017 by the American Institute of Ultrasound in Medicine.)

Background: Little experience exists with the heart rate correction of J-Tpeak and Tpeak-Tend intervals., Methods: In a population of 176 female and 176 male healthy subjects aged 32.3±9.8 and 33.1±8.4years, respectively, curve-linear and linear relationship to heart rate was investigated for different sections of the JT interval defined by the proportions of the area under the vector magnitude of the reconstructed 3D vectorcardiographic loop., Results: The duration of the JT sub-section between approximately just before the T peak and almost the T end was found heart rate independent. Most of the JT heart rate dependency relates to the beginning of the interval. The duration of the terminal T wave tail is only weakly heart rate dependent., Conclusions: The Tpeak-Tend is only minimally heart rate dependent and in studies not showing substantial heart rate changes does not need to be heart rate corrected. For any correction formula that has linear additive properties, heart rate correction of JT and JTpeak intervals is practically the same as of the QT interval. However, this does not apply to the formulas in the form of Int/RR a since they do not have linear additive properties., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Philosophy, merits and limitations of a novel method for wide QRS complex tachycardia differentiation, based on a scoring system and called the ventricular tachycardia (VT) score, were explained. The following criteria were assigned one point: initial dominant R wave in V1; initial r>40 ms in V1 or V2; notched S in V1; initial R wave in aVR; lead II RWPT≥50 ms; and absence of an RS in leads V1-V6. Atrioventricular dissociation (including fusion/capture beats and partial dissociation) was assigned two points. We recommend ≥3 VT score points for a firm diagnosis of VT. A cut-off ≥1 point can be used for diagnosis of VT when highest overall accuracy rather than error-free diagnosis is desired. However, in case of VT score of 0-2 (i.e., not fully diagnostic ECG), we recommend using other options (electrophysiological study, clinical data, previous and following ECGs, etc.) for confirming the diagnosis., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Introduction: Most contemporary 12-lead electrocardiogram (ECG) devices offer computerized diagnostic proposals. The reliability of these automated diagnoses is limited. It has been suggested that incorrect computer advice can influence physician decision-making. This study analyzed the role of diagnostic proposals in the decision process by a group of fellows of cardiology and other internal medicine subspecialties., Materials and Methods: A set of 100 clinical 12-lead ECG tracings was selected covering both normal cases and common abnormalities. A team of 15 junior Cardiology Fellows and 15 Non-Cardiology Fellows interpreted the ECGs in 3 phases: without any diagnostic proposal, with a single diagnostic proposal (half of them intentionally incorrect), and with four diagnostic proposals (only one of them being correct) for each ECG. Self-rated confidence of each interpretation was collected., Results: Availability of diagnostic proposals significantly increased the diagnostic accuracy (p<0.001). Nevertheless, in case of a single proposal (either correct or incorrect) the increase of accuracy was present in interpretations with correct diagnostic proposals, while the accuracy was substantially reduced with incorrect proposals. Confidence levels poorly correlated with interpretation scores (rho≈2, p<0.001). Logistic regression showed that an interpreter is most likely to be correct when the ECG offers a correct diagnostic proposal (OR=10.87) or multiple proposals (OR=4.43)., Conclusion: Diagnostic proposals affect the diagnostic accuracy of ECG interpretations. The accuracy is significantly influenced especially when a single diagnostic proposal (either correct or incorrect) is provided. The study suggests that the presentation of multiple computerized diagnoses is likely to improve the diagnostic accuracy of interpreters., (Copyright © 2017 Elsevier B.V. All rights reserved.)