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Background Real-world data on the use of left bundle branch area pacing (LBBAP) as an alternative novel pacing strategy to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT) remains scarce. We aimed to investigate the outcomes of LBBAP as an alternative to BVP as a method of CRT. Methods Electronic databases were searched for studies on the use of LBBAP as CRT and studies that compared LBBAP with BVP. The main outcomes examined were changes in New York Heart Association classification, left ventricular end-diastolic diameter, left ventricular ejection fraction, and paced QRS duration post CRT device implantation. Results Our meta-analysis included 8 nonrandomized studies with a total of 527 patients who underwent LBBAP as CRT. In studies with a BVP comparison group, patients with LBBAP had a greater reduction in paced QRS (mean difference [MD], 27.91 msec; 95% confidence interval [CI], 22.33-33.50), and a greater improvement in New York Heart Association class (MD, 0.59; 95% CI, 0.28-0.90) and left ventricular ejection fraction (MD, 6.77%; 95% CI, 3.84-9.71). Patients with underlying left bundle branch block appeared to benefit the most from LBBAP compared with patients without underlying left bundle branch block. Conclusions LBBAP might be a reasonable option for patients who meet indications for CRT, particularly in those who have limited anatomy or do not benefit from CRT. Randomized trials are needed to compare LBBAP with BVP for CRT and to identify which populations might benefit the most from LBBAP., Image, graphical abstract

Objective: Knowledge of factors causing pacing-induced cardiomyopathy (PICM) is incomplete. We sought to estimate the incidence and predisposing factors for PICM and evaluate if the risk they portend adds up. Methods: Single centre retrospective study where consecutive patients with preserved LVEF undergoing pacemaker (PM) implantation between 2012 and 2018 were analysed. Results: A total of 749 patients (68.4 % male; mean age 59.2 ± 14.08 years) were included in the analysis. PICM developed in 74 (9.9%) patients over a median follow up of 2.2 years (IQR 1.1–3.2). Pre-implant LVEF, paced QRS duration and RV pacing burden were independent predictors of PICM. Using 90 % specificity cut-off values for LVEF and paced QRS, and the value separating lowest tertile of RV pacing from the higher tertiles, three risk factors were identified: (i) baseline LVEF 160 msec, and (iii) RV pacing burden > 33 %. Patients with two or more risk factors were at the highest risk (OR 11.62, 95 % CI 4.62–29.21, p-value

A septuagenarian female with cardiac sarcoidosis suffered from drug refractory ventricular tachycardia (VT) requiring multiple implantable cardioverter-defibrillator shocks. The QRS complex during the VT was very similar to that during sinus rhythm although the QRS width during the VT (142 ms) was relatively wider than that during sinus rhythm (107 ms). The VT exit was located on the ventricular septum close to the His-bundle recording region. However, the critical pathway of this VT was detected on the anterior free wall of the left ventricle (LV), and a radiofrequency application at that site could terminate the VT. No Purkinje potentials were recorded there during the VT or sinus rhythm. According to the electrophysiological study, 3-D mapping, and the response to the ablation, the critical circuit of the VT was surrounded by a protected area of scar associated with cardiac sarcoidosis. As a result, the VT circuit was connected to the basal septal area close to the His-Purkinje system as an outer loop of the VT circuit. This unique trajectory of the VT might have caused a similar QRS morphology to that of sinus rhythm, and the relatively narrow QRS complex despite the critical isthmus was located on the anterior free wall of the LV.

Background Adaptive cardiac resynchronization therapy (aCRT) is known to have clinical benefits over conventional CRT, but the mechanisms are unclear. Objective Compare effects of aCRT and conventional CRT on electrical dyssynchrony. Methods A prospective, double-blind, 1:1 parallel-group assignment randomized controlled trial in patients receiving CRT for routine clinical indications. Participants underwent cardiac computed tomography and 128-electrode body surface mapping. The primary outcome was change in electrical dyssynchrony measured on the epicardial surface using noninvasive electrocardiographic imaging before and 6 months post-CRT. Ventricular electrical uncoupling (VEU) was calculated as the difference between the mean left ventricular (LV) and right ventricular (RV) activation times. An electrical dyssynchrony index (EDI) was computed as the standard deviation of local epicardial activation times. Results We randomized 27 participants (aged 64 ± 12 years; 34% female; 53% ischemic cardiomyopathy; LV ejection fraction 28% ± 8%; QRS duration 155 ± 21 ms; typical left bundle branch block [LBBB] in 13%) to conventional CRT (n = 15) vs aCRT (n = 12). In atypical LBBB (n = 11; 41%) with S waves in V5-V6, conduction block occurred in the anterior RV, as opposed to the interventricular groove in strict LBBB. As compared to baseline, VEU reduced post-CRT in the aCRT (median reduction 18.9 [interquartile range 4.3–29.2 ms; P = .034]), but not in the conventional CRT (21.4 [-30.0 to 49.9 ms; P = .525]) group. There were no differences in the degree of change in VEU and EDI indices between treatment groups. Conclusion The effect of aCRT and conventional CRT on electrical dyssynchrony is largely similar, but only aCRT harmoniously reduced interventricular dyssynchrony by reducing RV uncoupling., Graphical abstract

Background Although His bundle pacing (HBP) has been shown to improve left ventricular ejection fraction (LVEF), its impact on mitral regurgitation (MR) remains uncertain. Objectives The aim of this study was to evaluate change in functional MR after HBP in patients with left ventricular (LV) systolic dysfunction. Methods Paired echocardiograms were retrospectively assessed in patients with reduced LVEF (

A 58-year-old woman with nonischemic cardiomyopathy underwent an ablation for refractory ventricular fibrillation (VF). In addition to elimination of the premature ventricular contraction triggering VF, substrate ablation entailed elimination of dormant Purkinje potentials, which were unmasked in regions where local pacing revealed a narrow QRS with stimulus QRS latency. VF trigger and abnormal Purkinje ablation completely eliminated the refractory VF. (Level of Difficulty: Intermediate.), Central Illustration

Background In patients with cardiac resynchronization therapy defibrillators (CRT-Ds), intracardiac impedance measured by dedicated CRT-D software may be used to monitor hemodynamic changes. We investigated the relationship of hemodynamic parameters assessed by intracardiac impedance and by echocardiography in a controlled clinical setting. Methods The study enrolled 68 patients (mean age, 66 ± 9 years; 74% males) at 12 investigational sites. The patients had an indication for CRT-D implantation, New York Heart Association class II/III symptoms, left ventricular ejection fraction 15%–35%, and a QRS duration ≥150 ms. Two months after a CRT-D implantation, hemodynamic changes were provoked by overdrive pacing. Intracardiac impedance was recorded at rest and at four pacing rates ranging from 10 to 40 beats/min above the resting rate. In parallel, echocardiography measurements were performed. We hypothesized that a mean intra-individual correlation coefficient (rmean) between stroke impedance (difference between end-systolic and end-diastolic intracardiac impedance) measured by CRT-D and the aortic velocity time integral (i.e., stroke volume) determined by echocardiography would be significantly larger than 0.65. Results The hypothesis was evaluated in 40 patients with complete data sets. The rmean was 0.797, with a lower confidence interval bound of 0.709. The study hypothesis was met (p = 0.007). A stepwise reduction of stroke impedance and stroke volume was observed with increasing heart rate. Conclusions Intracardiac impedance measured by implanted CRT-Ds correlated well with the aortic velocity time integral (stroke volume) determined by echocardiography. The impedance measurements bear potential and are readily available technically, not requiring implantation of additional material beyond standard CRT-D system., Highlights • Intracardiac impedance measurement feature (ICI-MF) is integrated in some CRT-Ds. • We studied relationship between echo hemodynamic parameters and ICI-MF of CRT-Ds. • Stroke volume by echo correlated well with stroke impedance by ICI-MF of CRT-Ds. • Stepwise reduction in stroke impedance and stroke volume with increasing heart rate. • The ICI-MF bears potential and requires only a ‘standard’ CRT-D system implantation.

Background Ectopic cycle length (ECL) and the distribution patterns of ventricular bigeminy and trigeminy, expressed as their postextrasystolic intervals (PEIs) and interectopic intervals (IEIs), have been poorly pursued. Objective Based on modulation theory, we hypothesized that the PEIs of bigeminy and trigeminy determine their IEIs and ECL. Methods Ambulatory electrocardiograms of 1290 patients with ventricular premature complexes (≥3000/day) were studied. To quantify their distribution pattern on the PEI vs IEI curve (PIC), we introduced the following 2 ratios: PEI of trigeminy to PEI of bigeminy ratio (T/B-PEI) and IEI of trigeminy to IEI of bigeminy ratio (T/B-IEI). Distribution patterns were divided into 3 types by T/B-PEI: standard type (1.20). ECL was defined as the average of the bigeminy and trigeminy intervals in the standard type, and bigeminy intervals in the other 2 types. Results T/B-IEI disclosed significant linear relationship with T/B-PEI (P < .0001). ECLs were longest in the standard type (1905 ± 347 ms; n = 426), followed by the intermediate type (1520 ± 239 ms; n = 607) and reverse type (1317 ± 227 ms; n = 227) (P < .0001). Trigeminy PEI/ECL in the standard type (0.450 ± 0.074) was significantly shorter than that of the other 2 types (P < .0001). Conclusion We confirmed that T/B-PEI determines T/B-IEI and ECL by discriminating the 3 distribution patterns. Among them, trigeminy PEI/ECL decided the 2 types of modulation by the first sinus QRS, starting at the early delay phase or the later acceleration phase., Graphical abstract

An 86-year-old man with paroxysmal atrial fibrillation on flecainide, a class IC antiarrhythmic, presented with cardiac arrest. The patient had extremely wide QRS complexes with inconsistent pacemaker capture on electrocardiography. Due to cardiac failure and renal failure, the patient developed progressive flecainide toxicity, which led to pacemaker failure, and ultimately, death. (Level of Difficulty: Beginner.), Central Illustration

Myocarditis is an inflammatory disease of the myocardium with high morbidity and mortality; however, definite prognostic factors are still unclear. Therefore, we aimed to evaluate the predictor of clinical outcomes of acute myocarditis focusing on electrocardiographic findings. The overall result of the study consists of a total of 51 patients demonstrated that wide QRS duration is a meaningful factor for predicting the fulminant course of acute myocarditis. This finding may encourage timely mechanical support resulting in better clinical outcomes.

Background: Bidirectional ventricular tachycardia (BD-VT) is an intriguing arrhythmia, characterized by a beat-to-beat alternation of the QRS polarity on electrocardiogram. Currently there is no simple BD-VT animal model. Objective: We report a simple animal model of BD-VT induced by caffeine and dobutamine (C+D) challenge in normal rats in which the arrhythmia can be attenuated by dantrolene (a ryanodine receptor stabilizer) treatment, but not by the pacemaker channel blocker ivabradine treatment. Methods: Adult (4–5 months old) Sprague-Dawley rats (both sexes) were randomized into C+D (n = 8, received caffeine 120 mg/kg intraperitoneally [IP] and dobutamine 60 μg/kg IP, sequentially) and control (n = 8) groups. In addition, a group of 7 rats were pretreated with dantrolene (10 mg/kg, IP) 30 minutes before the C+D challenge and another group of 8 rats were pretreated with ivabradine (5 mg/kg, IP) 30 minutes before the C+D challenge. Results: C+D challenge induced spontaneous premature ventricular contractions (PVCs) in 7 of 8 rats and BD-VT (lasted 4.3 ± 2.9 minutes, terminated spontaneously) in 6 of 8 (75%) rats. No ventricular arrhythmia was induced in the control group (P < .05 vs C+D group). Dantrolene treatment significantly decreased BD-VT (1 of 7 rats in the Dantrolene+C+D group vs 6 of 8 rats in C+D group, P < .05). Ivabradine treatment did not affect C+D-induced BD-VT (7 of 8 rats in the Ivabradine+C+D group vs 6 of 8 in the C+D group, P > .05). Conclusion: Caffeine and dobutamine challenge induces BD-VT in a majority of normal rats. Stabilizing cardiac ryanodine receptors with dantrolene treatment can significantly decrease the occurrence of BD-VT, but pacemaker channel blocker ivabradine treatment does not have effect in this animal model.

Background In this study we report our experience in implanting MICRA TPS (transcatheter pacing system) at various RV sites; observing its safety, and impact on paced QRS in Indian population. Material & methods 35 patients with MICRA TPS deployed from March 2017 to December 2019 at Army Hospital Research and Referral, New Delhi, at RVOT, apical septum and mid septum of RV were enrolled in the study. These patents were followed up and impact of implantation site, procedure related complications, change in pacing parameters, left ventricular ejection fraction and duration of paced QRS were monitored. Results Sick sinus syndrome was the commonest indication of pacing in this study (51.5%), followed by high degree AV block (34.2%). Mean follow up of 1.4 years showed no change in left ventricular ejection fraction, electrical parameters or change in pacing thresholds after implantation. Mean pQRS was broadest (166.60 ms) in apically implanted MICRA TPS and narrowest in mid septum group 139.33 ms. Among 35 cases, in our study one patient developed pericardial effusion, and other had intermittent diaphragmatic pacing. Conclusion Among these three implantation sites mid septum deployment is associated with narrowest paced QRS in Indian population.

Nondrug therapy for arrhythmia patients had been developed dramatically until recent years. Cardiac resynchronization therapy (CRT), a nondrug therapy for arrhythmia, is especially utilized for the treatment of left ventricular (LV) severe heart failure caused by cardiac dyssynchrony. Prolonged QRS duration (≧130 ms) is strongly used as a CRT indication criterion, but QRS is not the direct clinical index of mechanical contraction delay of the LV myocardium. Therefore, identifying the presence of dyssynchrony by diagnostic imaging is necessary. Echocardiography is widely used for the assessment of dyssynchrony as a standard diagnostic imaging. Several studies have addressed the efficacy of cardiovascular magnetic resonance feature tracking (CMR-FT) in the diagnosis of dyssynchrony for arrythmia patients. In addition, cardiac implantable electronic devices (CIEDs) were not available to examine CMR until recent years; however, new MR-conditional CIEDs have become available for use before and after CRT. Recently, diagnostic imaging using CMR-FT has been attracting attention for the assessment of dyssynchrony. However, a strong metal artifact caused by CIEDs may make the analysis difficult after CRT implantation. Strain analysis using short-axis (SA) cine CMR overcame this issue of artifact by enabling slice selection by avoiding artifact. Moreover, circumferential strain has superiority over other strain methods with respect to sensitivity, and we focused on these advantages. This case illustrates that circumferential strain with CMR-FT using SA cine CMR is useful in the assessment of improvement of myocardial motion after CRT and can provide useful additional information with imaging to determine the responders of CRT.

The phenomenon of a “double fire,” double atrioventricular nodal (AVN) response or dual AVN nonreentrant tachycardia (DAVNNT) first described in 1975 and published until the present mainly as isolated case reports, is a rare clinically manifested arrhythmia. Specific electrocardiographic sign of this infrequent phenomenon is that 1 sinus beat is followed by 2 narrow or wide (as a result of aberrancy) QRS complexes1,2 owing to the simultaneous anterograde conduction via fast and slow pathways (FP, SP) of the functionally dissociated AVN. Atypical bypass fibers with decremental conduction is another rare clinical entity. Electrocardiographic recognition of those structures during sinus rhythm (SR) may be difficult owing to the presence of subtle or no preexcitation. Premature ventricular complexes (PVC) ablated from Koch’s triangle is also an infrequent entity.3 Crossing key points for all of them might be QRS linking, atypical accessory fibers, or crux cordis, making differential diagnosis challenging. We describe a case of idiopathic frequent monomorphic PVCs from the basal ventricular septum with a possible diagnosis as 1:2 response phenomenon over atypical accessory fibers. Key Teaching Points • “Double fire” might be a heterogenous group of arrhythmias with different substrates, mechanisms, and electrocardiogram (ECG) manifestation in which 1:2 atrioventricular nodal (AVN) response composes only some part. Anatomical and physiological substrates for 1:2 response phenomenon are functional dissociation of the AVN (with specific conditions) as a solo entity, accessory Mahaim fibers as another distinct entity, or a combination of both. This may explain the presence of 1:2 response phenomenon in similar proportion of male and female patients compared to AVN reentrant tachycardia. • In our case it was impossible to manifest anterograde conduction over bypass structures during atrial pacing, but the accurate preliminary analysis of electrocardiogram (ECG) allowed us to suspect Mahaim fibers and carry out mapping of Koch’s triangle. As a consequence, registered M-potential, along with the results of pacing (selective capture) and radiofrequency ablation, confirm the diagnosis. Based on this we made the following conclusion: while it is impossible, with atrial pacing maneuvers, to validate conduction down the Mahaim fibers during the electrophysiology study, this fact does not exclude the origin of atypical accessory fibers above the AV ring. • ECG and electrophysiological signs of 1:2 response over Mahaim fibers resembles premature ventricular contraction with exit site at the para-Hisian space. High burden and ineffective antiarrhythmic drug treatment promote ablation therapy as a treatment of choice. The described specific properties and manifestations should allow one to suspect atypical accessory fiber as a substrate in similar cases and carry out correct planning of cardiac mapping procedures, avoiding “unnecessary” high-risk application at the para-Hisian space.

Background: The cardiac manifestations of late-onset hereditary transthyretin amyloidosis with p.A97S variant have not been extensively studied, and the prognostic factors remain unclear. Methods: The clinical profile, echocardiography, and ECG of patients diagnosed with ATTR p.A97S polyneuropathy between 2000 and 2016 were retrospectively collected. 67 patients with ATTR p.A97S were collected. Results: A total of 82% of patients met the criteria for left ventricular (LV) hypertrophy. Reduced global longitudinal strain (GLS) was noted in 42.1% of patients, and 14% of patients had a relative apical sparing pattern. A low voltage pattern in the ECG was observed in 31.3% of patients, while 64.2% presented with a pseudoinfarction pattern. End-systolic LV inner dimension (HR: 2.25 (95% CI: 1.01–5.01), p = 0.048), reduced GLS (HR: 5.26 (1.08–25.0), p = 0.039), relative apical longitudinal strain (RALS>1, HR: 8.57 (1.69–43.3), p = 0.009), increased E/A ratio (HR: 6.51 (1.17–36.4), p = 0.033), and increased QRS duration (HR: 1.02 (1.00–1.04), p = 0.05) were correlated with reduced survival in univariate analysis. Multivariate analysis revealed reduced RALS was significantly correlated with reduced survival (HR: 13.00 (1.81–93.45), p = 0.011). Conclusion: Our findings reveal that ATTR p.A97S is a cardiomyopathy as well as a polyneuropathic syndrome. Routine use of more contemporary echocardiographic techniques are recommended to identify cardiac amyloidosis and provide prognostic information. Keywords: Hereditary transthyretin amyloidosis, Familial amyloidotic polyneuropathy, p.A97S, Global longitudinal strain

Chest pain may be rarely associated with left bundle branch block (LBBB)-mediated ventricular dys-synchrony has been reported. This article reports 2 such cases, where left bundle branch area pacing resulted in resolution of the LBBB and associated symptoms. By adjusting the atrioventricular delays, the QRS duration was narrowed further by achieving fusion with the intrinsic activation wavefront. (Level of Difficulty: Beginner.), Graphical abstract, Chest pain related to left bundle branch block (LBBB)-mediated ventricular dys-synchrony has been reported. This article reports 2 such cases, where…

The heart is the single most important organ of the human body. By studying the ECG signal any abnormalities in the heart’s tempo can be identified. The QRS complex is the most prominent feature of an ECG signal. However, the detection of this feature is hampered by the presence of high and low-frequency noises in the ECG signal and abrupt changes in the signal’s morphology. This paper presents a new method of QRS detection using advanced adaptive multilevel thresholding (AAMT) with selective statistical false peak elimination (SSFPE). Firstly, a band-pass filter is used to filter out most of the unwanted noise and interference to aid the detection operation. Then, AAMT is applied to the entire ECG record to find the location and amplitudes of the pseudo peaks. Next, SSFPE is employed to eliminate false peaks resulting from electromyogram (EMG) and any other high-frequency noise that has not been eliminated in the filtering stage. Finally, after most of the peaks are correctly identified a search back stage is included to find any low amplitude true peaks that might have been missed in the peak detection stage. The proposed method is tested on the MIT-BIH arrhythmia and Fantasia databases and shows high accuracy in detection compared to many state-of-the-art QRS detection methods. The method yields high sensitivity, positive predictivity, and a low detection error rate of 99.85%, 99.91%, and 0.25%, respectively, for the MIT-BIH arrhythmia and 99.98%, 99.90%, and 0.12%, respectively for the Fantasia database.

Background: Prolonged QT intervals are reported in patients with COVID-19. Additionally, virus particles in heart tissue and abnormal troponin levels have been reported. Consequently, we hypothesize that cardiac electrophysiologic abnormalities may be associated with COVID-19. Methods: This is a retrospective study between March 15th, 2020 and May 30th, 2020 of 828 patients with COVID-19 and baseline ECG. Corrected QT (QTc) and QRS intervals were measured from ECGs performed prior to intervention or administration of QT prolonging drugs. QTc and QRS intervals were evaluated as a function of disease severity (patients admitted versus discharged; inpatients admitted to medical unit vs ICU) and cardiac involvement (troponin elevation >0.03 ng/ml, elevated B-natriuretic peptide (BNP) or NT pro-BNP >500 pg/ml). Multivariable analysis was used to test for significance. Odds ratios for predictors of disease severity and mortality were generated. Findings: Baseline QTc of inpatients was prolonged compared to patients discharged (450.1±30.2 versus 423.4±21.7 msec, p

Objective: To examine long-term outcomes after tetralogy of Fallot (TOF) repair. Methods: Single-centre retrospective study of 293 patients aged ≥16 years with previous TOF repair at a median age of 2.6 years (IQR:1.1–5.1 years). Surgical approach was trans-atrial (51% (149/293)), right ventriculotomy (34% (101/293)) and unknown (15%, 43/293). Results: After a median adult centre follow-up of 9 years (IQR:3.9–15.5 years, max 40), survival was excellent (n = 284, 97%). Age-adjusted survival was 99%, 95%, and 83% at 20, 40, and 60 years of age, respectively. Over half required ≥1 pulmonary valve (PV) intervention (166/293, 57%). Arrhythmia endpoints occurred in 24% (70/293) including atrial arrhythmia in 12% (34/293) and ventricular arrhythmia in 6% (18/293). Freedom from PV intervention and arrhythmia reduced with time (85% and 95% at 20, 46% and 82% at 40, and 16% and 31% at 60 years of age, respectively). The vast majority have excellent functional status at latest follow-up (NYHA Class I/II: 99.5%, 202/203). Independent risk factors for lower RVEF at latest cardiac magnetic resonance imaging (CMR) were male sex (p = 0.01), PV intervention (p = 0.02), increased QRS duration on ECG on latest follow-up (p

When mapping premature ventricular contractions (PVCs) originating from around the right ventricular outflow tract (RVOT) or left ventricular outflow tract (LVOT), insulated myocardial pathway conduction that is connected to an exit to the ventricular myocardium is sometimes observed.1, 2 Insulated myocardial pathways are usually detected as discrete or fractionated prepotentials preceding the QRS onset during PVCs, but sometimes they are detected as late potentials during sinus rhythm (SR).3, 4, 5 Although the existence of insulated myocardial pathways has been reported,1, 2, 3, 4, 5, 6 the electrophysiological and anatomic characteristics of the insulated myocardial pathways have not been fully clarified. Here we present the case of a PVC with an insulated myocardial pathway for which the detailed electrophysiological and anatomic characteristics were evident.

Background Conduction channels have been demonstrated within the postinfarct scar and seem to be co-located with the isthmus of ventricular tachycardia (VT). Mapping the local scar potentials (SPs) that define the conduction channels is often hindered by large far-field electrograms generated by healthy myocardium. Objective The purpose of this study was to map conduction channel using ripple mapping to categorize SPs temporally and anatomically. We tested the hypothesis that ablation of early SPs would eliminate the latest SPs without direct ablation. Methods Ripple maps of postinfarct scar were collected using the PentaRay (Biosense Webster) during normal rhythm. Maps were reviewed in reverse, and clusters of SPs were color-coded on the geometry, by timing, into early, intermediate, late, and terminal. Ablation was delivered sequentially from clusters of early SPs, checking for loss of terminal SPs as the endpoint. Results The protocol was performed in 11 patients. Mean mapping time was 65 ± 23 minutes, and a mean 3050 ± 1839 points was collected. SP timing ranged from 98.1 ± 60.5 ms to 214.8 ± 89.8 ms post QRS peak. Earliest SPs were present at the border, occupying 16.4% of scar, whereas latest SPs occupied 4.8% at the opposing border or core. Analysis took 15 ± 10 minutes to locate channels and identify ablation targets. It was possible to eliminate latest SPs in all patients without direct ablation (mean ablation time 16.3 ± 11.1 minutes). No VT recurrence was recorded (mean follow-up 10.1 ± 7.4 months). Conclusion Conduction channels can be located using ripple mapping to analyze SPs. Ablation at channel entrances can eliminate the latest SPs and is associated with good medium-term results.

[EN] Background and objective: Atrial fibrillation (AF) is the most common cardiac arrhythmia in the world. It is associated with significantly increased morbidity and mortality. Diagnosis of the disease can be based on the analysis of the electrical atrial activity, on quantification of the heart rate irregularity or on a mixture of the both approaches. Since the amplitude of the atrial waves is small, their analysis can lead to false results. On the other hand, the heart rate based analysis usually leads to many unnecessary warnings. Therefore, our goal is to develop a new method for effective AF detection based on the analysis of the electrical atrial waves. Methods: The proposed method employs the fact that there is a lack of repeatable P waves preceding QRS complexes during AF. We apply the operation of spatio-temporal filtering (STF) to magnify and detect the prominent spatio-temporal patterns (STP) within the P waves in multi-channel ECG recordings. Later we measure their distances (PQ) to the succeeding QRS complexes, and we estimate dispersion of the obtained PQ series. For signals with normal sinus rhythm, this dispersion is usually very low, and contrary, for AF it is much raised. This allows for effective discrimination of this cardiologic disorder. Results: Tested on an ECG database consisting of AF cases, normal rhythm cases and cases with normal rhythm restored by the use of cardioversion, the method proposed allowed for AF detection with the accuracy of 98 . 75% on the basis of both 8-channel and 2-channel signals of 12 s length. When the signals length was decreased to 6 s, the accuracy varied in the range of 95% - 97 . 5% depending on the number of channels and the dispersion measure applied. Conclusions: Our approach allows for high accuracy of atrial fibrillation detection using the analysis of electrical atrial activity. The method can be applied to an early detection of the desease and can advantageously be used to decrease the number of false warnings in systems based on the analysis of the heart rate., The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article. This research is partially supported by statutory funds of the Depart-ment of Cybernetics, Nanotechnology and Data Processing, Sile-sian University of Technology, BK2021. Francisco Castells receives research funds from the National Research Program RETOS under grant PID2019-109547RB-I0 0 from the Ministry of Science, Spanish Government. Jader Giraldo received funds from Universidad Tecnologica de Bolivar, CartagenaColombia, (grantcode: C2018P022) . The work was performed using the infrastructure supported by POIG.02.03.0124099/13 grant: GeCONiI-Upper Silesian Center for Computational Science and Engineering.

Introduction Studies on the normal electrocardiogram limits in African populations are limited, especially in sub-Saharan Africa. There is no literature describing normal ECG limits in Angolans. Objectives The aim of this study is to establish the normal ECG limits for adult Angolans, without established heart disease, stratified by gender and age. Methods A cross-sectional study was performed, involving 2179 participants from a population in northern Angola, without established heart disease, aged between 15 and 74 years. A 12‑lead ECG and a rhythm strip were recorded for all participants and analysed and processed by the University of Glasgow software and encoded by the Minnesota Code. The normal range of the electrocardiographic parameters were established as the 2nd and 98th percentiles of the measurement distribution per age group and gender. Mann-Whitney and Kruskal-Wallis tests were used for two independent groups and Bonferroni adjustments were used for multiple testing. GAMLSS models were used to obtain the continuous age-dependent percentile curves. Results The normal range of the ECG differed between men and women: heart rate 49 to 100 bpm vs. 55 to 108 bpm, P wave duration 81 to 130 ms vs. 84 to 130 ms, PR interval 119 to 210 ms vs. 120 to 202 ms, QRS duration 74 to 110 ms vs. 70 to 104 ms, QT interval 324 to 441 ms vs. 314 and 438 ms, P-wave axis − 29 to 850 vs. -18 to 810, QRS-wave axis − 13 to 850 vs. -180 and 820, T-wave axis 0 to 720 vs. -8 to 730, Sokolow-Lyon index 2.13 to 6.21 mV vs. 1.60 to 4.87 mV, Cornell index 0.17 to 6.24 mV vs. 0.14 mV to 4.35 mV. Conclusions The values described for the electrocardiographic measurements above can act as a reference framework for Angolan adults without established heart disease. Our study suggests that the normal range of most ECG parameters vary according to age and sex and the ECG diagnostic criteria must therefore be specific for these demographic measures.

Proper measurement of the QT interval on the 12-lead body-surface ECG is challenging in daily practice. Even more difficult is its correct estimation in the presence of repolarization abnormalities, arrhythmias or bundle-branch blocks (BBB). The QT interval results from two parts of the ECG: (1) the QRS complex, describing the excitation of the ventricles and (2) the JT interval, describing the repolarisation of the ventricles. Prolongation of the QRS width - like in the presence of BBB - entails prolongation of the QT interval, making the estimation of the true repolarisation time challenging. The US recommendations for the standardization and interpretation of the ECG suggest focusing on the JT interval in presence of BBB. However, in clinical practice physicians have become more familiar with the interpretation of QT-interval measurements than with the interpretation of the JT Interval. In the last decade, a simple formula for the estimation of the "modified QT interval" in the presence of left or right BBB has been developed and evaluated. In this formula, the modified QT interval is calculated by subtracting 50% of the length of the BBB-QRS from the measured QT interval (QT(m) = QT(BBB) - 50% QRS(BBB)). Subsequently, rate-correction formula should be applied as usual. In this review, we discuss the determination of the QT-interval in the presence of BBB and summarize the origin and application of the modified QT-interval formula. (C) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction: Antiarrhythmic drugs therapies are currently going through a turning point. The high risk that exists during the treatments has led to an ongoing search for new non-invasive toxicity risk biomarkers. Methods: We propose the use of spatial biomarkers obtained through the quaternion algebra, evaluating the dynamics of the cardiac electrical vector in a non-invasive way in order to detect abnormal changes in ventricular heterogeneity. In groups of patients with and without history of Torsade de Pointes undergoing a Sotalol challenge, we compute the radius and the linear and angular velocities of QRS complex and T-wave loops. From these signals we extract significant features in order to compute a risk patient classifier. Results: Using machine learning techniques and statistical analysis, the combinations of few indices reach a pair of sensitivity/specificity of 100%/100% when separating patients with arrhythmogenic substrate. Several biomarkers not only measure drug-induced changes significantly but also observe differences in at-risk patients outperforming current standards. Discussion: Alternative biomarkers were able to describe pre-existing risk of patients. Given the high levels of significance and performance, these results could contribute to a better understanding of the torsadogenic substrate and to the safe development of drug therapies. Fil: Cruces, Pablo Daniel. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Ingeniería Biomédica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina Fil: Torkar, Drago. Institut Jožef Stefan; Eslovenia Fil: Arini, Pedro David. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Ingeniería Biomédica; Argentina

Background: The common GLA gene mutation p.F113L causes late-onset phenotype of Fabry disease (FD) with predominant cardiac manifestations. A founder effect of FD due to this mutation was found in the Portuguese region of Guimarães. Our study aims to deepen the knowledge on the natural history of this late-onset variant. Methods: 203 consecutive adult Fabry patients with p.F113L mutation (79 males; mean age 46 ± 18 years), from this region, were submitted at baseline to a predefined diagnostic protocol. The occurrence of FD manifestations was analyzed in each decade of age in both genders. Results: In males, left ventricular hypertrophy (40.2%) and late gadolinium enhancement (21.4%) arose over 30 years; heart failure (HF) (21.9%), ventricular tachycardia (8.9%) and conduction disorders over 40 years; and bifascicular (13.1%) and complete atrioventricular blocks (5.9%) beyond 50 years of age. Cardiac manifestations occurred more commonly and 1–2 decades earlier in males; their frequency increased with age. Septum and posterior wall thickness, LV mass, QRS interval duration and pro-BNP levels increased with age in both genders. Mean survival free from HF (64 ± 1 vs. 76 ± 2 years) and pacemaker (71 ± 2 vs. 86 ± 1 years) was higher in females (p

Three different T-wave morphological indices that were previously found to be predictive of the risk of cardiovascular complications are considered; namely the spatial angle between the QRS complex and T-wave vectorcardiographic loops, the T-wave morphology dispersions (TMDs) that expresses the spread of vectorcardiographic projections into different leads of a standard 12-lead electrocardiogram (ECG), and the T-wave residua that measure nondipolar components of the T-wave signals in a standard ECG. The sex difference of these indices has been investigated in a population of 176 healthy female and 176 healthy male subjects in whom long-term daytime 12-lead Holter recordings were made. The heart rate dependency of the T-wave morphological indices has also been studied. Spatial QRS-T angles were found approximately 10–15 degrees smaller in females compared to males. In both sexes, QRS-T angles increased with increasing heart rate, but the sex difference was almost heart rate independent. TMD showed little heart rate dependency. On average, females showed TMD values approximately 3–4 degrees larger than males. Relative T-wave residuals were found substantially larger in females compared to males. In females compared to males, on average the residuals also increased approximately twice as fast with increasing heart rate.

The sex differences in ventricular structure and electrophysiological characteristics under normal/physiological conditions are well described. These differences are more pronounced in cardiac pathology associated with structural changes of myocardium that can consequently create a substrate for initiating and maintaining ventricular arrhythmias. This chapter reviews structural changes of myocardium in the most common cardiac pathologies leading to ventricular arrhythmias with the focus on the sex difference. The prevalence of ventricular arrhythmias is lower in women; on the other hand, women have a higher risk of drug-induced torsade de pointes. Women have a lower prevalence of obstructive coronary artery disease and more often preserved left ventricular function compared to men; on the other hand, they have a higher prevalence of symptoms, a higher rate of functional microvascular disability, and more adverse outcomes. Women have lower prevalence of left ventricular hypertrophy compared to men with comparable blood pressure. They have more serious obesity, more visceral fat, and more associated pathologies (diabetes mellitus, hypertension, sleep apnea, metabolic syndrome), i.e., conditions affecting the myocardial structure; however, they have less arrhythmia in premenopausal period. Some of the differences decrease after menopause, suggesting a possible effect of sexual hormones. Current imaging methods provide a deeper insight into the structural changes of the heart in cardiac pathology, and thus provide a solid basis for understanding links between structural changes, ventricular activation and repolarization processes, QRS patterns, and ventricular arrhythmias.

Sex-specific differences in electrocardiographic (ECG) abnormalities are well established and should be recognized by the practicing physician. There are baseline heart rate (HR) and HR variability differences among healthy men and women. Furthermore, ventricular depolarization and repolarization manifest on the 12 lead ECG as QRS and ST intervals have been the best described changes. These sex-specific ECG patterns form the basis of disease predilection for both sexes. QT intervals are longer in women and ST height is greater in men. Thus, long QT syndrome is more common in females, whereas ventricular early repolarization pattern, J-point ST elevation, as well as Brugada syndrome are more common in males. We will describe in detail these ECG differences, as well as the likely physiologic mechanisms for such differences.

The standard 12 lead electrocardiogram (ECG) contains significant sex differences. One possibly unrecognized factor separating male from female ECGs is the amount of ST junctional elevation in V2 and V3, which is relatively much higher in males than in females. Another important differentiator, particularly in younger individuals, is higher QRS voltage in males compared with females. This means that all ECG criteria for left ventricular hypertrophy, for example, should be sex dependent. QRS duration is known to be longer in males by the order of 8–10 ms, though the corrected QT interval is shorter in males compared to females by approximately 10–15 ms depending on the correction formula. All of this means that many criteria for interpreting the ECG must be sex dependent. Failure to acknowledge this basic fact may result in less sensitive or less specific criteria as the case may be in different situations.

Physiological data in healthy subjects show that QRS duration is shorter in females compared to males. QRS duration is also shorter in subjects of African origin compared to Caucasians. The same sex difference is present in both race strata, thus QRS duration progressively increases from African females to Caucasian females, to African men, and to Caucasian men. This chapter shows data of 523 healthy subjects. These data also show that the QRS durations are heart rate dependent in a nonuniform fashion. While heart rate increases lead to the increases in QRS duration in approximately 40% of the healthy population, in the remaining 60% of the population, heart rate increases led to QRS complex shortening. This might have importance for the implementation of the guidelines for cardiac resynchronization therapy initiation.

While several large, randomized clinical trials have shown a clinical benefit with the use of cardiac resynchronization therapy (CRT) in patients with left ventricular dysfunction, mild to advanced heart failure, and a wide QRS duration, sex-specific differences in CRT outcomes need special attention. However, reporting sex-specific outcomes in prior CRT studies has been limited by the small number of women enrolled in these trials. In this chapter, we will review currently available data on clinical experience with the use of CRT in women, focusing on outcome data from clinical trials, registries, and metaanalyses. We will additionally discuss pathophysiological differences between men and women and how these could explain sex differences in CRT outcomes.

This chapter will discuss differences in response to cardiac resynchronization therapy (CRT) between men and women. This chapter will specifically address data derived from registries, metaanalyses, and observational studies that compared clinical and echocardiographic data. Data will be given as to differences in response to CRT between men and women as measured by echocardiographic parameters of reverse cardiac remodeling. In addition, we will address differences in clinical response and mortality between men and women as well as the difference between men and women in regard to QRS duration above which a favorable response is seen.

Cardiac resynchronization therapy (CRT) is an established therapeutic option for the subset of patients with heart failure (HF), reduced ejection fraction (EF), and dyssynchrony evidenced by electrocardiography. Benefit from CRT has been proven in many clinical trials, yet a sizeable proportion of these patients with wide QRS do not respond to this intervention, despite the updated practice guidelines. Several echocardiographic indices, targeting mechanical rather than electrical dyssynchrony, have been suggested to address this issue, but research so far has not succeeded in providing a single and simple measurement with adequate sensitivity and specificity for identification of responders. While there is still ongoing research in this field, echocardiography proves helpful in other aspects of CRT implementation, such as site selection for left ventricular (LV) lead pacing and optimization of pacing parameters during follow-up visits. Keywords: Heart failure, cardiac resynchronization therapy, biventricular pacing, echocardiography

Introduction: Premature ventricular complex (PVCs) detected from long-term ECG recordings have been associated with an increased risk of ischemic stroke. However, there was limited data about the association between high PVCs burdens (>10%) and stroke-like symptoms without a prior diagnosis of stroke or transient ischemic attack in the long-term follow up. Methods: The Kosin University 24-hours holter monitoring, echocardiography, electrocardiogram (ECG) database were reviewed from 2013 to 2015 to identify patients with frequent PVCs (>10%). We compared the long-term clinical outcomes between the patients with frequent PVCs (>10%) and control group without PVC. Results: Among 572 patients who underwent 24-hours holter monitoring, finally, 373 consecutive patients (mean age; 59.5 ± 15.8 years, 45.2% male) were enrolled. Among them, 203(54.4%) patients had high PVCs burdens (>10%). There was no difference of the baseline characteristics. In the long term follow-up, PVCs burden was not associated with PVCs -related symptoms (P = 0.210). In univariate analysis, female, non-sustained ventricular tachycardia (VT), sinus QRS duration, PVC coupling interval (CI), post- PVC CI, and late precordial R-wave transition of PVCs were associated with PVCs-related symptoms. In multivariate analysis, non-sustained VT (P = 0.022) and late precordial R-wave transition of PVCs (P = 0.044) were independent risk factors for PVCs-related stroke-like symptoms with frequent idiopathic PVCs > 10%. Conclusion: High PVCs burdens (>10%) were associated with and stroke-like symptoms without a prior diagnosis of stroke or transient ischemic attack in the long-term follow up, suggesting more intensive medical therapy with close clinical follow-up will be required. Keywords: Premature ventricular complex, Stroke-like symptoms, Transient ischemic attack, Clinical outcomes

Background With increasing use of cardiac resynchronization therapy (CRT), treating physicians should be familiar with different electrocardiographic (ECG) patterns of left ventricular (LV) lead and biventricular (BiV) pacing. However, there are a few publications on ECG patterns during BiV pacing. Purpose This study was sought to determine different ECG patterns in patients with BiV pacing. Methods Twelve-lead ECGs during BiV pacing (right ventricular leads at apex and LV leads in one of the lateral coronary veins) were analyzed in 181 consecutive patients (121 male; mean age, 62.0 ± 13.5 years) with advanced heart failure and baseline left bundle branch block pattern after at least 6-month of uncomplicated CRT. Results During BiV pacing, 65% of the patients showed a dominant R wave in V1. There was a right axis deviation in 57% in frontal plane. However, a left superior axis emerged in 34% and normal frontal plane axis in 9%. Sequential BiV pacing (73% vs. 58%, P = 0.04) and pacing from posterolateral coronary vein (80% vs. 60%, p = 0.045) were more likely to present with a dominant R wave in V1. In sequential pacing, AV interval was significantly longer in patients with negative complex in V1 than in those with positive complex (124 ± 21 vs. 116 ± 8.0, p = 0.005). A Q/q wave was detected in 85% of patients in lead I and 78% in lead aVL. Conclusions BiV pacing from lateral coronary venous branches and right ventricular apex characteristically presented with dominant R wave in V1, Q/q wave in leads I and aVL, and right or left superior axis. However, a negative complex in V1, QRS axis in other quadrants, and lack of Q/q wave in leads I and aVL did not necessarily indicate a problem.

Background and Objectives: We analyzed Lead II in patients undergoing an Oral Flecainide Challenge test (FCT), to identify any pointers that could predict a positive FCT and thereby help in recognition of latent BS. Methods: The following parameters in lead II were retrospectively analyzed from the pre-test ECG in 62 patients undergoing FCT for suspected BS: The presence or absence of S waves, S wave amplitude, duration and upslope duration; J point parameters- Early repolarization, QRS notch, and QRS Slur; ST segment parameters-lack of isoelectric ST segment, ST duration and QT interval. Results: 48 had positive FCT (Group-1) while 14 were negative for FCT(Group-2). Lack of an isoelectric ST segment (50% vs 14.29%, p = 0.018) and slurring of QRS (33.33% vs 0%, p = 0.014) was more common in Group-1 than Group-2. Group-1 had shorter ST segment duration (median 81.5 (IQR 64–103.5) vs 110 (IQR 90–132), p = 0.002) and shorter ST: QT ratio (median 0.28 (IQR 0.22–0.35) vs 0.23 (0.18–0.27), p = 0.007). QRS notch/depressed J point (87.5%), QRS slur (100%), and lack of isoelectric ST segment (92.31%) had high sensitivity for predicting an inducible Type 1 Brugada pattern. Combining two parameters- ST: QT ratio

Cardiac resynchronization therapy (CRT) using a biventricular pacing system has been an effective therapeutic strategy in patients with symptomatic heart failure with a reduced left ventricular ejection fraction (LVEF) of 35% or less and a QRS duration of 130 ms or more. The etiology of heart failure can be classified as either ischemic or non-ischemic cardiomyopathy. Ischemic etiology of patients receiving CRT is prevalent predominantly in North America, moderately in Europe, and less so in Japan. CRT reduces mortality similarly in both ischemic and non-ischemic cardiomyopathy, whereas reverse structural left ventricular remodeling occurs more favorably in non-ischemic cardiomyopathy. Because the substrate for ventricular arrhythmias appears to be more severe in cases of ischemic as compared with non-ischemic cardiomyopathy, the use of an implantable cardioverter-defibrillator (ICD) backup method could prolong the long-term survival, especially of patients with ischemic cardiomyopathy, even in the presence of CRT. The aim of this review article is to summarize the effects of CRT on outcomes and the role of ICD backup in ischemic and non-ischemic cardiomyopathy.

Six ECG patterns are found more frequently in healthy black adults than in whites. These patterns are presumably benign, but also may resemble those of malignant disease. 1) Healthy black adults show higher QRS voltage, and more often meet ECG criteria for left ventricular hypertrophy (LVH). Associated repolarization abnormalities can produce ST segment elevation (STE) that resembles ST elevation MI (STEMI). 2) The pattern of benign anterior STE, seen often in males, is more common in black subjects. Similar to LVH, this pattern may falsely suggest STEMI. 3) Both early repolarization (ER) and benign inferolateral STE are more common in black patients. Although they may convey a higher risk of fatal arrhythmias or cardiac death in white populations, it does not appear that black subjects with these patterns show a similar risk. 4) The persistent juvenile T wave inversion pattern shows asymmetric T wave inversion (TWI) in V1-V4, without ST segment deviations. It is most common in black females, and is considered benign. However, this pattern can also resemble the anterior TWI of arrhythmogenic right ventricular cardiomyopathy (ARVC). 5) A pattern of anterior TWI with associated J point elevation is a common finding in the black population, especially athletes. It could suggest hypertrophic cardiomyopathy, but can be presumed to be a benign finding in black athletes, when TWI is limited to V1-V4 and preceded by J point elevation. 6) TWI in the lateral precordial leads, usually associated with end-QRS slurring or notches is seen much more often in apparently healthy black subjects than white subjects. Unlike the anterior TWI pattern, however, it cannot be presumed benign. In conclusion, awareness of these ECG patterns may help to avoid unnecessary diagnostic or therapeutic interventions, but also encourage appropriate investigations.

BACKGROUND Subclinical changes on the electrocardiogram are risk factors for cardiovascular mortality. Recognition and knowledge of electrolyte associations in cardiac electrophysiology are based on only in vitro models and observations in patients with severe medical conditions.OBJECTIVES This study sought to investigate associations between serum electrolyte concentrations and changes in cardiac electrophysiology in the general population.METHODS Summary results collected from 153,014 individuals (54.4% women; mean age 55.1 +/- 12.1 years) from 33 studies (of 5 ancestries) were meta-analyzed. Linear regression analyses examining associations between electrolyte concentrations (mmol/l of calcium, potassium, sodium, and magnesium), and electrocardiographic intervals (RR, QT, QRS, JT, and PR intervals) were performed. The study adjusted for potential confounders and also stratified by ancestry, sex, and use of antihypertensive drugs.RESULTS Lower calcium was associated with longer QT intervals (-11.5 ms; 99.75% confidence interval [CI]: -13.7 to -9.3) and JT duration, with sex-specific effects. In contrast, higher magnesium was associated with longer QT intervals (7.2 ms; 99.75% CI: 1.3 to 13.1) and JT. Lower potassium was associated with longer QT intervals (-2.8 ms; 99.75% CI: -3.5 to -2.0), JT, QRS, and PR durations, but all potassium associations were driven by use of antihypertensive drugs. No physiologically relevant associations were observed for sodium or RR intervals.CONCLUSIONS The study identified physiologically relevant associations between electrolytes and electrocardiographic intervals in a large-scale analysis combining cohorts from different settings. The results provide insights for further cardiac electrophysiology research and could potentially influence clinical practice, especially the association between calcium and QT duration, by which calcium levels at the bottom 2% of the population distribution led to clinically relevant QT prolongation by >5 ms. (C) 2019 by the American College of Cardiology Foundation.

Ventricular depolarization dispersion refers mainly to heterogeneity in interlead QRS durations. Here, we propose the spatial variance (SVd) to describe depolarization dispersion about a mean QRS morphology. We hypothesize that waveform changes can be more accurate than interval changes at measuring QRS heterogeneity, and less sensitive to delineation errors. To prove this, SVd was computed on 36 dyssyn-chrony patients either in sinus rhythm (SVdB) or under nHB (SVdHB), and on 32 control subjects with native conduction (SVdN). In the normal ECG, there are interlead sets that produce maximal (SVdNmax) and minimal (SVdNmin) spatial variance. In Baseline patients, SVdB significantly increased from controls in the minimal variance situation (p < 0.005), deviating one or more leads from the normal morphology (similar in all the ensemble) and consequently increasing the interlead distance. The opposite held for the maximal variance situation, where it was expected a wide span of morphologies in health, there was a tendency to stacking in morphologies at baseline (p

Background: In previous guidelines, acute coronary syndromes (ACS) with new or presumably new left bundle branch block (LBBB) were an indication for reperfusion treatment, preferably with primary angioplasty. Recent guidelines also included the presence of right bundle branch block (RBBB) in this recommendation. It was our objective to evaluate in a population of patients with ACS the differential impact of RBBB and LBBB in prognosis. Methods: Consecutive patients included prospectively in a single-centre registry of ACS were included in the study. Patients were analyzed according to baseline ECG characteristics (normal QRS, LBBB or RBBB). Primary outcome was all-cause mortality at one-year follow-up. We used Cox-proportional hazards models to assess the predictive value for the primary outcome. Results: A total of 3990 patients were included in, with a mean age of 64 (13) years, 72% males, 3.4% with LBBB and 4.3% with RBBB. Patients with BBB were older, with more previous history of myocardial infarction and coronary revascularization and higher prevalence of cardiovascular risk factors (except smoking). Medical treatment was similar but they were less often submitted to angioplasty. In univariate analysis, BBB patients had worst outcome (Log-rank, p

Expert knowledge and proper techniques are necessary for diagnosing and treating fetal cardiac disease. Fetal arrhythmia represents an important part of fetal cardiac disease as it conveys abnormalities in the electrophysiological state of the heart. Arrhythmias can be caused by rate or rhythm alterations or by abnormalities in QRS or QT intervals. Fetal echocardiography has been the gold standard for pediatric cardiologists since it assesses multiple aspects of fetal cardiovascular pathology. In parallel, artificial intelligence techniques are being designed to provide additional support to experts in the medical field in terms of detection and accuracy. The present manuscript describes the development of a prototype meant to be an auxiliary for the detection of fetal arrhythmias by analyzing the fetal heart rate (FHR) and its variability. It consists of a portable electrocardiograph and a mobile application that, together, extract the fetal electrocardiogram for its analysis to finally render a first diagnosis. Conducted tests with synthetic signals based on clinical fetal arrhythmia provided a detection rate of 88.88%. Results from tests with pregnant women may indicate that the proposed prototype can be used to render a first diagnosis without entirely depending on expert assistance. This prototype might be helpful to perform routine check-ups in the second or third trimester in pathological pregnancies associated with high risk of onset/progression of fetal arrhythmias. In addition, medical practitioners could use it to corroborate a given diagnosis or in scenarios where there is an insufficiency of human experts to attend a high population of patients. Keywords: Expert system, Fetal arrhythmias, Fetal electrocardiogram (fECG), Fetal heart rate (FHR), Mobile application

Electromechanical association in a normal heart results in synchronous regional left ventricular (LV) contraction. Differences in the timing of regional contraction may be associated with the failing human heart. Interest in echocardiographic assessment of synchrony began with applications for pacing therapy, in particular cardiac resynchronization therapy (CRT), also known as biventricular pacing. Current clinical practice is to select heart failure patients with reduced ejection fraction by electrocardiographic criteria of QRS complex widening or left bundle branch block morphology. Although CRT often results in improvement in symptoms, LV reverse remodeling, and prolonging life, one-third to one-half of patients do not appear to benefit and are referred to as nonresponders. It was observed that patients with measurable dyssynchrony at baseline before CRT had a much more favorable response to CRT than patients who lacked baseline dyssynchrony. Interest in measuring regional timing of LV contraction with echocardiographic techniques remains high to gain a better understanding of CRT response and prognosis. Tissue Doppler imaging and, in particular, speckle tracking strain measures have been widely utilized. However, the field advanced to reveal that mechanical dyssynchrony was more complicated than originally thought. A more recent understanding of regional myocardial discoordination has emerged as differences in regional contraction from substrates of electrical delay, contractile heterogeneity, and fibrosis or scar. Defining the strain patterns of contraction and stretch appear promising to help identify the electromechanical substrate that is associated with the most favorable outcome after CRT. This chapter will review the progress in understanding of mechanical dyssynchrony, define the current state of the art, and project potential future clinical applications of assessing cardiac synchrony.

QRS complex delineation is the second step or task just after beat detection, consisting in identifying QRS onset and offset. Wave delineation is useful for the computation of waveform duration, area, and morphology parameters, as well as for the computation of PR, QT, and ST intervals. Because of the great QRS morphological variations in ECG signals, it is difficult to design automatic and widely applicable algorithms. Additionally, the lack of a universally accepted rule defining the ECG waves onset and offset has been an extra complication to systematize ECG waves delineation. Despite the inherent difficulties, a wide diversity of algorithms has been proposed in the literature, most of them starting from the R-wave peak and defining forward and backward seek windows. Commonly, the signal amplitude is remarkably low near the wave boundaries and the noise level can be even higher than the signal itself. Therefore preprocessing techniques are required in order to enhance the proper waves and fiducial points. Considering that different QRS morphologies are related to heterogeneous spectral content, accuracy in determining onsets and ends may require variable or adaptive filtering parameters, or even multiple versions of filtered signals. In this chapter, we propose to compare the performance of different already published QRS delineation algorithms under different scenarios, including noise interference, physiological noise, different arrhythmia classes, and QRS morphology alterations, different leads from a specific record, and also evaluate computational approaches for solving a broad range of problems/challenges.