Wide QRS Complex Research Articles

Comparison of the effectiveness of various valsalva maneuvers in the management of stable narrow and wide QRS complex tachycardia in the emergency department

Purpose: Narrow and wide QRS complex tachycardias are among the causes of arrhythmia in patients frequently admitted to the emergency department (ED). The first recommended step in the management of patients with a stable narrow and wide QRS tachycardia is a vagal maneuver. Althougah there are many maneuvers that can provide vagal stimulation, the most effective vagal maneuver is still unknown. This study aims at determining the most effective vagal maneuver by comparing the four most commonly used maneuvers.
 Materials and methods: One hundred and thirty-two patients were included in this study; they were randomly and equally distributed into four groups. Carotid sinus massage (CSM) was applied to the first group, the REVERT method was applied to the second group (a 10-cc injector was used), a modified REVERT method was applied to the third group (a 60-cc injector was used), and the abeslang (wooden tongue depressor) method was applied to the fourth group. During these four applications, the patients’ vital signs were monitored, and preparations were made for any emergency.
 Results: Of the 132 patients included in the study, 61 (46.2%) were males, and 71 (53.8%) were females. The average age of the patients was 56.3 years. One hundred and twenty-six had narrow QRS tachycardias, and 6 had stable wide QRS tachycardias. The patients were randomly distributed into 4 groups. In the 1st group, 1 patient (3%) returned to a normal rhythm with the CSM method. In the 2nd group, 3 patients (9.1%) returned to a normal rhythm with the REVERT method. Nine patients (27.3%) in the 3rd group returned to a normal rhythm with the modified REVERT method. 6 patients (18.2%) in the 4th group returned to normal rhythm with the abeslang method. None of the stable wide QRS tachycardias responded to vagal stimulation methods.
 Conclusion: The modified REVERT and abeslang methods are preferred primarily in patients entering the ED with the complaint of a stable narrow or wide QRS tachycardia in the case that a vagal maneuver is to be applied. On the other hand, a vagal maneuver is not effective in the management of a stable wide QRS tachycardia.

Sex-specific Evaluation of Ventricular Ejection Fraction and End-Systolic Volume Applied to Cardiac Resynchronization Therapy.

Cardiac resynchronization therapy (CRT) can decrease the risk of heart failure (HF) events in relatively asymptomatic patients with a reduced ejection fraction (EF) and wide QRS complex. However, individual response to this type of therapy varies widely. Often based on either EF increase or end-systolic volume (ESV) decrease as criterion, a subgroup of super-responders has been described. Therefore, it is important to determine factors that can predict a favorable response and identify those patients who may benefit from CRT. With this goal in mind we explored the possible role of ESV.To improve insight in ventricular pump function we previously introduced the volume regulation graph (VRG), relating ESV to end-diastolic volume (EDV). An individual patient is uniquely defined by the prevailing working point in the volume domain. The traditional metric EF can be graphically derived for each working point. The nonlinear association between EF and ESV is given by EF = 1 + γ {ESV / (δ - ESV)}, with empirical constants γ and δ. The impact of CRT super-responders on EF can be evaluated, taking into account sex-specific ESV values. Based on available regression equations we modeled the impact on EF (as percent points) resulting from CRT-induced fractional ESV changes expressed as % of baseline ESV. Our analysis confirms clinical findings, indicating that CRT super-responders are likely to be women, and clarify why a specific reduction of ESV cannot be directly translated into EF improvement. We propose that the EF as CRT criterion should be abandoned and replaced by sex-specific ESV evaluations.Clinical Relevance- Response to CRT should be evaluated in a sex-specific manner. The smaller heart size in women has implications for the interpretation of percentwise reductions of ESV and their translation into an associated increase of EF.

Cardiac contractility modulation therapy in patients with implanted cardiac resynchronization therapy: results of the 2 year follow-up

Aim. Cardiac contractility modulation (CCM) is a device therapy for patients with heart failure with reduced ejection fraction (HFrEF), most of the data on its programming are concerned patients with narrow QRS and of limited follow up. Our aim was to propose programming approach for Optimizer device in setting of wide QRS complex and fragmented ventricular local activation.Methods. We enrolled 11 patients with HFrEF (median age, 8 males, median NYHA class 3) and LBBB-related wide QRS complex, who underwent Optimizer™ device implantation. Three patients got Optimizer™ IV system and eight patients were implanted Optimizer™ Smart. Ten patients were previously implanted with CRT-D due to HFrEF and LBBB; one patient received CRT-D after Optimizer™ implantation.Results. During the implantation procedure ventricular local sense (LS) channel signal fragmentation was detected in all patients. In five patients signal detection was optimized by lead relocation. In six patients LS signal sensitivity limitations were resolved by programming. At two-year follow-up survival 4 patients died of noncardiac causes (1 intracranial hemorrhage, 1 gastrointestinal bleeding and 2 - terminal kidney failure). At 12-month follow-up we observed a non-significant improvement in 6-minute walking distance (300 vs 305, p=0.093), NYHA class (2.75 vs 2, p=0.085), MLHF score (53 vs 42, p=0.109) and left ventricular ejection fraction (LVEF) (30 vs 33.5, p=0.212).Conclusion. CCM system implantation is feasible and safe in patients with HFrEF and LBBB-related wide QRS complex. Device programming maneuvers can resolve the challenges of ventricular local signal detection in these patients.

Wide QRS Complex Tachycardia after Catheter Ablation of Bundle Branch Reentrant Tachycardia: What is the Mechanism?

Wide QRS Complex Tachycardia after Catheter Ablation of Bundle Branch Reentrant Tachycardia: What is the Mechanism?

Diagnostic accuracy of different ECG-based algorithms in wide QRS complex tachycardia: a systematic review and meta-analysis

ObjectiveSeveral ECG-based algorithms have been proposed to enhance the effectiveness of distinguishing Wide QRS complex tachycardia (WCT), but a comprehensive comparison of their accuracy is still lacking. This meta-analysis aimed...

Comparison of two artificial intelligence-augmented ECG approaches: Machine learning and deep learning.

Artificial intelligence-augmented ECG (AI-ECG) refers to the application of novel AI solutions for complex ECG interpretation tasks. A broad variety of AI-ECG approaches exist, each having differing advantages and limitations relating to their creation and application. To provide illustrative comparison of two general AI-ECG modeling approaches: machine learning (ML) and deep learning (DL). Two AI-ECG algorithms were developed to carry out two separate tasks using ML and DL, respectively. ML modeling techniques were used to create algorithms designed for automatic wide QRS complex tachycardia differentiation into ventricular tachycardia and supraventricular tachycardia. A DL algorithm was formulated for the task of comprehensive 12‑lead ECG interpretation. First, we describe the ML models for WCT differentiation, which rely upon expert domain knowledge to identify and formulate ECG features (e.g., percent monophasic time-voltage area [PMonoTVA]) that enable strong diagnostic performance. Second, we describe the DL method for comprehensive 12‑lead ECG interpretation, which relies upon the independent recognition and analysis of a virtually incalculable number of ECG features from a vast collection of standard 12‑lead ECGs. We have showcased two different AI-ECG methods, namely ML and DL respectively. In doing so, we highlighted the strengths and weaknesses of each approach. It is essential for investigators to understand these differences when attempting to create and apply novel AI-ECG solutions.

Baseline mechanical dyssynchrony is associated with better diastolic function in patients undergoing cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 research and innovative program under the Marie Sklodowska -Curie grant agreement No. 860745. Background Outcome after cardiac resynchronization therapy has been shown to be worse in patients with diastolic dysfunction. Aim We aim at investigating the association between baseline mechanical dyssynchrony (Dyss) and diastolic function, both assessed using conventional 2D echocardiography in heart failure patients undergoing cardiac resynchronization therapy (CRT). Methods Datasets of 219 patients were retrospectively analyzed, including full echocardiographic diastolic function assessment before CRT implantation. Using the guideline approach (Nagueh et al 2016) for estimating left atrial pressure (LAP), patients were classified as elevated LAP (eLAP = 49%), normal LAP (nLAP = 40%), and undetermined LAP (uLAP = 11%). Patients with nLAP and uLAP together were referred to as non-elevated LAP (non-eLAP = 51%). Dyss was defined as the presence of apical rocking (ApRock) and /or septal flash (SF). All baseline characteristics, comorbidities, ECG data and left atrial (LA) strain components (reservoir, conduit, and pump strains) were collected and analyzed. The amount of CRT-induced LV reverse remodeling was assessed at 12±6 months after CRT and was defined as percentage decrease of LV end-systolic volume (LVESV) compared to baseline. Patients were followed up for a mean of 4.8 years (interquartile range (IQR): 2.7–6.0) for all-cause mortality. Results Compared to patients without Dyss, patients with Dyss were significantly more of female sex (39% vs. 14%), had less diabetes mellitus (21 vs. 34%), had lower serum creatinine (1.2±0.5 vs. 1.4±0.6 mg/dl) and less prevalence of ischemic cardiomyopathy, 43% vs. 68%). They used significantly more ACEi (91% vs. 76%). ECG data showed that they had less prevalence of AF (8 vs. 22%) and had wider QRS complex (158±18 vs. 152±18 msec), P-values <0.05 for all comparisons. Baseline LV volumes and EF were not significantly different between patients with and without Dyss. Patients with Dyss show less prevalence of eLAP compared to patients without Dyss (30% vs. 60%, P <0.001, figure A). Additionally, they had better LA function on all LA strain indices (Figure B). In the multivariable analysis for predicting the association with eLAP, the presence of Dyss was independently associated with less eLAP after adjusting for most of the baseline variables (HR: 0.31, CI: 0.1–0.7, P <0.01). At follow up, patients who had both Dyss and non-eLAP before CRT showed the largest amount of LV reverse remodeling compared to other patients. Similarly, the patients with Dyss and non-eLAP showed the best survival compared to other groups (figure C). Conclusion The presence of mechanical dyssynchrony is associated with better diastolic function and lower estimated LAP before CRT. Additionally, the combination of Dyss and non-eLAP before CRT was associated with the most CRT-induced LV reverse remodeling and best long-term survival.

The Application of a New, Modified Algorithm for the Differentiation of Regular Ventricular and Pre-excited Tachycardias.

The three-step Brugada group algorithm is the only published electrocardiographical (ECG) algorithm for differentiating ventricular tachycardia (VT) from pre-excited tachycardia (PXT) as a cause of regular wide QRS complex tachycardia (WCT). This study aimed to improve the diagnostic accuracy of the Brugada group algorithm. This study modified the Brugada group algorithm by adding a new aVR lead criterion (initial positive deflection in lead aVR and the QRS complex area above the baseline is greater than the area below the baseline). The Brugada group algorithm and the new, modified four-step algorithm in 300 WCT ECGs (241 VTs, 59 PXTs) was applied. If any of the criteria were fulfilled, VT was diagnosed; if none were fulfilled, a diagnosis of PXT was established. The test accuracy, VT diagnosis sensitivity, and negative predictive value (NPV) of the new, modified algorithm were significantly greater than that of the Brugada group algorithm: test accuracy 220 of 300 (73%) vs 182 of 300 (61%); sensitivity 73% vs 55% (p<0.001 for both); NPV 40% vs 31% (p=0.0205). The VT diagnosis specificity of the Brugada group algorithm was greater than that of the new, modified algorithm (83% vs 75%; p=0.019). There was no significant difference between the new, modified and Brugada group algorithms in the positive predictive values (92% vs 93%, respectively) for a VT diagnosis, and positive and negative likelihood ratio values (2.87 vs 3.26; 0.36 vs 0.54, respectively). The new, modified algorithm proved to be more sensitive for the differentiation of VT from PXT than the Brugada group algorithm.

Ventricular dyssynchrony assessed by ultra-high-frequency electrocardiography predicts the response to biventricular cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by the European Regional Development Fund - Project ENOCH No.CZ.02.1.01/0.0/0.0/16_019/0000868, by the project National Institute for Research of Metabolic and Cardiovascular Diseases (Programme EXCELES, ID Project No. LX22NPO5104) - Funded by the European Union – Next Generation EU, by the Ministry of Health of the Czech republic, grant number NU21-02-00584, and by the CAS project RVO:68081731. Background Ultra-High-Frequency ECG (UHF-ECG) visualizes ventricular dyssynchrony during spontaneous and paced rhythms. It is unknown whether the UHF-ECG can be used to predict the response to Biventricular cardiac resynchronization therapy (CRT) in patients with heart failure and wide QRS complex. Purpose To show a predictive value of UHF-ECG dyssynchrony parameters in patients with an indication of Biventricular CRT. Methods This prospective study included consecutive patients with heart failure NYHA II-III, LVEF ≤ 35%, and QRS duration &amp;gt; 120 ms of nonRBBB morphology. All patients received biventricular CRT. Clinical data, UHF-ECG ventricular dyssynchrony assessment were done before, and echocardiography also six months after the CRT. A positive response was defined by a change in LVESV ≥ 10%. Ventricular dyssynchrony parameter e-DYS was defined as a difference between the first and last UHF-ECG ventricular activation. Results The study population included 92 patients of mean age 66±9 years, 76% men, LVEF 24±9%, and 45% with ischemic cardiomyopathy. The average change of the LVEF after six months of CRT was 5% and was greater in non-ischemic than ischemic CMP (7% vs. 3%, p &amp;lt; 0.001). 29% of the patients were nonresponders to CRT by the LVESV change. The optimal value of e-DYS to predict response after CRT was 47 ms (sensitivity 78%, specificity 79%). In univariate analysis, the e-DYS &amp;gt; 47 ms, QRSd ≥ 150ms, female sex, presence of non-ischemic heart disease, and Strauss LBBB were significant predictors of response; however, after multivariate analysis, only e-DYS &amp;gt; 47 ms remained significant predictor of response after CRT (p = 0.008). Conclusion In nonRBBB patients with heart failure and CRT indication, UHF-ECG electrical ventricular dyssynchrony during the spontaneous rhythm is the predictor of echocardiographic response to CRT.

Diagnostic Value of Slow Conduction Index in Differential Diagnosis of Wide &lt;i&gt;QRS&lt;/i&gt; Complex Arrhythmias with Left Bundle Branch Block Morphology

BACKGROUND: Differential diagnosis of arrhythmias with wide QRS complexes remains an unresolved problem in clinical practice. After decades of careful research, many different criteria and algorithms have been proposed, but many of them are not quite accurate and effective in real clinical conditions. One of the approaches is to use ECG to estimate the speed of propagation of excitation through the ventricular myocardium. The estimation is based on the ratio of the amplitudes of the initial and final parts of the QRS complex, in particular, using the slow conduction index.&#x0D; AIM: To study the possibility of using the slow conduction index in the differential diagnosis of arrhythmias with wide QRS complexes and to carry out a detailed comparative analysis of the diagnostic value of this criterion in all 12 ECG leads with evaluation and comparison of the obtained values of diagnostic accuracy.&#x0D; MATERIALS AND METHODS: The study included 280 single wide QRS complexes with a form of left bundle branch block (LBBB) detected during one-day and multi-day ECG monitoring in randomly selected 28 patients. For a detailed analysis, a comparison of the original 12-lead ECG and individual scalable ECG graphs for selected leads was carried out, followed by measurement of the absolute values of the total amplitudes during the initial and final 40 ms wide QRS complexes. For a qualitative and quantitative assessment of diagnostic significance, ROC analysis was used to determine the informative value of a diagnostic test based on sensitivity (Sn), specificity (Sp) and diagnostic accuracy (Acc).&#x0D; RESULTS: According to the obtained values of Sn, Sp and Acc, all 12 leads were arranged in the following order as the diagnostic value of the slow conduction index decreased: aVL, V2, aVF, V5, III, V1, V4, II, aVR, V6, V3 and I. In the first six ECG leads, Acc was consistently above 90%, gradually decreasing in the next six leads from 89% to 67%, respectively (p 0.001 for all leads).&#x0D; CONCLUSIONS: The results of this study showed that the slow conduction index can be used in any ECG leads as a criterion for the differential diagnosis of arrhythmias with wide QRS complexes with a form of LBBB. The study also demonstrated the importance of a comprehensive approach to the analysis of the form of the QRS complex and the need for a consistent detailed analysis of the existing criteria for the differential diagnosis of arrhythmias with wide QRS complexes in different clinical groups of patients.

PO-02-012 A SYSTEMATIC REVIEW AND META-ANALYSIS OF CARDIAC RESYNCHRONIZATION THERAPY IN INOTROPE-DEPENDENT HEART FAILURE

Several studies have shown cardiac resynchronization therapy (CRT) to be beneficial in the management of heart failure (HF) with systolic dysfunction, widened QRS complex length, and New York Heart Association (NYHA) class III or IV. However, whether CRT is viable in HF patients who require inotropic support is still a matter of debate. To assess outcomes of CRT in end-stage inotrope-dependent HF. Following PRISMA guidelines, we searched Medline, EMBASE, Scopus, and Cochrane Library until December 31st 2021, with the following terms: “end-stage heart failure,” “catecholamine-dependent overt heart failure,” “inotrope-dependent heart failure,” “advanced heart failure,” “New York Heart Association class IV,” “NYHA class IV.” These terms were combined with “cardiac resynchronization therapy” OR “CRT” OR “biventricular device”. Studies were included if: 1) HF patients required on inotropic support at CRT implantation; 2) patients were at least 18 years old; and 3) provided a clear definition of “inotrope dependence” or “inability to wean.” A meta-analysis with random effects was performed in R (Version 3.5.1) with data presented as mean ± standard deviation. 9 studies comprised of 168 inotrope-dependent HF patients (mean age 64.4 ± 5.8 years, 79.6% male, 41.7% non-ischemic cardiomyopathy, mean QRS duration 173.9 ± 13.2 ms, 82.1% NYHA Class IV) were included for meta-analysis. Hospitalization rate for recurrence of HF 12-18 months post-CRT was 21% (95%CI: 15-28%, I2=0%, P=0.41, Fig 1C) and survival at 12 months post-CRT was 71% (95%CI: 58-83%, I2=68%, P<0.01, Fig 1D). A significant majority were weaned off inotropes at 93% (95%CI: 83-99%, I2=69%, P<0.01, Fig 1E) and 39% (95%CI: 19-61%, I2=69%, P<0.01, Fig 1H) improved to NYHA class II. A considerable proportion at 40% (95%CI: 15-68%, I2=88%, P<0.01, Fig 1G) improved to NYHA class III, but 12% (95%CI: 5-12%, I2=45%, P=0.09, Fig 1F) did not improve from NYHA class IV. Responders tended be male (85.7% vs. 40%, P=0.015, Table 1), have a history of left bundle branch block (71.4% vs. 30%, P=0.036, Table 1) or an increased left ventricular end-diastolic volume (274.3 mL vs. 225.9 mL, P=0.038, Table 1). Our findings suggest that CRT is a viable option for end-stage inotrope-dependent HF. Responders appear to be male with evidence of preserved diastolic function or a history of a left bundle branch block. Further work is necessary to optimize patient selection.Tabled 1Table 1 - Characteristics of Responders and Non-Responders to CRT. Data are presented as Mean ± Standard Deviation with percentages shown in brackets.FactorResponders to CRT (n=21)Non-Responders to CRT (n=10)p-valueMean Age (Years)65.5 ± 3.957.8 ± 5.80.412Males (%)18 (85.7)4 (40)0.015Hypertension (%)8 (38.1)2 (20)0.281Diabetes Mellitus (%)8 (38.1)2 (20)0.281Non-Ischemic Cardiomyopathy (%)18 (85.7)8 (80)0.528Atrial Fibrillation (%)8 (38.1)2 (20)0.281Left Bundle Branch Block (%)15 (71.4)3 (30)0.036Left Ventricular Ejection Fraction (%)19.5 ± 0.1524.1 ± 0.90.036Left Ventricular End-Systolic Volume (mL)218.2 ± 1.9175.5 ± 5.50.016Left Ventricular End-Diastolic Volume (mL)274.3 ± 7.2225.9 ± 6.10.038Pre-CRT QRS Length (ms)168.7 ± 8.4152.9 ± 6.10.298Post-CRT QRS Length (ms)156.7 ± 4.6149.7 ± 4.40.346 Open table in a new tab

The emergence and destiny of automated methods to differentiate wide QRS complex tachycardias

Cancer is a disease related to uncontrolled growth and spreading of affected cells via a blood torrent. Breast cancer (BC) is a cancer type that originates mainly in milk glands and ducts of the breast; however, it can also metastasise from the breast to other areas of the body. Various factors, such as smoking, physical activity, obesity, alcohol, and poor nutrition, contribute to the development of this condition. In addition, genetic alterations, such as gene mutations and chromosomal abnormalities, result in the loss of function of tumour suppressor genes (TSG) or increased oncogenes (OG) activity/oncogenes activation. Currently, cancer is associated with an aberrant epigenetic regulation that modifies both OG activation and TSG silencing. The discipline of epigenetics focuses on studying modifications, such as DNA methylation, differential histone modifications, and micro-RNA at promoter sites during gene expression. For example, aberrant methylations could be associated with BC development, wherein some biocompounds, including polyphenols, have shown effects as chemopreventive agents. However, it remains unclear if biocompounds can induce epigenetic changes or regulate other metabolic pathways. The present chapter offers an overview of the epigenetic regulation effect of polyphenols on breast cancer.

Ventricular pre-excitation in cats: 17 cases

ObjectivesAtrioventricular accessory pathways are abnormal electrical connections between the atria and ventricles that predispose to ventricular pre-excitation (VPE) and tachycardias. AnimalsSeventeen cats with VPE and 15 healthy matched-control cats. Material and methodsMulticenter case-control retrospective study. Clinical records were searched for cats with VPE, defined as preserved atrioventricular synchrony, reduced PQ interval, and increased QRS complex duration with a delta wave. Clinical, electrocardiography, echocardiographic, and outcome data were collated. ResultsMost cats with VPE were male (16/17 cats), non-pedigree cats (11/17 cats). Median age and mean body weight were 5.4 years (0.3–11.9 years) and 4.6 ± 0.8 kg, respectively. Clinical signs at presentation included lethargy (10/17 cats), tachypnea (6/17 cats), and/or syncope (3/17 cats). In two cats, VPE was an incidental finding. Congestive heart failure was uncommon (3/17 cats). Nine (9/17) cats had tachyarrhythmias: 7/9 cats had narrow QRS complex tachycardia and 2/9 cats had wide QRS complex tachycardia. Four cats had ventricular arrhythmias. Cats with VPE had larger left (P < 0.001) and right (P < 0.001) atria and thicker interventricular septum (P = 0.019) and left ventricular free wall (P = 0.028) than controls. Three cats had hypertrophic cardiomyopathy. Treatment included different combinations of sotalol (5/17 cats), diltiazem (5/17 cats), atenolol (4/17 cats), furosemide (4/17 cats), and platelet inhibitors (4/17 cats). Five cats died, all from cardiac death (median survival time 1882 days [2–1882 days]). ConclusionsCats with VPE had a relatively long survival, albeit showing larger atria and thicker left ventricular walls than healthy cats.

Incidental WPW Pattern in a Patient of Acute Coronary Syndrome: Case Report and Review of Literature

Electrocardiographic features of a short PR interval, a delta wave, and a wide QRS complex constitutes a Wolff-Parkinson-White (WPW) pattern. Asymptomatic electrocardiographic findings are defined as a WPW pattern. Symptomatic patients with these electrocardiographic features have WPW syndrome. WPW syndrome may predispose to arrhythmias such as paroxysmal atrial tachycardia, atrial fibrillation and ventricular tachycardia. Patient’s with WPW syndrome at risk for sudden cardiac death. It is important to recognize the common electrocardiographic characteristics of WPW pattern. The advent of electrophysiological studies (EPS) and radiofrequency ablation has revolutionized the management of WPW syndrome. We are presenting an incidental case report of WPW pattern in a middle aged female with acute coronary syndrome. Keywords: Wolff-Parkinson-White Syndrome, Wolff-Parkinson-White Pattern, Pre-excitation, Accessory pathway, WPW pattern in ACS

Usefulness of Doppler Transthoracic Echocardiography for the Diagnosis of Wide–QRS Complex Tachycardia

Usefulness of Doppler Transthoracic Echocardiography for the Diagnosis of Wide–QRS Complex Tachycardia

Ventricular conduction abnormality in patients with mild to moderate cardiomyopathy.

In mild-to-moderate cardiomyopathy, cardiac resynchronization therapy (CRT) is indicated in patients with high burden of right ventricular pacing but not in those with intrinsic ventricular conduction abnormalities. We hypothesized that CRT positively impacts outcomes of patients with intrinsic ventricular conduction delay and left ventricular ejection fraction (LVEF) of 36%-50%. Of 18 003 patients with LVEF ≤ 50%, 5966 (33%) patients had mild-to-moderate cardiomyopathy, of whom 1741 (29%) have a QRS duration ≥120 ms. Patients were followed to the endpoints of death and heart failure (HF) hospitalization. Outcomes were compared between patients with narrow versus wide QRS. Of the 1741 patients with mild-to-moderate cardiomyopathy and wide QRS duration, only 68 (4%) were implanted with a CRT device. Over a median follow-up of 3.35 years, 849 (51%) died and 1004 (58%) had a HF hospitalization. The adjusted risk of death (hazard ratio (HR) = 1.11, p = 0.046) and of death or HF hospitalization (HR = 1.10, p = 0.037) were significantly higher in patients with wide versus narrow QRS duration. In patients with wide QRS complex, CRT was associated with reduction in the adjusted risk of death (HR = 0.47, p = 0.020) and of death or HF hospitalization (HR = 0.58, p = 0.008). Patients with mild-to-moderate cardiomyopathy and wide QRS duration are rarely implanted with CRT devices and have worse outcomes compared to those with narrow QRS. Randomized trials are needed to examine if CRT has salutary effects in this population.

A rapid wide complex tachycardia

A rapid wide complex tachycardia

Frequent accelerated idioventricular rhythm in an otherwise healthy child: a case report and review of literature

BackgroundAccelerated idioventricular rhythm (AIVR) is a wide QRS complex dysrhythmia that, as far as pediatric population is concerned, occurs mostly in children with underlying systemic or heart disease. Its clinical course is thought to be typically benign in otherwise healthy children and treatment to be completely needless. Existing guidelines/recommendations are based entirely on cases that had low daily burden of AIVR, and those referring to treatment itself are very unspecific. Pharmacologic therapy has been mostly unsuccessful and catheter ablation as a way of treatment has been only sporadically reported. This article is a case report with a literature review that aims to practically separate the age groups into newborn and older children and to emphasize the different clinical outcomes of children with occasional and frequent AIVR. There are only a few cases so far describing undesirable outcomes of this condition, and most of these patients had high daily burden of AIVR. To be more specific, among 38 healthy children older than 1 year reported in total, 6 had undesirable outcomes, short-term in terms of developing malignant arrhythmia or long-term in terms of developing cardiomyopathy/heart failure.Case presentationAn 11-year-old boy had been referred to our center for a workup of incidentally discovered wide-complex arrhythmia. He was asymptomatic, with no underlying cardiac or systemic diseases. Continuous heart rate monitoring detected AIVR during most time of monitoring. In 24-h Holter-ECG, wide QRS complexes accounted for 73%. With parental consent, we conducted an electrophysiological study accompanied by radiofrequent ablation of ectopic focus, which lead to an instantaneous sinus rhythm that continued during the entire follow-up.ConclusionAIVR is a rare dysrhythmia in the pediatric population, typically considered benign. Nevertheless, more than a few cases evidence its harmful potential, short-term in terms of developing malignant arrhythmia or long-term in terms of developing cardiomyopathy. Gathering more knowledge and experience along with conducting further studies is essential for the enhancement of understanding this condition, and selecting potentially vulnerable patients as well as their treatment.

Management of hemodynamically stable wide QRS complex tachycardia in patients with implantable cardioverter defibrillators.

The preparation phase includes reversal of potential arrhythmia "triggers", mild patient sedation, and patient monitoring for therapy delivery. Based on resource availability and competences, the most adequate therapeutic approach is chosen. This choice depends on whether a device specialist is readily available or not. In the case of ES in a "high-risk" patient an accelerated patient management protocol is advocated, which considers urgent ventricular tachycardia transcatheter ablation with or without mechanical cardiocirculatory support. Therapeutic phase is based on the use of intravenous anti-arrhythmic drugs mostly indicated in this clinical context are presented. Device interrogation is very important in this phase when sustained monomorphic VT diagnosis is confirmed, then ICD ATP algorithms, based on underlying VT cycle length, are proposed. In high-risk patients with intractable ES, intensive patient management considers MCS and transcatheter ablation. The patient is hospitalized for further diagnostics and management aimed at preventing arrhythmia recurrences.

Amitriptyline intoxication in bullfrogs causes widening of QRS complexes in electrocardiogram.

Amitriptyline intoxication is caused by its suicidal or accidental overdose. In the present study, by intravenously injecting 1.5 or 3.0 mg/kg amitriptyline into bullfrogs, we actually revealed that amitriptyline causes the widening of QRS complexes in electrocardiogram (ECG). In simultaneous recordings of the cardiac action potential, amitriptyline decreased the slope of phase 0 in the action potential, indicating the inhibition of the inward sodium currents during this phase. The following treatment with sodium bicarbonate quickly restored the widened QRS complexes in the ECG, demonstrating the counteraction with the sodium channel blockade caused by amitriptyline. The dual recordings of ECG waveforms and the action potential in cardiomyocytes enabled us to demonstrate the mechanisms of characteristic ECG abnormalities caused by amitriptyline intoxication.