Intraventricular Conduction Delay Research Articles

Progression of ECG in hydroxychloroquine overdose

Hydroxychloroquine overdose is associated with myocardial toxicity and conduction disorders.We report a case of hydroxychloroquine overdose that demonstrated a rapid progressive intraventricular conduction delay and QT prolongation resulting in significant bradycardia and shock despite aggressive treatment. We describe the rare capture of abrupt abnormalities of this overdose in sequential electrocardiograms in the immediate hours post-ingestion.

Convolutional Neural Network-Based ECG-Assisted Diagnosis for Coal Workers.

To process and extract electrocardiogram (ECG, ECG, or EKG) features using a convolutional neural network (CNN) to establish an ECG-assisted diagnosis model. Coal workers who underwent physical examinations at Gequan Mine Hospital and Dongpang Mine Hospital of Hebei Jizhong Energy from July 2020 to September 2020 were selected as the study subjects. The ECG images were preprocessed. We use Python software and convolutional neural network to establish ECG images recognition and classification model.We usecalibration curve, calibration-in-the-large, Brier score, specificity, sensitivity, F1 score, Kappa value, accuracy, and area under the curve (AUC) of ROC to evaluate the performance of the model. The number of abnormal ECG results was 849, and the rate of abnormal results was 25.02%. The test set accuracies of the sinus bradycardia model, nonspecific intraventricular conduction delay model, myocardial ischemia model, and sinus tachycardia model were 97.66%, 96.49%, 93.62%, and 93.02%, respectively; sensitivities were 96.63%, 96.30%, 96.88% and 95.24%, respectively; specificities were 98.78%, 96.67%, 86.67%, and 90.90%, respectively; Brier scores were 0.03, 0.07, 0.09, and 0.11, respectively; Calibration-in-the-large values were 0.026, 0.110, 0.041, and 0.098, respectively. The convolutional neural network model can accurately identify the main ECG abnormality types of coal workers. Additionally, the main ECG abnormalities in these coal company workers were sinus bradycardia, non-specific intraventricular conduction delay, myocardial ischemia, and sinus tachycardia.

Abstract 9873: Erroneous Electrocardiographic Interpretations and Its Clinical Implications

Introduction: Advancement of artificial intelligence (AI) has aided clinicians in the interpretation of electrocardiograms (ECGs) serving as an essential tool to provide rapid triage and care. However, in some cases, AI can misinterpret an ECG and may mislead the interpreting physician. Therefore, we aimed to describe the rate of ECG misinterpretation and its potential clinical impact in patient's management Methods: We performed a retrospective descriptive analysis of misinterpreted ECGs and its clinical impact from May 28, 2020 to May 9, 2021. An electrophysiologist screened ECGs with confirmed diagnosis of atrial fibrillation (AF), sinus tachycardia (ST), sinus bradycardia (SB), intraventricular conduction delay (IVCD), and premature atrial contraction (PAC) that were performed in the emergency department. We then classified the misinterpreted ECGs as pseudo-AF, ST, SB, IVCD, or PAC into the correct diagnosis, and reviewed the misinterpreted ECGs and medical records to evaluate inappropriate use of antiarrhythmic drugs (AAD), beta-blockers (BB), calcium channel blockers (CCB), anticoagulation, or resource utilization of cardiology and/or electrophysiology (EP) consultation. Results: A total of 4,969 ECGs were screened with diagnoses of AF (2,282), IVCD (296), PAC (972), SB (895), and ST (638). Among these, 101 ECGs (2.02%) were misinterpreted. Pseudo-AF (58%) was the most common followed by pseudo-PAC (15%), pseudo-ST (13%), pseudo-IVCD (8%) and pseudo-SB (6%). Patients with misinterpreted ECGs were aged 76.6±11.6yr with male (52.5%) predominance and hypertension being the most prevalent (83.2%) comorbid condition. The misinterpretation of ECGs led to the inappropriate use of BB (19.8%), CCB (5.0%), AAD therapy (7.9%), anticoagulation (30.7%) in patients with pseudo-AF, as well as inappropriate resource utilization including cardiology (41.6%) and EP (8.9%) consultations. Conclusions: Misinterpretation of ECGs may lead to inappropriate medical therapies and increased resource utilization. Therefore, it is essential to encourage physicians to carefully examine AI interpreted ECG’s, especially those interpreted as having AF.

Abstract 14604: Arrhythmia Burden With Right-Heart Catheterization: A Systematic Review and Meta-Analysis

Background: Current guidelines cite complete heart block as a complication of invasive hemodynamic monitoring. This was described to be higher in those with existing intraventricular conduction delays. The objective of this meta-analysis was to evaluate the true risk of arrhythmias and pacemaker implantation rates in patients undergoing right-heart catheterization or with pulmonary artery catheter use. Methods: A literature search was performed from inception until May 2022. Studies that reported incidence rates of arrhythmias in those undergoing right-heart catherization or with pulmonary catheter use, including right- (RBBB) and left-bundle branch (LBBB), were included. Some studies described the development of complete heart block (CHB) and need for pacing. Results: Six single-center studies were included in our analysis with a total of 8, 077 right-heart catheter insertions. All patients had continuous ECG monitoring. Most frequently reported arrhythmia was premature ventricular ectopy (56.4%). No fatal ventricular arrhythmias were described and when noted, RBBB was transient in nature (0.2%, n=12/7577). The risk of CHB was 12.8% (n=24) in those with pre-existing LBBB (n=187). Pacing needs were infrequently described, but when reported was 6.3% (n=10) of concordant CHB and LBBB (n=160), and this was 0.2% of all described LBBB patients (n=6292) ( Figure ). Conclusion: Most arrhythmias were benign and transient in nature. The risk of CHB requiring pacing needs was only 0.2%. This begs the question of true burden of the theoretical complication of CHB with invasive hemodynamic monitoring, and most evidence is from decades ago.

The Relationship of Conduction Disorder and Prognosis in Patients with Acute Coronary Syndrome.

Conduction disorders with a widened QRS are associated with poor prognosis in patients with acute coronary syndrome (ACS). Conduction disorders include left bundle branch block (LBBB), right bundle branch block (RBBB), and nonspecific intraventricular conduction delay (NICD). Previous studies did not have conflicting results regarding the type of bundle branch block (BBB) with the worst prognosis, and few studies have focused on the prognosis of patients with NICD. Patients with ACS were enrolled between January 2005 and December 2019, and their medical history (International Classification of Diseases codes) was obtained from the Chang Gung Research Database. Age, sex, comorbidities, left ventricular ejection fraction (LVEF), and drug use were compared between the patients with and without conduction disorders. The following clinical outcomes were compared between patients with and without conduction disorders: heart failure (HF) hospitalization, cardiovascular (CV) mortality, and all-cause mortality. After propensity score matching, the Kaplan-Meier curve analysis for HF hospitalization, CV mortality, and all-cause mortality were compared among patients with LBBB, RBBB, and NICD. This study enrolled a total of 33970 participants and involved 3392 and 30578 patients with and without conduction disorders, respectively. Older age and a higher prevalence of comorbidities were noted in patients with conduction disorders. Lower mean LVEF was exhibited in the patients with conduction disorders (with vs. without; 44.64 ± 20.73% vs. 49.85 ± 20.63%; p < 0.001). During the 3-year follow-up period, higher incidences of HF hospitalization (21.55% vs. 17.51%; p < 0.001), CV mortality (17.98% vs. 12.14%; p < 0.001), and all-cause mortality (38.86% vs. 31.15%; p < 0.001) were noted in the patients with conduction disorder. After ACS events, 10.0% of patients presented with conduction disorders, with LBBB in 3.3%, RBBB in 6.0%, and NICD in 0.7%. The lowest mean of LVEF was presented in the patients with NICD (LBBB vs. RBBB vs. NICD; 41.00 ± 19.47% vs. 47.73 ± 20.82% vs. 34.57 ± 20.02%; p < 0.001). Among the three groups, the highest incidence of HF hospitalization was noted in patients with LBBB after propensity score matching. The lowest incidence of CV and all-cause mortality was observed in patients with RBBB. After adjustment of age, gender, comorbidities, medication, and mean LVEF, those with LBBB had the highest hazard ratio for major adverse cardiovascular events (MACEs) of 1.113 (p=0.029; 95% CI = 1.013-1.266). In the ACS population, patients with conduction delay had a poor prognosis due to a higher prevalence of comorbidities and lower mean LVEF. Among the patients with LBBB, RBBB, and NICD, those with LBBB and NICD had a higher incidence of HF hospitalization, CV mortality, and all-cause mortality. Patients with NICD had the lowest mean LVEF compared to those with LBBB and RBBB. Patients with LBBB had a significantly highest HR of MACE.

Non-specific intraventricular conduction delay or atypical LBBB - How to predict acute coronary occlusion?

We describe two patient cases with acute coronary syndrome (ACS) and broad QRS in the acute phase electrocardiogram (ECG). The patients' ECG findings resembled left bundle branch block (LBBB), but with atypical features. Broad QRS not fulfilling the criteria for LBBB or right bundle branch block (RBBB) is diagnosed as non-specific intraventricular conduction delay (NSIVCD). The case report deals with the challenges of predicting acute coronary occlusion in patients with NSIVCD in their acute phase ECG. In one of the cases, the ECG changed from typical LBBB to NSIVCD or atypical LBBB with the development of systolic dysfunction and clinical heart failure.

Cardiac resynchronization considerations in left bundle branch block.

Cardiac resynchronization therapy (CRT) via biventricular pacing (BiVP) is an established treatment for patients with left ventricular systolic heart failure and intraventricular conduction delay resulting in wide QRS. Seminal trials demonstrating mortality benefit from CRT were conducted in patients with wide left bundle branch block (LBBB) pattern on electrocardiogram (ECG) and evidence of clinical heart failure. The presence of conduction block was assumed to correlate with commonly applied criteria for LBBB. More recent data has challenged this assertion, revealing that LBBB pattern may include distinct underlying pathophysiology, including patients with complete conduction block, either at the left-sided His fibers or the proximal left bundle, intact Purkinje activation with wide LBBB-like QRS, and patients demonstrating both proximal block and distal delay. Currently, BiVP-CRT is indicated for all QRS duration ≥150 ms and may be considered for BBB patterns from 130 to 149 ms with robust clinical data to support its use. Despite this, however, there remains a significant number of non-responders to BVP. Conduction system pacing (CSP) has emerged as an alternative approach to deliver CRT and correct QRS in patients with conduction block. Newer hybrid approaches which combine CSP and traditional BiVP-CRT and may hold promise for patients with IP or mixed-level block. As various approaches to CRT continue to be studied, physiologic phenotyping of the LBBB pattern remains an important consideration.

EP News: Case Reports

Cardiac amyloidosis is often underdiagnosed or diagnosed after significant symptoms of cardiomyopathy are manifest. The development of recent disease-modifying therapeutics prompts the need for earlier diagnosis of transthyretin cardiac amyloidosis, to which a tissue diagnosis remains the criterion standard for diagnosis. Takano et al (https://doi.org/10.1016/j.hrcr.2022.05.008) shared a case of a 72-year-old man with a history of hypertension who presented with recurrent syncope. An electrocardiogram showed low-amplitude R waves and sinus rhythm with a nonspecific intraventricular conduction delay.

Mortality and readmission risk in relation to QRS duration among patients hospitalized for heart failure with preserved ejection fraction

BackgroundIn ambulatory patients with heart failure (HF) with preserved ejection fraction (HFpEF), QRS prolongation (QRS > 120 msec) and left bundle branch block (LBBB) each carry an increased risk of cardiovascular mortality and/or HF hospitalization. Less is known about implications of conduction abnormalities following an acute HF hospitalization for HFpEF. Methods and resultsA retrospective cohort of 1454 patients discharged from after a HF hospitalization between 2015 and 2019 with ejection fraction (EF) ≥ 45% were identified (age 75.1 ± 10.8 years, EF 58.5% ± 10.2%). All patients' electrocardiograms were classified by QRS duration (prolonged – 545 [37.5%] vs. normal [QRS ≤ 120 msec] 909 [62.5%]). QRS prolongation was comprised of: LBBB (4.2%), right bundle branch block (RBBB, 18.3%), intraventricular conduction delay (9.7%), and ventricularly paced (9.7%). Over 4.09 ± 1.00 years, 769 (52.9%) patients died. Survival was similar between normal and prolonged QRS cohorts with an age and sex adjusted hazard ratio of 1.01 (95%CI: 0.87–1.17, p = 0.16). Recurrent HF hospitalization occurred in 91 (16.7%) with QRS prolongation vs. 90 (9.9%) without (odds ratio: 1.82 [95%CI: 1.33–2.50, p < 0.001]). RBBB carried 2.26 higher odds of recurrent HF hospitalization (95%CI: 1.56–3.28). ConclusionsFollowing a HF hospitalization, QRS prolongation increased the odds of re-admission for HF in patients with HFpEF without differences in overall mortality.

The usefulness of His bundle pacing in a heterogeneous population of patients with impaired left ventricular systolic function.

His bundle pacing (HBP) maintains a physiological activation pattern of ventricular activation, and in patients with intraventricular conduction delay (IVCD) it can normalize wide QRS duration. A total of 181 patients from the HBP registry were enrolled into a the study, which was conducted at the Department of Electrocardiology in Katowice, Poland. The patients had left ventricular ejection fraction (LVEF) < 50% and were implanted between November 2015 and April 2019. The HBP indications were as follows: 1) bradycardia and atrioventricular conduction disturbances with expected high pacing burden, 2) IVCD, LVEF ≤ 35%, with an indication for resynchronization therapy, 3) the need to upgrade to resynchronization therapy due to pacing-induced cardiomyopathy. Pacing parameters and echocardiographic and clinical data were assessed for up to 2 years of follow-up (FU). His bundle pacing was successful in 154 (85.1%) patients. Eighty-two patients completed a 6-month FU. The mean age was 70.6 ± 9.23 years, and 79% were males. At 6 months FU LVEF improved from 35.3 ± 8.22% to 43.1 ± 10.14% (p < 0.0001), and indexed left ventricular end-systolic volume (LVESVi) decreased from 63.1 ± 25.21 mL/m² to 51.9 ± 22.79 mL/m² (p < 0.0001). In 53.1%, the LVESVi reduction was greater than 15%. The improvement in LVEF and LVESVi was also observed after 24 months of FU. His bundle pacing in permanently paced patients when LVEF is reduced below 50% is associated with improvement in LVEF and reverse left ventricle remodeling.

Bundle branch block and nonspecific intraventricular conduction delay prevalence using Chinese nationwide survey data.

ObjectiveWe aimed to determine the prevalence of and the factors associated with intraventricular conduction disturbance in the Chinese population.MethodsElectrocardiographic data from 42,031 people were retrospectively analysed. The weighted prevalences of left bundle branch block (LBBB), right bundle branch block (RBBB), bifascicular block and nonspecific intraventricular conduction delay (NS-IVCD) were calculated. The independently associated factors were determined using logistic regression analysis.ResultsThe weighted prevalence for Chinese people older than 45 years was 0.17% for LBBB, 2.16% for RBBB and 0.44% for NS-IVCD. The weighted prevalence for RBBB combined with left anterior fascicular block was 0.17%, and 0.05% for RBBB combined with left posterior fascicular block. There were significant differences in the weighted prevalences of RBBB and NS-IVCD between men and women. The weighted prevalence of LBBB and RBBB increased markedly with increasing age. Age and diabetes were independent factors associated with LBBB, compared with age and sex for RBBB and sex and coronary artery disease for NS-IVCD.ConclusionsThis study provided reliable data for the weighted prevalence of and factors associated with LBBB, RBBB and NS-IVCD in Chinese adults.

Electrical Dyssynchrony in Cardiac Amyloidosis: Prevalence, Predictors, Clinical Correlates, and Outcomes

BackgroundConduction-system involvement in cardiac amyloidosis (CA) is common. The prevalence, clinical correlates and impact on outcome related to ventricular electrical dyssynchrony in CA remain insufficiently elucidated. MethodsData from a prospectively maintained registry of patients with CA diagnosed in the Cleveland Clinic’s amyloidosis clinic was used to determine the frequency of electrical dyssynchrony (defined as a QRS > 130 msec). The relation with the clinical profile and clinical outcome was assessed. To determine the impact of hypertrophy on QRS prolongation, a QRS-matched cohort without CA was used for comparison of cardiac magnetic resonance imaging. ResultsA total of 1140 patients with CA (39% AL, 61% TTR) were evaluated, of whom 230 (20%) had electrical dyssynchrony. The type of conduction block was predominantly a right bundle branch block (BBB, 48%) followed by left BBB (35%) and intraventricular conduction delay (17%). Presence of transthyretin amyloidosis (ATTR-CA), older age, male gender, white race, and coronary artery disease were independently (P< 0.05 for all) associated with electrical dyssynchrony, and patients were more commonly prescribed a mineralocorticoid receptor antagonist. In ATTR-CA, specifically, every increase in ATTR-CA disease stage was associated with a 1.55-fold (1.23--1.95; P< 0.001) increased odds for electrical dyssynchrony. In a subset of patients with CA who underwent cardiac magnetic resonance imaging (n = 41), left ventricular mass index was unrelated to the QRS duration (r = 0.187; P = 0.283) in CA, in contrast to a non-CA QRS-matched cohort (r = 0.397; P< 0.001). Patients with electrical dyssynchrony were more symptomatic at initial presentation, as illustrated by a higher New York Heart Association class (P= 0.041). During a median follow-up of 462 days (IQR:138--996 days), a higher proportion of patients with electrical dyssynchrony died from all-cause death (P= 0.037) or developed a permanent pacing indication (3% vs 10.4%; P< 0.001) during follow-up. ConclusionElectrical dyssynchrony is common in CA, especially in ATTR-CA, and is associated with worse functional status and clinical outcome. Given the high rate of permanent pacing indications at follow-up, additional studies are necessary to determine the best monitoring and pacing strategies in CA.

High-risk ECG patterns in ST elevation myocardial infarction for mortality prediction

AimWe explored the pre-intervention (first medical contact) electrocardiographic (ECG) patterns and their relation to survival among patients with acute myocardial infarction, who presented either with ST elevation (ST elevation myocardial infarction, STEMI) or LBBB, and who underwent emergent coronary angiography in a region with a 24/7/365 STEMI network. MethodsThis is a retrospective analysis of 1363 consecutive patients hospitalized for first STEMI between the years 2014 and 2018. We assessed the prognostic significance of a variety of ECG categories, including location of ST elevation, severity of ischemia, intraventricular and atrioventricular conduction disorders, atrial fibrillation or flutter, junctional rhythms, heart rate, left ventricular hypertrophy and Q waves. The primary outcome was all-cause mortality between January 2014 and the end of 2020. ResultsThe mean age of the patients was 67.9 (SD 12.8) years. The majority were treated by percutaneous coronary intervention (93.8%, n = 1278). Median follow-up time was 3.7 years (IQR 2.5–5.1 years) during which 22.5% (n = 307) of the patients died. According to Cox regression analysis, adjusted for pre-existing conditions and age, the ECG variables with statistically significant association with survival were elevated heart rate (>100 bpm) (HR 2.34, 95% CI 1.75–3.12), atrial fibrillation or flutter (HR 1.94, 95% CI 1.41–2.67), left bundle branch block (LBBB) (HR 2.62, 95% CI 1.49–4.63) and non-specific intraventricular conduction delay (NIVCD) (HR 1.85, 95% CI 1.22–2.89). ConclusionHigher heart rate, atrial fibrillation or flutter, LBBB and NIVCD are associated with worse outcome in all-comers with STEMI. Ischemia severity was not associated with impaired prognosis.

What Body Surface Mapping Has Taught Us About Ventricular Conduction Disease Implications for Cardiac Resynchronization Therapy and His Bundle Pacing

The degree and pattern of conduction disease seem determinant when assessing potential cardiac resynchronization therapy (CRT) candidates. In the present review, the authors discuss the available noninvasive techniques that can be used to acquire ventricular activation time maps. They describe what body surface mapping has taught us about left bundle branch block, right bundle branch block, intraventricular conduction delay, and right ventricular pacing and discuss the ability of derived parameters of electrical dyssynchrony to predict long-term clinical response to CRT or His bundle pacing.

Non-specific intraventricular conduction delay and ventricular pre-excitation: “Pseudo-P wave”, warning for it!

Atrial fibrillation (AF) is the most common cardiac arrhythmia in adults with substantial morbidity and mortality. The diagnosis of AF is established by electrocardiogram showing heart rhythm without clear P waves with irregular RR intervals. The electrocardiographic diagnosis of AF is not always easy and can still hide pitfalls even for the most experienced cardiologist. We present the case of an 86 years old patient admitted to our hospital for Covid-19 infection affected by dilated cardiomyopathy with an electrocardiogram showing a non-specific intraventricular conduction delay mimicking sinus rhythm in the presence of AF.

Abstract 60: Mortality Following Heart Failure Hospitalization By QRS Duration In Patients With Preserved Ejection Fraction

Background: Heart failure with preserved ejection fraction (HFpEF) comprises almost half of all heart failure (HF) diagnoses. Similar to HF with reduced ejection fraction (HFrEF), HFpEF carries up to a 75% 5-year mortality following HF hospitalization. However, unlike its corollary, HFpEF has exceedingly limited therapeutic options to alter its natural history. While QRS prolongation (QRS &gt; 120 msec) carries prognostic significance in HFrEF, less is known about the implications of this conduction abnormality in HFpEF. Objective: To determine the association of QRS prolongation with survival among patients with HFpEF following HF hospitalization. Methods: A retrospective review of 1,454 patients with left ventricular EF ≥ 45% discharged from the Minneapolis VA Medical Center between 2015 and 2019 from a HF hospitalization. All patients’ electrocardiograms (ECG) were classified by QRS duration as either prolonged (QRS &gt;120 msec) or narrow complex (QRS ≤120 msec). Those with prolonged QRS were further subtyped as: left bundle branch block (LBBB), right bundle branch block (RBBB), intraventricular conduction delay (IVCD), or ventricular paced (VP) rhythm. Results: Of the 1,454 patients (mean age 75.1 ± 10.8 years, 97.7% male, and mean EF 58.5% ± 10.2%), 545 (37.5%) had QRS prolongation. Specifically, 61 (4.2%) had LBBB, 266 (18.3%) had RBBB, 77 (5.3%) had IVCD and 141 (9.7%) had VP. Over 4.09 ± 1.00 years of follow up, 769 (52.9%) of the patients died (Table). Patients with a narrow QRS had a similar survival relative to those with a QRS &gt;120 msec with an age and sex adjusted hazard ratio of 1.01 (95% CI: 0.87-1.17, p = 0.16) (Figure). Conclusions: The mortality rate is exceedingly high in patients with HFpEF discharged after a HF hospitalization. While the QRS interval was not significantly associated with near-term survival in this analysis, these data suggest that studies with greater statistical power and follow-up duration are warranted.

Influence of Capture Selectivity and Left Intrahisian Block on QRS Characteristics During Left Bundle Branch Pacing.

This study sought to examine QRS and intracardiac characteristics during selective (S) and nonselective (NS) left bundle branch pacing (LBBP) from direct left septal recordings. Criteria for S-LBBP and NS-LBBP have not been validated with intracardiac mapping. Pacing was performed from multielectrode Purkinje recordings below the left-sided His. S-LBBP and NS-LBBP were performed in patients with narrow QRS (n=9), right bundle branch block (n=3), intraventricular conduction delay (n=5), and left bundle branch block (n=10). QRS duration was measured from stimulus onset (QRSst) and from the intrinsicoid deflection of the R-wave in V1-V2 (QRSid) to QRS end. Retrograde left bundle branch conduction was assessed by stimulus-to-retrograde His intervals. Among 27 patients analyzed, 20 demonstrated both NS- and S-LBBP and were studied in paired comparisons. NS-LBBP resulted in narrower QRS compared to S-LBBP (QRSst: 163ms [interquartile range (IQR): 144-179ms] vs 181ms [IQR: 173-203 ms]; P< 0.001; QRSid: 125ms [IQR: 117-142 ms] vs 150ms [IQR: 135-157 ms]; P< 0.001). Left ventricular activation time was also significantly shorter for NS-LBBP compared to S-LBBP (88ms [IQR: 75-111 ms] vs97ms [IQR: 82-123 ms]; P = 0.019). Leftintrahisian block was bidirectional in 10 patients with long retrograde stimulus-to-His intervals. QRSst duration was significantly longer in patients with complete conduction blockcomparedto those with intact Purkinje activation during NS-LBBP (181ms [IQR: 162-195 ms] vs 157ms [IQR: 139-168 ms]; P =0.022). In contrast to His-bundle pacing, S-LBBP predominantly yields a wide QRS as a result of delayed RBB synchronization, whereas NS-LBBP results in shorter QRS duration because of recruitment of the basal right ventricular septum. A wider-paced morphology of LBBP was noted in patients with complete conduction block caused by bidirectional left intrahisian block. Achievement of narrow QRS during LBBP is predicated upon capture nonselectivity or programmed atrioventricular fusion, rather than intrinsic physiologic synchrony from left bundle branch stimulation.

Preprocedural and procedural variables that predict new-onset conduction disturbances after transcatheter aortic valve replacement

BackgroundConduction disturbances are a common complication after transcatheter aortic valve replacement (TAVR). The aim of this study was to investigate the preprocedural and procedural variables that predict new-onset conduction disturbances post-TAVR (hereafter CD/CDs).MethodsConsecutive patients who underwent TAVR during December 2009–March 2021 at the Faculty of Medicine Siriraj Hospital, Mahidol University—Thailand’s largest national tertiary referral center—were enrolled. Patients with prior implantation of a cardiac device, periprocedural death, or unsuccessful procedure were excluded. Clinical and electrocardiographic data, preprocedural imaging, including membranous septum (MS) length, and procedural variables, including implantation depth (ID), were analyzed. CD was defined as new left or right bundle branch block, significant intraventricular conduction disturbance with QRS interval ≥ 120 ms, new high-grade atrioventricular block, or complete heart block. Multivariate binary logistic analysis and receiver operating characteristic (ROC) curve analysis were used to identify independent predictors and the optimal ∆MSID (difference between the MS length and ID) cutoff value, respectively.ResultsA total of 124 TAVR patients (mean age: 84.3 ± 6.3 years, 62.1% female) were included. The mean Society of Thoracic Surgeons score was 7.3%, and 85% of patients received a balloon expandable transcatheter heart valve. Thirty-five patients (28.2%) experienced a CD, and one-third of those required pacemaker implantation. The significant preprocedural and procedural factors identified from univariate analysis included intraventricular conduction delay, mitral annular calcification, MS length ≤ 6.43 mm, self-expanding device, small left ventricular cavity, and ID ≥ 6 mm. Multivariate analysis revealed MS length ≤ 6.43 mm (adjusted odds ratio [aOR] 9.54; 95% CI 2.56–35.47; p = 0.001) and ∆MSID < 0 mm (adjusted odds ratio [aOR] 10.77; 95% CI 2.86–40.62; p = < 0.001) to be independent predictors of CD. The optimal ∆MSID cutoff value for predicting conduction disturbances was less than 0 mm (area under the receiver operating characteristic curve [AuROC]: 0.896).ConclusionThis study identified MS length ≤ 6.43 mm and ∆MSID < 0 mm as independent predictors of CDs. ∆MSID < 0 was the strongest and only modifiable predictor. Importantly, we expanded the CD criteria to cover all spectrum of TAVR-related conduction injury to lower the threshold of this sole modifiable risk. The optimal ∆MSID cutoff value was < 0 mm.Trial registration: TCTR, TCTR20210818002. Registered 17 August 2021—Retrospectively registered, http://www.thaiclinicaltrials.org/show/TCTR 20210818002.

Frequency of fragmented QRS in sports activity: a pilot study.

Fragmented QRS (fQRS), is a marker of intraventricular conduction delay. No sufficient data are available regarding the presence in different sports disciplines. The present study aims to evaluate the frequency of fQRS in athletes and the morphological myocardial associated pattern. This retrospective study of 5 years, involved 605 subjects and evaluated for the eligibility in competitive sport activity. A sample of 100 subjects for 6 kinds of sport was considered. Fragmented QRS was defined as the presence, during a resting ECG, of various RSR' patterns in at least two contiguous leads. All subjects had an echocardiographic examination. fQRS was found in 47 athletes of the 605 subjects. fQRS+ subjects were older than fQRS- (33.17 vs. 24.12 P<0.001) and were predominantly male (89.4% vs. 10,6% P=0.007). The presence of fQRS had a different prevalence among sports. Fragmented QRS was independently associated with age (OR=1.026, 95% CI 1.006-1.047; P=0.010), sex (OR=0.354, 95% CI 0.133-0.943; P=0.038), left ventricle cardiac mass index values (OR=1.017, 95% CI 1.001-1.033; P=0.033) and E peak (OR=0.979, 0.959-0.999; P=0.043) in multivariate analysis. The prevalence of fQRS in sport disciplines appears to be around 13% to 2% with major evidence among older male subjects. Despite the presence of physiological hypertrophy in athletes, no significant influence was found regarding the type of sport practiced on the prevalence of fQRS. A larger investigation will be necessary to validate this first hypothesis.

Electrocardiographic markers of cardiac resynchronization therapy response: delayed time to intrinsicoid deflection onset in lateral leads.

Cardiac resynchronization therapy (CRT) has emerged as an important intervention for patients with heart failure (HF) with reduced ejection fraction and delayed ventricular activation. In these patients, CRT has demonstrated to improve quality of life, promote reverse left ventricular (LV) remodeling, reduce HF hospitalizations, and extend survival. However, despite advancements in our understanding of CRT, a significant number of patients do not respond to this therapy. Several invasive and non-invasive parameters have been assessed to predict response to CRT, but the electrocardiogram (ECG) has remained as the prevailing screening method albeit with limitations. Ideally, an accurate, simple, and reproducible ECG marker or set of markers would dramatically overcome the current limitations. We describe the clinical utility of an old ECG parameter that can estimate ventricular activation delay: the onset to intrinsicoid deflection (ID). Based on the concept of direct measurement of ventricular activation time (intrinsic deflection onset), time to ID onset measures on the surface ECG the time that the electrical activation time takes to reach the area subtended by the corresponding surface ECG lead. Based on this principle, the time to ID on the lateral leads can estimate the delay activation to the lateral LV wall and can be used as a predictor for CRT response, particularly in patients with non-specific intraventricular conduction delay or in patients with left bundle branch block and QRS < 150 ms. The aim of this review is to present the current evidence and potential use of this ECG parameter to estimate LV activation and predict CRT response.