Criteria for intraventricular conduction disturbances and pre-excitation. World Health Organizational/International Society and Federation for Cardiology Task Force Ad Hoc

A Revised Definition of Left Bundle Branch Block Using Time to Notch in Lead I

Importance

Current left bundle branch block (LBBB) criteria are based on animal experiments or mathematical models of cardiac tissue conduction and may misclassify patients. Improved criteria would impact referral decisions and device type for cardiac resynchronization therapy.

Objective

To develop a simple new criterion for LBBB based on electrophysiological studies of human patients, and then to validate this criterion in an independent population.

Design, Setting, and Participants

In this diagnostic study, the derivation cohort was from a single-center, prospective study of patients undergoing electrophysiological study from March 2016 through November 2019. The validation cohort was assembled by retrospectively reviewing medical records for patients from the same center who underwent transcatheter aortic valve replacement (TAVR) from October 2015 through May 2022.

Exposures

Patients were classified as having LBBB or intraventricular conduction delay (IVCD) as assessed by intracardiac recording.

Main Outcomes and Measures

Sensitivity and specificity of the electrocardiography (ECG) criteria assessed in patients with LBBB or IVCD.

Results

A total of 75 patients (median [IQR] age, 63 [53-70.5] years; 21 [28.0%] female) with baseline LBBB on 12-lead ECG underwent intracardiac recording of the left ventricular septum: 48 demonstrated complete conduction block (CCB) and 27 demonstrated intact Purkinje activation (IPA). Analysis of surface ECGs revealed that late notches in the QRS complexes of lateral leads were associated with CCB (40 of 48 patients [83.3%] with CCB vs 13 of 27 patients [48.1%] with IPA had a notch or slur in lead I; P = .003). Receiver operating characteristic curves for all septal and lateral leads were constructed, and lead I displayed the best performance with a time to notch longer than 75 milliseconds. Used in conjunction with the criteria for LBBB from the American College of Cardiology/American Heart Association/Heart Rhythm Society, this criterion had a sensitivity of 71% (95% CI, 56%-83%) and specificity of 74% (95% CI, 54%-89%) in the derivation population, contrasting with a sensitivity of 96% (95% CI, 86%-99%) and specificity of 33% (95% CI, 17%-54%) for the Strauss criteria. In an independent validation cohort of 46 patients (median [IQR] age, 78.5 [70-84] years; 21 [45.7%] female) undergoing TAVR with interval development of new LBBB, the time-to-notch criterion demonstrated a sensitivity of 87% (95% CI, 74%-95%). In the subset of 10 patients with preprocedural IVCD, the criterion correctly distinguished IVCD from LBBB in all cases. Application of the Strauss criteria performed similarly in the validation cohort.

Conclusions and Relevance

The findings suggest that time to notch longer than 75 milliseconds in lead I is a simple ECG criterion that, when used in conjunction with standard LBBB criteria, may improve specificity for identifying patients with LBBB from conduction block. This may help inform patient selection for cardiac resynchronization or conduction system pacing.

Prevalence and Clinical Significance of Intraventricular Conduction Disturbances in Hospitalized Children

Introduction: Data on the prevalence and clinical significance of interventricular conduction disturbances (IVCDs) in children are scarce. While incomplete right bundle branch blocks (IRBBBs) seem to be the most frequent and benign findings, complete bundle blocks and fascicular blocks are often seen in children with congenital/acquired cardiac conditions. This study aims to delineate the prevalence and the diagnostic accuracy of IVCD in children admitted to a paediatric cardiology unit. Methods: Children admitted to the paediatric cardiology unit between January 2010 and December 2020 who had an ECG were included in the study. IVCDs were diagnosed according to standard criteria adjusted for age. Results: Three thousand nine hundred and ninety-three patients were enrolled. The median age was 3.1 years (IQR: 0.0-9.2 years), and 52.7% were males. IVCDs were present in 22.5% of the population: 17.4% of the population presented with IRBBBs, 4.8% with a complete right bundle branch block (CRBBB), 0.1% with a complete left bundle branch block (CLBBB), 0.2% with a left anterior fascicular block (LAFB) and 0.2% with a combination of CRBBB and LAFB. Also, 26% of children with congenital heart disease had an IVCD, and 18% of children with an IVCD had previous cardiac surgery. The overall sensitivity of IVCD in detecting a cardiac abnormality was 22.2%, with a specificity of 75.5%, a PPV of 83.1% and an NPV of 15.1%, but the values were higher for CLBBB and LAFB. Conclusions: IVCDs were present in one-fifth of children admitted to the cardiology unit. IRBBB was the most frequent disturbance, while CRBBB, CLBBB and fascicular blocks were much rarer, though they had a higher predictive value for cardiac abnormalities.

R-R' interval in the left bundle branch block predicts long-term outcomes after cardiac resynchronization therapy by estimating greater mechanical dyssynchrony and viable myocardium

BACKGROUND

Typical left bundle branch block (LBBB) shows 2 peaks of the R wave, which reflect activation reaching the interventricular septum (R) and posterolateral wall (R') sequentially.

OBJECTIVE

The purpose of this study was to investigate the relationship among R-R' interval (RR'), mechanical dyssynchrony, extent of viable myocardium, and long-term outcomes in cardiac resynchronization therapy (CRT) candidates.

METHODS

The study enrolled 49 patients (34 men; mean age: 69 ± 11 years) with LBBB who received CRT. The LBBB definition used requires the presence of mid-QRS notching in leads V1, V2, V5, V6, I, and aVL. Baseline evaluations were QRS duration (QRSd) and RR' measured from the 12-lead electrocardiogram; eyeball dyssynchrony (apical rocking and septal flash) and opposing-wall delay by speckle tracking from echocardiography, and extent of viable myocardium assessed by thallium-201 single-photon emission computed tomography. Primary outcomes included the combination of all-cause death and heart failure-related hospitalization.

RESULTS

RR' predicted volumetric response better than QRSd (area under the curve 0.73 vs 0.67, respectively). The long RR' group (≥48 ms) revealed more frequent eyeball dyssynchrony and significantly greater radial (SL) and circumferential dyssynchrony (AP and SL) and %viable segment than the short RR' group. In multivariate regression analysis, only RR' ≥48 ms was independently associated with higher event-free survival rates following CRT (hazard ratio 0.21; P = .014).

CONCLUSION

These findings suggest that RR' in complete LBBB was associated with mechanical dyssynchrony, extent of viable myocardium, and long-term outcomes following CRT.

Useful Electrocardiographic Signs to Support the Prediction of Favorable Response to Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) is a cornerstone therapeutic opportunity for selected patients with heart failure. For optimal patient selection, no other method has been proven to be more effective than the 12-lead ECG, and hence ECG characteristics are extensively researched. The evaluation of particular ECG signs before the implantation may improve selection and, consequently, clinical outcomes. The definition of a true left bundle branch block (LBBB) seems to be the best starting point with which to select patients for CRT. Although there are no universally accepted definitions of LBBB, using the classical LBBB criteria, some ECG parameters are associated with CRT response. In patients with non-true LBBB or non-LBBB, further ECG predictors of response and non-response could be analyzed, such as QRS fractionation, signs of residual left bundle branch conduction, S-waves in V6, intrinsicoid deflection, or non-invasive estimates of Q-LV which are described in newer publications. The most important and recent study results of the topic are summarized and discussed in this current review.

Interatrial Block Association With Adverse Cardiovascular Outcomes in Patients Without a History of Atrial Fibrillation

BACKGROUND

Interatrial block (IAB) is associated with thromboembolism and atrial arrhythmias. However, prior studies included small patient cohorts so it remains unclear whether IAB predicts adverse outcomes particularly in context of atrial fibrillation (AF)/atrial flutter (AFL).

OBJECTIVES

This study sought to determine whether IAB portends increased stroke risk in a large cohort in the presence or absence of AFAF/AFL.

METHODS

We performed a 5-center retrospective analysis of 4,837,989 electrocardiograms (ECGs) from 1,228,291 patients. IAB was defined as P-wave duration ≥120 ms in leads II, III, or aVF. Measurements were extracted as .XML files. After excluding patients with prior AF/AFL, 1,825,958 ECGs from 458,994 patients remained. Outcomes were analyzed using restricted mean survival time analysis and restricted mean time lost.

RESULTS

There were 86,317 patients with IAB and 355,032 patients without IAB. IAB prevalence in the cohort was 19.6% and was most common in Black (26.1%), White (20.9%), and Hispanic (18.5%) patients and least prevalent in Native Americans (9.2%). IAB was independently associated with increased stroke probability (restricted mean time lost ratio coefficient [RMTLRC]: 1.43; 95% CI: 1.35-1.51; tau = 1,895), mortality (RMTLRC: 1.14; 95% CI: 1.07-1.21; tau = 1,924), heart failure (RMTLRC: 1.94; 95% CI: 1.83-2.04; tau = 1,921), systemic thromboembolism (RMTLRC: 1.62; 95% CI: 1.53-1.71; tau = 1,897), and incident AF/AFL (RMTLRC: 1.16; 95% CI: 1.10-1.22; tau = 1,888). IAB was not associated with stroke in patients with pre-existing AF/AFL.

CONCLUSIONS

IAB is independently associated with stroke in patients with no history of AF/AFL even after adjustment for incident AF/AFL and CHA2DS2-VASc score. Patients are at increased risk of stroke even when AF/AFL is not identified.

Challenged Atrioventricular Node Ablation in a Patient With Atrial Fibrillation With Rapid Ventricular Rate and Wide QRS Complex

This case report describes a patient in their 60s with a history of palpitations for more than 10 years and dyspnea for 3 years who had undergone a single-chamber pacemaker implant 10 years prior for sick sinus syndrome with paroxysmal atrial fibrillation.

Improved evaluation of left ventricular hypertrophy using the spatial QRS-T angle by electrocardiography

Electrocardiographic (ECG) signs of left ventricular hypertrophy (LVH) lack sensitivity. The aim was to identify LVH based on an abnormal spatial peaks QRS-T angle, evaluate its diagnostic performance compared to conventional ECG criteria for LVH, and its prognostic performance. This was an observational study with four cohorts with a QRS duration < 120 ms. Based on healthy volunteers (n = 921), an abnormal spatial peaks QRS-T angle was defined as ≥ 40° for females and ≥ 55° for males. In other healthy volunteers (n = 461), the specificity of the QRS-T angle to detect LVH was 96% (females) and 98% (males). In patients with at least moderate LVH by cardiac imaging (n = 225), the QRS-T angle had a higher sensitivity than conventional ECG criteria (93–97% vs 13–56%, p < 0.001 for all). In clinical consecutive patients (n = 783), of those who did not have any LVH, 238/556 (43%) had an abnormal QRS-T angle. There was an association with hospitalization for heart failure or all-cause death in univariable and multivariable analysis. An abnormal QRS-T angle rarely occurred in healthy volunteers, was a mainstay of moderate or greater LVH, was common in clinical patients without LVH but with cardiac co-morbidities, and associated with outcomes.

Validation of CalECG software for primary prevention heart failure patients: Reducing inter-observer measurement variability

BACKGROUND

In primary prevention heart failure patients the 12‑lead electrocardiogram (ECG) may be useful for the prediction of ventricular arrhythmias. However, inter-observer measurement variability first needs to be identified and any software used, validated.

OBJECTIVE

To compare manual ECG measures with CalECG software and to assess the reliability of visual recognition of fragmented QRS (fQRS) by advanced cardiology trainees.

METHODS

30 pre-implant ECGs were assessed on patients who met guidelines for primary prevention Implantable Cardiac Defibrillator. Parameters included RR, PR, QT, QRS duration, axis location, fQRS and T wave peak to T wave end (TpTe). ECGs were analyzed by members of the cardiology department with different levels of experience, and compared to CalECG software. Interobserver agreement was assessed using Fleiss' Kappa (κ) and intraclass correlation coefficients (ICC). Pearson correlation coefficient (r) was used to compare human and software measures.

RESULTS

Strong/very strong correlation was recorded across manual ECG measures (ICC = 0.749-0.979, p ≤ 0.0001) with moderate/strong correlation for TpTe (ICC = 0.547-0.765, p ≤ 0.001). Advanced cardiology trainees demonstrated substantial agreement on ECG interpretation (κ = 0.788, p ≤ 0.0001), however, reliability of fQRS assessment was only moderate for identification (κ = 0.5, p ≤ 0.0001) and fair for location (κ = 0.295, p = 0.001). CalECG software showed strong/very strong correlation with manual measurement for standard measures (r = 0.756-0.977, p ≤ 0.001). Concordance between human and software TpTe measurements varied between leads, with V5 showing a non-significant weak correlation (r = 0.197).

CONCLUSION

CalECG software showed strong/very strong correlation with standard manual measures which affirms its use in ECG analysis. Advanced cardiology trainees showed greater variability in the identification and location of fQRS.

New permanent bundle-branch block and long-term prognosis of patients with new onset ST-elevation myocardial infarction who underwent percutaneous coronary intervention

Aim: The aim of the study was to evaluate the potential predictive value of permanent RBBB and LBBB for longer-term prognosis in patients with new-onset STEMI who underwent percutaneous coronary intervention (PCI).

Methods: Patients with new-onset STEMI that underwent emergency PCI at our department from June 2012 to September 2020 were included in the study. Gensini score (GS) was employed to evaluate the severity of coronary lesions. The primary endpoint of the study was the occurrence of major adverse cardiac and cerebrovascular events (MACCEs), the composite of cardiac mortality, recurrence of myocardial infarction, cardiac shock, stroke, stent thrombosis, or revascularization. We also set all-cause mortality as a secondary endpoint.

Results: Out of the 547 patients, 29 patients had new-onset permanent LBBB, 51 patients had new-onset permanent RBBB, and 467 patients had no bundle-branch block (BBB). The occurrence of no BBB, new permanent LBBB, or RBBB was not associated with the severity of coronary artery lesions as evaluated by the GS. After follow-up at an average of 43.93 months, MACCEs occurred in 52 patients. Kaplan-Meier analysis showed that patients with new-onset RBBB were at greater risk for MACCEs compared to those with new onset LBBB (χ² = 5.107, p = 0.021). Also, an independent correlation was found between new permanent RBBB and LBBB and MACCEs risk. The adjusted hazard ratios (HRs) were 6.862 [95% confidence interval (CI) of 3.764–12.510] for the new-onset permanent RBBB and 3.395 (95% CI of 1.280–9.005) for LBBB, compared to those with no BBB, respectively (both p < 0.05).

Conclusion: New onset permanent RBBB in patients with new onset STEMI who underwent PCI may be correlated independently with increased risk of poor long-term prognosis.

Compelling new electrocardiographic markers for automatic diagnosis

BACKGROUND AND OBJECTIVE

The automatic diagnosis of heart diseases from the electrocardiogram (ECG) signal is crucial in clinical decision-making. However, the use of computer-based decision rules in clinical practice is still deficient, mainly due to their complexity and a lack of medical interpretation. The objetive of this research is to address these issues by providing valuable diagnostic rules that can be easily implemented in clinical practice. In this research, efficient diagnostic rules friendly in clinical practice are provided.

METHODS

In this paper, interesting parameters obtained from the ECG signals analysis are presented and two simple rules for automatic diagnosis of Bundle Branch Blocks are defined using new markers derived from the so-called FMM_ecg delineator. The main advantages of these markers are the good statistical properties and their clear interpretation in clinically meaningful terms.

RESULTS

High sensitivity and specificity values have been obtained using the proposed rules with data from more than 35,000 patients from well known benchmarking databases. In particular, to identify Complete Left Bundle Branch Blocks and differentiate this condition from subjects without heart diseases, sensitivity and specificity values ranging from 93% to 99% and from 96% to 99%, respectively. The new markers and the automatic diagnosis are easily available at https://fmmmodel.shinyapps.io/fmmEcg/, an app specifically developed for any given ECG signal.

CONCLUSIONS

The proposal is different from others in the literature and it is compelling for three main reasons. On the one hand, the markers have a concise electrocardiographic interpretation. On the other hand, the diagnosis rules have a very high accuracy. Finally, the markers can be provided by any device that registers the ECG signal and the automatic diagnosis is made straightforwardly, in contrast to the black-box and deep learning algorithms.

What Intracardiac Tracings Have Taught Us About Left Bundle Branch Block

Current electrocardiogram (ECG) criteria for left bundle branch block (LBBB) are largely based on early work in animal models or on mathematical models of cardiac activation. The resulting criteria have modest specificity, and up to one-third of patients who meet current ECG criteria for LBBB may have intact conduction through their His-Purkinje systems. Intracardiac tracings offer the ability to accurately discriminate between LBBB and other causes of delayed activation, which may facilitate the development of more accurate ECG criteria. Assessing these distinctions are particularly salient to applications for conduction system pacing.

Defining left bundle branch block according to the new 2021 European Society of Cardiology criteria

Correctly diagnosing left bundle branch block (LBBB) is fundamental, as LBBB occurs frequently in heart failure and may trigger a vicious cycle of progressive left ventricular dysfunction. Moreover, a correct diagnosis of LBBB is pivotal to guide cardiac resynchronisation therapy. Since the LBBB diagnostic criteria were recently updated by the European Society of Cardiology (ESC), we assessed their diagnostic accuracy compared with the previous ESC 2013 definition. We further discuss the complexity of defining LBBB within the context of recent insights into the electromechanical pathophysiology of LBBB.

A Case With Inferior Wall Myocardial Infarction and Conduction Abnormalities: Addressing the Diagnostic Challenges

Conduction disturbances are an important complication of ST-elevation myocardial infarction (STEMI). Conduction disturbances such as fascicular blocks and bundle branch blocks are associated with alteration of QRS morphology and secondary ST-T wave changes that can influence the diagnosis of acute myocardial ischemia. We report an interesting case where a patient presented with inferior wall myocardial infarction (MI), right bundle branch block (RBBB), and left anterior hemiblock (LAHB). We discuss the challenges in diagnosing MI in such patients, including the impact of QRS changes in RBBB and LAHB, their influence on diagnosis of STEMI, and differentiation of combined first-degree AV block and bifascicular block from trifascicular block.

Cardiovascular Complications of Interatrial Conduction Block: JACC State-of-the-Art Review

Interatrial block (IAB) is an electrocardiographic pattern describing the conduction delay between the right and left atria. IAB is classified into 3 degrees of block that correspond to decreasing conduction in the region of Bachmann's bundle. Although initially considered benign in nature, specific subsets of IAB have been associated with atrial arrhythmias, elevated thromboembolic stroke risk, cognitive impairment, and mortality. As the pathophysiologic relationships between IAB and stroke are reinforced, investigation has now turned to the potential benefit of early detection, atrial imaging, cardiovascular risk factor modification, antiarrhythmic pharmacotherapy, and stroke prevention with oral anticoagulation. This review provides a contemporary overview of the epidemiology, pathophysiology, diagnosis, and management of IAB, with a focus on future directions.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Rhythm disturbances following rapid-deployment aortic valve replacement

Objectives

There have been reports of postoperative conduction disturbances after rapid-deployment aortic valve replacement. Our objective was to assess electrocardiogram changes in patients undergoing this procedure and review the literature on this topic.

Methods

In this retrospective case series, clinical data were extracted from patient records at St Vincent's Hospital Melbourne and the Australia New Zealand Society of Cardiac and Thoracic Surgeons database. Electrocardiogram data were obtained at baseline and postoperatively on day 5 and at week 6 and reviewed for rhythm disturbances and intracardiac conduction problems. Pacemaker status was also recorded.

Results

From 2013 to 2017, 100 consecutive patients underwent rapid-deployment aortic valve replacement with 1 valve type at our institution. Three patients were excluded because of paced rhythm preoperatively, leaving 97 patients (mean age 74.7 ± 8.12 years; 56.7% male) for analysis. Some 18.6% of patients developed new left bundle branch block at 5 days postoperatively and only 4.1% of patients found with persistent left bundle branch block at 6-week follow-up compared with preoperatively. No significant changes were observed in the frequencies of atrial fibrillation, first-degree heart block, and right bundle branch block. However, there was evidence of increases in paced rhythm and subsequent need for a permanent pacemaker. A total of 14 patients (14.4%) had a permanent pacemaker implanted at an average of 11.1 ± 2.9 days postoperatively.

Conclusions

Rhythm disturbances and conduction abnormalities are noted with the rapid-deployment aortic valves used at our institution, but appear comparable to other rapid-deployment aortic valve replacement bioprostheses. These abnormalities may be related to the effect of the sub-annular stent frame of the valve system and implantation technique.

Better CRT Response in Patients Who Underwent Atrioventricular Node Ablation or Upgrade From Pacemaker: A Nomogram to Predict CRT Response

Background: Response rates for cardiac resynchronization therapy (CRT) in patients without intrinsic left bundle-branch block (LBBB) morphology are poor.

Objective: We sought to develop a nomogram model to predict response to CRT in patients without intrinsic LBBB.

Methods: We searched electronic health records for patients without intrinsic LBBB who underwent CRT at Mayo Clinic. Logistic regression and Cox proportional hazards regression analysis were performed for the odds of response to CRT and risk of death, respectively. Results were used to develop the nomogram model.

Results: 761 patients without intrinsic LBBB were identified. Six months after CRT, 47.8% of patients demonstrated improvement of left ventricular ejection fraction by more than 5%. The 1-, 3-, and 5-year survival rates were 95.9, 82.4, and 66.70%, respectively. Patients with CRT upgrade from pacemaker [odds ratio (OR), 1.67 (95% CI, 1.05–2.66)] or atrioventricular node (AVN) ablation [OR, 1.69 (95% CI, 1.09–2.64)] had a greater odds of CRT response than those patients who had new implant, or who did not undergo AVN ablation. Patients with right bundle-branch block had a low response rate (39.2%). Patients undergoing AVN ablation had a lower mortality rate than those without ablation [hazard ratio, 0.65 (95% CI, 0.46–0.91)]. Eight clinical variables were automatically selected to build a nomogram model and predict CRT response. The model had an area under the receiver operating characteristic curve of 0.71 (95% CI, 0.63–0.78).

Conclusions: Among patients without intrinsic LBBB undergoing CRT, upgrade from pacemaker and AVN ablation were favorable factors in achieving CRT response and better long-term outcomes.

Sex-related differences in the clinical characteristics of wild-type transthyretin amyloidosis cardiomyopathy

BACKGROUND

A significant male predominance has been reported in wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). Hence, female cases of ATTRwt-CM are overlooked, and sex-related differences in ATTRwt-CM remain unclear. This study aimed to examine sex-related differences in clinical characteristics and diagnostic approaches in ATTRwt-CM.

METHODS

We retrospectively analyzed 199 consecutive patients who were diagnosed with ATTRwt-CM and evaluated sex-related differences in clinical characteristics, imaging parameters, biomarkers, and diagnostic approaches.

RESULTS

Twenty-nine patients (15%) were female. These female patients were significantly older at diagnosis (77.1 ± 6.5 years vs. 82.9 ± 4.8 years; p<0.001) and had a more advanced New York Health Association functional class (2.2 ± 0.7 vs. 2.6 ± 0.8; p = 0.006) than their male counterparts. The median B-type natriuretic peptide levels were significantly higher (236 pg/mL vs. 394 pg/mL; p = 0.017) in female patients. Echocardiography revealed that the mean interventricular septum diameter was thinner (15.7 ± 2.6 mm vs. 14.1 ± 2.5 mm; p = 0.004) and left ventricular ejection fraction (LVEF) was preserved (51.2 ± 10.2% vs. 57.2 ± 9.1%; p = 0.003) in female patients. The mean heart-to-contralateral ratio obtained using ^99mTc-labeled pyrophosphate (^99mTc-PYP) was significantly lower (1.89 ± 0.33 vs. 1.63 ± 0.20; p < 0.001), moderate to severe aortic stenosis was more frequently observed (5% vs. 45%; p < 0.001), and the frequency of histological diagnosis was significantly lower (77% vs. 59%; p = 0.036) in female patients.

CONCLUSIONS

Female patients with ATTRwt-CM were predominantly octogenarians and less hypertrophic and had preserved LVEF and weaker cardiac uptake of the ^99mTc-PYP tracer compared with male patients. These characteristics contribute to the underdiagnosis of ATTRwt-CM in female patients.

Clinical characteristics and the severity of coronary atherosclerosis of different subtypes of bundle-branch block

BACKGROUND

Right bundle-branch block (RBBB) and left bundle-branch block (LBBB) play a role in the pathogenesis and progression of coronary artery disease (CAD). However, the clinical features and the severity of coronary artery disease associated with different subtypes of bundle-branch block, according to time of new appearance, is not well characterized in patients with no known CAD.

METHODS

We retrospectively analyzed data pertaining to consecutive patients with RBBB or LBBB who underwent coronary angiography. The severity of coronary lesions was evaluated using the SYNTAX score. The differential effect of new-onset RBBB, old RBBB, new-onset LBBB, and old LBBB on the severity of CAD and its association with clinical characteristics was quantified. Multivariate logistic regression analysis was performed to evaluate the effect of RBBB and LBBB on the degree of coronary atherosclerosis in patients without known CAD.

RESULTS

Out of the 243 patients, 72 patients had old LBBB, 37 had new-onset LBBB, 93 patients had old RBBB, and 41 patients had new-onset RBBB. On univariate analysis, age, systolic blood pressure, diastolic blood pressure, creatinine, serum glucose, and glycosylated hemoglobin level were associated with high SYNTAX score (p < .05 for all). Patients in the new-onset RBBB, old RBBB, new-onset LBBB, and old LBBB groups showed significant differences in baseline characteristics and coronary atherosclerosis (p < .05 for all). However, there were no significant between-group differences with respect to the degree of coronary atherosclerosis as assessed by SYNTAX score.

CONCLUSIONS

New-onset RBBB, old RBBB, new-onset LBBB, and old LBBB were not associated with the severity of coronary lesions as assessed by SYNTAX score in patients without known CAD.

Aortic valve implantation-induced conduction block as a framework towards a uniform electrocardiographic definition of left bundle branch block

Introduction

New-onset left bundle branch block (LBBB) following transcatheter or surgical aortic valve replacement (LBBB_AVI) implies a proximal pathogenesis of LBBB. This study compares electrocardiographic characteristics and concordance with LBBB definitions between LBBB_AVI and non-procedure-induced LBBB controls (LBBB_control).

Methods

All LBBB_AVI patients at Ghent University Hospital between 2013 and 2019 were enrolled in the study. LBBB_AVI patients were matched for age, sex, ischaemic heart disease and ejection fraction to LBBB_control patients in a 1:2 ratio. For inclusion, a non-strict LBBB definition was used (QRS duration ≥ 120 ms, QS or rS in V1, absence of Q waves in V5-6). Electrocardiograms were digitally analysed and classified according to three LBBB definitions: European Society of Cardiology (ESC), Strauss and American Heart Association (AHA).

Results

A total of 177 patients (59 LBBB_AVI and 118 LBBB_control) were enrolled in the study. LBBB_AVI patients had more lateral QRS notching/slurring (100% vs 85%, p = 0.001), included a higher percentage with a QRS duration ≥ 130 ms (98% vs 86%, p = 0.007) and had a less leftward oriented QRS axis (−15° vs −30°, p = 0.013) compared to the LBBB_control group. ESC and Strauss criteria were fulfilled in 100% and 95% of LBBB_AVI patients, respectively, but only 18% met the AHA criteria. In LBBB_control patients, concordance with LBBB definitions was lower than in the LBBB_AVI group: ESC 85% (p = 0.001), Strauss 68% (p < 0.001) and AHA 7% (p = 0.035). No differences in electrocardiographic characterisation or concordance with LBBB definitions were observed between LBBB_AVI and LBBB_control patients with lateral QRS notching/slurring.

Conclusion

Non-uniformity exists among current LBBB definitions concerning the detection of proximal LBBB. LBBB_AVI may provide a framework for more consensus on defining proximal LBBB.

Supplementary Information

The online version of this article (10.1007/s12471-021-01565-8) contains supplementary material, which is available to authorized users.

Predictors of high-degree conduction disturbances and pacemaker implantation after transcatheter aortic valve replacement: Prognostic role of the electrophysiological study

BACKGROUND

Predictors of high-degree atrioventricular block (HAVB) after transcatheter aortic valve replacement (TAVR) are recognized, but the electrophysiological study's (EPS) role is still a subject to debate. The objective of our study was to determine factors associated with PPM implantation including the potential role of EPS before and/or after TAVR.

METHODS AND RESULTS

Seventy four consecutive patients (pts) were included and 21 pts (28.4%) received a PPM during the immediate postoperative follow-ups (until Day 5): HAVB in 15 pts (71.4%), prophylactic implantation due to a documented increased HV interval ≥ 95-100 ms plus LBBB in 2 pts (9.5%), a high-degree HV block evidenced at the EPS plus LBBB in 3 pts (14.3%) and one additional patient was implanted for AV-block in presence of AFib (4.8%). In the multivariate model 1 including parameters before TAVR, both prosthesis diameter and PR lengthening remained significantly associated with PPM as well RBBB. In the multivariate model 2 including parameters after TAVR, only HV remained significantly associated with the risk of PPM (OR = 1.15 (1.05-1.26), p = .004). When all the significant variables in models 1 and 2 were analyzed together in model 3, only HV after TAVR remained significantly associated with an increased risk of PPM.

CONCLUSIONS

In this prospective observational study, it was revealed that a Day 4-5 EPS is likely to more precisely stratify the risk of PPM implantation regarding its ability to discover asymptomatic severe infra-hisian conduction disturbances particularly in presence of LBBB. Multivariate analysis confirmed the prognostic value of HV alteration.

Validation of Normal P-Wave Parameters in a Large Unselected Pediatric Population of North-Western Romania: Results of the CARDIOPED Project

Aims

Reference values of the P-wave on 12 lead electrocardiograms are lacking for children and adolescents in Eastern Europe. Hence, the present study is aimed at determining the standard values of the P-wave in children and adolescents based on ECG data from the CARDIOPED project, a large-scale general population of children who participated in a screening program in Transylvania, Romania.

Methods and Results

A total of 22,411 ECGs of participants aged 6 to 18 years old from a school-based ECG screening were obtained between February 2015 and December 2015 in Transylvania, Romania. Three pediatric cardiologists manually reviewed each ECG. P-wave duration, voltage, axis, and correlation with gender and age were analyzed. The mean P-wave duration was 88 ± 10.7 ms, with a maximum duration of 128 ms. P-wave showed a positive correlation with age but did not differ between sexes. There was a positive correlation between the P-wave duration and the heart rate, but not with the body max index. The mean P-wave axis was 40.4 ± 31.1, and the mean P-wave amplitude was 0.12 ± 0.03 mV.

Conclusion

In this study on many pediatric subjects, we have provided normal limits for the P-wave in Romanian children aged 6-18 years. Our findings are useful for creating interpretation guidelines for pediatric ECG.

Short P-Wave Duration is a Marker of Higher Rate of Atrial Fibrillation Recurrences after Pulmonary Vein Isolation: New Insights into the Pathophysiological Mechanisms Through Computer Simulations

Background Short ECG P-wave duration has recently been demonstrated to be associated with higher risk of atrial fibrillation (AF). The aim of this study was to assess the rate of AF recurrence after pulmonary vein isolation in patients with a short P wave, and to mechanistically elucidate the observation by computer modeling. Methods and Results A total of 282 consecutive patients undergoing a first single-pulmonary vein isolation procedure for paroxysmal or persistent AF were included. Computational models studied the effect of adenosine and sodium conductance on action potential duration and P-wave duration (PWD). About 16% of the patients had a PWD of 110 ms or shorter (median PWD 126 ms, interquartile range, 115 ms-138 ms; range, 71 ms-180 ms). At Cox regression, PWD was significantly associated with AF recurrence (P=0.012). Patients with a PWD <110 ms (hazard ratio [HR], 2.20; 95% CI, 1.24-3.88; P=0.007) and patients with a PWD ≥140 (HR, 1.87, 95% CI, 1.06-3.30; P=0.031) had a nearly 2-fold increase in risk with respect to the other group. In the computational model, adenosine yielded a significant reduction of action potential duration 90 (52%) and PWD (7%). An increased sodium conductance (up to 200%) was robustly accompanied by an increase in conduction velocity (26%), a reduction in action potential duration 90 (28%), and PWD (22%). Conclusions One out of 5 patients referred for pulmonary vein isolation has a short PWD which was associated with a higher rate of AF after the index procedure. Computer simulations suggest that shortening of atrial action potential duration leading to a faster atrial conduction may be the cause of this clinical observation.

P-Wave Changes Associated with Chiari Network in the Right Atrium

The Chiari network (CN) is a mobile, net-like structure occasionally present in the right atrium, near the opening of the inferior vena cava and coronary sinus. While typically asymptomatic, it may contribute to thromboembolism or right atrial pathologies. Here, we hypothesized that existing differences in P-wave morphology on electrocardiograms (ECG) may be associated with atrial conduction changes. Seventy-one children with a CN were recruited and matched to 60 healthy controls. P-wave duration, P-wave amplitude, P dispersion (Pd), QRS, PR, QT, and QTc (calculated with Bazett formula) intervals were measured and compared. Between the control and the patient groups, the mean P-wave duration was 78.1 ms and 88.7 ms, P amplitude was 1.3 mm and 1.1 mm, and Pd was 18.9 and 35.5 ms, respectively. These differences were statistically significant across all measurements (p < 0.05). Atrial conduction may be affected in patients with CN, and these patients may then develop atrial arrhythmia.

Long-term outcome of pre-specified ECG patterns in acute coronary syndrome

BACKGROUND

Long-term outcome of real-life acute coronary syndrome (ACS) patients with selected ECG patterns is not well known.

PURPOSE

To survey the 10-year outcome of pre-specified ECG patterns in ACS patients admitted to a university hospital.

METHODS

A total of 1184 consecutive acute coronary syndrome patients in 2002-2003 were included and followed up for 10 years. The patients were classified into nine pre-specified ECG categories: 1) ST elevation; 2) pathological Q waves without ST elevation; 3) left bundle branch block (LBBB); 4) right bundle branch block (RBBB) 5) left ventricular hypertrophy (LVH) without ST elevation except in leads aVR and/or V₁; 6) global ischemia ECG (ST depression ≥0.5 mm in 6 leads, maximally in leads V_4-5 with inverted T waves and ST elevation ≥0.5 mm in lead aVR); 7) other ST depression and/or T wave inversion; 8) other findings and 9) normal ECG.

RESULTS

Any abnormality in the ECG, especially Q waves, LBBB, LVH and global ischemia, had negative effect on outcome. In age- and gender adjusted Cox regression analysis, pathological Q waves (HR 2.28, 95%CI 1.20-4.32, p = .012), LBBB (HR 3.25, 95%CI 1.65-6.40, p = .001), LVH (HR 2.53, 95%CI 1.29-4.97, p = .007), global ischemia (HR 2.22, 95%CI 1.14-4.31, p = .019) and the combined group of other findings (HR 3.01, 95%CI 1.56-6.09, p = .001) were independently associated with worse outcome.

CONCLUSIONS

During long-term follow-up of ACS patients, LBBB, ECG-LVH, global ischemia, and Q waves were associated with worse outcome than a normal ECG, RBBB, ST elevation or ST depression with or without associated T-wave inversion. LBBB was associated with the highest mortality rates.

Clinical characteristics and natural history of wild-type transthyretin amyloid cardiomyopathy in Japan

Aims

The focus on wild‐type transthyretin amyloid cardiomyopathy (ATTRwt‐CM) is increasing because of novel treatment options. There is currently no report on a large number of Japanese patients with ATTRwt‐CM. The study aimed to examine the characteristics and prognosis of ATTRwt‐CM in Japan.

Methods and results

Consecutive patients (78.5 ± 6.4 years old at diagnosis) with ATTRwt‐CM diagnosed at Kumamoto University Hospital between December 2002 and December 2019 were retrospectively reviewed. Data, including demographic characteristics, co‐morbidities, clinical manifestations at diagnosis, laboratory results, electrocardiographic and echocardiographic data, imaging and pathological findings, and treatment were obtained. Of 129 patients included in this study, 110 patients (85%) were male. The median period from initial symptom onset to diagnosis was 15.5 (2–75) months. Heart failure was the most common clinical manifestation leading to diagnosis (61%) and initial manifestations (49%). Of 106 patients, carpal tunnel syndrome was observed in 57 patients (54%), and the median period from initial symptom onset to diagnosis was 96 (48–120) months. Histopathological confirmation of transthyretin amyloid was achieved in 94 patients (73%), including 66 (51%) and 28 cases (22%) with endomyocardial and extracardiac biopsies. During the observation period (median 15.0 [inter‐quartile range, 5.4–33.2] months after diagnosis), 34 patients (26%) died. Of these, 27 patients (79%) had cardiovascular deaths (heart failure, 25; sudden death, two). The median survival duration was 58.9 months and the 5 years' survival rate was 48%. According to a multivariate Cox hazard analysis, age [hazard ratio (HR), 1.14; 95% confidence interval (CI), 1.05–1.23, P = 0.002] and low serum sodium levels (HR, 0.89; 95% CI, 0.79–0.996; P = 0.04) contributed to all‐cause mortality, and low serum sodium levels contributed to hospitalization for heart failure (HR, 0.86; 95% CI, 0.77–0.96; P = 0.005).

Conclusions

Clinical characteristics and prognosis of ATTRwt‐CM patients in Japan were examined. Carpal tunnel syndrome can be considered an indication for diagnosis of ATTRwt‐CM. Age and low serum sodium level were significant predictive factors of all survival outcomes. The clinical features of ATTRwt‐CM should be recognized to provide appropriate treatment.

Combination of Left Ventricular End-Diastolic Diameter and QRS Duration Strongly Predicts Good Response to and Prognosis of Cardiac Resynchronization Therapy

Background

Approximately 20–40% of recipients of cardiac resynchronization therapy (CRT) do not respond to it based on the current patient selection criteria. The purpose of this study was to identify baseline parameters that can predict CRT response and to evaluate the effect of those predictive parameters on long-term prognosis.

Methods

This was a retrospective, nonrandomized, noncontrolled cohort study. Patients who received CRT in our centre were divided into responders and nonresponders by the definition of CRT response (an increase in left ventricular ejection fraction (LVEF) of ≥5% and improvement of ≥1 New York Heart Association (NYHA) class from baseline to the 6-month follow-up).

Results

Of the 101 patients, 68 were responders and 33 were nonresponders. Left ventricular end-diastolic diameter (LVEDD; OR: 0.88, 95% CI: 0.81–0.95, P=0.001) and QRS duration (OR: 1.07, 95% CI: 1.04–1.10, P < 0.001) were independent predictors of CRT response. The combination of LVEDD and QRS duration was more valuable for predicting CRT response (AUC 0.836; 95% CI: 0.76–0.91; P < 0.001). Moreover, the combination of LVEDD ≤ 71 mm and QRS duration ≥ 170 ms had a low incidence of all-cause mortality, HF hospitalisation, and the composite endpoint. In addition, baseline LVEDD had a positive correlation with QRS duration (R=0.199, P=0.046). Responders to CRT had better LV reverse remodeling.

Conclusion

The combination of LVEDD and QRS duration provided more robust prediction of CRT response. Moreover, the combination of LVEDD ≤ 71 mm and QRS duration ≥ 170 ms was associated with a low incidence of all-cause mortality, HF hospitalisation, and the composite endpoint. Our results may be useful to provide individualized patient selection for CRT.

Natural history and clinical significance of isolated complete left bundle branch block without associated structural heart disease

OBJECTIVE

Left bundle branch block (LBBB), which is associated with underlying cardiac disease, is believed to play a role in the pathogenesis of cardiomyopathy through delays in interventricular conduction, leading to dyssynchrony. However, this has not been established in previous studies. It is unclear whether LBBB indicates clinically advanced cardiac disease or is an independent factor responsible for increased mortality and the development of heart failure. We investigated the natural history of isolated LBBB without any associated structural heart disease in order to determine its clinical significance.

METHODS

We performed a retrospective chart review on consecutive patients who fulfilled the 12-lead electrocardiographic (ECG) criteria for complete LBBB and had a normal echocardiogram with no evidence of structural heart disease and left or right ventricular systolic dysfunction within three months of the initial ECG between January 1, 2000 and December 31, 2009. We excluded patients with documented coronary artery disease (CAD) at any time, any structural heart disease, or cardiac devices. We evaluated the primary endpoints of mortality and incidence of cardiomyopathy, as well as any heart failure hospitalizations over a 1- and 10-year period.

RESULTS

We identified 2522 eligible patients. The mean follow-up duration was 8.4±3.2 years. The one-year mortality rate was 7.8%, with a 10-year mortality rate of 22.0%. The incidence of cardiomyopathy over one year was 3.2% and over 10 years was 9.1%. There was no significant difference in QRS duration between patients who were alive and those that were deceased at 10 years (141+/-18 vs. 141+/-17 ms; p=0.951) and patients with and without cardiomyopathy at 10 years (142±17 vs. 141±17 ms; p=0.532).

CONCLUSION

Isolated LBBB occurring without structural heart disease, ventricular dysfunction, or CAD is associated with a low mortality rate and incidence of cardiomyopathy.

Progression of incomplete toward complete left bundle branch block: A clinical and electrocardiographic analysis

Background

Complete left bundle branch block (cLBBB) is associated with increased cardiovascular mortality and heart failure. On the contrary, the clinical relevance of incomplete left bundle branch block (iLBBB) is less known. This study investigated the profile and outcome of iLBBB patients and assessed the risk of progression to cLBBB.

Methods

Patients diagnosed with iLBBB between July 2013 and April 2018 were retrospectively included. Subsequently, echo‐ and electrocardiographic examinations at time of iLBBB diagnosis and during follow‐up, as well as progression to non‐strict cLBBB and strict cLBBB, were evaluated.

Results

The study enrolled 321 patients (33% female, age 74 ± 11 years). During the follow‐up of 21 (8;34) months, 33% of iLBBB patients evolved to non‐strict cLBBB and 27% to strict cLBBB. iLBBB patients who evolved to non‐strict or strict cLBBB were older, had more frequently reduced left ventricular ejection fraction, and had more often QRS notching/slurring in the lateral leads and inferior leads, compared to patients without progression to cLBBB. In multivariate analysis, only QRS notching/slurring in the lateral leads was independently associated with progression to non‐strict cLBBB (odds ratio 4.64, p < .001) and strict cLBBB (odds ratio 9.6, p < .001). iLBBB patients with QRS notching/slurring had a progression rate to non‐strict cLBBB of 52% and 49% to strict cLBBB.

Conclusion

Among patients with iLBBB, up to one third of the patients progress to cLBBB within a period of 2 years. The presence of QRS notching/slurring in the lateral leads during iLBBB was the strongest predictor for progression toward cLBBB.

Intra-Atrial Block: Definition and Relationship to Atrial Fibrillation and Other Adverse Outcomes

In 1916, Bachmann first reported on the inter-auricular time interval. However relatively little attention was paid to this ECG measurement for decades. Then, in 1956, Samuel Bradley and Henry JJ Marriott reported on intra-atrial block (IAB) in 4,500 ECGs.As defined by them, IAB was a P wave duration of 0.12 sec or longer. Since that time, others have defined IAB as 0.11 sec or longer or 0.12 sec or longer. Several authors have suggested subcategories, such as first-, second-, and third-degree patterns and some have defined specific intra-atrial and inter-atrial pathways. These are of electrocardiographic interest but have not been substantiated as related to different clinical outcomes. Many disorders have been associated with IAB. More importantly, however, IAB has been associated with several adverse outcomes, including sinus node dysfunction, atrial tachyarrhythmias - especially atrial fibrillation, thromboembolic events, and increased mortality. This brief review will detail the above to emphasize to ECG readers the importance of not overlooking IAB in their interpretations.

Mortality and Sudden Cardiac Death Risk Stratification Using the Noninvasive Combination of Wide QRS Duration and Late Gadolinium Enhancement in Idiopathic Dilated Cardiomyopathy

BACKGROUND

The aim of this study was to investigate whether the combination of QRS duration ≥120 ms (wide QRS duration [wQRS]) and late gadolinium enhancement (LGE) is a precise prognostic indicator for dilated cardiomyopathy.

METHODS AND RESULTS

We investigated the association between the combination of LGE plus wQRS and the primary end point (all-cause death) and a composite of sudden cardiac death (SCD) or aborted SCD in 531 patients with dilated cardiomyopathy. We also analyzed the association between the combination of LGE and wQRS and these end points among patients with a class I indication for implantable cardioverter defibrillator implantation. We divided study patients into 3 groups according to LGE status and QRS duration: 2 negative indices (LGE negative and narrow QRS), 1 positive index (LGE positive or wQRS), or 2 positive indices (LGE positive and wQRS), and followed them for 3.8 years. Multivariable Cox regression analysis identified 2 positive indices as a significant predictor of all-cause death (hazard ratio, 4.29 [1.19-15.47]; P=0.026). Among 317 patients with a class I indication for implantable cardioverter defibrillator, the 5-year event rate of SCD or aborted SCD was the lowest in the 2 negative indices group (1.4%). With propensity score-matching cohorts, the 2 negative indices group had a significantly lower event rate of SCD or aborted SCD than the other 2 groups (hazard ratio, 0.12 [0.01-0.97]; P=0.046).

CONCLUSIONS

The combination of LGE and wQRS provides additional prognostic stratification compared with LGE status alone and might improve the appropriate use of implantable cardioverter defibrillator therapy in patients with dilated cardiomyopathy.

Combination of Commonly Examined Parameters Is a Useful Predictor of Positive 99 mTc-Labeled Pyrophosphate Scintigraphy Findings in Elderly Patients With Suspected Transthyretin Cardiac Amyloidosis

BACKGROUND

A recent study revealed a high prevalence of transthyretin (TTR) cardiac amyloidosis (CA) in elderly patients. ^{99 m}Tc-labeled pyrophosphate (^{99 m}Tc-PYP) scintigraphy is a remarkably sensitive and specific modality for TTR-CA, but is only available in specialist centres; thus, it is important to raise the pretest probability. The aim of this study was to evaluate the characteristics of patients with ^{99 m}Tc-PYP positivity and make recommendations about patient selection for ^{99 m}Tc-PYP scintigraphy.Methods and Results:We examined 181 consecutive patients aged ≥70 years who underwent ^{99 m}Tc-PYP scintigraphy at Kumamoto University Hospital between January 2012 and December 2018. Logistic regression analyses showed that high-sensitivity cardiac troponin T (hs-cTnT) ≥0.0308 ng/mL, left ventricular posterior wall thickness ≥13.6 mm, and wide QRS (QRS ≥120 ms) were strongly associated with ^{99 m}Tc-PYP positivity. We developed a new index for predicting ^{99 m}Tc-PYP positivity by adding 1 point for each of the 3 factors. The ^{99 m}Tc-PYP positive rate increased by a factor of 4.57 for each 1-point increase (P<0.001). Zero points corresponded to a negative predictive value of 87% and 3 points corresponded to a positive predictive value of 96% for ^{99 m}Tc-PYP positivity.

CONCLUSIONS

The combination of biochemical (hs-cTnT), physiological (wide QRS), and structural (left ventricular posterior wall thickness) findings can raise the pretest probability for ^{99 m}Tc-PYP scintigraphy. It can assist clinicians in determining management strategies for elderly patients with suspected CA.

Prognostic Implication of Ventricular Conduction Disturbance Pattern in Hospitalized Patients with Acute Heart Failure Syndrome

Background and Objectives

Conflicting data exist regarding the prognostic implication of ventricular conduction disturbance pattern in patients with heart failure (HF). This study investigated the prognostic impact of ventricular conduction pattern in hospitalized patients with acute HF.

Methods

Data from the Korean Acute Heart Failure registry were used. Patients were categorized into four groups: narrow QRS (<120 ms), right bundle branch block (RBBB), left bundle branch block (LBBB), and nonspecific intraventricular conduction delay (NICD). The NICD was defined as prolonged QRS (≥120 ms) without typical features of LBBB or RBBB. The primary endpoint was the composite of all-cause mortality or rehospitalization for HF aggravation within 1 year after discharge.

Results

This study included 5,157 patients. The primary endpoint occurred in 39.7% of study population. The LBBB group showed the highest incidence of primary endpoint followed by NICD, RBBB, and narrow QRS groups (52.5% vs. 49.7% vs. 44.4% vs. 37.5%, p<0.001). In a multivariable Cox-proportional hazards regression analysis, LBBB and NICD were associated with 39% and 28% increased risk for primary endpoint (LBBB hazard ratio [HR], 1.392; 95% confidence interval [CI], 1.152–1.681; NICD HR, 1.278; 95% CI, 1.074–1.520) compared with narrow QRS group. The HR of RBBB for the primary endpoint was 1.103 (95% CI, 0.915–1.329).

Conclusions

LBBB and NICD were independently associated with an increased risk of 1-year adverse event in hospitalized patients with HF, whereas the prognostic impacts of RBBB were limited.

Trial Registration

ClinicalTrials.gov Identifier: NCT01389843

Influence of Left Bundle Branch Block on the Electrocardiographic Changes Induced by Acute Coronary Artery Occlusion of Distinct Location and Duration

Background: Electrocardiographic (ECG) diagnosis of acute myocardial ischemia is hampered in the presence of left bundle branch block (LBBB).

Objectives: We analyzed the influence of location and duration of myocardial ischemia on the ECG changes in pigs with LBBB.

Methods: LBBB was acutely induced in 14 closed chest anesthetized pigs by local electrical ablation. Thereafter, episodes of 5 min catheter balloon occlusion followed by 10 min reperfusion of the left anterior descending (LAD), left circumflex (LCX), and right (RCA) coronary arteries were done sequentially in 5 pigs. Additionally, a 3-h occlusion of these arteries was performed separately in the other 9 pigs. A 15-lead ECG including leads V7 to V9 was continuously recorded.

Results: Ablation induced LBBB showed QRS widening, loss of r wave in V1, and predominant R waves in V2 to V9. After 5 min of ischemia the occluded artery could be identified in all cases: the LAD by R waves and ST elevation in V1–V3; the LCX by both ST segment elevation in II, III, aVF, V7 to V9 and ST segment depression in V1 to V4; and the RCA by ST depression and new S-waves in all precordial leads. Three hours after coronary occlusion, ST segment changes declined progressively and only the LAD occlusion could be reliably recognized.

Conclusion: LBBB did not mask the ECG recognition of the occluded coronary artery during the first 60 min of ischemia, but 3 h later only the LAD occlusion could be reliably identified. ST elevation in leads V7 to V9 is specific of LCX occlusion and it could be useful in the diagnosis of acute myocardial ischemia in the presence of LBBB.

True complete left bundle branch block reveals dyssynchrony evaluated by semiconductor single-photon emission computed tomography

BACKGROUND

Conventional complete left bundle branch block (CLBBB) criteria sometimes result in a false-positive diagnosis that does not represent dyssynchrony. Recently, true CLBBB criteria have been proposed to detect responders to cardiac resynchronization therapy (CRT), although their correlation with severity of dyssynchrony or natural prognosis is unclear.

METHODS

Ninety-four consecutive patients (74 ± 9 years, 63 men) with conventional CLBBB during sinus rhythm underwent semiconductor SPECT. They were divided into two groups: patients with true CLBBB and others. True CLBBB was characterized by the mid-QRS notching/slurring and wide QRS duration (male, ≥140 milliseconds; female, ≥130 milliseconds). Multivariate analysis was performed to detect left ventricular dyssynchrony (LVD), defined as bandwidth ≥145° and/or phase standard deviation (SD) ≥43°. Primary endpoints (hospitalization for heart failure or cardiac death) were evaluated.

RESULTS

True CLBBB had wider bandwidth (145 ± 83° vs 110 ± 64°, P = 0.024) and higher phase SD (48 ± 26° vs 35 ± 19°, P = 0.007). Ejection fraction (EF), end-diastolic volume (EDV), summed rest score (SRS), and the presence of ischemic heart disease (IHD) showed no differences between groups (P = 0.401, 0.591, 0.165, and 0.212, respectively). Multivariate analysis revealed that true CLBBB, EF, and EDV were significant predictors of LVD (odds ratio, 12.6, 0.90, 1.03; P = 0.003, 0.002, 0.022, respectively). At 3-year follow-up (median 667 days), primary endpoints were comparable in both groups (log-rank, P = 0.92).

CONCLUSIONS

Patients with true CLBBB had more severe dyssynchrony on single-photon emission computed tomography than patients with nontrue CLBBB. On the other hand, the two groups showed no differences in EF, EDV, the presence of IHD, hospitalization for heart failure, and cardiac death.

Left bundle branch block and the evolving role of QRS morphology in selection of patients for cardiac resynchronization

BACKGROUND

The clinical significance of left bundle branch block (LBBB) has recently expanded with the discovery of a strong association with better outcomes in patients receiving cardiac resynchronization therapy.

METHODS

Several milestones have contributed to the current understanding on the role of LBBB in clinical practice.

RESULT

Sunao Tawara described the arrangement of components of what he called the cardiac conduction system from the atrioventricular node to the terminal Purkinje fibers that connect to the working myocardium, and his hypotheses on how it functions remain current. Mauricio Rosenbaum and colleagues developed the bifascicular model of the left-sided conduction system that explains the characteristic electrocardiographic changes associated with propagation disturbances in its components. Andrés Ricardo Pérez-Riera and others have disputed the bifascicular model as oversimplified and have emphasized the role of the left septal fascicle. Marcelo Elizari and colleagues have explained the importance of masquerading bundle branch block. Elena Sgarbossa and colleagues developed a scheme to recognize ST elevation myocardial infarction in patients with left bundle branch block which remains current after more than 20 years. Enrique Cabrera and others identified electrocardiographic signs of remote myocardial infarction.

CONCLUSION

Substantial progress has been made in the understanding of LBBB, yet its role in clinical practice continues to evolve and important gaps remain to which research should be directed.

Usefulness of Electrocardiographic Left Atrial Abnormality to Predict Response to Cardiac Resynchronization Therapy in Patients With Mild Heart Failure and Left Bundle Branch Block (a Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy Substudy)

Cardiac resynchronization therapy (CRT) has proven prognostic benefits in patients with heart failure (HF) with left bundle branch block (LBBB) QRS morphology. Electrocardiographic left atrial (LA) abnormality has been proposed as a noninvasive marker of atrial remodeling. We aimed to assess the impact of electrocardiographic LA abnormality for prognosis in patients with HF treated with CRT. Baseline resting 12-lead electrocardiograms recorded from 941 patients enrolled in the CRT arm of the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy was processed automatically using Glasgow algorithm, which included automated assessment of P-wave terminal force in lead V₁ (PTF-V₁) as a marker of LA abnormality. A PTF-V₁ of ≥0.04 mm⋅s was considered abnormal. The primary end point was HF event and/or death. Total mortality and appropriate defibrillator therapies were the secondary end points. At baseline 550, patients treated with CRT with a defibrillator had LBBB QRS morphology and normal PTF-V₁. Normal PTF-V₁ was associated with significant risk reduction for all assessed end points and for the primary end point comprised a hazard ratio of 0.55 (95% confidence interval 0.36 to 0.84) compared with patients with LBBB with abnormal PTF-V₁ (n = 120), and a hazard ratio of 0.42 (95% confidence interval 0.32 to 0.55) compared with patients with implanted defibrillator (n = 729). In CRT-treated patients with HF, electrocardiographic LA abnormality appears to be an electrocardiographic indicator of poor long-term outcome in patients with LBBB. In conclusion, our data suggest that PTF-V₁ bears additive prognostic information in the context of CRT, thus further strengthening the role of electrocardiographic diagnostics in risk stratification of patients with HF.

Multipoint pacing via a quadripolar left-ventricular lead: preliminary results from the Italian registry on multipoint left-ventricular pacing in cardiac resynchronization therapy (IRON-MPP)

Aims

This registry was created to describe the experience of 76 Italian centres with a large cohort of recipients of multipoint pacing (MPP) capable cardiac resynchronization therapy (CRT) devices.

Methods and results

A total of 507 patients in whom these devices had been successfully implanted were enrolled between August 2013 and May 2015. We analysed: (i) current clinical practices for the management of such patients, and (ii) the impact of MPP on heart failure clinical composite response and on the absolute change in ejection fraction (EF) at 6 months. Multipoint pacing was programmed to ‘ON’ in 46% of patients before discharge. Methods of optimizing MPP programming were most commonly based on either the greatest narrowing of the QRS complex (38%) or the electrical delays between the electrodes (34%). Clinical and echocardiographic follow-up data were evaluated in 232 patients. These patients were divided into two groups according to whether MPP was programmed to ‘ON’ (n = 94) or ‘OFF’ (n = 138) at the time of discharge. At 6 months, EF was significantly higher in the MPP group than in the biventricular-pacing group (39.1 ± 9.6 vs. 34.7 ± 7.6%; P < 0.001). Even after adjustments, early MPP activation remained an independent predictor of absolute increase in LVEF of ≥5% (odds ratio 2.5; P = 0.001). At 6 months, an improvement in clinical composite score was recorded in a greater proportion of patients with MPP-ON than in controls (56 vs. 38%; P = 0.009). On comparing optimal MPP and conventional vectors, QRS was also seen to have decreased significantly (P < 0.001).

Conclusion

This study provides information that is essential in order to deal with the expected increase in the number of patients receiving MPP devices in the coming years. The results revealed different practices among centres, and establishing the optimal programming that can maximize the benefit of MPP remains a challenging issue. Compared with conventional CRT, MPP improved clinical status and resulted in an additional increase in EF.

Clinical Trial Registration

http://www.clinicaltrial.gov/. Unique identifier: NCT02606071.

Comparison of four LBBB definitions for predicting mortality in patients receiving cardiac resynchronization therapy

BACKGROUND

Left bundle branch block (LBBB) is considered an important prognostic parameter in cardiac resynchronization therapy (CRT). We aimed to evaluate, in a sizeable cohort of patients with CRT, long-term mortality, and morbidity according to four different electrocardiographic definitions of LBBB.

METHODS

This longitudinal cohort study included consecutive patients who underwent CRT device implantation in our institution in years 2006-2014. Two endpoints were assessed: (a) death from any cause or urgent heart transplantation, and (b) death from any cause or heart failure admission. All preimplantation ECGs were analyzed by three physicians blinded to outcome and categorized as LBBB or non-LBBB according to four definitions.

RESULTS

A total of 552 CRT patients entered survival analysis. According to the conventional definition, 350 (63.4%) patients had LBBB, and the Marriott, WHO/AHA, and Strauss definitions identified LBBB in 254 (46.0%), 218 (39.5%) and 226 (40.9%) patients, respectively. During the 9 years of observation, 232 patients died, the combined endpoint was met by 292 patients. The Strauss LBBB definition was significantly better to the other definitions in predicting survival (Kaplan-Meier analysis with comparison of C-statistics). Multivariate Cox regression model showed that LBBB was the major determinant of all-cause mortality with the Strauss definition having the lowest hazard ratio (0.51) of the four studied definitions.

CONCLUSIONS

Criteria included in various definitions of LBBB result in a diagnosis of LBBB in divergent groups of patients. Differences in LBBB definitions have clinical consequences, as patients without 'complete/true' LBBB probably get no mortality benefit from CRT.

Acute biventricular hemodynamic effects of cardiac resynchronization therapy in right bundle branch block

BACKGROUND

Controversy remains regarding the use of cardiac resynchronization therapy (CRT) in patients with heart failure with right bundle branch block (RBBB) and reduced left ventricular (LV) ejection fraction. Moreover, little is known about acute hemodynamic changes with CRT in this subgroup as compared with patients with left bundle branch block (LBBB).

OBJECTIVE

The purpose of this study was to evaluate the acute biventricular hemodynamic response of CRT and other pacing configurations, including the effects of atrioventricular (AV) delay and atrial pacing, to understand the effects of CRT in RBBB.

METHODS

Forty patients (9 with RBBB and 31 with LBBB) undergoing CRT implantation underwent temporary pacing with varying configurations and AV delay. The acute hemodynamic response was assessed via invasive measurements of dP/dt_max (maximal rate of change in pressure) in the left ventricle (LV) as well as the right ventricle (RV) in patients with RBBB.

RESULTS

Patients with LBBB had a greater LV dP/dt_max response to CRT than did patients with RBBB. In patients with RBBB, single- or dual-site RV pacing configurations resulted in greater increases in RV dP/dt_max than did biventricular pacing. Optimal AV delays that maximized RV dP/dt_max were shorter than optimal AV delays for LV dP/dt_max. Furthermore, AV delays chosen to maximize improvement in RV dP/dt_max frequently resulted in negative effects on LV dP/dt_max.

CONCLUSION

These findings demonstrate a complex relationship between pacing configuration, AV delay, and hemodynamic responses. The biventricular hemodynamic response in patients with heart failure with RBBB might be improved by optimizing pacing modalities and AV delays. This may be particularly important in patients with diseases in whom RV failure predominates, such as patients with pulmonary hypertension and LV assist device.

Intraventricular Delay and Blocks

From the atrioventricular node, electrical activation is propagated to both ventricles by a system of specialized conducting fibers, His Purkinje System (HPS), guaranteeing a fast, synchronous depolarization of both ventricles. From the predivisional common stem, a right and left branch separate, subdividing further in a fairly predictable fashion. Synchronous ventricular activation results in a QRS with specific characteristics and duration of less than 110 milliseconds. Block or delay in any part of the HPS changes the electrocardiographic (ECG) morphology. This article discusses the use and limitations of standard ECG in detecting abnormal ventricular propagation in specific areas of the HPS.

Mechanical dispersion is associated with poor outcome in heart failure with a severely depressed left ventricular function and bundle branch blocks

OBJECTIVES

Bundle branch blocks (BBB)-related mechanical dyssynchrony and dispersion may improve patient selection for device therapy, but their effect on the natural history of this patient population is unknown.

METHODS

A total of 155 patients with LVEF ≤ 35% and BBB, not treated with device therapy, were included. Mechanical dyssynchrony was defined as the presence of either septal flash or apical rocking. Contraction duration was assessed as time interval from the electrocardiographic R-(Q-)wave to peak longitudinal strain in each of 17 left ventricular segments. Mechanical dispersion was defined as either the standard deviation of all time intervals (dispersion_SD) or as the difference between the longest and shortest time intervals (dispersion_delta). Patients were followed for cardiac mortality during a median period of 33 months.

RESULTS

Mechanical dyssynchrony was not associated with survival. More pronounced mechanical dispersion_delta was found in patients with dyssynchrony than in those without. In the multivariate regression analysis, patients' functional class, diabetes mellitus and dispersion_delta were independently associated with mortality.

CONCLUSIONS

Mechanical dispersion, but not dyssynchrony, was independently associated with mortality and it may be useful for risk stratification of patients with heart failure (HF) and BBB. Key Messages Mechanical dispersion, measured by strain echocardiography, is associated with poor outcome in heart failure with a severely depressed left ventricular function and bundle branch blocks. Mechanical dispersion may be useful for risk stratification of patients with heart failure and bundle branch blocks.

Utility of incomplete right bundle branch block as an isolated ECG finding in children undergoing initial cardiac evaluation

OBJECTIVE

This study evaluates the ability of experienced pediatric electrophysiologists (EPs) to reliably classify incomplete right bundle branch block (IRBBB) and assesses its clinical utility as an isolated ECG finding in a group of healthy outpatient children without prior cardiac evaluation.

DESIGN

We performed a retrospective analysis of all electrocardiographic and echocardiographic records at Boston Children's Hospital between January 1, 2005, and December 31, 2014. Echocardiographic diagnoses were identified if registered between the date of the index electrocardiogram and the ensuing year. A selected subset of 473 ECGs was subsequently reanalyzed in a blinded manner by six pediatric EPs to determine the consistency with which the finding of IRBBB could be assigned.

RESULTS

Of the 331 278 ECGs registered in the BCH database, 32 127 (9.7%) met inclusion criteria and were analyzed for the prevalence of isolated right bundle conduction disturbance findings. The mean age was 12.1 ± 4.0 years, and the population was 49% male. Of the 32 127 ECGs, 72.5% were coded normal, 3.0% were coded IRBBB, and 0.5% were coded complete right bundle branch block (CRBBB). A total of 7.3% of patients coded as normal had an ensuing echocardiogram, compared to 12.5% coded IRBBB. Echo findings were recorded in 0.1% of normal and 0.2% of IRBBB. Patients with ASD-secundum type were no more likely to have isolated IRBBB on previous ECG than the general population (2.5% vs 3.0%). Analysis of inter-reader variability in ECG findings and conduction disturbance identification was high (range of IRBBB prevalence 1-20% among readers). Reinterpretation of ECGs using explicit diagnostic criteria did not demonstrate consistent discrimination of IRBBB and Normal ECGs.

CONCLUSIONS

IRBBB is not uncommon in a healthy school age population and is observed to have high inter-reader variability. It was associated with increased use of echocardiographic exam but was not associated with increased rate of echocardiographic findings when compared with rates for normal ECGs.