AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology

Characterization of conduction system activation in the postinfarct ventricle using ripple mapping

BACKGROUND

Three-dimensional (3D) mapping of the ventricular conduction system is challenging.

OBJECTIVE

The purpose of this study was to use ripple mapping to distinguish conduction system activation to that of adjacent myocardium in order to characterize the conduction system in the postinfarct left ventricle (LV).

METHODS

High-density mapping (PentaRay, CARTO) was performed during normal rhythm in patients undergoing ventricular tachycardia ablation. Ripple maps were viewed from the end of the P wave to QRS onset in 1-ms increments. Clusters of >3 ripple bars were interrogated for the presence of Purkinje potentials, which were tagged on the 3D geometry. Repeating this process allowed conduction system delineation.

RESULTS

Maps were reviewed in 24 patients (mean 3112 ± 613 points). There were 150.9 ± 24.5 Purkinje potentials per map, at the left posterior fascicle (LPF) in 22 patients (92%) and at the left anterior fascicle (LAF) in 15 patients (63%). The LAF was shorter (41.4 vs 68.8 mm; P = .0005) and activated for a shorter duration (40.6 vs 64.9 ms; P = .002) than the LPF. Fourteen of 24 patients had left bundle branch block (LBBB), with 11 of 14 (78%) having Purkinje potential-associated breakout. There were fewer breakouts from the conduction system during LBBB (1.8 vs 3.4; 1.6 ± 0.6; P = .039) and an inverse correlation between breakout sites and QRS duration (P = .0035).

CONCLUSION

We applied ripple mapping to present a detailed electroanatomic characterization of the conduction system in the postinfarct LV. Patients with broader QRS had fewer LV breakout sites from the conduction system. However, there was 3D mapping evidence of LV breakout from an intact conduction system in the majority of patients with LBBB.

Disease severity, arrhythmogenesis, and fibrosis are related to longer action potentials in tetralogy of Fallot

BACKGROUND

Arrhythmias may originate from surgically unaffected right ventricular (RV) regions in patients with tetralogy of Fallot (TOF). We aimed to investigate action potential (AP) remodelling and arrhythmia susceptibility in RV myocardium of patients with repaired and with unrepaired TOF, identify possible correlations with clinical phenotype and myocardial fibrosis, and compare findings with data from patients with atrial septal defect (ASD), a less severe congenital heart disease.

METHODS

Intracellular AP were recorded ex vivo in RV outflow tract samples from 22 TOF and three ASD patients. Arrhythmias were provoked by superfusion with solutions containing reduced potassium and barium chloride, or isoprenaline. Myocardial fibrosis was quantified histologically and associations between clinical phenotype, AP shape, tissue arrhythmia propensity, and fibrosis were examined.

RESULTS

Electrophysiological abnormalities (arrhythmias, AP duration [APD] alternans, impaired APD shortening at increased stimulation frequencies) were generally present in TOF tissue, even from infants, but rare or absent in ASD samples. More severely diseased and acyanotic patients, pronounced tissue susceptibility to arrhythmogenesis, and greater fibrosis extent were associated with longer APD. In contrast, APD was shorter in tissue from patients with pre-operative cyanosis. Increased fibrosis and repaired-TOF status were linked to tissue arrhythmia inducibility.

CONCLUSIONS

Functional and structural tissue remodelling may explain arrhythmic activity in TOF patients, even at a very young age. Surprisingly, clinical acyanosis appears to be associated with more severe arrhythmogenic remodelling. Further research into the clinical drivers of structural and electrical myocardial alterations, and the relation between them, is needed to identify predictive factors for patients at risk.

Novel electrocardiographic classification for stroke prediction in atrial fibrillation patients undergoing cardioversion

BACKGROUND

Abnormal conduction, structure, and function of the atrial myocardium predispose to atrial fibrillation (AF) and stroke. The usefulness of electrocardiographic indices in predicting stroke or systemic embolism (SSE) in patients undergoing cardioversion (CV) for AF remains unknown, especially in those at low estimated risk.

OBJECTIVE

We systematically evaluated the performance of various P-wave abnormalities (PWAs) in predicting SSE 30 days after CV (derivation cohort) and in the long term (validation cohort).

METHODS

Electrocardiograms (n = 1773) of AF patients undergoing an acute CV were manually reviewed. The 30-day post-CV data were used to derive a composite PWA variable. The electrocardiographic findings were validated by the long-term follow-up of patients with no anticoagulation. Electrocardiograms of 27 CAREBANK study patients with right atrial appendage biopsies were further analyzed for histopathologic validation.

RESULTS

During data derivation, the best performance was found with a combination of prolonged P-wave (≥180 ms), deflected P-wave morphology in lead II, biphasic P-waves in inferior leads, or increased P-terminal force (≥80 mm·ms) as markers for extensive PWA. In the validation cohort, 219 of 874 (25.1%) had extensive PWA. During a median follow-up of 4.9 years, there were 51 patients (5.8%) with SSE in total. In a competing risk model, PWA predicted SSE (adjusted hazard ratio, 2.1 per category; 95% CI, 1.4-3.1; P < .001). Areas under the curve for SSE at 3 years were 0.77, 0.79, and 0.86 for PWA, CHA2DS2-VASc, score, and their combination, respectively. On histologic evaluation, extensive PWA was associated with interstitial fibrosis (P = .033).

CONCLUSION

Novel electrocardiographic PWA classification provided additional prognostic insight in AF patients.

Associated factors with the occurrence of in-hospital cardiac arrest in patients admitted to internal medicine wards for non-cardiovascular causes

BACKGROUND AND OBJECTIVE

In-hospital cardiac arrest (IHCA) has a low survival rate, so it is essential to recognize the cases with the highest probability of developing it. The aim of this study is to identify factors associated with the occurrence of IHCA.

MATERIAL AND METHODS

A single-center case-control study was conducted including 65 patients admitted to internal medicine wards for non-cardiovascular causes who experienced IHCA, matched with 210 admitted controls who did not present with IHCA.

RESULTS

The main reason for admission was pneumonia. The most prevalent comorbidity was arterial hypertension. Four characteristics were strongly and independently associated with IHCA presentation, these are electrical left ventricular hypertrophy (LVH) (OR: 13.8; 95% IC: 4.7-40.7), atrial fibrillation (OR: 9.4: 95% CI: 4.3-20.6), the use of drugs with known risk of torsades de pointes (OR: 2.7; 95% CI: 1.3-5.5) and the combination of the categories known risk plus conditional risk (OR: 17.1; 95% CI: 6.7-50.1). The first two detected in the electrocardiogram taken at the time of admission.

CONCLUSION

In admitted patients for non-cardiovascular causes, the use of drugs with a known risk of torsades de pointes, as well as the detection of electrical LVH and atrial fibrillation in the initial electrocardiogram, is independently associated with a higher probability of suffering a IHCA.

Pilot study to evaluate left-to-right ventricular offset in biventricular pacing-comparison of electrocardiographic imaging and ECG

INTRODUCTION

Biventricular pacing (BiVp) improves outcomes in systolic heart failure patients with electrical dyssynchrony. BiVp is delivered from epicardial left ventricular (LV) and endocardial right ventricular (RV) electrodes. Acute electrical activation changes with different LV-RV stimulation offsets can help guide individually optimized BiVp programming. We sought to study the BiVp ventricular activation with different LV-RV offsets and compare with 12-lead ECG.

METHODS

In five patients with BiVp (63 ± 17-year-old, 80% male, LV ejection fraction 27 ± 6%), we evaluated acute ventricular epicardial activation, varying LV-RV offsets in 20 ms increments from -40 to 80 ms, using electrocardiographic imaging (ECGI) to obtain absolute ventricular electrical uncoupling (VEUabs, absolute difference in average LV and average RV activation time) and total activation time (TAT). For each patient, we calculated the correlation between ECGI and corresponding ECG (3D-QRS-area and QRS duration) with different LV-RV offsets.

RESULTS

The LV-RV offset to attain minimum VEUabs in individual patients ranged 20-60 ms. In all patients, a larger LV-RV offset was required to achieve minimum VEUabs (36 ± 17 ms) or 3D-QRS-area (40 ± 14 ms) than that for minimum TAT (-4 ± 9 ms) or QRS duration (-8 ± 11 ms). In individual patients, 3D-QRS-area correlated with VEUabs (r 0.65 ± 0.24) and QRS duration correlated with TAT (r 0.95 ± 0.02). Minimum VEUabs and minimum 3D-QRS-area were obtained by LV-RV offset within 20 ms of each other in all five patients.

CONCLUSIONS

LV-RV electrical uncoupling, as assessed by ECGI, can be minimized by optimizing LV-RV stimulation offset. 3D-QRS-area is a surrogate to identify LV-RV offset that minimizes LV-RV uncoupling.

Interaction of left ventricular size with the outcome of cardiac resynchronization therapy in Japanese patients

BACKGROUND

We analyzed the influence of the QRS duration (QRSd) to LV end-diastolic volume (LVEDV) ratio on cardiac resynchronization therapy (CRT) outcomes in heart failure patients classified as III/IV per the New York Heart Association (NYHA) and with small body size.

HYPOTHESIS

We proposed the hypothesis that the QRSd/LV size ratio is a better index of the CRT substrate.

METHODS

We enrolled 114 patients with advanced heart failure (NYHA class III/IV, and LV ejection fraction >35%) who received a CRT device, including those with left bundle branch block (LBBB) and QRSd ≥120 milliseconds (n = 60), non-LBBB and QRSd ≥150 milliseconds (n = 30) and non-LBBB and QRSd of 120-149 milliseconds (n = 24).

RESULTS

Over a mean follow-up period of 65 ± 58 months, the incidence of the primary endpoint, a composite of all-cause death and hospitalization for heart failure, showed no significant intergroup difference (43.3% vs. 50.0% vs. 37.5%, respectively, p = .72). Similarly, among 104 patients with QRSd/LVEDV ≥ 0.67 (n = 54) and QRSd/LVEDV < 0.67 (n = 52), no significant differences were observed in the incidence of the primary endpoint (35.1% vs. 51.9%, p = .49). Nevertheless, patients with QRSd/LVEDV ≥ 0.67 showed better survival than those with QRSd/LVEDV < 0.67 (14.8% vs. 34.6%, p = .0024).

CONCLUSION

Advanced HF patients with a higher QRSd/LVEDV ratio showed better survival in this small-body-size population. Thus, the risk is concentrated among those with a larger QRSd, and patients with a relatively smaller left ventricular size appeared to benefit from CRT.

QRS-T angle: is it a specific parameter associated with sudden cardiac death in type 2 diabetes? Results from the SURDIAGENE and the Mini-Finland prospective cohorts

AIMS/HYPOTHESIS

Type 2 diabetes is associated with a high risk of sudden cardiac death (SCD), but the risk of dying from another cause (non-SCD) is proportionally even higher. The aim of the study was to identify easily available ECG-derived features associated with SCD, while considering the competing risk of dying from non-SCD causes.

METHODS

In the SURDIAGENE (Survie, Diabete de type 2 et Genetique) French prospective cohort of individuals with type 2 diabetes, 15 baseline ECG parameters were interpreted among 1362 participants (mean age 65 years; HbA1c 62±17 mmol/mol [7.8±1.5%]; 58% male). Competing risk models assessed the prognostic value of clinical and ECG parameters for SCD after adjusting for age, sex, history of myocardial infarction, N-terminal pro b-type natriuretic peptide (NT-proBNP), HbA1c and eGFR. The prospective Mini-Finland cohort study was used to externally validate our findings.

RESULTS

During median follow-up of 7.4 years, 494 deaths occurred including 94 SCDs. After adjustment, frontal QRS-T angle ≥90° (sub-distribution HR [sHR] 1.68 [95% CI 1.04, 2.69], p=0.032) and NT-proBNP level (sHR 1.26 [95% CI 1.06, 1.50] per 1 log, p=0.009) were significantly associated with a higher risk of SCD. Nevertheless, frontal QRS-T angle was the only marker not to be associated with causes of death other than SCD (sHR 1.08 [95% CI 0.84, 1.39], p=0.553 ). These findings were replicated in the Mini-Finland study subset of participants with diabetes (sHR 2.22 [95% CI 1.05, 4.71], p=0.04 for SCD and no association for other causes of death).

CONCLUSIONS/INTERPRETATION

QRS-T angle was specifically associated with SCD risk and not with other causes of death, opening an avenue for refining SCD risk stratification in individuals with type 2 diabetes.

Association between cardiac conduction block and cardiovascular disease and all-cause mortality: The kailuan study

BACKGROUND

Although bundle branch block and atrioventricular block are recognized to be association with cardiovascular disease (CVD) and mortality, the relationship between cardiac conduction block (CCB) and both CVD and all-cause mortality has yet to be explored.

AIMS

To explore the relationship between CCB and CVD and all-cause mortality.

METHODS AND RESULTS

We included 145,805 subjects (mean age 49.7 years, 81.2% males) from the kailuan study. CCB was diagnosed through a 12‑lead electrocardiograph (ECG). Mortality and CVD events were ascertained through multiple sources, including a municipal social insurance institution, hospital records, death certificates, and regular active follow-ups. After a mean follow-up of 12.5 years, 18,301 cases developed all-cause mortality. After excluding 4443 subjects with CVD presence at baseline, 13,208 cases of CVD occurred among the 141,362 study subjects during follow-up. Compared with non-CCB group, the cumulative incidence of CVD and all-cause mortality for CCB group was 18.38% VS 12.14% and 33.45% VS 14.18%, respectively. The multivariable-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) with CCB group were 1.25(1.17-1.34) for CVD, and 1.31(1.25-1.38) for all-cause mortality. Additionally, there were generally stronger associations for CCB with all-cause mortality and CVD in younger participants compared with their older counterparts (Ps-interaction <0.001).

CONCLUSION

CCB can increase the risk of CVD and all-cause mortality in the general population. Our findings highlight the importance of strategies for preventing CCB to reduce the risk of CVD and mortality.

Association Between ECG Abnormalities and Mortality in a Low-Risk Population

BACKGROUND

The ECG is a simple, noninvasive screening method for cardiovascular disease and arrhythmia. The impact of ECG abnormality on mortality is not certain in low-risk populations. To address this, we evaluated the association between ECG abnormality and mortality.

METHODS AND RESULTS

We retrospectively assessed baseline ECG and all-cause mortality and cardiovascular mortality in 660 383 patients presenting for medical check-ups. Baseline ECG abnormalities were classified according to the Minnesota Code. Among the total 660 383 participants, 23 609 (3.6%) had major and 110 038 (16.7%) had minor ECG abnormalities. All-cause mortality occurred in 7751 patients (1.1%) and cardiovascular mortality in 1180 (0.18%) over a median follow-up period of 8.8 years. Major ECG abnormalities were associated with all-cause mortality (hazard ratio [HR], 1.11 [95%, 1.03-1.2]) and cardiovascular mortality (HR, 1.92 [95% CI, 1.63-2.27]) compared with no ECG abnormalities. All-cause mortality was associated with right atrial enlargement (HR, 2.11 [95% CI, 1.1-4.07]), left atrial enlargement (HR, 1.76 [95% CI, 1.1-2.84]), sinus tachycardia (HR, 1.52 [95% CI, 1.15-2.01]), complete atrioventricular block (HR, 2.1 [95% CI, 1.05-4.2]), atrial fibrillation (HR, 1.52 [95% CI, 1.26-1.84]), and left ventricular hypertrophy (HR, 1.15 [95% CI, 1.02-1.3]). Cardiovascular mortality was associated with left atrial enlargement (HR, 4.52 [95% CI, 2.15-9.5]), atrial fibrillation (HR, 3.22 [95% CI, 2.33-4.46]), left ventricular hypertrophy (HR, 1.72 [95% CI, 1.35-2.19]), major Q-wave abnormality (HR, 1.6 [95% CI, 1.08-2.39]), and major ST-T abnormality (HR, 1.76 [95% CI, 1.01-3.04]).

CONCLUSIONS

ECG abnormalities, including left atrial enlargement, left ventricular hypertrophy, atrial fibrillation, and major Q-wave and ST-T abnormalities, were associated with cardiovascular mortality in a low-risk population.

The Danish Nationwide Electrocardiogram (ECG) Cohort

The electrocardiogram (ECG) is a non-invasive diagnostic tool holding significant clinical importance in the diagnosis and risk stratification of cardiac disease. However, access to large-scale, population-based digital ECG data for research purposes remains limited and challenging. Consequently, we established the Danish Nationwide ECG Cohort to provide data from standard 12-lead digital ECGs in both pre- and in-hospital settings, which can be linked to comprehensive Danish nationwide administrative registers on health and social data with long-term follow-up. The Danish Nationwide ECG Cohort is an open real-world cohort including all patients with at least one digital pre- or in-hospital ECG in Denmark from January 01, 2000, to December 31, 2021. The cohort includes data on standardized and uniform ECG diagnostic statements and ECG measurements including global parameters as well as lead-specific measures of waveform amplitudes, durations, and intervals. Currently, the cohort comprises 2,485,987 unique patients with a median age at the first ECG of 57 years (25th-75th percentiles, 40-71 years; males, 48%), resulting in a total of 11,952,430 ECGs. In conclusion, the Danish Nationwide ECG Cohort represents a novel and extensive population-based digital ECG dataset for cardiovascular research, encompassing both pre- and in-hospital settings. The cohort contains ECG diagnostic statements and ECG measurements that can be linked to various nationwide health and social registers without loss to follow-up.

Robust Artificial Intelligence Tool for Atrial Fibrillation Diagnosis: Novel Development Approach Incorporating Both Atrial Electrograms and Surface ECG and Evaluation by Head-to-Head Comparison With Hospital-Based Physician ECG Readers

BACKGROUND

Atrial fibrillation (AF) increases risk of embolic stroke, and in postoperative patients, increases cost of care. Consequently, ECG screening for AF in high-risk patients is important but labor-intensive. Artificial intelligence (AI) may reduce AF detection workload, but AI development presents challenges.

METHODS AND RESULTS

We used a novel approach to AI development for AF detection using both surface ECG recordings and atrial epicardial electrograms obtained in postoperative cardiac patients. Atrial electrograms were used only to facilitate establishing true AF for AI development; this permitted the establishment of an AI-based tool for subsequent AF detection using ECG records alone. A total of 5 million 30-second epochs from 329 patients were annotated as AF or non-AF by expert ECG readers for AI training and validation, while 5 million 30-second epochs from 330 different patients were used for AI testing. AI performance was assessed at the epoch level as well as AF burden at the patient level. AI achieved an area under the receiver operating characteristic curve of 0.932 on validation and 0.953 on testing. At the epoch level, testing results showed means of AF detection sensitivity, specificity, negative predictive value, positive predictive value, and F1 (harmonic mean of positive predictive value and sensitivity) as 0.970, 0.814, 0.976, 0.776, and 0.862, respectively, while the intraclass correlation coefficient for AF burden detection was 0.952. At the patient level, AF burden sensitivity and positive predictivity were 96.2% and 94.5%, respectively.

CONCLUSIONS

Use of both atrial electrograms and surface ECG permitted development of a robust AI-based approach to postoperative AF recognition and AF burden assessment. This novel tool may enhance detection and management of AF, particularly in patients following operative cardiac surgery.

Impact of Transjugular Intracardiac Echocardiography-Guided Self-Expandable Transcatheter Aortic Valve Implantation on Reduction of Conduction Disturbances

BACKGROUND

A high permanent pacemaker implantation (PPI) risk remains a concern of self-expandable transcatheter aortic valve implantation, despite the continued improvements in implantation methodology. We aimed to assess the impact of real-time direct visualization of the membranous septum using transjugular intracardiac echocardiography (ICE) during transcatheter aortic valve implantation on reducing the rates of conduction disturbances including the need for PPI.

METHODS

Consecutive patients treated with Evolut R and Evolut PRO/PRO+ from February 2017 to September 2022 were included in this study. We compared outcomes between the conventional implantation method using the 3-cusps view (3 cusps without ICE group), the recent method using cusp-overlap view (cusp overlap without ICE group), and our novel method using ICE (cusp overlap with ICE group).

RESULTS

Of the 446 patients eligible for analysis, 211 (47.3%) were categorized as the 3 cusps without ICE group, 129 (28.9%) were in the cusp overlap without ICE group, and 106 (23.8%) comprised the cusp overlap with ICE group. Compared with the 3 cusps without ICE group, the cusp overlap without ICE group had a smaller implantation depth (2.2 [interquartile range, 1.0-3.5] mm versus 4.3 [interquartile range, 3.3-5.4] mm; P<0.001) and lower 30-day PPI rates (7.0% versus 14.2%; P=0.035). Compared with the cusp overlap without ICE group, the cusp overlap with ICE group had lower 30-day PPI rates (0.9%; P=0.014), albeit with comparable implantation depths (1.9 [interquartile range, 0.9-2.9] mm; P=0.150). Multivariable analysis showed that our novel method using ICE with the cusp-overlap view was independently associated with a 30-day PPI rate reduction. There were no group differences in 30-day all-cause mortality (1.4% versus 1.6% versus 0%; P=0.608).

CONCLUSIONS

Our novel implantation method using transjugular ICE, which enable real-time direct visualization of the membranous septum, achieved a predictably high position of prostheses, resulting in a substantial reduction of conduction disturbances requiring PPI after transcatheter aortic valve implantation.

Value of q waves in lateral and left precordial leads in patients with left bundle branch block to predict the response to cardiac resynchronization therapy

BACKGROUND

The cardiac resynchronization therapy (CRT) non-response rate can reach 30% in heart failure (HF) patients with left bundle branch block (LBBB). This study aimed to evaluate the value of baseline q waves in leads I, V5, or V6 in predicting response to CRT in patients with HF and LBBB.

METHODS

Patients with HF (left ventricular ejection fraction ≤35%) and LBBB receiving CRT implantation were retrospectively enrolled. Baseline characteristics and electrocardiogram parameters, including lateral and left precordial q waves were evaluated. Non-response to CRT was defined as the improvement of left ventricular ejection fraction (LVEF) < 5% at a 6-month follow-up.

RESULTS

A total of 132 patients (mean age 63.0 ± 10.4 years, 94 [71.2%] male) were included. Among them, 32 patients with q waves in leads I, V5, or V6 were classified into the qLBBB (+) group, and the rest without q waves in these leads were defined as the qLBBB (-) group. The CRT non-response rate in the qLBBB (+) group was markedly higher than that in the qLBBB (-) group (68.8% vs. 33.3%, p < .001). Multivariable logistic regression analysis revealed that the presence of baseline q waves in leads I, V5, or V6 remained significantly associated with a higher rate of CRT non-response in patients with HF and LBBB (odds ratio: 4.8, 95% confidence interval: 1.5-15.0, p = .007).

CONCLUSION

Any q wave in leads I, V5, or V6 was an independent predictive factor for CRT non-response in patients with HF and LBBB.

The electrocardiographic manifestations of pectus excavatum before and after surgical correction

BACKGROUND

Pectus excavatum (PEx) can cause cardiopulmonary limitations due to cardiac compression and displacement. There is limited data on electrocardiogram (ECG) alterations before and after PEx surgical repair, and ECG findings suggesting cardiopulmonary limitations have not been reported. The aim of this study is to explore ECG manifestations of PEx before and after surgery including associations with exercise capacity.

METHODS

A retrospective review of PEx patients who underwent primary repair was performed. ECGs before and after surgical correction were evaluated and the associations between preoperative ECG abnormalities and cardiopulmonary function were investigated.

RESULTS

In total, 310 patients were included (mean age 35.1 ± 11.6 years). Preoperative ECG findings included a predominant negative P wave morphology in V1, and this abnormal pattern significantly decreased from 86.9% to 57.4% (p < 0.001) postoperatively. The presence of abnormal P wave amplitude in lead II (>2.5 mm) significantly decreased from 7.1% to 1.6% postoperatively (p < 0.001). Right bundle branch block (RBBB) (9.4% versus 3.9%, p < 0.001), rsr' patterns (40.6% versus 12.9%, p < 0.001), and T wave inversion in leads V1-V3 (62.3% vs 37.7%, p < 0.001) were observed less frequently after surgery. Preoperative presence of RBBB (OR = 4.8; 95%CI 1.1-21.6) and T wave inversion in leads V1-3 (OR = 2.3; 95%CI 1.3-4.2) were associated with abnormal results in cardiopulmonary exercise testings.

CONCLUSION

Electrocardiographic abnormalities in PEx are frequent and can revert to normal following surgery. Preoperative RBBB and T wave inversion in leads V1-3 suggested a reduction in exercise capacity, serving as a marker for the need for further cardiovascular evaluation of these patients.

Electrocardiographic Z-axis QRS-T voltage-time-integral in patients with typical right bundle branch block - Correlation with echocardiographic right ventricular size and function

BACKGROUND

Right bundle branch block (RBBB) can be benign or associated with right ventricular (RV) functional and structural abnormalities. Our aim was to evaluate QRS-T voltage-time-integral (VTI) compared to QRS duration and lead V1 R' as markers for RV abnormalities.

METHODS

We included adults with an ECG demonstrating RBBB and echocardiogram obtained within 3 months of each other, between 2010 and 2020. VTIQRS and VTIQRST were obtained for 12 standard ECG leads, reconstructed vectorcardiographic X, Y, Z leads and root-mean-squared (3D) ECG. Age, sex and BSA-adjusted linear regressions were used to assess associations of QRS duration, amplitudes, VTIs and lead V1 R' duration/VTI with echocardiographic tricuspid annular plane systolic excursion (TAPSE), RV tissue Doppler imaging S', basal and mid diameter, and systolic pressure (RVSP).

RESULTS

Among 782 patients (33% women, age 71 ± 14 years) with RBBB, R' duration in lead V1 was modestly associated with RV S', RV diameters and RVSP (all p ≤ 0.03). QRS duration was more strongly associated with RV diameters (both p < 0.0001). AmplitudeQRS-Z was modestly correlated with all 5 RV echocardiographic variables (all p ≤ 0.02). VTIR'-V1 was more strongly associated with TAPSE, RV S' and RVSP (all p ≤ 0.0003). VTIQRS-Z and VTIQRST-Z were among the strongest correlates of the 5 RV variables (all p < 0.0001). VTIQRST-Z.√BSA cutoff of ≥62 μVsm had sensitivity 62.7% and specificity 65.7% for predicting ≥3 of 5 abnormal RV variables (AUC 0.66; men 0.71, women 0.60).

CONCLUSION

In patients with RBBB, VTIQRST-Z is a stronger predictor of RV dysfunction and adverse remodeling than QRS duration and lead V1 R'.

Post-transcatheter aortic valve implantation isolated PR prolongation: incidence and clinical significance

AIMS

Conduction abnormalities post-transcatheter aortic valve implantation (TAVI) are common. Post-TAVI PR prolongation was mainly studied as an adjunct to new-onset bundle branch block. The net effect of isolated PR prolongation (IPRP) without post-TAVI QRS changes is not well known. The aim of this study was to define the incidence and clinical significance of post-TAVI IPRP.

METHODS AND RESULTS

A total of 1108 consecutive TAVI patients were reviewed. Patients with IPRP were compared with patients without post-TAVI electrocardiogram (ECG) changes. Clinical outcomes included permanent pacemaker implantation (PPI) and overall mortality. A total of 146 patients with IPRP were compared with 290 patients without post-TAVI ECG changes. At 1 year follow-up, 4 (2.7%) and 7 (2.4%) patients underwent PPI (P = 0.838) and 10 (6.8%) and 25 (8.6%) died (P = 0.521), from the study and control groups, respectively. No patient with IPRP and narrow QRS underwent PPI during 1 year post-TAVI, and all death events were non-cardiac except one unknown cause. Permanent pacemaker implantation rates among patients with IPRP and wide QRS were higher (n = 4, 12.1%), compared with patients with wide QRS without post-TAVI ECG change (n = 3, 4%) however not reaching statistical significance (P = 0.126). Multivariate Cox proportional hazards model demonstrated that in patients with narrow QRS, neither PR prolongation nor baseline or maximal PR intervals was associated with the combined endpoint of PPI and mortality. However, in patients with wide QRS, baseline PR intervals and QRS width, but not PR prolongation were associated with the combined outcome.

CONCLUSION

Post-TAVI IPRP in patients with narrow QRS is not associated with adverse outcome. This finding may translate clinically into a more permissive approach to these patients.

Improvement in electrocardiographic parameters of repolarization related to sudden death in patients with ventricular dysfunction and left bundle branch block after cardiac resynchronization through His bundle pacing

BACKGROUND

Cardiac resynchronization therapy (CRT) through permanent His bundle pacing (p-HBP) normalizes interventricular conduction disorders and QRS. Similarly, there are immediate and long-term changes in repolarization, which could be prognostic of a lower risk of sudden death (SD) at follow-up. We aimed to compare the changes in different electrocardiographic (ECG) repolarization parameters related to the risk of SD before and after CRT through p-HBP.

METHODS

In this prospective, descriptive single-center study (May 2019 to December 2021), we compared the ECG parameters of repolarization related to SD in patients with non-ischemic dilated cardiomyopathy, left bundle branch block (LBBB), and CRT indications, at baseline and after CRT through p-HBP.

RESULTS

Forty-three patients were included. Compared to baseline, after CRT through p-HBP, there were immediate significant changes in the QT interval (ms): 445 [407.5-480] vs 410 [385-440] (p = 0.006), QT dispersion (ms): 80 [60-100] vs 40 [40-65] (p < 0.001), Tp-Te (ms): 90 [80-110] vs 80 [60-95] (p < 0.001), Tp-Te/QT ratio: 0.22 [0.19-0.23] vs 0.19 [0.16-0.21] (p < 0.001), T wave amplitude (mm): 6.25 [4.88-10] vs - 2.5 [- 7-2.25] (p < 0.001), and T wave duration (ms): 190 [157.5-200] vs 140 [120-160] (p = 0.001). In the cases of the corrected QT (Bazzett and Friederichia) and the Tp-Te dispersion, changes only became significant at 1 month post-implant (468.5 [428.8-501.5] vs 440 [410-475.25] (p = 0.015); 462.5 [420.8-488.8] vs 440 [400-452.5] (p = 0.004), and 40 [30-52.5] vs 30 [20-40] (p < 0.001), respectively) (Table 1). Finally, two parameters did not improve until 6 months post-implant: the rdT/JT index, 0.25 [0.21-0.28] baseline vs 0.20 [0.19-0.23] 6 months post-implant (p = 0.011), and the JT interval, 300 [240-340] baseline vs 280 [257-302] 6 months post-implant (p = 0.027). Additionally, most of the parameters continued improving as compared with immediate post-implantation.

CONCLUSIONS

After CRT through His bundle pacing and LBBB correction, there was an improvement in all parameters of repolarization related to increased SD reported in the literature.

Electrocardiographic manifestations of pulmonary stenosis versus pulmonary hypertension

BACKGROUND

Right ventricular hypertrophy can be caused by conditions such as pulmonary stenosis and pulmonary hypertension. ECG is a readily available and affordable test, the aim of this study was the evaluation of the electrocardiographic aspects of pulmonary stenosis, and pulmonary hypertension.

METHODS

A list of patients diagnosed with isolated pulmonary stenosis and pulmonary hypertension patients hospitalized and treated between 2019 and 2021 were extracted from the hospital archives. Furthermore, the ECG of the patients was analyzed in terms of the prevalence of the variables in the study using FECG Caliper software. Finally, the data of 93 patients (in both groups) were analyzed.

RESULTS

In this study, 46 patients were in the severe pulmonary stenosis group, and 49 were in the severe or moderate-to-severe pulmonary hypertension group. The heart rate in the pulmonary hypertension group was significantly higher. R/S > 1 in precordial leads differs between the two groups and higher amplitude R wave in V1(p-value = 0.05). in the pulmonary stenosis group. While in the pulmonary hypertension group, R wave growth occurs later, and this ratio is greater than one after V4. Bundle block in the form of RBBB(p-value <0.001) and maximum QRS duration is more in the pulmonary stenosis group(p-value = 0.001).

CONCLUSION

Our findings show the different strains of the right ventricle in two groups. It can be concluded that the effects of severe pulmonary stenosis on the ECG are more on the QRS wave and in the form of a block, while severe pulmonary hypertension affects the ST segment and T wave.

Shallow suture at ventricular septal defect may safely reduce right bundle branch block

BACKGROUND

To avoid rhythm disturbance, sutures for ventricular septal defect closure have been traditionally placed 2∼5 mm or more away from the edge of the ventricular septal defect. However, the traditional suturing method appears to induce right bundle branch block and tricuspid valve regurgitation after ventricular septal defect closure more than our alternative technique, shallow suturing just at the edge of the ventricular septal defect (shallower bites at the postero-inferior margin). We aimed to verify our clinical experience of perimembranous ventricular septal defect repair.

METHODS

The alternative shallow suturing method has been applied since 2003 at our institution. We retrospectively reviewed the clinical data of 556 isolated perimembranous ventricular septal defect patients who underwent surgical closure from 2000 to 2019. We investigated the postoperative occurrence of right bundle branch block or progression of tricuspid regurgitation and analysed risk factors for right bundle branch block and tricuspid regurgitation.

RESULTS

Traditional suturing method (Group T) was used in 374 cases (66.8%), and alternative suturing method (Group A) was used in 186 cases (33.2%). The right bundle branch block occurred more frequently in Group T (39.6%) than in Group A (14.9%). In multivariable logistic regression analysis, Group T and patch material were significant risk factors for late right bundle branch block. More patients with progression of tricuspid regurgitation were found in Group T.

CONCLUSIONS

Shallow suturing just at the edge of the ventricular septal defect may reduce the rate of right bundle branch block occurrence and tricuspid regurgitation progression without other complications.

The QRS frontal plane axis changes during left bundle branch block after transcatheter aortic valve replacement

BACKGROUND AND AIMS

Left bundle branch block (LBBB) is common after transcatheter aortic valve replacement (TAVR) and associated with a left or normal QRS axis. We aim to assess the QRS frontal plane axis shift changes during LBBB after TAVR and determine if the risk of procedure-related high degree atrioventricular block (AVB) is affected by QRS axis shift changes.

METHODS AND RESULTS

In a retrospective single-center study of 720 consecutive patients who underwent TAVR, 141 (19.6%) with normal baseline QRS duration developed a new LBBB after TAVR and constituted the study group. Most patients (59.6%) were females and the mean age of the cohort was 81.2 ± 6 years.

RESULTS

As compared with the baseline QRS axis before TAVR, the occurrence of LBBB was associated with a leftward QRS axis shift (by 40 ± 28.3°) in 73% of the study patients and a rightward (by 18.6 ± 19.4°) or no change in QRS axis in 25.6% and 1.4% of the study patients, respectively. A left QRS axis (-30°) was observed in 14.9% and 38.3% of the study patients before and after TAVR, respectively. The group of patients exhibiting a rightward or no QRS axis shift had a greater incidence of high degree AVB than the group of patients exhibiting a leftward QRS axis shift (18.4% vs. 6.8%, p = .056).

CONCLUSION

Although post TAVR-LBBB is associated with a leftward QRS axis shift in most patients, a non-negligible proportion of patients (27%) exhibited a rightward or no QRS axis shift. The latter group tend to have a higher risk of developing high degree AVB.

Conduction System Pacing for Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) via biventricular pacing (BiVP-CRT) is considered a mainstay treatment for symptomatic heart failure patients with reduced ejection fraction and wide QRS. However, up to one-third of patients receiving BiVP-CRT are considered non-responders to the therapy. Multiple strategies have been proposed to maximize the percentage of CRT responders including two new physiological pacing modalities that have emerged in recent years: His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). Both pacing techniques aim at restoring the normal electrical activation of the ventricles through the native conduction system in opposition to the cell-to-cell activation of conventional right ventricular myocardial pacing. Conduction system pacing (CSP), including both HBP and LBBAP, appears to be a promising pacing modality for delivering CRT and has proven to be safe and feasible in this particular setting. This article will review the current state of the art of CSP-based CRT, its limitations, and future directions.

Relationship between baseline electrocardiographic measurements and outcomes in patients with high-risk heart failure: Insights from the VerICiguaT Global Study in Subjects with Heart Failure with Reduced Ejection Fraction (VICTORIA) trial

AIMS

Whether electrocardiographic (ECG) measurements predict mortality in chronic heart failure with reduced ejection fraction (HFrEF) is unknown.

METHODS AND RESULTS

We studied 4880 patients from the Vericiguat Global Study in Subjects with Heart Failure with Reduced Ejection Fraction (VICTORIA) trial with a baseline 12-lead ECG. Associations between ECG measurements and mortality were estimated as hazard ratios (HR) and adjusted for the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) risk score, N-terminal pro-B-type natriuretic peptide, and index event. Select interactions between ECG measurements, patient characteristics and mortality were examined. Over a median of 10.8 months, there were 824 cardiovascular (CV) deaths (214 sudden) and 1005 all-cause deaths. Median age was 68 years (interquartile range [IQR] 60-76), 24% were women, median ejection fraction was 30% (IQR 23-35), 41% had New York Heart Association class III/IV, and median MAGGIC score was 24 (IQR 19-28). After multivariable adjustment, significant associations existed between heart rate (per 5 bpm: HR 1.02), QRS duration (per 10 ms: HR 1.02), absence of left ventricular hypertrophy (HR 0.64) and CV death, and similarly so with all-cause death (HR 1.02; HR 1.02; HR 0.61, respectively). Contiguous pathologic Q waves were significantly associated with sudden death (HR 1.46), and right ventricular hypertrophy with all-cause death (HR 1.44). The only sex-based interaction observed was for pathologic Q waves on CV (men: HR 1.05; women: HR 1.64, pinteraction  = 0.024) and all-cause death (men: HR 0.99; women: HR 1.57; pinteraction  = 0.010). Whereas sudden death doubled in females, it did not differ among males (male: HR 1.25, 95% confidence interval [CI] 0.87-1.79; female: HR 2.50, 95% CI 1.23-5.06; pinteraction  = 0.141).

CONCLUSION

Routine ECG measurements provide additional prognostication of mortality in high-risk HFrEF patients, particularly in women with contiguous pathologic Q waves.

Conduction System Pacing versus Conventional Biventricular Pacing for Cardiac Resynchronization Therapy: Where Are We Heading?

Over the last few years, pacing of the conduction system (CSP) has emerged as the new standard pacing modality for bradycardia indications, allowing a more physiological ventricular activation compared to conventional right ventricular pacing. CSP has also emerged as an alternative modality to conventional biventricular pacing for the delivery of cardiac resynchronization therapy (CRT) in heart failure patients. However, if the initial clinical data seem to support this new physiological-based approach to CRT, the lack of large randomized studies confirming these preliminary results prevents CSP from being used routinely in clinical practice. Furthermore, concerns are still present regarding the long-term performance of pacing leads when employed for CSP, as well as their extractability. In this review article, we provide the state-of-the-art of CSP as an alternative to biventricular pacing for CRT delivery in heart failure patients. In particular, we describe the physiological concepts supporting this approach and we discuss the future perspectives of CSP in this context according to the implant techniques (His bundle pacing and left bundle branch area pacing) and the clinical data published so far.

Interpreting the ECG in patients with chest pain and right bundle branch block: A case report

A patient with right bundle branch block (RBBB) presented with chest pain. An ECG showed ST-elevation in leads V1, V2, and aVR, with widespread ST-depression in leads II, aVF, I, aVL, and V4-6. The initial ECG interpretation missed ST-elevation myocardial infarction (STEMI), as ST-elevation thresholds were not reached. Non-urgent angiography showed severe left anterior descending artery stenosis requiring percutaneous coronary intervention. The course was complicated by cardiac arrest necessitating resuscitation and dual chamber pacemaker placement with left bundle branch pacing. This case report outlines the deficiencies of the current voltage criteria for identification of anterior STEMI in patients with RBBB.

Does targeted positioning of the left ventricular pacing lead towards the latest local electrical activation in cardiac resynchronization therapy reduce the incidence of death or hospitalization for heart failure?

BACKGROUND

Cardiac resynchronization therapy (CRT) improves symptoms, health-related quality of life and long-term survival in patients with systolic heart failure (HF) and shortens QRS duration. However, up to one third of patients attain no measurable clinical benefit from CRT. An important determinant of clinical response is optimal choice in left ventricular (LV) pacing site. Observational data have shown that achieving an LV lead position at a site of late electrical activation is associated with better clinical and echocardiographic outcomes compared to standard placement, but mapping-guided LV lead placement towards the site of latest electrical activation has never been investigated in a randomized controlled trial (RCT). The purpose of this study was to evaluate the effect of targeted positioning of the LV lead towards the latest electrically activated area. We hypothesize that this strategy is superior to standard LV lead placement.

METHODS

The DANISH-CRT trial is a national, double-blinded RCT (ClinicalTrials.gov NCT03280862). A total of 1,000 patients referred for a de novo CRT implantation or an upgrade to CRT from right ventricular pacing will be randomized 1:1 to receive conventional LV lead positioning preferably in a nonapical posterolateral branch of the coronary sinus (CS) (control group) or targeted positioning of the LV lead to the CS branch with the latest local electrical LV activation (intervention group). In the intervention group, late activation will be determined using electrical mapping of the CS. The primary endpoint is a composite of death and nonplanned HF hospitalization. Patients are followed for a minimum of 2 years and until 264 primary endpoints occurred. Analyses will be conducted according to the intention-to-treat principle. Enrollment for this trial began in March 2018, and per April 2023, a total of 823 patients have been included. Enrollment is expected to be complete by mid-2024.

CONCLUSIONS

The DANISH-CRT trial will clarify whether mapping-guided positioning of the LV lead according to the latest local electrical activation in the CS is beneficial for patients in terms of reducing the composite endpoint of death or nonplanned hospitalization for heart failure. Results from this trial are expected to impact future guidelines on CRT.

CLINICALTRIALS

GOV IDENTIFIER

NCT03280862.

Hemodynamic forces from 4D flow magnetic resonance imaging predict left ventricular remodeling following cardiac resynchronization therapy

BACKGROUND

Patients with heart failure and left bundle branch block (LBBB) may receive cardiac resynchronization therapy (CRT), but current selection criteria are imprecise, and many patients have limited treatment response. Hemodynamic forces (HDF) have been suggested as a marker for CRT response. The aim of this study was therefore to investigate left ventricular (LV) HDF as a predictive marker for LV remodeling after CRT.

METHODS

Patients with heart failure, EF < 35% and LBBB (n = 22) underwent CMR with 4D flow prior to CRT. LV HDF were computed in three directions using the Navier-Stokes equations, reported in median N [interquartile range], and the ratio of transverse/longitudinal HDF was calculated for systole and diastole. Transthoracic echocardiography was performed before and 6 months after CRT. Patients with end-systolic volume reduction ≥ 15% were defined as responders.

RESULTS

Non-responders had smaller HDF than responders in the inferior-anterior direction in systole (0.06 [0.03] vs. 0.07 [0.03], p = 0.04), and in the apex-base direction in diastole (0.09 [0.02] vs. 0.1 [0.05], p = 0.047). Non-responders had larger diastolic HDF ratio compared to responders (0.89 vs. 0.67, p = 0.004). ROC analysis of diastolic HDF ratio for identifying CRT non-responders had AUC of 0.88 (p = 0.005) with sensitivity 57% and specificity 100% for ratio > 0.87. Intragroup comparison found higher HDF ratio in systole compared to diastole for responders (p = 0.003), but not for non-responders (p = 0.8).

CONCLUSION

Hemodynamic force ratio is a potential marker for identifying patients with heart failure and LBBB who are unlikely to benefit from CRT. Larger-scale studies are required before implementation of HDF analysis into clinical practice.

Cardiac resynchronization therapy for patients with heart failure and nonspecific intraventricular conduction delay

The efficacy of cardiac resynchronization therapy (CRT) in heart failure patients with left bundle branch block (LBBB) is well established with Class I or IIa recommendation according to 2021 ESC Guidelines on cardiac pacing and CRT, whereas non-LBBB morphology is less recommended. There is insufficient evidence that proves patients with NICD could benefit from CRT. As patients with NICD are characterized by heterogeneity, the effect of CRT on these patients is still controversial. Although the proportion of NICD in the population is lower than that of LBBB patients, it is still worth investigating the effects of CRT on patients with NICD in an era of His-Purkinje conduction system pacing (HPCSP).

Bilateral Bundle Branch Block

Left bundle branch block (LBBB) and right bundle branch block (RBBB) are classic manifestations of bundle branch conduction disorders. However, a third form that is uncommon and underrecognized may exist that has features and pathophysiology of both: bilateral bundle branch block (BBBB). This unusual form of bundle branch block exhibits an RBBB pattern in lead V1 (terminal R wave) and an LBBB pattern in leads I and aVL (absence of S wave). This unique conduction disorder may confer an increased risk of adverse cardiovascular events. BBBB patients may be a subset of patients that respond well to cardiac resynchronization therapy.

The R-wave amplitude in V1 on baseline electrocardiogram correlates with the occurrence of high-degree atrioventricular block following left bundle branch block after transcatheter aortic valve replacement

AIMS

Several procedural and electrocardiogram (ECG) parameters have been associated with the occurrence of high-degree atrioventricular block (AVB) requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement (TAVR). We hereunder sought to assess if the baseline R-wave amplitude in V1 ECG lead of patients with normal QRS duration undergoing TAVR is associated with a higher patient's risk for developing high-degree AVB following left bundle branch block (LBBB).

METHODS AND RESULTS

In this retrospective single-centre study in 720 consecutive patients who underwent TAVR, 141 (19.6%) patients with normal QRS duration developed a new LBBB after TAVR. The 24 (17%) patients who underwent PPI for reasons other than high-degree AVB were excluded from further analysis. In the remaining 117 study patients, 14 (12%) developed high-degree AVB requiring PPI (Group 1) while the remaining 103 (88%) patients did not (Group 2). There were no significant differences in baseline demographic or procedural characteristics nor in PR interval, QRS duration, and QRS axis between these two groups. The incidence of left anterior hemiblock was higher in Group 1 (3 of 14, 21.4%) than that in Group 2 (9 of 103, 8.7%), but the difference was not statistically significant (P = 0.156). The R-wave amplitude in V1 was smaller in Group 1 than that in Group 2 (0.029 ± 0.04 mV vs. 0.11 ± 0.14 mV, P = 0.0316). In the receiver-operating characteristics analysis, the cutoff for R-wave amplitude pre-TAVR was 0.03 mV, area under the curve = 0.7219 (P = 0.0002).

CONCLUSION

The R-wave amplitude in lead V1 during baseline ECG in patients with normal QRS duration may predict the occurrence of high-degree AVB following new LBBB after TAVR.

Significant Delayed Activation on the Right Ventricular Outflow Tract Represents Complete Right Bundle-Branch Block Pattern in Brugada Syndrome

Background The appearance of complete right bundle-branch block (CRBBB) in Brugada syndrome (BrS) is associated with an increased risk of ventricular fibrillation. The pathophysiological mechanism of CRBBB in patients with BrS has not been well established. We aimed to clarify the significance of a conduction delay zone associated with arrhythmias on CRBBB using body surface mapping in patients with BrS. Methods and Results Body surface mapping was recorded in 11 patients with BrS and 8 control patients both with CRBBB. CRBBB in control patients was transiently exhibited by unintentional catheter manipulation (proximal RBBB). Ventricular activation time maps were constructed for both of the groups. We divided the anterior chest into 4 areas (inferolateral right ventricle [RV], RV outflow tract [RVOT], intraventricular septum, and left ventricle) and compared activation patterns between the 2 groups. Excitation propagated to the RV from the left ventricle through the intraventricular septum with activation delay in the entire RV in the control group (proximal RBBB pattern). In 7 patients with BrS, excitation propagated from the inferolateral RV to the RVOT with significant regional activation delay. The remaining 4 patients with BrS showed a proximal RBBB pattern with the RVOT activation delay. The ventricular activation time in the inferolateral RV was significantly shorter in patients with BrS without a proximal RBBB pattern than in control patients. Conclusions The CRBBB morphology in patients with BrS consisted of 2 mechanisms: (1) significantly delayed conduction in the RVOT and (2) proximal RBBB with RVOT conduction delay. Significant RVOT conduction delay without proximal RBBB resulted in CRBBB morphology in patients with BrS.

Comparison of the relation of the ESC 2021 and ESC 2013 definitions of left bundle branch block with clinical and echocardiographic outcome in cardiac resynchronization therapy

INTRODUCTION

We aimed to investigate the impact of the 2021 European Society of Cardiology (ESC) guideline changes in left bundle branch block (LBBB) definition on cardiac resynchronization therapy (CRT) patient selection and outcomes.

METHODS

The MUG (Maastricht, Utrecht, Groningen) registry, consisting of consecutive patients implanted with a CRT device between 2001 and 2015 was studied. For this study, patients with baseline sinus rhythm and QRS duration ≥ 130ms were eligible. Patients were classified according to ESC 2013 and 2021 guideline LBBB definitions and QRS duration. Endpoints were heart transplantation, LVAD implantation or mortality (HTx/LVAD/mortality) and echocardiographic response (LVESV reduction ≥15%).

RESULTS

The analyses included 1.202, typical CRT patients. The ESC 2021 definition resulted in considerably less LBBB diagnoses compared to the 2013 definition (31.6% vs. 80.9%, respectively). Applying the 2013 definition resulted in significant separation of the Kaplan-Meier curves of HTx/LVAD/mortality (p < .0001). A significantly higher echocardiographic response rate was found in the LBBB compared to the non-LBBB group using the 2013 definition. These differences in HTx/LVAD/mortality and echocardiographic response were not found when applying the 2021 definition.

CONCLUSION

The ESC 2021 LBBB definition leads to a considerably lower percentage of patients with baseline LBBB then the ESC 2013 definition. This does not lead to better differentiation of CRT responders, nor does this lead to a stronger association with clinical outcomes after CRT. In fact, stratification according to the 2021 definition is not associated with a difference in clinical or echocardiographic outcome, implying that the guideline changes may negatively influence CRT implantation practice with a weakened recommendation in patients that will benefit from CRT.

Right Ventricular Electromechanical Dyssynchrony and Its Relation to Right Ventricular Remodeling, Dysfunction, and Exercise Capacity in Ebstein Anomaly

BACKGROUND

Abnormal atrioventricular and intraventricular electrical conduction and dysfunction of the functional right ventricle (fRV) are common in Ebstein anomaly (EA). However, fRV mechanical dyssynchrony and its relation to fRV function are poorly characterized. We evaluated fRV mechanical dyssynchrony in EA patients in relation to fRV remodeling, dysfunction, and exercise intolerance.

METHODS

We retrospectively analyzed data from nonoperated EA patients and age-matched controls who underwent echocardiography, cardiovascular magnetic resonance imaging, and cardiopulmonary exercise testing to quantify right ventricular (RV) remodeling, dysfunction, and exercise capacity. The relation of these to fRV dyssynchrony was retrospectively investigated. Right ventricular mechanical dyssynchrony was defined by early fRV septal activation (right-sided septal flash), RV lateral wall prestretch/late contraction, postsystolic shortening, and intra-RV delay using two-dimensional strain echocardiography. The SD of time to peak shortening among the fRV segments was calculated as a parameter of mechanical dispersion.

RESULTS

Thirty-five EA patients (10 of whom were <18 years of age) and 35 age-matched controls were studied. Ebstein anomaly patients had worse RV function and increased intra-RV dyssynchrony versus controls. Nineteen of 35 (54%) EA patients had early septal activation with simultaneous stretch and consequent late activation and postsystolic shortening of RV lateral segments. Intra-fRV mechanical delay correlated with fRV end-diastolic volume index (r = 0.43, P < .05) and fRV end-systolic volume index (r = 0.63, P < .001). The fRV ejection fraction was lower in EA with versus without right-sided septal flash (44.9 ± 11.0 vs 54.2 ± 8.2, P = .012). The fRV mechanical dispersion correlated with the percentage of predicted peak VO₂ (r = -0.35, P < .05).

CONCLUSIONS

In EA, fRV mechanical dyssynchrony is associated with fRV remodeling, dysfunction, and impaired exercise capacity. Mechanical dyssynchrony as a therapeutic target in selected EA patients warrants further study.

The critically low levels of vitamin D predicts the resolution of the ST-segment elevation after the primary percutaneous coronary intervention

AIMS

To investigate the role of vitamin D2 on the resolution of ST-segment elevation (STE) after a primary percutaneous coronary intervention (PCI), as serum levels of vitamin D have been associated with the severity of coronary artery disease.

METHODS AND RESULTS

All patients who underwent PCI for STEMI were screened for enrolment. Vitamin D2 levels were measured on admission along with other biochemical and haematologic assays. The electrocardiography (ECG) was recorded upon arrival and 60 min after the completion of PCI. The primary endpoint of the study was a ≥ 50% resolution of ST-segment amplitude (+STR) when compared to the initial ECG. A logistic regression multivariate analysis was performed to examine the association of STR with all confounding variables, including the admission levels of vitamin D. Receiver-operator characteristics analysis was used to determine the cut-off value of vitamin D that was predictive of STR. Although there was no difference in STR based on standard classification of vitamin D sufficiency, critically low levels of vitamin D (<7.5 ng/mL) were significantly associated with the absence of STR after PCI (AUC was 0.65 ± 0.07; p < 0.001). Critical vitamin D deficiency was a moderate predictor of STR in these patients, with a sensitivity of 86% and specificity of 54%.

CONCLUSION

We concluded that although levels below ten ng/mL were generally accepted as vitamin D deficiency, only critically low levels of this vitamin (<7.5 ng/dL) reliably predicted the resolution of ST-segment after a primary PCI for patients with STEMI.

Success rates, challenges and troubleshooting of left bundle branch area pacing as a cardiac resynchronization therapy for treating patients with heart failure

Cardiac resynchronization therapy (CRT) is an important treatment of heart failure patients with reduced left ventricular ejection fraction (LVEF) and asynchrony of cardiac electromechanical activity. Left bundle branch area pacing (LBBaP) is a novel physiological pacing modality that appears to be an effective method for CRT. LBBaP has several advantages over the traditional biventricular-CRT (BiV-CRT), including a low and stable pacing capture threshold, a high success rate of implantation, a short learning curve, and high economic feasibility. However, LBBaP is not suitable for all heart failure patients needing a CRT and the success rates of LBBaP in heart failure patients is lower because of myocardial fibrosis, non-specific intraventricular conduction disturbance (IVCD), enlargement of the right atrium or right ventricle, etc. In this literature review, we summarize the success rates, challenges, and troubleshooting of LBBaP in heart failure patients needing a CRT.

Clinical and electrocardiographic features in acute total left main coronary artery occlusion without collateral circulation

BACKGROUNDS

Study concerning the clinical features, electrocardiogram (ECG) findings and outcomes in patients presenting with acute total occlusion of left main coronary artery (LM) without collateral circulation is limited.

METHODS

25 patients with acute total LM occlusion without collateral circulation by emergency coronary angiography, from muti-center registry, were retrospectively studied. The clinical and angiographic characteristics, ECG and in-hospital mortality were reviewed.

RESULTS

Nineteen patients (76%) presented with cardiogenic shock. Twelve (60%, 12/20) patients had coronary slow flow or no reflow phenomenon after primary percutaneous coronary intervention (PCI). The in-hospital mortality rate was 88% (n = 22). All the patients presented with ST-segment elevation myocardial ischemia (STEMI) pattern, mostly involving leads I, aVL, V2, V3, V4, V5 and ST-segment depression in leads II, III and aVF.

CONCLUSIONS

Acute total LM occlusion without collateral circulation portends high in-hospital mortality. Anterior ST elevation in the precordial leads from V2 to V4 through V6, and ST elevation in leads I and aVL, accompanying with ST depression in the inferior leads is associated with acute total LM occlusion without collateral circulation.

New-onset persistent left bundle branch block following sutureless aortic valve replacement

OBJECTIVE

To evaluate the incidence, predictive factors and prognostic value of new-onset persistent left bundle branch block (NOP-LBBB) in patients undergoing sutureless surgical aortic valve replacement (SU-SAVR).

METHODS

A total of 329 consecutive patients without baseline conduction disturbances or previous permanent pacemaker implantation (PPI) who underwent SU-SAVR with the Perceval valve (LivaNova Group, Saluggia, Italy) in two centres from 2013 to 2019 were included. Patients were on continuous ECG monitoring during hospitalisation and 12-lead ECG was performed after the procedure and at hospital discharge. NOP-LBBB was defined as a new postprocedural LBBB that persisted at hospital discharge. Baseline, procedural and follow-up clinical and echocardiography data were collected in a dedicated database.

RESULTS

New-onset LBBB was observed in 115 (34.9%) patients, and in 76 (23.1%) persisted at hospital discharge. There were no differences in baseline and procedural characteristics between patients with (n=76) and without (n=253) NOP-LBBB. After a median follow-up of 3.3 years (2.3-4.4 years), patients with NOP-LBBB had a higher incidence of PPI (14.5% vs 6.3%, p=0.016), but exhibited similar rates of all-cause mortality (19.4% vs 19.2%, p=0.428), cardiac mortality (8.1% vs 9.4%, p=0.805) and heart failure readmission (21.0% vs 23.2%, p=0.648), compared with the no/transient LBBB group. NOP-LBBB was associated with a decrease in left ventricular ejection fraction (LVEF) at 1-year follow-up (delta: -5.7 vs +0.2, p<0.001).

CONCLUSIONS

NOP-LBBB occurred in approximately a quarter of patients without prior conduction disturbances who underwent SU-SAVR and was associated with a threefold increased risk of PPI along with a negative impact on LVEF at follow-up.

Incorporating structural abnormalities in equivalent dipole layer based ECG simulations

Introduction: Electrical activity of the myocardium is recorded with the 12-lead ECG. ECG simulations can improve our understanding of the relation between abnormal ventricular activation in diseased myocardium and body surface potentials (BSP). However, in equivalent dipole layer (EDL)-based ECG simulations, the presence of diseased myocardium breaks the equivalence of the dipole layer. To simulate diseased myocardium, patches with altered electrophysiological characteristics were incorporated within the model. The relation between diseased myocardium and corresponding BSP was investigated in a simulation study. Methods: Activation sequences in normal and diseased myocardium were simulated and corresponding 64-lead BSP were computed in four models with distinct patch locations. QRS-complexes were compared using correlation coefficient (CC). The effect of different types of patch activation was assessed. Of one patient, simulated electrograms were compared to electrograms recorded during invasive electro-anatomical mapping. Results: Hundred-fifty-three abnormal activation sequences were simulated. Median QRS-CC of delayed versus dyssynchronous were significantly different (1.00 vs. 0.97, p < 0.001). Depending on the location of the patch, BSP leads were affected differently. Within diseased regions, fragmentation, low bipolar voltages and late potentials were observed in both recorded and simulated electrograms. Discussion: A novel method to simulate cardiomyopathy in EDL-based ECG simulations was established and evaluated. The new patch-based approach created a realistic relation between ECG waveforms and underlying activation sequences. Findings in the simulated cases were in agreement with clinical observations. With this method, our understanding of disease progression in cardiomyopathies may be further improved and used in advanced inverse ECG procedures.

ST-segment depression in atrioventricular nodal reentrant tachycardia: Important finding or just an artifact?

BACKGROUND

The ST segment is component of the QRS-T complex located between the QRS and the T wave. ST segment changes during tachycardia with narrow QRS mainly takes the form of ST segment depression. This phenomenon is often observed in young healthy people for whom an ischemic background is unlikely.

MATERIALS AND METHODS

The study included 104 patients (71 women and 33 men) with paroxysmal narrow QRS complex tachycardia. In all patients electrophysiological study was performed and the diagnosis of atrioventricular nodal reentrant tachycardia was established. The arrhythmogenic substrate was then eliminated successfully by subsequent ablation using radiofrequency energy which confirmed the diagnosis, all patients had measured QRS components - QR, RS and RJ during the tachycardia and during the sinusrhythm. All of the measurements were done in lead V5.

RESULTS

The difference RJ-QR during tachycardia and sinus rhythm correlated negatively with tachycardia cycle length (R = 0.356, P = .001), first slowly, then rapidly reaching the cycle value of about 300 ms, then it decreases, stabilizing at the cycle level of about 270. By separating the RJ-QR in tachycardia and in the sinus rhythm from the tachycardia cycle, we can see that the correlation described in this point is largely due to the correlation between the heart rate and RJ-QR length in tachycardia.

CONCLUSIONS

In patients with atrioventricular nodal reentrant tachycardia, there is a significant ST-segment depression during tachycardia episodes and the degree of this change is related to tachycardia cycle length. The most probable explanation of the ST-segment depression is the overlap of the QRS complex on the preceded T wave. This phenomenon is also influenced by some intrinsic properties of the individual electrocardiogram. It is possible to rule out ischemic origin of the presented ST segment change.

Effect of calcium in patients with pulseless electrical activity and electrocardiographic characteristics potentially associated with hyperkalemia and ischemia-sub-study of the Calcium for Out-of-hospital Cardiac Arrest (COCA) trial

OBJECTIVE

The Calcium for Out-of-hospital Cardiac Arrest (COCA) trial was recently conducted and published. This pre-planned sub-study evaluated the effect of calcium in patients with pulseless electrical activity (PEA) including subgroup analyses based on electrocardiographic characteristics potentially associated with hyperkalemia and ischemia.

METHODS

Patients aged ≥ 18 years were included if they had a non-traumatic out-of-hospital cardiac arrest and received adrenaline. The trial drug consisted of calcium chloride (5 mmol) or saline placebo given after the first, and again after the second, dose of adrenaline for a maximum of two doses. This sub-study analyzed patients with PEA as their last known rhythm prior to receiving the trial drug. Outcomes were return of spontaneous circulation and survival at 30 days.

RESULTS

104 patients were analyzed. In the calcium group, 9 patients (20 %) achieved return of spontaneous circulation vs 23 patients (39 %) in the placebo group (risk ratio 0.51; 95 %CI 0.26, 1.00). Subgroup analyses based on electrocardiographic characteristics potentially associated with hyperkalemia and ischemia showed similar results. At 30 days, 1 patient (2.2 %) was alive in the calcium group while 8 patients (13.6 %) were alive in the placebo group (risk ratio 0.16; 95 %CI 0.02, 1.26).

CONCLUSION

In adults with out-of-hospital cardiac arrest presenting with PEA, effect estimates suggested harm of calcium administration as compared to placebo but with wide confidence intervals. Results were consistent for patients with electrocardiographic characteristics potentially associated with hyperkalemia and ischemia. The results do not support calcium administration based strictly on electrocardiographic findings seen during out-of-hospital cardiac arrest.

Conduction disorders after transcatheter aortic valve implantation: A comparison between SAPIEN 3 and SAPIEN 3 Ultra balloon-expandable valves

Background

Conduction disorders (CD) are the most common complications after Transcatheter Aortic Valve Implantation (TAVI). The last generation of Edwards balloon expandable valves, the SAPIEN 3 Ultra (S3U), is provided with an external sealing skirt that aims to further reduce paravalvular leakage (PVL) compared to SAPIEN 3 (S3) and could potentially lead to higher CD rate. We sought to investigate the rate of new-onset CD in patients undergoing TAVI with the S3 or S3U valve.

Methods

We included 582 consecutive patients undergoing TAVI in a single high-volume Center. Patients with previously implanted pacemaker and Valve in valve procedures were excluded. CD rate was evaluated early after implantation and at discharge.

Results

No significant difference in the overall CD rate was found between S3 and S3U patients both immediately after the procedure (S3 45.5% vs. S3U 41.8%, p = 0.575) and at discharge (S3 30.4% vs. S3U 35.6%, p = 0.348) with low rate of permanent pacemaker implantation (S3 6.3% vs. S3U 5.5%, p = 0.749). No significant differences were found also in patients with pre-existing atrial fibrillation (S3 8.2% vs. S3U 5%, p = 0.648). A significantly lower rate of PVL was found with S3U compared to S3 (S3 42% vs. S3U 26%, p = 0.007). According to the manufacturer’s guidelines we confirmed that S3U were implanted in a significantly higher position compared to S3 (S3 4.89 ± 1.57 mm vs. S3U 4.47 ± 1.36 mm, p = 0.001).

Conclusion

No significant difference in the rate of CD, including the need for PPM implantation, was found in patients undergoing TAVI with the S3 compared to S3U. Moreover, S3U significantly reduced the PVL rate.

St-Segment Yüksekliği Olan Akut Koroner Sendromlu Hastalarda Bel Çevresinin Mortalite ve Morbidite Üzerine Etkisi

Aim: Obesity is a known risk factor for cardiovascular diseases. However, there are also studies showing that increased body mass index is unexpectedly protective in myocardial infarction. More studies are needed to elucidate this situation, known as the obesity paradox. This study was conducted to investigate the relationship between waist circumference and mortality and morbidity in acute ST elevated myocardial infarct (STEMI). Material and Method: This is a prospective and observational study. Patients diagnosed with STEMI on electrocardiography (ECG) were included in the study. Immediately after the exhalation, waist circumference (WC) was measured on a horizontal plane at a point equidistant from the lowest floating rib and the upper border of the iliac crest. The role of waist circumference in the development of mortality and major cardiac events within 1 month was evaluated. Results: A total of 106 patients admitted to the emergency department with STEMI were included in the study. While increased waist circumference was associated with mortality, it was insignificant in terms of major adverse cardiovascular event (MACE) development. Low BMI is significant in terms of decreased mortality and MACE. Conclusions: The use of WC as an indicator of body fat ratio rather than weight in STEMI may be more valuable in the evaluation of mortality and MACE.

Yield of the electrophysiological study in patients with new-onset left bundle branch block after transcathether aortic valve replacement: The PR interval matters

Background

Studies suggest that performing an electrophysiological study (EPS) may be useful to identify patients with new-onset left bundle branch block (LBBB) post-TAVR at risk of atrioventricular block. However, tools to optimize the yield of such strategy are needed. We therefore aimed to investigate whether 12-lead ECG changes post-TAVR may help identify patients with abnormal EPS findings.

Materials and methods

Consecutive patients with new-onset LBBB post-TAVR who underwent EPS were included. PR and QRS intervals were measured on 12-lead ECG pre-TAVR and during EPS. Abnormal EPS was defined as an HV interval > 55 ms.

Results

Among 61 patients, 28 (46%) had an HV interval > 55 ms after TAVR. Post-TAVR PR interval and ΔPR (PR-post–pre-TAVR) were significantly longer in patients with prolonged HV (PR: 188 ± 38 vs. 228 ± 34 ms, p < 0.001, ΔPR: 10 ± 30 vs. 34 ± 23 ms, p = 0.001), while no difference was found in QRS duration. PR and ΔPR intervals both effectively discriminated patients with HV > 55 ms (AUC = 0.804 and 0.769, respectively; p < 0.001). A PR > 200 ms identified patients with abnormal EPS results with a sensitivity of 89% and a negative predictive value (NPV) of 88%. ΔPR ≥ 20 ms alone provided a somewhat lower sensitivity (64%) but combining both criteria (i.e., PR > 200 ms or ΔPR ≥ 20 ms) identified almost every patients with abnormal HV (sensitivity = 96%, NPV = 95%). Selecting EPS candidate based on both criteria would avoid 1/3 of exams.

Conclusion

PR interval assessment may be useful to select patients with new-onset LBBB after TAVR who may benefit most from an EPS. In patients with PR ≤ 200 ms and ΔPR < 20 ms the likelihood of abnormal EPS is very low independently of QRS changes.

Predictors of late arrhythmic events after generator replacement in Brugada syndrome treated with prophylactic ICD

Introduction

Predictors of late life-threatening arrhythmic events in Brugada syndrome (BrS) patients who received a prophylactic ICD implantation remain to be evaluated. The aim of the present long-term multicenter study was to assess the incidence and clinical-electrocardiographic predictors of late life-threatening arrhythmic events in BrS patients with a prophylactic implantable cardioverter defibrillator (ICD) and undergoing generator replacement (GR).

Methods

The study population included 105 patients (75% males; mean age 45 ± 14years) who received a prophylactic ICD and had no arrhythmic event up to first GR.

Results

The median period from first ICD implantation to last follow-up was 155 (128-181) months and from first ICD Implantation to the GR was 84 (61-102) months. During a median follow-up of 57 (38-102) months after GR, 10 patients (9%) received successful appropriate ICD intervention (1.6%/year). ICD interventions included shock on ventricular fibrillation (n = 8 patients), shock on ventricular tachycardia (n = 1 patient), and antitachycardia pacing on ventricular tachycardia (n = 1 patient). At survival analysis, history of atrial fibrillation (log-rank test; P = 0.02), conduction disturbances (log-rank test; P < 0.01), S wave in lead I (log-rank test; P = 0.01) and first-degree atrioventricular block (log-rank test; P = 0.04) were significantly associated with the occurrence of late appropriate ICD intervention. At Cox-regression multivariate analysis, S-wave in lead I was the only independent predictor of late appropriate ICD intervention (HR: 9.17; 95%CI: 1.15-73.07; P = 0.03).

Conclusions

The present study indicates that BrS patient receiving a prophylactic ICD may experience late appropriate intervention after GR in a clinically relevant proportion of cases. S-wave in lead I at the time of first clinical evaluation was the only independent predictor of persistent risk of life-threatening arrhythmic events. These findings support the need for GR at the end of service regardless of previous appropriate intervention, mostly in BrS patients with conduction abnormalities.

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

Objective

We aimed to determine the prevalence of and the factors associated with intraventricular conduction disturbance in the Chinese population.

Methods

Electrocardiographic 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.

Results

The 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.

Conclusions

This study provided reliable data for the weighted prevalence of and factors associated with LBBB, RBBB and NS-IVCD in Chinese adults.

Mobile Cardiac Acoustic Monitoring System to Evaluate Left Ventricular Systolic Function in Pacemaker Patients

The mobile cardiac acoustic monitoring system is a promising tool to enable detection and assist the diagnosis of left ventricular systolic dysfunction (LVSD). The objective of the study was to evaluate the diagnostic value of electromechanical activation time (EMAT), an important cardiac acoustic biomarker, in quantifying LVSD among left bundle branch pacing (LBBP) and right ventricular apical pacing (RVAP) patients using a mobile acoustic cardiography monitoring system. In this prospective single-center observational study, pacemaker-dependent patients were consecutively enrolled. EMAT, the time from the start of the pacing QRS wave to first heart sound (S1) peak; left ventricular systolic time (LVST), the time from S1 peak to S2 peak; and ECG were recorded simultaneously by the mobile cardiac acoustic monitoring system. LVEF was measured by echocardiography. A logistic regression model was applied to evaluate the association between EMAT and reduced EF (LVEF < 50%). A total of 105 pacemaker-dependent patients participated. The RVAP group (n = 58) displayed a significantly higher EMAT than the LBBP group (n = 47) (150.95 ± 19.46 vs. 108.23 ± 12.26 ms, p < 0.001). Pearson correlation analysis revealed a statistically significant negative correlation between EMAT and LVEF (p < 0.001). Survival analysis showed the sensitivity and specificity of detecting LVEF to be < 50% when EMAT ≥ 151 ms were 96.00% and 96.97% in the RVAP group. In LBBP patients, the sensitivity and specificity of using EMAT ≥ 110 ms as the cutoff value for the detection of LVEF < 50% were 75.00% and 100.00%. There was no significant difference in LVST with or without LVSD in the RVAP group (p = 0.823) and LBBP group (p = 0.086). Compared to LVST, EMAT was more helpful to identify LVSD in pacemaker-dependent patients. The cutoff point of EMAT for diagnosing LVEF < 50% differed regarding the pacing type. Therefore, the mobile cardiac acoustic monitoring system can be used to identify the progress of LVSD in pacemaker patients.