Intraventricular Conduction Disturbances Research Articles

Cardiac manifestations in myotonic dystrophy type 1

Aim. To characterize cardiac damage in myotonic dystrophy type 1 (MD1), which is the most common form of hereditary primary muscular pathology in adults.Material and methods. Forty-eight patients with MD1 (31 men, 17 women, mean age 39,2±9,3 years) underwent clinical examination, neuropsychological examination, lipid profile assessment, electrocardiography (ECG), Holter ECG monitoring, and echocar-diography. Four clinical cases are presented that demonstrate clear cardiac manifestations of MD1.Results. The patients did not complain of arrhythmias or chest pain, while 7 (14,6%) had complaints of exercise shortness of breath. Cardiac conduction disorders occurred in 18 (37,5%) patients, which were represented by firstand second-degree atrioventricular (AV) block, his bundle and intraventricular conduction disturbances. According to Holter monitoring, heart rate <60 bpm was recorded in 46 (95,8%) patients, of which 2 (4,2%) were <30 bpm. One (2.1%) patient had atrial fibrillation. According to echocardiography, ventricular enlargement was detected in 3 (6,3%) patients, and atrial enlargement — in 8 (16,7%). None of the patients had an ejection fraction <50%.Conclusion. Cardiac involvement is a common manifestation of MD1. Full cardiac examination can help not only improve the quality of life of patients, but also avoid possible side effects of the prescribed treatment.

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.

Cardiac implantable electronic devices in Bulgaria: results from the electronic registry BG-Pace for 2022

The current study analyses the activity on cardiac pacing in Bulgaria in 2022 based on data derived from a national registry of patients with cardiac implantable electronic devices (CIEDs). Materials and methods. Data from the national registry BG-Pace for 2022 was studied retrospectively. Demographic data, procedure and device type, pacing mode, etiology, symptoms, preimplantation ECG, number of implantations, and centre and operator volumes were analyzed. Results: Four thousand seven hundred seventy devices were implanted by 45 operators in 30 centers. Median age was 76 (IQR 69-82, 14-98) years, and male patients were 2843 (59,6%). The most significant number of implantations were carried out in the age group 70-79 years. The most commonly implanted CIEDs were antibradycardia devices - 578,8/million. Of them, conduction system pacing was used in 111 (2.3%). Implanted cardioverter-defibrillators demonstrated a growth compared to previous periods and reached 31.9/million. Cardiac resynchronization defibrillators implantations also shown a growth to 15.9/million. A considerable increase was found with implantable loop-recorders, which reached 8.8/million. Number of implantations per center was 115.5 (IQR 53-261.,3, 3-546), and 76,5 (IQR 36,8-154,8, 3-364) devices per operator. Dual chamber devices were most commonly implanted with a share of 83.1% in AVB I and II degrees, 72.5% in complete AVB, 82.6% in intraventricular conduction disturbances, and in 66.8% in patients with sick sinus syndrome. Pacing modes allowing for atrial sensing were most frequently implanted – 62.4% of all implantations for conduction disturbances. There was a significant increase in the use of VVI mode with increasing age (P<0.001). Conclusion: The national registry BG-Pace includes systematic clinical, demographical, and procedural data for CIED implantations in Bulgaria. There is a growth in the implantation rates compared to previous periods, but they remain lower than the average number for Europe.

Characterization and comparison of rhythm disturbances after atrial or arterial switch surgeries for dextro-transposition of the great arteries: a long-term follow-up study

Abstract Introduction and objectives Dextro-transposition of the great arteries (D-TGA) is a congenital heart disease (CHD) palliated with atrial switch (ATR-S) and, more recently, with arterial switch (ART-S). As late complications from ATR-S are expected, novel challenges from ART-S surgery arises. Our aim was to evaluate these patients’ (pts) arrhythmic disturbances after a long-term follow-up. Methods We retrospectively analyzed D-TGA pts born between 1974 and 2001 and followed in Adult CHD Outpatient Clinic at a tertiary care hospital. Clinical records were used to collect pts data. Results A total of 79 pts were enrolled with a mean follow-up time after surgery of 27±6 years. Pts median age was 27 years-old and 46% were female. 54% were submitted to ATR-S, while 46% underwent ART-S; median age at intervention was 13 months and 10 days, respectively. Focusing arrhythmic events (Table 1), almost all ART-S pts remained in sinus rhythm versus 64% of ATR-S (p=0.002). The latter presented significantly higher frequencies of arrythmias (41% vs 3%, p < 0.001), mainly atrial flutter or fibrillation (26% vs 0%), as well as bradyarrhythmias (12% vs 0%). Chronotropic incompetence was also more frequent after ATR-S (46% vs 9%, p=0.011). Inversely, intraventricular (IV) conduction disturbances were more frequent after ART-S (54% vs 15%, p < 0.001), the majority due to incomplete right bundle branch block. Cardiac Implantable Electronic Devices (CIED) were implanted in 6 pts (5 pacemakers and 1 implantable cardioverter defibrillator) and 1 patient was submitted to catheter ablation of cavotricuspid isthmus, all of them from ATR-S group. The overall median time to first arrhythmia was 23±9 years. Conclusion ATR-S presented significantly fewer pts in sinus rhythm and higher rates of chronotropic incompetence, as well as need for CIED. Additionally, ATR-S pts had higher rates of arrhythmia development, namely supraventricular (SV) ones. These findings highlight the advantages of ART-S over ATR-S in reducing SV arrhythmias occurrence. Curiously, IV conduction disturbances, mainly incomplete right bundle brunch block, were more frequent after ART-S. This fact emphasizes the importance of long-term follow-up of all pts, regardless of the initial surgical approach, as ART-S pts were not arrhythmic-free. Our work raises awareness for arrhythmic disturbances in this subgroup of CHD pts, irrespective of surgical strategy adopted.Table 1

Cancelled STEMI patients: what happen to them?

Abstract Introduction In the STEMI care network, the number of inappropriate cases sent to cathlab remains high 1. The use of technological innovations to share the diagnostic ECG tracing with the cardiology department has been shown to be effective in improving patient discrimination. Objective Our aim was to study the characteristics and prognosis (at discharge and 1-year follow-up) of patients whose transfer to the cathlab was cancelled. Material and Method Prospective study analysing all STEMI alert activations in 2022. Information on ECG pattern and clinical history was transmitted using an APP (ODiSEA 2-3) and used for cancellation. Patient characteristics, myocardial infarction, ECG activation pattern, angiography results, final diagnosis and clinical events during admission and 1-year follow-up were recorded. Patients who underwent urgent coronary angiography were excluded from the study. Results A total of 406 infarction codes were activated through the ODISEA APP. 122 (30%) of these were cancelled. The characteristics of the patients are shown in Table 1. Reasons for cancellation based on ECG pattern are shown in Figure 1.B. The most common were ST depression (23%) and intraventricular conduction disturbances (22.9%). The final diagnosis was ACS in 32.8% (STEMI 2.5%, NSTEMI 27% and unstable angina 3.3%). In the remaining 67.2%, the final diagnosis was atypical chest pain with negative biomarkers in 22.9%, arrhythmia in 17.2%, pericarditis in 9%, gastrointestinal pathology in 4.9%, heart failure in 4.9%, aortic dissection in 3.2%, PTE in 1.6% and other pathologies in 3.5%. (Figure 1.A). Coronary angiography was performed in 41 patients (33.6%). There were 36.6% with one vessel, 9.8% with two vessels and 22% with three vessels. Percutaneous revascularisation was required in 70% of patients. Discharge from the emergency department occurred in 46% of the patients. Hospital mortality occurred in 14 patients (11.4%). Of these, 3 (2.4%) were due to cardiac causes. Regarding events at 12 months, 6 (4.9%) were deaths (5 natural deaths and 1 due to cancer). 5 patients (4%) had ACS, 3 patients (2.4%) had stroke and 1 patient (0.8%) had digestive bleeding. Conclusions STEMI alert cancelled transfer patients are older, have more comorbidities and are less likely to have a final diagnosis of ACS or to have coronary lesions. They have a high rate of non-cardiovascular in-hospital mortality and a low rate of cardiovascular events at one year of follow-up.A.Final diagnosis. B. ECG patternTable 1.Patients characteristics

Patients cancelled after initial activation for suspected STEMI via the ODiSEA APP, what happens to them?

Abstract Introduction The use of technological innovation in STEMI care networks has been shown to be effective in sharing diagnostic ECG tracing and clinical information with the cardiology department, reducing the number of inappropriate cases transferred to the cathlab. These inappropriate cases have been shown to be more likely to die than those undergoing urgent coronary angiography, but data on incidence, cause of cancellation and prognosis are limited1. Objective Our aim was to investigate the characteristics and prognosis of patients in whom transfer to the cathlab was cancelled, compared with those who underwent emergent coronary angiography (EC). Material and Methods Prospective study analysing all STEMI alert activations during the year 2022. Information on ECG pattern and clinical history was transmitted using an APP (ODiSEA2,3). Based on the ECG pattern and clinical history, cancellations were made. Patient characteristics, myocardial infarction, ECG activation pattern, angiography results and in-hospital mortality were studied. Results A total of 406 infarction codes were activated through the ODISEA APP, of which 284 (70%) underwent EC and 122 (30%) were cancelled. The cancelled patients had a higher comorbidity than the transferred patients. The reasons for cancellation based on ECG patterns are shown in Figure 1. The most common were ST depression (23%), concave ST elevation (18.8%) and intraventricular conduction disturbances (22.9%). In addition, coronary angiography was performed in 33% of the cancelled patients compared to 99% of the transferred patients (p<0.001). The number of patients with coronary arteries without lesions was significantly higher in the cancelled group (31.7% vs. 9.6% p<0.001). In the EC group, 90.5% of patients presented with a final diagnosis of ACS, whereas in the cancelled group this was 32.8% (final diagnosis of STEMI 2.5% in the cancelled group vs. 83.5% in the CE group, p<0.001). Discharge from the emergency department was 46% in the cancellation group versus 2.7% in the transfer group (p<0.001). Finally, the in-hospital mortality rate was significantly higher in the cancelled group: 14 patients (11.4%) vs. 12 patients (4.2%) in the transferred group (p<0.001). Discussion Compared to patients who are transferred to a centre with cathlab, the subgroup of patients initially activated as STEMI alerts and eventually cancelled have a high comorbidity, a low probability of a final diagnosis of ACS and a high in-hospital.Table 1.Patients characteristicsFigure 1.ECG pattern

Long-term impact of pacemaker implantation after TAVI: a subgroup analysis according to previous intraventricular conduction disturbances

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Transcatheter aortic valve implantation (TAVI) is a worldwide accepted treatment for severe aortic stenosis (AS). Conduction system disturbances, frequently requiring permanent pacemaker (PM) implantation, remain one of the most common procedural complication. Whether the permanent ventricular pacing has a deleterious impact on the prognosis of this population remains unclear. Objectives To assess the long-term impact of permanent PM implantation in clinical outcomes after TAVI. Methods We performed a retrospective analysis of consecutive patients (P) who underwent TAVI between 2009 and 2021 in a single tertiary center.P with a PM implanted before TAVI or with in-hospital mortality were excluded from the analysis. PM implantation post-TAVI was defined as an implant during hospital stay after TAVI or in the first month after discharge. Kaplan Meier survival curves were used to estimate the impact of permanent PM after TAVI, regarding the composite endpoint of all-cause mortality and heart failure (HF) hospitalization during a 4 years follow-up period, and a comparison performed according to the presence or absence of baseline intraventricular conduction disturbances. Results 549 P (82±6.6 years, 56.8% female, left ventricular ejection fraction 53±10%, peak gradient 51±15.6 mmHg, aortic valve area 0.7± 0.2 cm2) were included. At baseline, 108 P (20%) had intraventricular conduction disturbances on ECG (50 P with right bundle branch block [RBBB] and 58 P with left bundle branch block [LBBB]). 127 P (23%) required PM implantation after TAVI. Baseline characteristics were similar between P with and without PM implantation, except for age, gender, previous valvular surgery and RBBB (Table 1). At 48 months follow-up, 35% (n=193) met the composite endpoint, that was similar between both groups (35.8% vs. 34.1%, p=0.731). Kaplan-Meier survival curves revealed no difference in the composite endpoint between the two groups (log-rank p=0.170). Further analysis of subgroups according to the presence or absence of baseline intraventricular conduction disturbances revealed a significant difference among the subgroup of P without previous intraventricular conduction disturbances that underwent PM implantation after TAVI (log rank p=0.02) (Fig 1). This difference in the composite endpoint after PM was not found in the subgroups of P with RBBB (log rank p=0.656) or LBBB (log rank p=0.975) at baseline (Fig 2).* Conclusions Permanent PM implant after TAVI does not have an impact on long-term HF hospitalization and mortality. However, in the specific subgroup of P without previous intraventricular conduction disturbances, PM implantation seems to be associated with worse prognosis.

Delayed ventricular conduction alters ventricular repolarization in patients with heart failure: an electrocardiographic imaging study

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Personal grant from the Dutch Heart Foundation. Background In the normal human heart, the polarity of the T-wave is concordant with the QRS complex. This phenomenon is often explained by longer repolarization of earlier activated regions. Patients with delayed ventricular conduction often have discordant T-waves, but the link to regional repolarization is unknown. Aim To compare epicardial repolarization-activation (RT-AT) relations in patients with heart failure and reduced ejection fraction (HFrEF) with those having a structural normal heart. Methods 14 patients with HFrEF and delayed ventricular conduction and 11 patients no history of structural heart disease and a normal surface ECG (nQRS) were analyzed using electrocardiographic imaging (ECGI). HFrEF patients were subcategorized as left bundle branch block (LBBB, n=6) or non-specified intraventricular conduction disturbance (IVCD, n=8). Noninvasive ECGI was used to assess epicardial activation (ATs) and repolarization times (RTs). RT-AT relationships were evaluated for 24 epicardial segments using linear regression analysis. Interventricular repolarization dispersion (inter-RTD) was defined as the difference between average left-ventricular (LV) and right-ventricular RT, while total epicardial repolarization dispersion (total-RTD) was defined as the standard deviation of all epicardial RTs. The maximum of the local RT gradients (RTG) was defined as their 95th percentile. RT parameters were described as median±IQR and Kruskal Wallis tests were used to evaluate the differences between the groups. Results An HFrEF patient’s representative 24-segment AT and RT bullseyes with a positive RT-AT relation (~depolarize last, repolarize last) is provided in Figure1A. A positive RT-AT slope was present in the majority of HFrEF patients (1.14±0.17 for LBBB and 1.16±0.55 for IVCD), whereas the nQRS group (-0.25±2.16) demonstrated an overall slightly negative slope with high variability (Figure 1B and 1C). Individual (thin lines) and group-averaged (thick lines) RT-AT slopes normalized for the earliest AT and earliest RT (in case of a positive RT-AT slope) or latest RT (in case of a negative slope) are visualized in Figure 1C. Both inter-RTD (41±25 for LBBB, 32±13 ms for IVCD, and 8±20 ms for nQRS) as well as total-RTD (34±9for LBBB, 34±12 ms for IVCD, and 24±8 ms for nQRS) was significantly higher in the LBBB and IVCD group compared to the nQRS group, whereas RTG did not differ between the groups (Figure 1B). RT-AT slopes, inter-RTD, total-RTD, and RTG did not significant differ between the LBBB and IVCD subgroup. Conclusion This ECGI study shows that in patients with HFrEF, later activated regions also have a later completion of repolarization, regardless of conduction delay, whereas a variable RT-AT relation is present in subjects with structural normal hearts. HFrEF additionally initiates a higher degree of interventricular and total repolarization dispersion.

PO-01-181 DELAYED VENTRICULAR CONDUCTION ALTERS VENTRICULAR REPOLARIZATION IN PATIENTS WITH HEART FAILURE: AN ELECTROCARDIOGRAPHIC IMAGING STUDY

In the normal human heart, the polarity of the T-wave is concordant with the QRS complex. This phenomenon is explained by longer repolarization of earlier activated regions. Patients with delayed ventricular conduction have discordant T-waves, but the link to regional repolarization is unknown. To compare epicardial repolarization-activation (RT-AT) relations in patients with heart failure and reduced ejection fraction (HFrEF) with those having a structural normal heart. 14 patients with HFrEF and delayed ventricular conduction and 11 patients no history of structural heart disease and a normal surface ECG (nQRS) were analyzed using ECG imaging (ECGI). HFrEF patients were categorized as left bundle branch block (LBBB, n=6) or non-specified intraventricular conduction disturbance (IVCD, n=8). ECGI was used to assess epicardial activation (ATs) and repolarization times (RTs). RT-AT relationships were evaluated for 24 segments using linear regression analysis. Interventricular repolarization dispersion (inter-RTD) was defined as the difference between average left-ventricular (LV) and right-ventricular RT, while total epicardial repolarization dispersion (total-RTD) was defined as the standard deviation of all epicardial RTs. The maximum of the local RT gradients (RTG) was defined as their 95th percentile. Kruskal Wallis tests were used to evaluate the differences between the groups. An HFrEF patient’s representative AT and RT bullseyes with a positive RT-AT relation (∼depolarize last, repolarize last) is provided in Figure1A. A positive RT-AT slope was present in the majority of HFrEF patients (1.14±0.17 for LBBB and 1.16±0.55 for IVCD), whereas the nQRS group (-0.25±2.16) demonstrated an overall slightly negative slope with high variability (Figure 1B and 1C). Individual (thin lines) and group-averaged (thick lines) RT-AT normalized slopes are visualized in Figure 1C. Both inter-RTD as well as total-RTD was significantly higher in the LBBB and IVCD group compared to the nQRS group, whereas RTG did not differ between the groups (Figure 1B). None of the RT parameters significantly differed between the LBBB and IVCD subgroup. This ECGI study shows that in patients with HFrEF, later activated regions also have a later completion of repolarization, regardless of conduction delay, whereas a variable RT-AT relation is present in subjects with structural normal hearts. HFrEF additionally initiates a higher degree of interventricular and total repolarization dispersion.

Dyssynchrony and Response to Cardiac Resynchronization Therapy in Heart Failure Patients With Unfavorable Electrical Characteristics

BackgroundAmong heart failure (HF) patients undergoing cardiac resynchronization therapy (CRT), those with unfavorable electrical characteristics (UEC) are less frequently CRT responders. ObjectivesIn this study, the authors sought to evaluate the relationship between preprocedural echocardiographic parameters of electromechanical dyssynchrony (EMD) and outcome following CRT. MethodsAmong 551 patients receiving CRT, 121 with UEC, defined as atypical left bundle branch, presence of right bundle branch block, or unspecified intraventricular conduction disturbance, were enrolled. Indices of EMD were presence of septal flash, apical rocking, septal deformation patterns, and global wasted work (GWW), determined with the use of speckle-tracking strain echocardiography. Endpoints were response to CRT, defined as a relative decrease in left ventricular end-systolic volume ≥15% at 9-month postoperative follow-up, and all-cause death or HF hospitalization during follow-up. ResultsAmong the 121 patients, 68 (56%) were CRT responders. In multivariate analysis, GWW ≥200 mm Hg% (adjusted odds ratio [aOR]: 4.17 [95% CI: 1.33-14.56]; P = 0.0182) and longitudinal strain septal contraction patterns 1 and 2 (aOR: 10.05 [95% CI: 2.82-43.97]; P < 0.001) were associated with CRT response. During a 46-month follow-up (IQR: 42-55 months), survival free from death or HF hospitalization increased with the number of positive criteria (87% for 2, 59% for 1, and 27% for 0). After adjustment for established predictors of outcome in patients receiving CRT, absence of either of the 2 criteria remained associated with a considerable increased risk of death and/or HF hospitalization (adjusted HR: 4.83 [95% CI: 1.84-12.68]; P = 0.001). ConclusionsIn patients with UEC, echocardiographic assessment of EMD may help to select patients who will derive benefit from CRT. (Echocardiography in Cardiac Resynchronization Therapy [Echo-CRT]; NCT02986633)

Prediction of conduction disturbances in patients undergoing transcatheter aortic valve replacement

AimTranscatheter aortic valve replacement (TAVR) can cause intraventricular conduction disturbances (ICA), particularly left bundle branch block (BBB) and high-degree atrioventricular block (HAVB). The aim of this study was to investigate clinical, anatomical, procedural, and electrophysiological parameters predicting ICA after TAVR.MethodsPatients with severe aortic stenosis (n = 203) without pacing devices undergoing TAVR with a self-expanding (n = 103) or balloon-expanding (n = 100) valve were enrolled. Clinical and anatomical parameters, such as length of the membranous septum (MS) and implantation depth, were assessed. His-ventricular interval (HVi) before and after implantation was determined. 12-lead-electrocardiograms (ECG) before, during and after 3 and 30 days after TAVR were analyzed for detection of any ICA.ResultsAmong 203 consecutive patients (aortic valve area 0.78 ± 0.18 cm2, age 80 ± 6 years, 54% male, left ventricular ejection fraction 52 ± 10%), TAVR led to a significant prolongation of infranodal conduction in all patients from 49 ± 10 ms to 59 ± 16 ms (p = 0.01). The HVi prolongation was independent of valve types, occurrence of HAVB or ICA. Fifteen patients (7%) developed HAVB requiring permanent pacemaker (PPM) implantation and 63 patients (31%) developed ICA within 30 days. Pre-existing BBB (OR 11.64; 95% CI 2.87–47.20; p = 0.001), new-onset left BBB (OR 15.72; 95% CI 3.05–81.03; p = 0.001), and diabetes mellitus (OR 3.88; 95% CI 1.30–15.99; p = 0.02) independently predicted HAVB requiring PPM. Neither pre-existing right BBB, a prolonged postHVi, increases in PR duration, any of the TAVR implantation procedural and anatomic nor echocardiographic characteristics were predictive for later HAVB.ConclusionsNew-onset left BBB and diabetes mellitus independently predicted HAVB requiring PPM after TAVR and helped to identify patients at risk. Electrophysiologic study (EPS) of atrioventricular conduction was neither specific nor predictive of HAVB and can be skipped.Trial registration numberNCT04128384 (https://www.clinicaltrials.gov).Graphical abstract

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.

The Primary Alteration of Ventricular Myocardium Conduction: The Significant Determinant of Left Bundle Branch Block Pattern.

Intraventricular conduction disturbances (IVCD) are currently generally accepted as ECG diagnostic categories. They are characterized by defined QRS complex patterns that reflect the abnormalities in the intraventricular sequence of activation that can be caused by pathology in the His-Purkinje conduction system (HP) or ventricular myocardium. However, the current understanding of the IVCD's underlying mechanism is mostly attributed to HP structural or functional alterations. The involvement of the working ventricular myocardium is only marginally mentioned or not considered. This opinion paper is focused on the alterations of the ventricular working myocardium leading to the most frequent IVCD pattern-the left bundle branch block pattern (LBBB). Recognizing the underlying mechanisms of the LBBB patterns and the involvement of the ventricular working myocardium is of utmost clinical importance, considering a patient's prognosis and indication for cardiac resynchronization therapy.

Abstract 12486: Impact of New-Onset Persistent Left Bundle Branch Block on Reverse Cardiac Remodeling and Clinical Outcomes After Transcatheter Aortic Valve Replacement

Background: The clinical implication of new-onset left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) remains controversial. We investigated the impact of new-onset persistent LBBB on reverse cardiac remodeling and clinical outcomes after TAVR. Methods: Among 478 patients who had undergone TAVR for symptomatic severe aortic stenosis from 2011 to 2021, we analyzed 364 patients after excluding patients with pre-existing intraventricular conduction disturbance or a pacing rhythm before or during the indexed hospitalization for TAVR. Echocardiographic variables of cardiac remodeling at baseline and 1 year after TAVR were comprehensively analyzed. The primary outcome was a composite of cardiovascular death and hospitalization for heart failure. Secondary outcomes were all-cause death and individual components of the primary outcome. Result: New-onset persistent LBBB occurred in 41 (11.3%) patients after TAVR. The no LBBB group showed a significant increase in the left ventricular (LV) ejection fraction and decreases in LV dimensions, the left atrial volume index, and LV mass index 1 year after TAVR (all p&lt;0.001). However, the new LBBB group showed no significant changes in these parameters. During a median follow-up of 18.1 months, the new LBBB group experienced a higher incidence of primary outcomes (hazard ratio [HR]: 5.03; 95% confidence interval [CI]: 2.60-9.73; p &lt; 0.001) and all-cause death (HR: 2.80; 95% CI: 1.38-5.69; p = 0.003). The data were similar after multivariable regression analysis. Conclusion: New-onset persistent LBBB after TAVR is associated with insufficient reverse cardiac remodeling and increased adverse clinical events.

Predictors of left ventricular dysfunction in hypertrophic cardiomyopathy: results from a nationwide registry

Abstract Introduction Progression of hypertrophic cardiomyopathy (HCM) with incident left ventricular (LV) dysfunction (HCM-LVSD) is associated with poor prognosis and advanced heart failure (HF). Prevalence ranges from 5–10% in previous studies. Identification of predictors of adverse remodeling may improve risk stratification and prognostication in HCM. Purpose To identify predictors of HCM-LVSD in a nationwide cohort of HCM patients (pts). Methods Retrospective study including all HCM pts enrolled in a European country-based nationwide registry. HCM-LVSD group included pts with LV ejection fraction (LVEF) ≤50% at baseline and pts who developed LV dysfunction/dilated phenotype during follow-up. Multivariate logistic regression was performed to identify predictors of HCM-LVSD. Results 1042 HCM patients (57.8% male, mean age at diagnosis 52 years) were included, of whom 81 (8%) belonged to the HCM-LVSD group. HCM-LVSD pts were mostly male (60.5%) and tended to be older at the time of diagnosis than those without LVSD (55 vs 52 years, p=0.054). HCM-LVSD pts were more often symptomatic at the index visit (84.1% vs 65.2%, p&amp;lt;0.001), with more functional impairment (New York Heart Association class III–IV: 18.5% vs 9.2%, p=0.021). Atrial fibrillation (21.3% vs 8.6%, p&amp;lt;0.001) and intraventricular conduction disturbances (28.6% vs 14.4%, p=0.002) were more prevalent in HCM-LVSD pts. HCM-LVSD pts had higher baseline left atrium (LA) volumes (52 vs 39 ml, p=0.001), lower LVEF (50 vs 67%, p&amp;lt;0.001) and higher rates of mitral regurgitation (79.0% vs 65.1%, p=0.011). Prevalence of obstructive HCM was lower in the HCM-LSVD group (25.3% vs 40.9%, p=0.007). Presence of late gadolinium enhancement (92.6% vs 74.6%, p=0.035) was more common in pts with LVSD. Baseline N-terminal pro–B-type natriuretic peptide was higher in HCM-LVSD (3839 vs 1281 pg/ml, p=0.027). There were no differences in the number and type of genetic variants between groups. In HCM-LVSD pts, implantation of cardioverter-defibrillators for secondary prevention was more frequent (28.6% vs 6.4%, p=0.002), as was the use of pacemaker (16.7% vs 7.0%, p=0.002). During a mean follow-up of 5.3±6.1 years, hospitalization for HF (50.0% vs 11.3%) and all-cause mortality (12.3% vs 2.9%, p&amp;lt;0.001) were more frequent in HCM-LVSD group. After multivariate analysis, higher LA volume (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01–1.05, p=0.003) and nonobstructive HCM (OR 2.74, 95% CI 1.03–7.27, p=0.043) were independent predictors of HCM-LVSD. Conclusions In this large nationwide cohort of HCM pts, prevalence of LVSD was 8%, in line with existing literature. In this cohort, larger LA volumes and nonobstructive HCM predicted progression to HCM-LVSD. Funding Acknowledgement Type of funding sources: None.

Prevalence and incidence of intraventricular conduction disturbances among Chinese adults: Results from the Kailuan study.

ObjectivesEpidemiological data on intraventricular conduction disturbances (IVCDs) are limited in the Chinese population. We aimed to investigate the prevalence and incidence of different types of IVCDs among Chinese adults.MethodsFrom June 2006 to October 2007, a total of 100,250 individuals from the Kailuan Study underwent electrocardiogram examinations. Follow-up visits were performed biennially. The prevalence and incidence of right bundle branch block (RBBB), incomplete RBBB (IRBBB), left bundle branch block (LBBB), incomplete LBBB, left anterior fascicular block (LAFB), left posterior fascicular block (LPFB) and non-specific IVCD (NIVCD) were calculated. Their association with risk factors and cardiovascular diseases was also investigated.ResultsThe prevalence and incidence of all IVCDs were 3.19 and 1.70%, respectively. RBBB, IRBBB, and LAFB were the IVCD types that had the highest prevalence and incidence. The prevalence (3.67% vs. 1.29%; P < 0.001) and incidence (1.93% vs. 0.84%; P < 0.001) of IVCDs were higher among males than among females. The prevalence and incidence of most IVCD types increased with age. IRBBB, LBBB, and LAFB were significantly associated with hypertension. LBBB and NIVCD were associated with diabetes mellitus. In addition, LBBB and LAFB were related to prior myocardial infarction.ConclusionIVCDs differ in prevalence and incidence according to sex and age group. They also show disparate associations with other cardiovascular comorbidities. These differences need to be considered in daily clinical practice.

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

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

Delta Increment in Pacing QRS Duration Predicts Cardiovascular Mortality in Patients with Pre-Existing Bundle Branch Block Receiving Permanent Pacemakers.

The clinical implication of pre-existing intraventricular conduction disturbance (IVCD) in permanent pacemaker (PPM) recipients is unknown. To explore the clinical outcomes in patients with pre-existing IVCD after implantation of PPMs. A total of 1424 patients who received PPMs were categorized into three groups by pre-procedural electrocardiography: patients without IVCD (n = 1045), patients with right bundle branch block (RBBB) (n = 309), and patients with left bundle branch block (LBBB) (n = 70). The primary outcome was cardiovascular (CV) mortality. Receiver operating characteristic curve analysis was performed to determine the optimal cut-off values of variable in predicting CV mortality. During follow-up, there was no significant difference in CV mortality between patients with and without IVCD. In multivariate analysis, independent predictors of CV mortality were age [hazard ratio (HR): 1.03; 95% confidence interval (95% CI): 1.00-1.05; p = 0.026], history of heart failure [HR: 1.98; 95% CI: 1.19-3.29; p = 0.009], chronic kidney disease [HR: 1.75; 95% CI: 1.11-2.74; p = 0.015] and increment in pacing QRS duration [HR: 1.01; 95% CI: 1.00-1.04; p = 0.038]. Delta increments in pacing QRS duration ≥ 43 msec [HR: 2.91; 95% CI: 1.23-6.83; p = 0.014] in patients with pre-existing RBBB, and ≥ 33 msec [HR: 11.44; 95% CI: 2.03-64.30; p = 0.006] in patients with pre-existing LBBB were independent determinants of CV mortality. There was no difference in CV mortality between patients with or without IVCD. However, wider pacing QRS duration increased the risk of CV mortality in PPM recipients, and delta increment in pacing QRS duration increased the risk of CV mortality in patients with pre-existing IVCD.

Impact of New-Onset Persistent Left Bundle Branch Block on Reverse Cardiac Remodeling and Clinical Outcomes After Transcatheter Aortic Valve Replacement.

BackgroundThe clinical implication of new-onset left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) remains controversial. We investigated the impact of new-onset persistent LBBB on reverse cardiac remodeling and clinical outcomes after TAVR.MethodsAmong 478 patients who had undergone TAVR for symptomatic severe aortic stenosis from 2011 to 2021, we analyzed 364 patients after excluding patients with pre-existing intraventricular conduction disturbance or a pacing rhythm before or during the indexed hospitalization for TAVR. Echocardiographic variables of cardiac remodeling at baseline and 1 year after TAVR were comprehensively analyzed. The primary outcome was a composite of cardiovascular death and hospitalization for heart failure. Secondary outcomes were all-cause death and individual components of the primary outcome.ResultNew-onset persistent LBBB occurred in 41 (11.3%) patients after TAVR. The no LBBB group showed a significant increase in the left ventricular (LV) ejection fraction and decreases in LV dimensions, the left atrial volume index, and LV mass index 1 year after TAVR (all p < 0.001). However, the new LBBB group showed no significant changes in these parameters. During a median follow-up of 18.1 months, the new LBBB group experienced a higher incidence of primary outcomes [hazard ratio (HR): 5.03; 95% confidence interval (CI): 2.60–9.73; p < 0.001] and all-cause death (HR: 2.80; 95% CI: 1.38–5.69; p = 0.003). The data were similar after multivariable regression analysis.ConclusionNew-onset persistent LBBB after TAVR is associated with insufficient reverse cardiac remodeling and increased adverse clinical events.

Development of atrioventricular and intraventricular conduction disturbances in patients undergoing transcatheter aortic valve replacement with new generation self-expanding valves: A real world multicenter analysis

BackgroundHigh degree cardiac conduction disturbances (HDCD) remain a major complication after transcatheter aortic valve replacement (TAVR), especially with self-expandable valves (SEV). Our aim was to investigate peri-procedural and in-hospital modification of atrioventricular and intracardiac conduction associated to new generation SEV implantation, and the development of new HDCD resulting in permanent pacemaker implantation (PPM) in patients undergoing TAVR. Methods and resultsThree-hundred forty-four consecutive patients with severe aortic stenosis who underwent TAVR with a new generation SEV [Evolut-R/Pro (n = 130), Acurate-neo (n = 79), Portico (n = 75) and Allegra (n = 60)] were included. An analysis of baseline, post-TAVR and pre-discharge ECG and procedural aspects were centrally performed. A significant increase in baseline PR interval (169.6 ± 28.2 ms) and QRS complex width (101.7 ± 25.9 ms) was noted immediately post-TAVR (188.04 ± 34.49; 129.55 ± 30.02 ms), with a partial in-hospital reversal (179.4 ± 30.1; 123.06 ± 30.94 ms), resulting in a net increase at hospital discharge of 12.6 ± 38.8 ms and 21.4 ± 31.6 ms (p < 0.001), respectively. The global incidence of new onset persistent HDCD at hospital discharge was 46.3%, with 17.7% of patients requiring PPM. Independent predictors of new onset HCDC at hospital discharge were valve recapture (OR: 2.8; 95% IC: 1.1–7.2, p = 0.033) and implantation depth ≥ 6 mm (OR: 1.9 05% IC 1.1–3.3, p = 0.015), while higher implantation (<3 mm (OR: 0.3, 95% IC 0.1–0.7, p = 0.014) and use of Acurate-Neo valve (OR: 0.4; 95% IC 0.2–0.8, p = 0.009) were protective factor. ConclusionsNew generation self-expanding aortic valves were associated with a significant increase in PR and QRS interval at hospital discharge leading to a very high rate of HDCD. While valve recapture and implantation depth were independent predictors for the occurrence of HDCD, use of Accurate-Neo valve was a protective factor.