Short- and Long-Term Outcomes in Patients With New-Onset Persistent Left Bundle Branch Block After Transcatheter Aortic Valve Replacement

Conduction dynamics over time after transcatheter aortic valve replacement: An expert review

New conduction disorders remain a frequent complication in current transcatheter aortic valve replacement (TAVR) era. Left bundle branch block (LBBB) occurs early in about 20-30 % of TAVR-patients, persists at 1 month in about 35-45 % of cases and will likely remain thereafter. Third-degree atrioventricular block (AV3B) affects approximately 15 % of patients. Pacemaker dependency gradually decreases throughout follow-up and approximately 25-35 % of patients remain pacemaker dependent at one year. We aimed to review what is currently known about the dynamics of acquired conduction disorders, including extraction of predictors, and how to interpret these dynamics in light of an early discharge policy.

Conduction Disturbances After Transcatheter Aortic Valve Replacement: An Update on Epidemiology, Preventive Strategies, and Management

Conduction disturbances (CDs) are common after transcatheter aortic valve replacement. Continuous improvements in preprocedural planification, implant techniques, and device design have markedly reduced periprocedural complications. However, CDs rate remains in the double-digit range. Because CDs after TAVR are associated with poorer outcomes, seeking a reduction in their occurrence is paramount. Several nonmodifiable and modifiable factors are associated with an increased risk of CDs. Previous right bundle branch block has been shown to have a strong association with pacemaker implant after TAVR. Among the modifiable factors, a lower implantation depth seems to be associated with a higher risk of CDs, and several implant strategies aiming to obtain a higher implant depth have shown promising results. This literature review provides a detailed description of updated evidence about the epidemiology, impact, and preventive and management strategies of CDs after TAVR. Also, based on these updated data, a fast-track protocol CDs management is proposed.

Transcatheter aortic valve implantation versus surgery: 4-year survival according to life expectancy

Background

In the last years, transcatheter aortic valve implantation (TAVI) indication has expanded to younger and lower risk patients. Consequently, interest in mid and long-term follow up and in the role of life expectancy, as a key factor for selecting the most tailored treatment, has grown. The aim of this retrospective study is to compare the 4-year survival of patients who underwent aortic valve replacement (AVR) vs. TAVI at our department.

Methods

From September 2017 to December 2020, 673 consecutive patients with severe aortic valve stenosis were enrolled for AVR (n = 283) or TAVI (n = 390). Inclusion criteria was isolated severe aortic stenosis, while exclusion criteria were redo surgery, valve-in-valve procedure and the need for concomitant surgical procedures. Based on the Lee index, patients were divided into four groups according to their 4-year life expectancy. Four-year survival was assessed and reported using the Kaplan-Meier method. A multivariate regression analysis of risk factors for 4-year mortality was performed.

Results

Four years survival is always superior in the AVR patients (89.8% vs. 75.6%, P < 0.001). Surgery is associated with a higher incidence of acute kidney injury (23% vs. 5.1%, P < 0.001), while TAVI is related to a higher incidence of new onset left bundle branch block (0 vs. 23.8%, P < 0.001), pace-maker implantation (2.5% vs. 11.8%, P = 0,02) and mild-to-moderate paravalvular leak (0.3% vs. 5.4%, P < 0.001). The independent risk factors for 4-years mortality are post-procedural AKI, poor mobility and transcatheter procedure.

Conclusion

In our analysis, 4 years survival is always superior in the AVR patients. Life expectancy is a key factor for selecting the most appropriate approach for each patient. A longer follow up is mandatory before extending TAVI indication to patients with a long-life expectancy.

Conduction Abnormalities after Transcatheter Aortic Valve Implantation: Incidence, Impact and Management Using CT Data Interpretation

The demonstrated safety and effectiveness of transcatheter aortic valve implantation (TAVI) among low surgical risk patients opened the road to its application in younger low-risk patients. However, the occurrence of conduction abnormalities and need for permanent pacemaker implantation remains a frequent problem associated with adverse outcomes. The clinical implications may become greater when TAVI shifts towards younger populations, highlighting the need for comprehensive strategies to address this issue. Beyond currently available clinical and electrocardiographic predictors, patient-specific anatomical assessment of the aortic root using multi-sliced CT (MSCT) imaging can refine risk stratification. Moreover, leveraging MSCT data for computational 3D simulations to predict device-anatomy interactions may help guide procedural strategy to mitigate conduction abnormalities. The aims of this review are to summarise the incidence and clinical impact of new left bundle branch block and permanent pacemaker implantation post-TAVI using contemporary transcatheter heart valves; and highlight the value of MSCT data interpretation to improve the management of this complication.

Beyond conduction impairment: Unveiling the profound myocardial injury in left bundle branch block

BACKGROUND

Left bundle branch block (LBBB) represents a frequently encountered conduction system disorder. Despite its widespread occurrence, a continual dilemma persists regarding its intricate association with underlying cardiomyopathy and its pivotal role in the initiation of dilated cardiomyopathy. The pathologic alterations linked to LBBB-induced cardiomyopathy (LBBB-CM) have remained elusive.

OBJECTIVE

This study sought to investigate the chronologic dynamics of LBBB to left ventricular dysfunction and the pathologic mechanism of LBBB-CM.

METHODS

LBBB model was established through main left bundle branch trunk ablation in 14 canines. All LBBB dogs underwent transesophageal echocardiography and electrocardiography before ablation and at 1 month, 3 months, 6 months, and 12 months after LBBB induction. Single-photon emission computed tomography imaging was performed at 12 months. We then harvested the heart from all LBBB dogs and 14 healthy adult dogs as normal controls for anatomic observation, Purkinje fiber staining, histologic staining, and connexin43 protein expression quantitation.

RESULTS

LBBB induction caused significant fibrotic changes in the endocardium and mid-myocardium. Purkinje fibers exhibited fatty degeneration, vacuolization, and fibrosis along with downregulated connexin43 protein expression. During a 12-month follow-up, left ventricular dysfunction progressively worsened, peaking at the end of the observation period. The association between myocardial dysfunction, hypoperfusion, and fibrosis was observed in the LBBB-afflicted canines.

CONCLUSION

LBBB may lead to profound myocardial injury beyond its conduction impairment effects. The temporal progression of left ventricular dysfunction and the pathologic alterations observed shed light on the complex relationship between LBBB and cardiomyopathy. These findings offer insights into potential mechanisms and clinical implications of LBBB-CM.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Rationale and Design of the Randomized Bayesian Multicenter COME-TAVI Trial in Patients With a New Onset Left Bundle Branch Block

Patients with new-onset left bundle branch block (LBBB) after transcatheter aortic valve implantation (TAVI) are at risk of developing delayed high-degree atrioventricular block. Management of new-onset LBBB post-TAVI remains controversial. In the Comparison of a Clinical Monitoring Strategy Versus Electrophysiology-Guided Algorithmic Approach in Patients With a New LBBB After TAVI (COME-TAVI) trial, consenting patients with new-onset LBBB that persists on day 2 after TAVI, meeting exclusion/inclusion criteria, are randomized to an electrophysiological study (EPS)-guided approach or 30-day electrocardiographic monitoring. In the EPS-guided approach, patients with a His to ventricle (HV) interval ≥ 65 ms undergo permanent pacemaker implantation. Patients randomized to noninvasive monitoring receive a wearable continuous electrocardiographic recording and transmitting device for 30 days. Follow-up will be performed at 3, 6, and 12 months. The primary endpoint is a composite outcome designed to capture net clinical benefit. The endpoint incorporates major consequences of both strategies in patients with new-onset LBBB after TAVI, as follows: (i) sudden cardiac death; (ii) syncope; (iii) atrioventricular conduction disorder requiring a pacemaker (for a class I or IIa indication); and (iv) complications related to the pacemaker or EPS. The trial incorporates a Bayesian design with a noninformative prior, outcome-adaptive randomization (initially 1:1), and 2 prespecified interim analyses once 25% and 50% of the anticipated number of primary endpoints are reached. The trial is event-driven, with an anticipated upper limit of 452 patients required to reach 77 primary outcome events over 12 months of follow-up. In summary, the aim of this Bayesian multicentre randomized trial is to compare 2 management strategies in patients with new-onset LBBB post-TAVI-an EPS-guided approach vs noninvasive 30-day monitoring. Trial registration number: NCT03303612.

Early Resolution of New-Onset Left Bundle Branch Block After Transcatheter Aortic Valve Implantation With the SAPIEN 3 Valve

New-onset left bundle branch block (LBBB) is common after transcatheter aortic valve implantation (TAVI) but can resolve in the post-TAVI period. We sought to examine the incidence, predictors, and outcomes of early resolution of new-onset LBBB among TAVI recipients with a SAPIEN 3 (S3) valve. Among 1,203 S3-TAVI recipients without a pre-existing pacemaker or wide QRS complex at our institution between 2016 and 2019, we identified 143 patients who developed new-onset LBBB during TAVI and divided them according to the resolution or persistence of LBBB by the next day post-TAVI to compare high-degree atrioventricular block (HAVB) and permanent pacemaker (PPM) rates. Patients with resolved LBBB (n = 74, 52%), compared with those with persistent LBBB, were more often women and had a shorter QRS duration at baseline and post-TAVI, with a smaller S3 size and a shallower implantation depth. A multivariable logistic regression model demonstrated significant associations of post-TAVI QRS duration (per 10 ms increase, odds ratio = 0.60 [95% confidence interval = 0.44 to 0.82]) and implantation depth (per 1-mm-depth-increase, 0.77 [0.61 to 0.97]) with a lower likelihood of LBBB resolution. No patient with resolved LBBB developed HAVB within 30 days post-TAVI. Meanwhile, 8 patients (11.6%) with persistent LBBB developed HAVB. The 2-year PPM rate was significantly higher after persistent LBBB than after resolved LBBB (30.3% vs 4.5%, log-rank p <0.001), mainly driven by higher 30-day PPM rate (18.8% vs 0.0%). In conclusion, about half of new-onset LBBBs that occurred during S3-TAVI resolved by the next day post-TAVI without HAVB. In contrast, new-onset persistent LBBB may need follow-up with ambulatory monitoring within 30 days because of the HAVB risk.

Epidemiology, evaluation, and management of conduction disturbances after transcatheter aortic valve replacement

Aortic stenosis is the most common valvulopathy requiring replacement by means of the surgical or transcatheter approach. Transcatheter aortic valve replacement (TAVR) has quickly become a viable and often preferred treatment strategy compared to surgical aortic valve replacement. However, transcatheter heart valve system deployment not infrequently injures the specialized electrical system of the heart, leading to new conduction disorders including high-grade atrioventricular block and complete heart block (CHB) necessitating permanent pacemaker implantation (PPI), which may lead to deleterious effects on cardiac function and patient outcomes. Additional conduction disturbances (e.g., new-onset persistent left bundle branch block, PR/QRS prolongation, and transient CHB) currently lack clearly defined management algorithms leading to variable strategies among institutions. This article outlines the current understanding of the pathophysiology, patient and procedural risk factors, means for further risk stratification and monitoring of patients without a clear indication for PPI, our institutional approach, and future directions in the management and evaluation of post-TAVR conduction disturbances.