Upgrading right ventricular pacemakers to biventricular pacing or conduction system pacing: a systematic review and meta-analysis

Outcomes of Left Bundle Branch Area Pacing Upgrade in Patients with Right Ventricular Pacing-Induced Cardiomyopathy

BACKGROUND

Pacemaker-induced cardiomyopathy (PICM) is an increasingly recognized consequence of right ventricular pacing (RVP), which can lead to significant decline in left ventricular ejection fraction (LVEF) and development of heart failure symptoms. Left bundle branch area pacing (LBBAP) is an effective strategy for cardiac resynchronization therapy (CRT), but its role in PICM is not well defined.

OBJECTIVE

This study sought to determine what the clinical and echocardiographic responses were in patients with PICM who underwent LBBAP.

METHODS

This was an observational, retrospective, multicenter study. Patient and lead-related characteristics along with clinical and echocardiographic data were tracked.

RESULTS

Sixty-four patients were included, with a mean LVEF of 36.5 ± 8.8 and New York Heart Association (NYHA) status of 2.72 ± 0.68 before LBBAP. Successful LBBAP was achieved with a significant reduction in QRS duration (172.5 ± 21.9 to 133.4 ± 19.2 ms, p<0.001) which was associated with an increase in LVEF by an average of 1.0 ± 17.7% (p<0.001), and an improvement in NYHA status (2.72 ± 0.68 to 1.75 ± 0.6, p<0.001). Lead extraction was performed in 18/64 patients (28%). Outcomes did not significantly differ between patients with ≥90% and <90% RV pacing burdens.

CONCLUSIONS

This study - the largest series investigating LBBAP for PICM to date - supports LBBAP as a viable, effective alternative to conventional CRT in PICM, offering improvements in cardiac function and patient symptoms. However, larger randomized trials are needed to validate these findings in a broader, more heterogeneous population.

European Society of Cardiology (ESC) clinical consensus statement on indications for conduction system pacing, with special contribution of the European Heart Rhythm Association of the ESC and endorsed by the Asia Pacific Heart Rhythm Society, the Canadian Heart Rhythm Society, the Heart Rhythm Society, and the Latin American Heart Rhythm Society

Conduction system pacing (CSP) is being increasingly adopted as a more physiological alternative to right ventricular and biventricular pacing. Since the 2021 European Society of Cardiology pacing guidelines, there has been growing evidence that this therapy is safe and effective. Furthermore, left bundle branch area pacing was not covered in these guidelines due to limited evidence at that time. This Clinical Consensus Statement provides advice on indications for CSP, taking into account the significant evolution in this domain.

Biventricular vs. right ventricular pacing devices in patients anticipated to require frequent ventricular pacing (BioPace)

AIMS

Right ventricular (RV) pacing may promote left ventricular (LV) dysfunction. Particularly in patients with preserved LV ejection fraction (LVEF), narrow QRS, and anticipated high ventricular pacing burden (HVPB), evidence is missing that biventricular (BiV) pacing can improve clinical outcome. We therefore evaluated whether implantation of a BiV pacing device (BiVPD) compared with a RV pacing device (RVPD) may improve clinical outcome in predominantly this kind of patients.

METHODS AND RESULTS

In the Biventricular Pacing for atrioventricular Block to Prevent Cardiac Desynchronization (BioPace) trial [multicentre, single-blinded (patients), randomized, parallel group], patients were equally allocated to either receive a BiVPD or a RVPD. Co-primary endpoints were (i) the composite of time to death or first heart failure hospitalization and (ii) survival time. We analysed 1810 randomized patients (median age: 73.5 years; female sex: 31.7%; mean LVEF 55.4%; mean QRS 118.4 ms), 902 to BiV and 908 to RV pacing. During mean follow-up of 68.8 months, the difference in the primary composite endpoint between both groups [346 vs. 363 events, hazard ratio (HR) 0.878; 95% confidence interval (CI) 0.756-1.020; P = 0.0882) or in mortality (305 vs. 307 deaths, HR 0.926; 95% CI 0.789-1.088; P = 0.3492) was smaller than 20%.

CONCLUSION

In patients, predominantly with preserved LVEF, narrow QRS, and HVPB, superiority of implanting BiVPDs compared with RVPDs could not be proven. Right ventricular pacing may be less harmful for this kind of patients than often suggested and primary BiV pacing does not clearly improve their clinical outcome.

CLINICAL TRIAL REGISTRATION

Registered in ClinicalTrials.gov, number NCT00187278 (https://clinicaltrials.gov/ct2/show/study/NCT00187278).

[Physiological pacing and heart failure : Hope or hype?]

The cornerstone of heart failure treatment consists of a four pillar drug therapy. Patients with existing heart failure and complete left bundle branch block, or patients with an indication for pacemaker therapy for bradycardia and heart failure, benefit from physiological stimulation. For patients with left bundle branch block and severely impaired left ventricular systolic pump function (HFrEF), cardiac resynchronisation therapy (CRT) has so far been the gold standard. However, it is now increasingly possible to stimulate the conduction system directly using new forms of stimulation and to achieve similar clinical results. At present, left bundle branch area pacing (LBBAP) is the form of stimulation most frequently investigated in clinical studies. A special situation arises in the case of pacemaker-induced cardiomyopathy with right ventricular apical pacing. Here, LBBAP is certainly a beacon of hope.

Upgrading Right Ventricular Pacing to Cardiac Resynchronization in HFrEF Patients Improves Symptoms and Functional Outcomes

BACKGROUND

In the BUDAPEST (Biventricular Upgrade on left ventricular reverse remodeling and clinical outcomes in patients with left ventricular Dysfunction and intermittent or permanent APical/SepTal right ventricular pacing)-CRT Upgrade randomized trial, the authors have demonstrated improved mortality and morbidity after cardiac resynchronization therapy (CRT) upgrade in patients with heart failure with reduced ejection fraction (HFrEF) with high right ventricular (RV) pacing burden.

OBJECTIVES

This substudy sought to examine the impact of CRT upgrade on symptoms, functional outcome, and exercise capacity.

METHODS

In the BUDAPEST-CRT Upgrade trial, 360 HFrEF patients with pacemaker or implantable cardioverter-defibrillator (ICD) and ≥20% RV pacing burden were randomly assigned (3:2) to cardiac resynchronization therapy with defibrillator (CRT-D) upgrade (n = 215) or ICD (n = 145). The prespecified tertiary endpoints were changes in quality of life (QoL) (EQ-5D-3L), NYHA functional class, 6-minute walk test, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels.

RESULTS

Up to 12 months, NYHA functional class improved in the CRT-D upgrade arm compared with ICD only (adjusted OR: 0.50 [95% CI: 0.32-0.80]; P = 0.003). A remarkable decrease was observed in NT-proBNP levels in the CRT-D arm (adjusted difference: -1,257 pg/mL [95% CI: -2,287 to -228 pg/mL]; P = 0.017). The progression of age-related worsening of QoL was moderated by CRT-D upgrade (EQ-5D-3L difference by each year: 0.015 [95% CI: 0.005-0.025]; P interaction = 0.003). However, exercise tolerance (6-minute walk test) remained unchanged in both groups.

CONCLUSIONS

HFrEF patients with pacemaker/ICD and ≥20% RV pacing burden receiving CRT upgrade showed a substantial improvement in NYHA functional class and decrease in natriuretic peptide levels, as compared with ICD alone. Moreover, CRT-D upgrade could moderate the progression of worsening of QoL attributed to ageing in this vulnerable, elderly patient population. (Biventricular Upgrade on left ventricular reverse remodeling and clinical outcomes in patients with left ventricular Dysfunction and intermittent or permanent APical/SepTal right ventricular pacing [BUDAPEST]-CRT Upgrade trial; NCT02270840).

Effectiveness of upgrade left bundle branch area pacing for right ventricular pacing-induced cardiomyopathy: Extra QRS shortening matters

Background and Objectives

Left bundle branch area pacing (LBBAP) has developed as a strategy for patients with pacing-induced cardiomyopathy (PICM). We aimed to compare the upgrade effectiveness between LBBAP and traditional biventricular pacing (BVP) in PICM patients.

Methods

Consecutive PICM patients with successful device upgrades were enrolled. The primary outcome was the echocardiographic response, defined as absolute left ventricular ejection fraction (LVEF) improvement ≥5% at 6-month follow up.

Results

A total of 92 patients were included. 61 underwent BVP and 31 underwent LBBAP. The median RVP burden was 96.8% (IQR: 93.0-99.0%). LBBAP achieved a shorter paced QRS duration (QRSd) compared with BVP (145.9 ± 22.4 ms vs. 157.5 ± 26.5 ms; p =.031). At 6 months, LBBAP had a higher echocardiographic response rate than BVP (67.7% vs. 39.3%, p =.019). LVEF increased from 37.8% ± 9.2% to 44.8% ± 10.2% (p <.001) in LBBAP compared with an improvement from 35.7% ± 8.9% to 38.2% ± 12.1% (p <.01) in BVP, with significantly greater change from baseline in LBBAP (7.0% ± 7.0% vs. 2.5% ± 8.7%; p =.024). Narrower pacing QRS after upgrade was associated with better echocardiographic response only in LBBAP but not in BVP. (P for interaction <.05). Both groups had similar rates of composite clinical outcome.

Conclusion

LBBAP improved echocardiographic response compared with BVP in PICM patients. The superior efficacy of LBBAP in reverse remodeling was dependent on improved electrical synchrony.

Post-Implant Global Longitudinal Strain as a Predictor of Pacing-Induced Cardiomyopathy in Patients with Preserved Ejection Fraction Undergoing Pacemaker Placement

Background

Right ventricular (RV) pacing exacerbates heart failure and increases cardiac mortality in patients with reduced ejection fraction (EF). However, its impact on left ventricular dysfunction in patients with preserved EF remains inconclusive. This study investigates the relationship between RV pacing, global longitudinal strain (GLS), and EF in patients with preserved EF.

Methods

This prospective registry study included patients with preserved EF (≥50%) undergoing de novo permanent pacemaker (PPM) implantation for atrioventricular block at Chosun University Hospital, South Korea, from 2018 to 2022. Echocardiographic evaluations were performed pre-implant, post-implant, and at 12 months, with follow-up visits every 3-6 months. Composite outcomes included cardiac death, heart failure hospitalization, pacing-induced cardiomyopathy (PICM), and biventricular pacing (BVP) upgrade.

Results

A total of 71 patients (28 males, mean age 73.1 years) were included. Following PPM implantation, significant declines in both EF and GLS were noted, especially in those with PICM. Over three years, 2 patients died, 6 were hospitalized, 7 developed PICM, and 3 underwent a BVP upgrade. Reduced post-implant GLS was an independent predictor of PICM (hazard ratios (HR) 1.715, 95% CI 1.174-2.504; p = 0.005). Receiver operating characteristic (ROC) analysis showed an area under curve (AUC) of 0.92 for GLS, with a GLS <-15.0 having 100% sensitivity and 80.9% specificity for predicting PICM.

Conclusions

Post-implant GLS is a reliable predictor of PICM in patients with preserved EF. Regular GLS monitoring can guide timely interventions, including guideline-directed medical therapy or BVP upgrades, to prevent deterioration and improve outcomes.

Deep Septal Pacing for Pacemaker-Induced Cardiomyopathy

INTRODUCTION

Right ventricular (RV) pacing can impair left ventricular function and cause heart failure, known as pacing-induced cardiomyopathy (PICM). Upgrade to cardiac resynchronization (CRT) is its usual treatment; recently left bundle branch area pacing (LBBAP) has emerged as a potential alternative. Deep septal pacing (DSP), a simplified alternative to LBBAP, is still able to achieve narrower paced QRS than during conventional RV pacing. The aim of this study was to assess the effect of DSP in a cohort of patients with PICM.

METHODS AND RESULTS

Consecutive patients diagnosed with PICM were included. The aim was to upgrade patients to DSP. The procedure was considered successful if a paced QRS duration ≤140 ms was obtained, in the absence of a terminal R wave in V1. Twelve patients were included. The mean baseline LVEF was 33% (SD 4%), and the mean percentage of RV pacing was 99% (SD 1%). All patients had symptomatic heart failure. The mean paced QRS duration was 172 ms (SD 14 ms) with RV pacing, and 130 ms (SD 7 ms) with DSP (mean difference 42 ms, p < 0.001). At 6 months, the mean LVEF after the upgrade was 46% (SD 9%), significantly superior to LVEF with RV pacing (p = 0.001), a mean improvement of 13% (SD 10%). All patients except one experienced an improvement in LVEF of at least 5%.

CONCLUSIONS

Our data suggest that DSP may be an effective and simpler alternative to biventricular or LBBAP in patients with PICM. Narrower paced QRS complexes can be achieved, which may lead to an improvement in left ventricular function.

Spatial ventricular gradient is associated with pacing-induced cardiomyopathy

BACKGROUND

Pacing-induced cardiomyopathy (PICM) is a frequent complication of right ventricular pacing that often requires reoperation for biventricular or conduction system pacing. Better methods for predicting PICM may inform initial pacing strategy and follow-up monitoring.

OBJECTIVE

The purpose of this study was to determine whether the spatial ventricular gradient (SVG), a vectorcardiographic marker of ventricular electrical and mechanical heterogeneity, is associated with the subsequent development of PICM.

METHODS

This was a retrospective study of patients with pacemakers implanted between 2003 and 2012 at the Hospital of the University of Pennsylvania. Baseline demographic, echocardiographic, and electrocardiographic parameters, including SVG magnitude, elevation, and azimuth, were measured from standard 12-lead electrocardiograms. Adjusted Cox proportional hazards modeling was used to assess the associations between the SVG and the risk of PICM over follow-up.

RESULTS

Of the 203 patients with a median age of 74 years (p25-p75 64-79), 110 (54%) male, and median baseline left ventricular ejection fraction 65% (p25-p75 57-70), 44 (22%) developed PICM during follow-up. In unadjusted Cox regression, male sex, native QRS duration in patients without bundle branch block, and both native and paced mean adjusted SVG azimuth predicted future PICM. After multivariable adjustment, higher tertile (tertile 3 vs tertiles 1-2) of the mean adjusted SVG azimuth before (adjusted hazard ratio 1.95; P = .047) and immediately after (adjusted hazard ratio 2.55; P=.003) pacemaker implantation remained significant predictors of PICM.

CONCLUSION

Assessment of the SVG both before and immediately after pacemaker implantation can help identify patients at elevated risk of PICM and may identify a cohort of patients who would be better served with initial biventricular or conduction system pacing.

Mid-Term Impact of Conduction System Pacing on Overall Cardiac Performance: A Non-Randomized, Prospective, Single-Center Echocardiographic Study

Introduction. Recently published data suggested significantly lower pacing-induced cardiomyopathy (PICM) incidence with conduction system pacing (CSP). Because most data evaluated only the impact on the left ventricle, this study aimed to assess changes in echocardiographic parameters of morphology and function for all heart chambers in patients with baseline preserved and mid-range LVEF over a medium-term follow-up period after CSP. Methods. A total of 128 consecutive patients with LVEF > 40% and successful CSP for bradyarrhythmic indication were prospectively enrolled. A complete 2D echocardiographic examination was performed at baseline and the last follow-up. Results. In total, 38 patients received His bundle pacing (HBP) and 90 received left bundle branch area pacing (LBBAP). The mean follow-up period was 699.2 ± 177.2 days, with 23 patients lost during this period. The ventricular pacing burden for the entire group was 97.2 ± 4.2%. Only three patients (2.9%) met the criteria for PICM. CSP led to a significant increase in LVEF (from 54.2 ± 7.9 to 56.7 ± 7.8%, p = 0.01) and a significant decrease in LV diastolic (from 107.2 ± 41.8 to 91.3 ± 41.8 mL, p < 0.001) and systolic (from 49.7 ± 21.4 to 39.5 ± 18.2 mL, p < 0.001) volumes. There were no significant changes in E/e', mitral regurgitation, atrial volumes, and right ventricle (RV) diameter. There was a significant improvement in RV function. Tricuspid regurgitation was the only parameter that worsened. There were no differences in evolution for each echocardiographic parameter between the HBP and the LBBAP groups. Conclusions. HBP and LBBAP are equally protective for harmful changes in both atria and ventricles. The prevalence of PICM, defined as a decrease in LVEF, is very low with CSP.

His Bundle Pacing and Left Bundle Branch Pacing in Patients with Heart Failure

BACKGROUND

His bundle pacing (HBP) and left bundle branch pacing (LBBP) are emerging therapies for patients with heart failure and conduction disorders, offering potential advantages over traditional pacing methods. These approaches aim to restore physiological conduction and improve cardiac function more effectively.

OBJECTIVE

This study aims to evaluate the efficacy and safety of HBP and LBBP in patients with heart failure and conduction disturbances, comparing these techniques to conventional pacing.

METHODS

A comprehensive review of recent studies and clinical trials was conducted, focusing on the performance of HBP and LBBP in improving cardiac function, reducing QRS duration, and enhancing overall patient outcomes. The analysis includes data on clinical efficacy, procedural safety, and long-term benefits associated with these pacing modalities.

RESULTS

Both HBP and LBBP have demonstrated significant improvements in cardiac function and clinical outcomes compared to conventional pacing. HBP effectively restores physiological conduction with improved synchronization and a reduction in QRS duration. LBBP has shown enhanced left ventricular activation, leading to better overall cardiac performance. Both techniques have been associated with a lower incidence of complications and a higher success rate in achieving optimal pacing thresholds.

CONCLUSIONS

HBP and LBBP offer promising alternatives to traditional pacing for patients with heart failure and conduction disorders. These advanced pacing strategies provide superior clinical outcomes and improved cardiac function with reduced risk of complications. Further research and clinical trials are needed to fully establish the long-term benefits and safety profiles of these techniques in diverse patient populations.

Reversible Dilated Cardiomyopathy in a Male Patient With Rheumatoid Arthritis: A Case Report

This case describes a rare instance of reversible dilated cardiomyopathy (DCM) in a 65-year-old Caucasian male with a significant past medical history of inflammatory rheumatoid arthritis (RA) controlled with rituximab and hydroxychloroquine (HCQ). The patient presented with acute onset of dyspnea on exertion and palpitations and was diagnosed with congestive heart failure in the context of DCM. Despite having no prior cardiac abnormalities, an EKG revealed a new left bundle branch block, and an echocardiogram demonstrated a severely reduced left ventricular ejection fraction (LVEF) of 10-15%. Left heart catheterization and coronary angiography revealed no evidence of coronary artery disease. Given the absence of an overt cause, drug-induced DCM was suspected; hence, rituximab and HCQ were discontinued. Other common causes of DCM, including alcohol abuse and virus-induced DCM, were excluded based on relevant testing. Seven to nine months after cessation of HCQ and rituximab, the patient's RA progressed, and treatment was initiated with IV tocilizumab, resulting in a good clinical response. At the 26-month follow-up, a repeat echocardiogram revealed mild mitral regurgitation with an LVEF which improved to 55%. At this point, Takotsubo cardiomyopathy was considered a potential cause of this patient's DCM due to its reversible nature. This case highlights the importance of comprehensive cardiac monitoring in symptomatic patients at high risk for cardiovascular disease, such as this patient with long-standing inflammatory disease. Physicians should work together to closely monitor and consider the serious potential risks of all treatment regimens.

Is Conduction System Pacing Going to Be the New Gold Standard for Cardiac Resynchronization Therapy?

The current gold standard in device therapy for advanced heart failure (HF), which has been firmly established in HF management for more than 25 years, is classical biventricular pacing (BiV-CRT). In the last decade, a new pacing modality called conduction system pacing (CSP) has emerged as a variant for advanced cardiac device therapy. It provides pacing with preserved intrinsic cardiac activation by direct stimulation of the specific cardiac conduction system. The term CSP integrates the modalities of HIS bundle pacing (HBP) and left bundle branch area pacing (LBBAP), both of which have provided convincing data in smaller randomized and big non-randomized studies for the prevention of pacemaker-induced cardiomyopathy and for providing effective cardiac resynchronization therapy in patients with classical CRT-indication (primary approach or after failed CRT). Recent American guidelines proposed the term "cardiac physiological pacing" (CPP), which summarizes CSP including left ventricular septal pacing (LVSP), a technical variant of LBBAP together with classical BiV-CRT. The terms HOT-CRT (HIS-optimized CRT) and LOT-CRT (LBBP-optimized CRT) describe hybrid technologies that combine CSP with an additional coronary-sinus electrode, which is sometimes useful in patients with advanced HF and diffuse interventricular conduction delay. If CSP continues providing promising data that can be confirmed in big, randomized trials, it is likely to become the new gold standard for patients with an expected high percentage of pacing (>20%), possibly also for cardiac resynchronization therapy. CSP is a sophisticated new treatment option that has the potential to raise the term "cardiac resynchronization therapy" to a new level. The aim of this review is to provide basic technical, anatomical, and functional knowledge of these new pacemaker techniques in order to facilitate the understanding of the different modalities, as well as to provide an up-to-date overview of the existing randomized and non-randomized evidence, particularly in direct comparison to right ventricular and classical biventricular pacing.

Comparative Analysis of Response to Cardiac Resynchronisation Therapy Upgrades in Patients with Implantable Cardioverter-Defibrillators and Pacemakers

Introduction: The efficacy of de novo cardiac resynchronisation therapy (CRT) in patients with heart failure (HF), left ventricular systolic dysfunction (LVSD), and a broad QRS morphology is well established. However, the optimal stage for upgrading patients with existing pacemakers (PPMs) or implantable cardioverter-defibrillators (ICDs) and HF with high-burden right ventricular (RV) pacing remains uncertain. Thus, this multicentre retrospective analysis compared patients with pre-existing PPMs or ICDs who underwent CRT upgrades to investigate the appropriate stage for CRT implantation in these patients and to assess the validity of treating both PPM and ICD recipients under the same recommendation level in the current guidelines. Materials and Methods: A total of 151 participants underwent analysis in this study, comprising 93 upgrades to cardiac resynchronisation therapy with pacemaker (CRT-P) and 58 upgrades to cardiac resynchronisation therapy with defibrillator (CRT-D) across three centres in the UK. The aim of the study was to investigate the safety and efficacy of upgrading to CRT from an existing conventional pacemaker or an ICD in the context of high-burden RV pacing. The analysis was conducted separately for each group, assessing changes in echocardiographic parameters, functional New York Heart Association (NYHA) class, and procedure-related complications. Results: The PPM group had a higher percentage RVP burden compared to the ICD group. Post-upgrade, NYHA functional class and EF and LV volumes improved in both groups; however, the response to an upgrade from a pacemaker was greater compared to an upgrade from an ICD. Post-procedural complication risks were similar across the two subgroups but significantly higher compared to de novo implantation. Conclusions: Within the CRT-P subgroup, participants exhibited better responses than their CRT-D counterparts, evident both in echocardiographic improvements and clinical outcomes. Furthermore, patients with non-ischemic cardiomyopathy (NICM) were better responders than those with ischaemic cardiomyopathy. These findings suggest that international guidelines should consider approaching each subgroup separately in the future.

New Insights into Pacing Induced Cardiomyopathy

Pacing induced cardiomyopathy (PICM) can occur as a complication due to pacing the right ventricle. Its precise definition varies across different studies, leading to uncertainty as to the best approach for managing this entity. More than 10% of patients who undergo chronic right ventricular pacing develop PICM. Risk factors associated with PICM include reduced left ventricular ejection fraction (LVEF), the proportion of right ventricular pacing, and paced QRS duration. The main approach to treating PICM has been upgrading to biventricular pacing cardiac resynchronization therapy when the LVEF decreases. However, emerging evidence suggest that conduction system pacing might provide an opportunity to manage PICM.

Long-term outcome after upgrade to cardiac resynchronization therapy: A propensity score-matched analysis

AIM

Cardiac resynchronization therapy (CRT) is a cornerstone in the management of chronic heart failure in patients with a broad or paced QRS. However, data on long-term outcome after upgrade to CRT are scarce.

METHODS AND RESULTS

This international, multicentre retrospective registry included 2275 patients who underwent a de novo or upgrade CRT implantation with a mean follow-up of 3.6 ± 2.7 years. The primary composite endpoint included all-cause mortality, heart transplantation, or ventricular assist device implantation. The secondary endpoint was first heart failure admission. Multivariable Cox regression and propensity score matching (PSM) analyses were performed. Patients who underwent CRT upgrade (n = 605, 26.6%) were less likely female (19.7% vs. 28.8%, p < 0.001), more often had ischeemic cardiomyopathy (49.8% vs. 40.2%, p < 0.001), and had worse renal function (median estimated glomerular filtration rate 50.3 ml/min/1.73 m2 [35.8-69.5] vs. 59.9 ml/min/1.73 m2 [43.0-76.5], p < 0.001). The incidence rate of the composite endpoint was 10.8%/year after CRT upgrade versus 7.1%/year for de novo implantations (p < 0.001). PSM for the primary endpoint resulted in 488 pairs. After propensity score matching, upgrade to CRT was associated with a higher chance to reach the composite endpoint (multivariable hazard ratio [HR] 1.35, 95% confidence interval [CI] 1.08-1.70), for both upgrade from pacemaker (multivariable HR 1.33, 95% CI 1.03-1.70) and implantable cardioverter-defibrillator (ICD) (multivariable HR 1.40, 95% CI 1.01-1.95). PSM for the secondary endpoint resulted in 277 pairs. After PSM, upgrade to CRT was associated with a higher chance for heart failure admission (HR 1.74, 95% CI 1.26-2.41).

CONCLUSION

In this retrospective analysis, the outcome of patients who underwent upgrades to CRT differed significantly from patients who underwent de novo CRT implantation, particularly for upgrades from ICD. Importantly, this difference in outcome does not imply a causal relation between therapy and outcome but rather a difference between two different patient populations.

Cost-effectiveness analysis of leadless cardiac resynchronization therapy

BACKGROUND

The Wireless Stimulation Endocardially for CRT (WiSE-CRT) system is a novel technology used to treat patients with dyssynchronous heart failure (HF) by providing leadless cardiac resynchronization therapy (CRT). Observational studies have demonstrated its safety and efficacy profile, however, the treatment cost-effectiveness has not previously been examined.

METHODS

A cost-effectiveness evaluation of the WiSE-CRT System was performed using a cohort-based economic model adopting a "proportion in state" structure. In addition to the primary analysis, scenario analyses and sensitivity analyses were performed to test for uncertainty in input parameters. Outcomes were quantified in terms of quality-adjusted life year (QALY) differences.

RESULTS

The primary analysis demonstrated that treatment with the WiSE-CRT system is likely to be cost-effective over a lifetime horizon at a QALY reimbursement threshold of £20 000, with a net monetary benefit (NMB) of £3781 per QALY. Cost-effectiveness declines at time horizons shorter than 10 years. Sensitivity analyses demonstrated that average system battery life had the largest impact on potential cost-effectiveness.

CONCLUSION

Within the model limitations, these findings support the use of WiSE-CRT in indicated patients from an economic standpoint. However, improving battery technology should be prioritized to maximize cost-effectiveness in times when health services are under significant financial pressures.

Phenogrouping and risk stratification of patients undergoing cardiac resynchronization therapy upgrade using topological data analysis

Choosing the optimal device during cardiac resynchronization therapy (CRT) upgrade can be challenging. Therefore, we sought to provide a solution for identifying patients in whom upgrading to a CRT-defibrillator (CRT-D) is associated with better long-term survival than upgrading to a CRT-pacemaker (CRT-P). To this end, we first applied topological data analysis to create a patient similarity network using 16 clinical features of 326 patients without prior ventricular arrhythmias who underwent CRT upgrade. Then, in the generated circular network, we delineated three phenogroups exhibiting significant differences in clinical characteristics and risk of all-cause mortality. Importantly, only in the high-risk phenogroup was upgrading to a CRT-D associated with better survival than upgrading to a CRT-P (hazard ratio: 0.454 (0.228-0.907), p = 0.025). Finally, we assigned each patient to one of the three phenogroups based on their location in the network and used this labeled data to train multi-class classifiers to enable the risk stratification of new patients. During internal validation, an ensemble of 5 multi-layer perceptrons exhibited the best performance with a balanced accuracy of 0.898 (0.854-0.942) and a micro-averaged area under the receiver operating characteristic curve of 0.983 (0.980-0.986). To allow further validation, we made the proposed model publicly available ( https://github.com/tokmarton/crt-upgrade-risk-stratification ).

Upgrade of right ventricular pacing to cardiac resynchronization therapy in heart failure: a randomized trial

BACKGROUND AND AIMS

De novo implanted cardiac resynchronization therapy with defibrillator (CRT-D) reduces the risk of morbidity and mortality in patients with left bundle branch block, heart failure and reduced ejection fraction (HFrEF). However, among HFrEF patients with right ventricular pacing (RVP), the efficacy of CRT-D upgrade is uncertain.

METHODS

In this multicentre, randomized, controlled trial, 360 symptomatic (New York Heart Association Classes II-IVa) HFrEF patients with a pacemaker or implantable cardioverter defibrillator (ICD), high RVP burden ≥ 20%, and a wide paced QRS complex duration ≥ 150 ms were randomly assigned to receive CRT-D upgrade (n = 215) or ICD (n = 145) in a 3:2 ratio. The primary outcome was the composite of all-cause mortality, heart failure hospitalization, or <15% reduction of left ventricular end-systolic volume assessed at 12 months. Secondary outcomes included all-cause mortality or heart failure hospitalization.

RESULTS

Over a median follow-up of 12.4 months, the primary outcome occurred in 58/179 (32.4%) in the CRT-D arm vs. 101/128 (78.9%) in the ICD arm (odds ratio 0.11; 95% confidence interval 0.06-0.19; P < .001). All-cause mortality or heart failure hospitalization occurred in 22/215 (10%) in the CRT-D arm vs. 46/145 (32%) in the ICD arm (hazard ratio 0.27; 95% confidence interval 0.16-0.47; P < .001). The incidence of procedure- or device-related complications was similar between the two arms [CRT-D group 25/211 (12.3%) vs. ICD group 11/142 (7.8%)].

CONCLUSIONS

In pacemaker or ICD patients with significant RVP burden and reduced ejection fraction, upgrade to CRT-D compared with ICD therapy reduced the combined risk of all-cause mortality, heart failure hospitalization, or absence of reverse remodelling.

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.

Conduction system pacing for cardiac resynchronization therapy: State of the art, current controversies, and future perspectives

Biventricular pacing (BVP) is the established treatment to perform cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and left bundle branch block (LBBB). However, BVP is an unnatural pacing modality still conditioned by the high percentage of non-responders and coronary sinus anatomy. Conduction system pacing (CSP)-His bundle pacing (HBP) and Left bundle branch area pacing (LBBAP)- upcomes as the physiological alternative to BVP in the quest for the optimal CRT. CSP showed promising results in terms of better electro-mechanical ventricular synchronization compared to BVP. However, only a few randomized control trials are currently available, and technical challenges, along with the lack of information on long-term clinical outcomes, limit the establishment of a primary role for CSP over conventional BVP in CRT candidates. This review provides a comprehensive literature revision of potential applications of CSP for CRT in diverse clinical scenarios, underlining the current controversies and prospects of this technique.