Cardiac resynchronization therapy (CRT) delivered with left ventricular (LV) epicardial pacing may increase arrhythmic risk through detrimental effects on ventricular repolarization. Leadless LV endocardial CRT including leadless left bundle branch area pacing (LBBAP) may mitigate this by preserving a more physiological transmural activation pattern.

This study aimed to evaluate the effect of leadless LV endocardial and leadless LBBAP on repolarization metrics derived from electrocardiographic imaging (ECGi).

Ten patients with leadless endocardial CRT systems underwent a temporary pacing plus ECGi study, testing right ventricular, LV, and biventricular pacing (BiVP) settings, as well as atrioventricular-optimized LV pacing. Epicardial electrograms were used to derive metrics of repolarization and activation-recovery interval dispersion. The primary outcome measurements were acute improvement (ie, reduction) from baseline (right ventricular pacing or underlying rhythm) of these repolarization metrics.

Ten patients were studied; 5 had received LV lateral wall endocardial pacing, and 5 had received LBBAP with leadless septal wall pacing. The optimal leadless pacing setting significantly improved biventricular dispersion of repolarization by 23.7% ± 14% (P < .01), and this effect was more pronounced with LBBAP (29.3% ± 15%, P = .01) vs lateral wall pacing (18% ± 12%, P = .03). Similar results were observed for activation-recovery interval dispersion and biventricular repolarization gradients. The most pronounced improvements were observed where LV-only pacing as opposed to BiVP was used, either through LBBAP or atrioventricular-optimized LV pacing from any endocardial location.

Optimized leadless LV endocardial lateral wall pacing and LBBAP improve ECGi-derived ventricular repolarization metrics. LV-only pacing seemed superior to endocardial BiVP, potentially reflecting repolarization heterogeneity caused by a collision of 2 paced wavefronts.

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is an established treatment of heart failure with reduced ejection fraction and wide QRS. Left bundle branch area pacing (LBBAP) has emerged as a physiologic alternative by directly engaging the His-Purkinje system, potentially improving electrical resynchronization and clinical outcomes.

The aim of the study was to compare the clinical outcomes between BVP and LBBAP in patients with left ventricular ejection fraction (LVEF) ≤50% undergoing CRT.

This multicenter observational study included patients with LVEF ≤50% receiving CRT with either LBBAP or BVP at 18 centers from January 2018 to June 2023. The primary outcome was a composite of all-cause mortality or first heart failure hospitalization (HFH). Secondary outcomes included separate analyses of HFH and all-cause mortality. Propensity score matching was used to balance baseline characteristics. Kaplan-Meier curves, Cox proportional hazards models, and competing risk analyses were performed.

A total of 2579 patients were included (BVP, 1118; LBBAP, 1461). In the propensity score-matched cohort (BVP, 780; LBBAP, 780), LBBAP demonstrated shorter paced QRS duration (129 ± 19 ms vs 143 ± 22 ms; P < .001). LBBAP was associated with a significantly lower risk of the composite primary outcome (hazard ratio [HR], 0.81; 95% confidence interval [CI], 0.66-0.98; P = .048) and reduced HFH (HR, 0.63; 95% CI, 0.49-0.82; P < .001). No significant difference in all-cause mortality was observed (HR, 0.82; 95% CI, 0.63-1.07; P = .156). Procedural complications were lower with LBBAP (3.5% vs 6.5%, P = .004).

LBBAP was associated with superior electrical resynchronization, fewer HFHs, and lower procedural complications compared with BVP in patients with LVEF <50% requiring CRT. Randomized trials are needed to confirm long-term benefits.

Heart failure (HF) is a major clinical challenge characterized by significant morbidity and mortality. Electrical conduction abnormalities play a critical role in HF pathophysiology and progression, often leading to suboptimal outcomes with conventional pacing techniques. Con-duction system pacing (CSP), encompassing His bundle pacing and left bundle branch area pacing, has emerged as a novel approach. Despite data come from observational studies, recent guidelines recommend that a specific population may benefit from CSP. However, significant practical considerations and challenges need to be clarified before CSP can be routinely implemented in clinical practice. The reliance on observational studies means that long-term clinical outcomes for HF patients remain uncertain until data from randomized controlled trials (RCTs) become available. Current CSP practices face challenges with lead implantation, mechanical stress on leads, and the need for more advanced tools and artificial intelligence integration to improve procedure efficacy and safety. Future large-scale RCTs are essential to identify optimal candidates and address these technical challenges, potentially leading to a paradigm shift in HF management.

Left bundle branch area pacing (LBBAP) and endocardial resynchronization (Endo-CRT) are alternatives to biventricular pacing for cardiac resynchronization therapy (CRT).

To compare the outcomes of LBBAP versus Endo-CRT using conventional pacing leads.

Patients with heart failure (HF) undergoing CRT with LBBAP or Endo-CRT were included. The primary efficacy outcome was a composite of HF-related hospitalization and all-cause mortality. The primary safety outcome was any procedure-related complication. Secondary outcomes included procedural characteristics, electrocardiographic, and echocardiographic parameters.

A total of 223 patients (LBBAP n = 197, Endo-CRT n = 26; mean age 69 ± 10.3 years, 32.3% female) were included. Patients in the LBBAP group had lower NYHA class, shorter preprocedural QRS durations (161 [142-183] vs. 180 [170-203] msec, p < .001), and a lower preprocedural spironolactone use (57.4% vs. 84.6%, p = .009) than patients in the Endo-CRT group. Fluoroscopy time was significantly shorter in patients undergoing LBBAP (11.4 [7.2-20] vs. 23 [14.2-34.5] min; p < .001). There was no significant difference in the primary efficacy outcome between both groups (Cox proportional HR 1.21, 95% CI 0.635-2.31; p = .56). During follow-up, patients undergoing LBBAP had a lower incidence of stroke than patients in the Endo-CRT group (0% vs. 11.5%, p = .001). Postprocedural LVEF (35% [25-45] vs. 40% [20-55]; p = .307) and change in LVEF (7% [0-20] vs. 11% [2-18]; p = .384) were similar between the LBBAP and the Endo-CRT groups, respectively.

LBBAP and Endo-CRT using conventional leads are associated with similar mortality and HF-related hospitalization, as well as improvements in LVEF. Endo-CRT is associated with longer fluoroscopy times and a higher risk of stroke.

We present a case of an 82-year-old woman who developed sustained heart failure with left ventricular dyssynchrony after the modified Bentall procedure. Persistent circulatory instability and complete atrioventricular block suggested coronary artery stenosis. Multidetector computed tomography revealed stenosis of the grafted portion of the coronary artery. The patient was successfully treated by coronary artery bypass grafting with simultaneous epicardial cardiac resynchronization therapy system implantation.

Biventricular pacing (BiVP) has been the cornerstone of cardiac resynchronization therapy (CRT) in the management of symptomatic heart failure patients with reduced ejection fraction (HFrEF) and electrical dyssynchrony despite guideline-directed medical therapy (GDMT). However, BiVP has some limitations, including technical difficulties and high non-response rates. Conduction system pacing encompassing His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) has recently emerged as a promising alternative to CRT in this group of patients. In this review, we explore the current evidence, guidelines, limitations, gaps in knowledge, and ongoing trials comparing CSP and BiVP for the management of HFrEF with electrical dyssynchrony.

An infant with DiGeorge syndrome, multiple comorbidities, and truncus arteriosus type II underwent repair complicated by heart block necessitating placement of a dual-chamber bipolar pacing system with right ventricular leads and subsequent resynchronization with placement of left ventricular apical pacing leads. Resynchronization therapy improved QRS duration from 180 ms to 100 ms and ejection fraction from 25% to 54% over the course of 4 weeks with gradual return to normal function and eventual discharge.

Introduction Heart failure develops as a result of dysfunction in the cardiac muscle, which impairs the heart's ability to pump blood effectively. For this reason, many studies have shown that cardiac resynchronization therapy (CRT) has significantly reduced symptoms and improved cardiac function in patients with heart failure. Echocardiography is crucial in assessing CRT response, as it helps differentiate between patients who benefit from CRT and those who do not by evaluating key parameters like left ventricular ejection fraction (LVEF), a critical parameter in determining CRT eligibility. However, few studies focus specifically on the effectiveness of echocardiography for assessing CRT response, with existing research limited by a lack of standardized protocols and inadequate predictive tools. Accordingly, this study aims to assess the role of echocardiography in evaluating the efficacy of CRT in patients with heart failure at King Faisal Cardiac Center. Methodology This was a retrospective analytical cohort study that included all adult patients diagnosed with heart failure and underwent CRT between January 2017 and December 2021 at King Faisal Cardiac Center, King Abdulaziz Medical City, Jeddah, Saudi Arabia. Data were obtained from the Cardiac Non-invasive Lab, which was selected for its essential diagnostic tools for comprehensive echocardiographic evaluation of CRT efficacy. Study subjects were over 18 years old, diagnosed with heart failure with reduced ejection fraction (LVEF <35%), underwent CRT, and had echocardiograms at baseline and at least six months post-therapy. The collected data were retrieved from electronic medical records (BestCare; ezCaretech Co., Ltd,Seoul, South Korea), including relevant demographics and echocardiographic parameters such as end-systolic volume (ESV), end-diastolic volume (EDV), and ejection fraction (EF). Statistical analysis, paired t-tests, and Shapiro-Wilk test to assess data normality were conducted to evaluate pre- and post-CRT changes, with significance set at P<0.05. Results A total of 53 heart failure patients met the inclusion and exclusion criteria. The results of the study indicate statistically significant differences in the mean EF before and after CRT increased from 29.09±6.52% to 33.3±10.69% (p-value=0.0014). The mean ESV decreased from 114.46±60.63 mL to 97.13±65.89 mL, demonstrating a clinically significant improvement (p=0.056), and the mean EDV decreased from 157.08±64.67 mL to 138.87±78.07 mL (p = 0.0158). Furthermore, the EF increased by 14.47%, and the ESV decreased by 15.14% after CRT. These findings indicate improvement in left ventricular function following CRT. Conclusion The study demonstrates significant improvements in echocardiographic parameters based on echocardiogram findings, particularly the outcomes of EF and ESV after CRT in patients with heart failure with reduced ejection fraction. These findings highlight the potential of CRT as an effective therapy and aid in detecting responders to treatment. Nevertheless, the study is limited by a relatively small sample size, exclusion of comorbidities, and short follow-up period. Therefore, further longitudinal studies with larger cohorts and consideration of comorbidities are recommended.

Approximately 40% of patients with heart failure (HF) who are eligible for cardiac resynchronization therapy (CRT) either fail to respond or are untreatable due to anatomical constraints.

To assess the safety and efficacy of a novel, leadless, left ventricular (LV) endocardial pacing system for patients at high risk for a CRT upgrade or whose coronary sinus (CS) lead placement/pacing with a conventional CRT system failed.

The SOLVE-CRT study was a prospective multicenter trial enrolling January 2018 through July 2022, with follow-up at 6 months. Data were analyzed from January 17, 2018, through February 15, 2023. The trial combined data from an initial randomized, double-blind study (n = 108) and a subsequent single-arm part (n = 75). It took place at 36 centers across Australia, Europe, and the US. Participants were nonresponders, previously untreatable (PU), or high-risk upgrades (HRU). All participants contributed to the safety analysis. The primary efficacy analysis (n = 100) included 75 PU-HRU patients from the single-arm part and 25 PU-HRU patients from the randomized treatment arm.

Patients were implanted with the WiSE CRT System (EBR Systems) consisting of a leadless LV endocardial pacing electrode stimulated with ultrasound energy delivered by a subcutaneously implanted transmitter and battery.

The primary safety end point was freedom from type I complications. The primary efficacy end point was a reduction in mean LV end systolic volume (LVESV).

The study included 183 participants; mean age was 68.1 (SD, 10.3) years and 141 were male (77%). The trial was terminated at an interim analysis for meeting prespecified stopping criteria. In the safety population, patients were either New York Heart Association Class II (34.6%) or III (65.4%). The primary efficacy end point was met with a 16.4% (95% CI, -21.0% to -11.7%) reduction in mean LVESV (P = .003). The primary safety end point was met with an 80.9% rate of freedom from type I complications (P < .001), which included 12 study device system events (6.6%), 5 vascular events (2.7%), 3 strokes (1.6%), and 7 cardiac perforations which mostly occurred early in the study (3.8%).

The SOLVE-CRT study has demonstrated that leadless LV endocardial pacing with the WiSE CRT system is associated with a reduction in LVESV in patients with HF. This novel system may represent an alternative to conventional CRT implants in some HF patient populations.

ClinicalTrials.gov Identifier: NCT0292203.

Left bundle branch area pacing (LBBAP) has emerged as a physiological alternative pacing strategy to biventricular pacing (BIVP) in cardiac resynchronization therapy (CRT). We aimed to assess the impact of LBBAP vs. BIVP on all-cause mortality and heart failure (HF)-related hospitalization in patients undergoing CRT.

Studies comparing LBBAP and BIVP for CRT in patients with HF with reduced left ventricular ejection fraction (LVEF) were included. The coprimary outcomes were all-cause mortality and HF-related hospitalization. Secondary outcomes included procedural and fluoroscopy time, change in QRS duration, and change in LVEF.

Thirteen studies (12 observational and 1 RCT, n = 3239; LBBAP = 1338 and BIVP = 1901) with a mean follow-up duration of 25.8 months were included. Compared to BIVP, LBBAP was associated with a significant absolute risk reduction of 3.2% in all-cause mortality (9.3% vs 12.5%, RR 0.7, 95% CI 0.57-0.86, p < 0.001) and an 8.2% reduction in HF-related hospitalization (11.3% vs 19.5%, RR 0.6, 95% CI 0.5-0.71, p < 0.00001). LBBAP also resulted in reductions in procedural time (mean weighted difference- 23.2 min, 95% CI - 42.9 to - 3.6, p = 0.02) and fluoroscopy time (- 8.6 min, 95% CI - 12.5 to - 4.7, p < 0.001) as well as a significant reduction in QRS duration (mean weighted difference:- 25.3 ms, 95% CI - 30.9 to - 19.8, p < 0.00001) and a greater improvement in LVEF of 5.1% (95% CI 4.4-5.8, p < 0.001) compared to BIVP in the studies that reported these outcomes.

In this meta-analysis, LBBAP was associated with a significant reduction in all-cause mortality as well as HF-related hospitalization when compared to BIVP. Additional data from large RCTs is warranted to corroborate these promising findings.

Cardiovascular and noncardiovascular comorbidities have been recognized as predictors of clinical response in patients receiving cardiac resynchronization therapy (CRT). However, data on vitamin D as a predictor of CRT response are conflicting.

We identified studies from MEDLINE and Embase databases, searching from inception to May 2024, to investigate the association between 25-OH vitamin D levels before CRT implantation and outcomes. Studies had to report 25-OH vitamin D levels or the proportion of patients with vitamin D insufficiency and categorize outcomes as CRT responders or nonresponders. We extracted mean 25-OH vitamin D and standard deviations for both groups from each study and calculated the pooled mean difference (MD). We also retrieved risk ratios, and 95% confidence intervals (CIs) for the association between vitamin D insufficiency and lack of CRT response, combining them using the generic inverse variance method.

Our meta-analysis included four studies. CRT responders had higher levels of 25-OH vitamin D than nonresponders, with a pooled MD of 8.04 ng/mL (95% CI: 3.16-12.93; I 2 = 48%, p < .001). Patients with vitamin D insufficiency before implantation had higher odds of lacking response to CRT, with a pooled RR of 3.28 (95% CI: 1.43-7.50; I 2 = 0%, p = .005) compared to those with normal vitamin D.

CRT responders had higher 25-OH vitamin D levels compared to nonresponders. Vitamin D insufficiency was associated with a higher risk of nonresponse to CRT. These findings highlight the importance of monitoring and managing vitamin D levels in these patients.

Left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) are referred to as left bundle branch area pacing.

This study investigated whether long-term clinical outcomes differ in patients undergoing LBBP, LVSP, and biventricular pacing (BiVP) for cardiac resynchronization therapy (CRT).

Consecutive patients with reduced left ventricular ejection fraction (LVEF <50%) undergoing CRT were prospectively enrolled if they underwent successful LBBP, LVSP, or BiVP. The primary composite end point was all-cause mortality or heart failure hospitalization. Secondary end points included all-cause mortality, heart failure hospitalization, and echocardiographic measures of reverse remodeling.

A total of 259 patients (68 LBBP, 38 LVSP, and 153 BiVP) were observed for a mean duration of 28.8 ± 15.8 months. LBBP was associated with a significantly reduced risk of the primary end point by 78% compared with both BiVP (7.4% vs 41.2%; adjusted hazard ratio [aHR], 0.22 [0.08-0.57]; P = .002) and LVSP (7.4% vs 47.4%; aHR, 0.22 [0.08-0.63]; P = .004]. The adjusted risk of all-cause mortality was significantly higher in LVSP than in BiVP (31.6% vs 7.2%; aHR, 3.19 [1.38-7.39]; P = .007) but comparable between LBBP and BiVP (2.9% vs 7.2%; aHR, 0.33 [0.07-1.52], P = .155). Propensity score adjustment also obtained similar results. LBBP showed a higher rate of echocardiographic response (ΔLVEF ≥10%: 60.0% vs 36.2% vs 16.1%; P < .001) than BiVP or LVSP.

LBBP yielded long-term clinical outcomes superior to those of BiVP and LVSP. The role of LVSP for CRT needs to be reevaluated because of its high mortality risk.

The objective of this study was to evaluate the association between comprehensive cardiac rehabilitation (CCR) completion and long-term clinical outcomes in patients with cardiac implantable electronic devices (CIED).

This retrospective cohort study included 834 patients with CIED who participated in CCR, which included a cardiopulmonary exercise test or 6-min walk test. Patients with a left ventricular ejection fraction ≤40%, predicted peak oxygen uptake ≤80%, or B-type natriuretic peptide level ≥80 pg/mL were eligible. The primary outcome was all-cause mortality.

After excluding 241 patients with duplicate records and 69 who underwent CCR in the outpatient department, the data of 524 patients were analyzed. Mean age was 64 ± 15 yr, 389 (74%) patients were men, left ventricular ejection fraction was 31 ± 15%, and 282 (54%) patients had a history of hospitalization for worsening heart failure. Of the patients referred for CCR, 294 (56%) completed the program, and an additional 230 patients started but did not complete CCR. Over a 3.7-yr median follow-up period, all-cause mortality occurred in 156 (30%) patients. Completers had lower all-cause mortality rates than non-completers (log-rank 15.77, P < .001). After adjusting for prognostic baseline characteristics, completers had 58% lower all-cause mortality risks than non-completers (HR = 0.42; 95% CI, 0.27-0.64, P < .001).

Three-mo CCR program completion was associated with lower mortality risks in patients with CIED. New programs or management methods are needed to decrease mortality risks, especially for those who cannot complete CCR programs.

Aim: There is a lack of data about the association between admission serum albumin levels and long-term mortality in heart failure (HF) patients with cardiac resynchronization therapy defibrillators (CRT-D). We aim to investigate this connection in HF patients with CRT-D. Methods: The study population consisted of 477 HF patients with CRT-D. The cohort was divided into three groups according to albumin values, and the relationship between these groups and long-term mortality were evaluated. Results: Long-term all-cause mortality (HR: 3.32, 95% CI: 2.12-6.84), appropriate (HR: 4.44, 95% CI: 2.44-8.06) and inappropriate (HR: 2.95, 95% CI: 1.88-6.02) shocks were higher in the low albumin group. Conclusion: Low albumin levels are associated with the long-term mortality and appropriate shock treatment in HF patients with CRT-D.

Left ventricular (LV) mechanical dyssynchrony (LVMD) is fundamental to the progression of heart failure and ventricular remodeling. The status of LVMD in different patterns of bundle branch blocks (BBB) is unclear. In this study, we analyzed the relationship between LVMD and left ventricular systolic dysfunction using real-time three-dimensional echocardiography (RT-3DE).

RT-3DE and conventional two-dimensional echocardiography were performed on 68 patients with left bundle branch block (LBBB group), 106 patients with right bundle branch block (RBBB group), and 103 patients without BBB (Normal group). The RT-3DE data sets provided time-volume analysis for global and segmental LV volumes. The LV systolic dyssynchrony index (LVSDI) was calculated using the standard deviation (SD) and maximal difference (Dif) of time to minimum segmental volume (tmsv) for LV segments adjusted by the R-R interval. LVMD was considered if the LVSDI (Tmsv-16-SD) was greater than or equal to 5%.

LVSDI is negatively and significantly correlated with left ventricular ejection fraction (LVEF), but not with BBB or QRS duration. The proportion of LVMD in the LBBB, RBBB, and Normal group was 30.88%, 28.30%, and 25.24%, respectively, and there was no significant difference.

In dilated cardiomyopathy, LVMD is more closely related to LVEF reduction than QRS morphology and duration.

Cardiorenal syndrome encompasses a dynamic interplay between cardiovascular and kidney disease, and its prevention requires careful examination of multiple predisposing underlying conditions. The unequal distribution of diabetes, heart failure, hypertension, and kidney disease requires special attention because of the influence of these conditions on cardiorenal disease. Despite growing evidence regarding the benefits of disease-modifying agents (e.g., sodium-glucose cotransporter 2 inhibitors) for cardiovascular, kidney, and metabolic (CKM) disease, significant disparities remain in access to and utilization of these essential therapeutics. Multilevel barriers impeding their use require multisector interventions that address patient, provider, and health system-tailored strategies. Burgeoning literature also describes the critical role of unequal social determinants of health, or the sociopolitical contexts in which people live and work, in cardiorenal risk factors, including heart failure, diabetes, and chronic kidney disease. This review outlines (i) inequality in the burden and treatment of hypertension, type 2 diabetes, and heart failure; (ii) disparities in the use of key disease-modifying therapies for CKM diseases; and (iii) multilevel barriers and solutions to achieve greater pharmacoequity in the use of disease-modifying therapies. In addition, this review provides summative evidence regarding the role of unequal social determinants of health in cardiorenal health disparities, further outlining potential considerations for future research and intervention. As proposed in the 2023 American Heart Association presidential advisory on CKM health, a paradigm shift will be needed to achieve cardiorenal health equity. Through a deeper understanding of CKM health and a commitment to equity in the prevention, detection, and treatment of CKM disease, we can achieve this critical goal.

Cardiac physiologic pacing (CPP) has become a well-established therapy for patients with cardiomyopathy (left ventricular ejection fraction <35%) in the presence of a left bundle branch block. In addition, CPP can be highly beneficial in patients with pacing-induced cardiomyopathy and patients with existing cardiomyopathy expected to have a right ventricular pacing burden of >40%. The benefits of CPP with traditional biventricular pacing are only realized if adequate resynchronization can be achieved. However, left ventricular lead implantation can be limited by individual anatomic variation within the coronary venous system and can be adversely affected by underlying abnormal myocardial substrate (i.e., scar tissue), especially if located within the basal lateral wall. In the last 7 years the investigation of conduction system pacing (CSP) and its potential salutary benefits are being realized and have led to a rapid evolution in the field of cardiac resynchronization pacing. However, supportive evidence for CSP for patients eligible for cardiac resynchronization remains limited compared with data available for biventricular cardiac resynchronization, mostly derived from leading CSP investigative centers. In this review, we perform an up-to-date comprehensive review of the available literature on CPP.

Heart failure is a significant cause of morbidity and mortality worldwide. Despite advancements in guideline-directed medical therapy and improvements in device-based therapies, patients with advanced heart failure have high rates of mortality regardless of ejection fraction. For patients with reduced ejection fraction who meet criteria, cardiac resynchronization therapy or implantable cardiac defibrillators are options available to improve outcomes. However, not all heart failure patients meet those criteria. Cardiac contractility modulation is an innovative therapy that serves to improve functional outcomes and quality of life, while also modifying pathologic gene expression and preventing further remodeling. In this article, we aim to discuss the major clinical trials investigating cardiac contractility modulation as a suitable therapy for patients with advanced heart failure.

Background and Objectives: Cardiac resynchronization therapy (CRT) is one of the effective therapeutic options in the treatment of systolic heart failure (HF) with persistent symptoms. This prospective study was designed to determine whether CRT with biventricular pacing would reduce the risk of development of atrial fibrillation (AF) and to identify predictors for AF occurrence. Materials and Methods: The study population consisted of 126 patients, with a mean age of 63.8 ± 9.1 years, who were eligible for CRT with biventricular pacing. Inclusion criteria were left ventricular ejection fraction (LVEF) ≤ 35%, QRS duration ≥ 130 msec, and persistent HF symptoms of New York Heart Association (NYHA) II or III, despite optimal drug therapy. Patients were followed for a period of 24 months and were evaluated through clinical, electrocardiographic, and echocardiographic examination at baseline (prior to CRT implantation), as well as at 6 and 24 months post-implantation. At the end of follow-up, patients were divided into clinical responders and non-responders based on the following criteria: decrease in NYHA class ≥ I, increase in LVEF ≥ 10%, and reduction in QRS duration ≥ 20 msec. Results: At follow-up, CRT was associated with a significant increase in LVEF (20.6 ± 6.9% pre-implantation, 32.9 ± 9.3% 24 months after implantation; p < 0.001), reduction in left ventricular end-diastolic and end-systolic diameters, and decrease in QRS duration (167.6 ± 14.3 msec pre-implantation, 131.7 ± 11.7 msec 24 months after implantation; p < 0.001), while left atrial (LA) diameter was slightly increased (p = 0.070). The frequency of AF occurrence increased after two years of follow-up (52.4% to 56.9%, p < 0.001). Significant predictors of AF occurrence in our study population were response to CRT-AF more frequent in non-responders (B = 8.134; p < 0.001), LA diameter-AF more frequent with larger LA diameter (B = 0.813; p < 0.001), and coronary sinus (CS) lead position-AF more frequent with posterolateral in comparison with lateral CS lead position (B = 5.159; p = 0.005). Conclusions: The results of our study provide new data on AF predictors in patients with HF subjected to CRT. There remains a permanent need for new predictors, which might help in patient selection and improvement in response rate.

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.

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.

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.

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.

Leadless permanent pacemakers represent an important innovation in cardiac device developments. Although transvenous permanent pacemakers have become indispensable in managing bradyarrhythmia and saving numerous lives, the use of transvenous systems comes with notable risks tied to intravascular leads and subcutaneous pockets. This drawback has spurred the creation of leadless cardiac pacemakers. Within this analysis, we compile existing clinical literature and proceed to evaluate the efficacy and safety of the Micra Transcatheter Pacing System. We also delve into the protocols for addressing a malfunctioning or end-of-life Micra as well as device extraction. Lastly, we explore prospects in this domain, such as the emergence of entirely leadless cardiac resynchronization therapy-defibrillator devices.

Cardiac resynchronisation therapy (CRT) reduces the risk of heart failure-related hospitalisations and all-cause mortality, as well as improving quality of life and functional status in patients with persistent heart failure symptoms despite optimal medical treatment and left bundle branch block. CRT has traditionally been delivered by implanting a lead through the coronary sinus to capture the left ventricular epicardium; however, this approach is associated with significant drawbacks, including a high rate of procedural failure, phrenic nerve stimulation, high pacing thresholds and lead dislodgement. Moreover, a significant proportion of patients fail to derive any significant benefit. Left bundle branch area pacing (LBBAP) has recently emerged as a suitable alternative to traditional CRT. By stimulating the cardiac conduction system physiologically, LBBAP can result in a more homogeneous left ventricular contraction and relaxation, thus having the potential to improve outcomes compared with conventional CRT strategies. In this article, the evidence supporting the use of LBBAP in patients with heart failure is reviewed.

Algorithms to automatically adjust atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) devices are common, but their clinical efficacy is unknown.

The purpose of this study was to evaluate automatic CRT algorithms in patients with heart failure for the reduction of mortality, heart failure hospitalizations, and clinical improvement.

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) in patients with CRT using automatic algorithms that change AV and VV intervals dynamically without manual input, on a beat-to-beat basis. We performed a subgroup analysis including intracardiac electrogram-based (EGM) algorithms and contractility-based algorithms.

Nine RCTs with 8531 participants were included, of whom 4275 (50.1%) were randomized to automatic algorithm. Seven of the 9 trials used EGM-based algorithms, and 2 used contractility sensors. There was no difference in all-cause mortality (10.3% vs 11.3%; odds ratio [OR] 0.90; 95% confidence interval [CI] 0.71-1.03; P = .13; I2 = 0%) or heart failure hospitalizations (15.0% vs 16.1%; OR 0.924; 95% CI 0.81-1.04; P = .194; I2 = 0%) between the automatic algorithm group and the control group. Study-defined clinical improvement was also not significantly different between groups (66.6% vs 63.3%; risk ratio 1.01; 95% CI 0.95-1.06; P = .82; I2 = 50%). In the contractility-based subgroup, there was a trend toward greater clinical improvement with the use of the automatic algorithm (75% vs 68.3%; OR 1.45; 95% CI 0.97-2.18; P = .07; I2 = 40%), which did not reach statistical significance. The overall risk of bias was low.

Automatic algorithms that change AV or VV intervals did not improve mortality, heart failure hospitalizations, or cardiovascular symptoms in patients with heart failure and CRT.

Left bundle branch area pacing (LBBP) is a novel conduction system pacing method to achieve effective physiological pacing and an alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) for patients with heart failure with reduced ejection fraction (HFrEF). We conduted this meta-analysis and systemic review to review current data comparing BVP and LBBP in patients with HFrEF and indications for CRT.

We searched PubMed/Medline, Web of Science, and Cochrane Library from the inception of the database to November 2022. All studies that compared LBBP with BVP in patients with HFrEF and indications for CRT were included. Two reviewers performed study selection, data abstraction, and risk of bias assessment. We calculated risk ratios (RRs) with the Mantel-Haenszel method and mean difference (MD) with inverse variance using random effect models. We assessed heterogeneity using the I2 index, with I2  > 50% indicating significant heterogeneity.

Ten studies (9 observational studies and 1 randomized controlled trial; 616 patients; 15 centers) published between 2020 and 2022 were included. We observed a shorter fluoroscopy time (MD: 9.68, 95% confidence interval [CI]: 4.49-14.87, I2  = 95%, p < .01, minutes) as well as a shorter procedural time (MD 33.68, 95% CI: 17.80-49.55, I2  = 73%, p < .01, minutes) during the implantation of LBBP CRT compared to conventional BVP CRT. LBBP was shown to have a greater reduction in QRS duration (MD 25.13, 95% CI: 20.06-30.20, I2  = 51%, p < .01, milliseconds), a greater left ventricular ejection fraction improvement (MD: 5.80, 95% CI: 4.81-6.78, I2  = 0%, p < .01, percentage), and a greater left ventricular end-diastolic diameter reduction (MD: 2.11, 95% CI: 0.12-4.10, I2  = 18%, p = .04, millimeter). There was a greater improvement in New York Heart Association function class with LBBP (MD: 0.37, 95% CI: 0.05-0.68, I2  = 61%, p = .02). LBBP was also associated with a lower risk of a composite of heart failure hospitalizations (HFH) and all-cause mortality (RR: 0.48, 95% CI: 0.25-0.90, I2  = 0%, p = .02) driven by reduced HFH (RR: 0.39, 95% CI: 0.19-0.82, I2  = 0%, p = .01). However, all-cause mortality rates were low in both groups (1.52% vs. 1.13%) and similar (RR: 0.98, 95% CI: 0.21-4.68, I2  = 0%, p = .87).

This meta-analysis of primarily nonrandomized studies suggests that LBBP is associated with a greater improvement in left ventricular systolic function and a lower rate of HFH compared to BVP. There was uniformity of these findings in all of the included studies. However, it would be premature to conclude based solely on the current meta-analysis alone, given the limitations stated. Dedicated, well-designed, randomized controlled trials and observational studies are needed to elucidate better the comparative long-term efficacy and safety of LBBP CRT versus BIV CRT.

Conduction system pacing (CSP) has been emerging over the last decade as a pacing option instead of conventional right ventricular (RV) pacing and biventricular (BiV) pacing. Numerous case reports, some observational studies and a few randomized control trials have looked at optimum pacing strategies for heart failure (HF) with left bundle branch block (LBBB) or cases where left ventricular (LV) dysfunction is anticipated due to chronic RV pacing (RVP). Evolution of pacing strategies from standard RVP to septal RVP, BiV pacing and now CSP have shown improving hemodynamic responses and possible ease of implantation of CSP systems. In this review article, we review the literature on the evolution of CSP and common scenarios where it might be beneficial.

Left bundle branch area pacing (LBBAP) for cardiac resynchronization therapy (CRT) is an alternative to biventricular pacing (BiVp).

The purpose of this study was to compare the outcomes between LBBAP and BiVp as an initial implant strategy for CRT.

In this prospective multicenter, observational, nonrandomized study, first-time CRT implant recipients with LBBAP or BiVp were included. The primary efficacy outcome was a composite of heart failure (HF)-related hospitalization and all-cause mortality. The primary safety outcomes were acute and long-term complications. Secondary outcomes included postprocedural New York Heart Association functional class and electrocardiographic and echocardiographic parameters.

A total of 371 patients (median follow-up of 340 days [IQR: 206-477 days]) were included. The primary efficacy outcome occurred in 24.2% in the LBBAP vs 42.4% in the BiVp (HR: 0.621 [95% CI: 0.415-0.93]; P = 0.021) group, driven by a reduction in HF-related hospitalizations (22.6% vs 39.5%; HR: 0.607 [95% CI: 0.397-0.927]; P = 0.021) without significant difference in all-cause mortality (5.5% vs 11.9%; P = 0.19) or differences in long-term complications (LBBAP: 9.4% vs BiVp: 15.2%; P = 0.146). LBBAP resulted in shorter procedural (95 minutes [IQR: 65-120 minutes] vs 129 minutes [IQR: 103-162 minutes]; P < 0.001) and fluoroscopy times (12 minutes [IQR: 7.4-21.1 minutes] vs 21.7 minutes [IQR: 14.3-30 minutes]; P < 0.001), shorter QRS duration (123.7 ± 18 milliseconds vs 149.3 ± 29.1 milliseconds; P < 0.001), and higher postprocedural left ventricular ejection fraction (34.1% ± 12.5% vs 31.4% ± 10.8%; P = 0.041).

LBBAP as an initial CRT strategy resulted in a lower risk of HF-related hospitalizations compared to BiVp. A reduction in procedural and fluoroscopy times, shorter paced QRS duration, and improvements in left ventricular ejection fraction compared with BiVp were observed.

Atrial fibrillation (AF) is associated with decreased cardiac resynchronization therapy (CRT) benefits compared to sinus rhythm (SR). Effective biventricular (BiV) pacing is a determinant of CRT success, but AF can interfere with adequate BiV pacing and affect clinical outcomes. We investigated the effect of device-detected AF on clinical outcomes and optimal BiV pacing in patients with heart failure (HF) treated with CRT.

We retrospectively analyzed 174 patients who underwent CRT implantation between 2012 and 2019 at a tertiary center. The optimal BiV pacing percentage was defined as ≥98%. Device-detected AF was defined as an atrial high-rate episode ≥180 beats per minute lasting more than 6 minutes during the follow-up period. We stratified the patients without preexisting AF at pre-implantation into device-detected AF and no-AF groups.

A total of 120 patients did not show preexisting AF at pre-implantation, and 54 had AF. Among these 120 patients, 19 (15.8%) showed device-detected AF during a median follow-up of 25.1 months. The proportion of optimal BiV pacing was significantly lower in the device-detected AF group than in the no-AF group (42.1% vs. 75.2%, p=0.009). The device-detected AF group had a higher incidence of HF hospitalization, cardiovascular death, and all-cause death than the no-AF group. The device-detected AF and previous AF groups showed no significant differences regarding the percentage of BiV pacing and clinical outcomes.

For HF patients implanted with CRT, device-detected AF was associated with lower optimal BiV pacing and worse clinical outcomes than no-AF.

Conduction system pacing (CSP) has emerged as a promising novel delivery method for Cardiac Resynchronisation Therapy (CRT), providing an alternative to conventional biventricular epicardial (BiV) pacing in indicated patients. Despite increasing popularity and widespread uptake, CSP has rarely been specifically examined in patients with atrial fibrillation (AF), a cohort which forms a significant proportion of the heart failure (HF) population. In this review, we first examine the mechanistic evidence for the importance of sinus rhythm (SR) in CSP by allowing adjustment of atrioventricular delays (AVD) to achieve the optimal electrical response, and thus, whether the efficacy of CSP may be significantly attenuated compared to conventional BiV pacing in the presence of AF. We next evaluate the largest clinical body of evidence in this field, related to patients receiving CSP following atrioventricular nodal ablation (AVNA) for AF. Finally, we discuss how future research may be designed to address the vital question of how effective CSP in AF patients is, and the potential hurdles we may face in delivering such studies.

Leadless pacing is a rapidly growing field. Initially designed to provide right ventricular pacing for those who were contraindicated for conventional devices, the technology is growing to explore the potential benefit of avoiding long-term transvenous leads in any patient who requires pacing. In this review, we first examine the safety and performance of leadless pacing devices. We then review the evidence for their use in special populations, such as patients with high risk of device infection, patients on haemodialysis, and patients with vasovagal syncope who represent a younger population who may wish to avoid transvenous pacing. We also summarise the evidence for leadless cardiac resynchronisation therapy and conduction system pacing and discuss the challenges of managing issues, such as system revisions, end of battery life and extractions. Finally, we discuss future directions in the field, such as completely leadless cardiac resynchronisation therapy-defibrillator devices and whether leadless pacing has the potential to become a first-line therapy in the near future.

This special article is the fifth in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors would like to thank the Editor-in-Chief, Dr Kaplan, the Associate Editor-in-Chief, Dr Augoustides, and the editorial board for the opportunity to author this series, which summarizes the key research papers in the electrophysiology (EP) field relevant to cardiothoracic and vascular anesthesiologists. These articles are shaping perioperative EP procedures and practices, such as pulsed-field ablation, cryoablation for first-line treatment for atrial fibrillation, advancements in conduction system pacing, safety issues related to smartphones and cardiac implantable electronic devices, and alterations in EP workflow as the world emerges from the COVID-19 pandemic. Special emphasis is placed on the implications of these advancements for the anesthetic care of patients undergoing EP procedures.

Heart failure (HF) is one of the leading causes of global health impairment. Current drugs are still limited in their effectiveness in the treatment and reversal of HF: for example, drugs for acute HF (AHF) help to reduce congestion and relieve symptoms, but they do little to improve survival; most conventional drugs for HF with preserved ejection fraction (HFpEF) do not improve the prognosis; and drugs have extremely limited effects on advanced HF. In recent years, progress in device therapies has bridged this gap to a certain extent. For example, the availability of the left ventricular assist device has brought new options to numerous advanced HF patients. In addition to this recognizable device, a range of promising novel devices with preclinical or clinical trial results are emerging that seek to treat or reverse HF by providing circulatory support, repairing structural abnormalities in the heart, or providing electrical stimulation. These devices may be useful for the treatment of HF. In this review, we summarized recent advances in novel devices for AHF, HFpEF, and HF with reduced ejection fraction (HFrEF) with the aim of providing a reference for clinical treatment and inspiration for novel device development.

Myocardial work is an emerging tool in echocardiography that incorporates left ventricular afterload into global longitudinal strain analysis. Myocardial work correlates with myocardial oxygen consumption, and work efficiency can also be assessed. Myocardial work has been evaluated in a variety of clinical conditions to assess the added value of myocardial work compared to left ventricular ejection fraction and global longitudinal strain. This review showcases the current use of myocardial work in adult echocardiography and its possible role in cardiac pathologies.

Non-responders to Cardiac Resynchronization Therapy (CRT) represent a high-risk, and difficult to treat population of heart failure patients. Studies have shown that these patients have a lower quality of life and reduced life expectancy compared to those who respond to CRT. Whilst the first-line treatment for dyssynchronous heart failure is "conventional" biventricular epicardial CRT, a range of novel pacing interventions have emerged as potential alternatives. This has raised the question whether these new treatments may be useful as a second-line pacing intervention for treating non-responders, or indeed, whether some patients may benefit from these as a first-line option. In this review, we will examine the current evidence for four pacing interventions in the context of treatment of conventional CRT non-responders: CRT optimization; multisite left ventricular pacing; left ventricular endocardial pacing and conduction system pacing.

Cardiac Resynchronization Therapy (CRT) is a widely used, device-based therapy for patients with left ventricle (LV) failure. Unfortunately, many patients do not benefit from CRT, so there is potential value in identifying this group of non-responders before CRT implementation. Past studies suggest that predicting CRT response will require diverse variables, including demographic, biomarker, and LV function data. Accordingly, the objective of this study was to integrate diverse variable types into a machine learning algorithm for predicting individual patient responses to CRT.

We built an ensemble classification algorithm using previously acquired data from the SMART-AV CRT clinical trial (n = 794 patients). We used five-fold stratified cross-validation on 80% of the patients (n = 635) to train the model with variables collected at 0 months (before initiating CRT), and the remaining 20% of the patients (n = 159) were used as a hold-out test set for model validation. To improve model interpretability, we quantified feature importance values using SHapley Additive exPlanations (SHAP) analysis and used Local Interpretable Model-agnostic Explanations (LIME) to explain patient-specific predictions.

Our classification algorithm incorporated 26 patient demographic and medical history variables, 12 biomarker variables, and 18 LV functional variables, which yielded correct prediction of CRT response in 71% of patients. Additional patient stratification to identify the subgroups with the highest or lowest likelihood of response showed 96% accuracy with 22 correct predictions out of 23 patients in the highest and lowest responder groups.

Computationally integrating general patient characteristics, comorbidities, therapy history, circulating biomarkers, and LV function data available before CRT intervention can improve the prediction of individual patient responses.