Conventional versus biventricular pacing in heart failure and bradyarrhythmia: the COMBAT study

Atrioventricular node ablation for atrial fibrillation in the era of conduction system pacing

Despite key advances in catheter-based treatments, the management of persistent atrial fibrillation (AF) remains a therapeutic challenge in a significant subset of patients. While success rates have improved with repeat AF ablation procedures and the concurrent use of antiarrhythmic drugs, the likelihood of maintaining sinus rhythm during long-term follow-up is still limited. Atrioventricular node ablation (AVNA) has returned as a valuable treatment option given the recent developments in cardiac pacing. With the advent of conduction system pacing, AVNA has seen a revival where pacing-induced cardiomyopathy after AVNA is felt to be overcome. This review will discuss the role of permanent pacemaker implantation and AVNA for AF management in this new era of conduction system pacing. Specifically, this review will discuss the haemodynamic consequences of AF and the mechanisms through which 'pace-and-ablate therapy' enhances outcomes, analyse historical and more recent literature across various pacing methods, and work to identify patient groups that may benefit from earlier implementation of this approach.

Is conduction system pacing a panacea for pacemaker therapy?

INTRODUCTION

While supported by robust evidence and decades of clinical experience, right ventricular apical pacing for bradycardia is associated with a risk of progressive left ventricular dysfunction. Cardiac resynchronization therapy for heart failure with reduced ejection fraction can result in limited electrical resynchronization due to anatomical constraints and epicardial stimulation. In both settings, directly stimulating the conduction system below the atrio-ventricular node (either the bundle of His or the left bundle branch area) has potential to overcome these limitations. Conduction system pacing has met with considerable enthusiasm in view of the more physiological electrical conduction pattern, is rapidly becoming the preferred option of pacing for bradycardia, and is gaining momentum as an alternative to conventional biventricular pacing.

AREAS COVERED

This article provides a review of the current efficacy and safety data for both people requiring treatment for bradycardia and the management of heart failure with conduction delay and discusses the possible future roles for conduction system pacing in routine clinical practice.

EXPERT OPINION

Conduction system pacing might be the holy grail of pacemaker therapy without the disadvantages of current approaches. However, hypothesis and enthusiasm are no match for robust data, demonstrating at least equivalent efficacy and safety to standard approaches.

Left Bundle Branch Area Pacing to Overcome Coronary Sinus Anatomy-Related Technical Problems Encountered during Implantation of Biventricular CRT-A Case Report

The results of clinical trials show that up to one-third of patients who are eligible for cardiac resynchronization therapy (CRT) do not benefit from biventricular pacing. The reasons vary, including technical problems related to left ventricle pacing lead placement in the appropriate branch of the coronary sinus. Herein, we present a case report of a patient with heart failure with reduced ejection fraction and left bundle branch block, in whom a poor coronary sinus bed made implantation of classic biventricular CRT impossible, but in whom, alternatively, rescue-performed left bundle branch area pacing allowed effective electrical and mechanical cardiac resynchronization. The report confirms that left bundle branch area pacing may be a rational alternative in such cases.

Conventional biventricular pacing is still preferred to conduction system pacing for atrioventricular block in patients with reduced ejection fraction and narrow QRS

It is well established that right ventricular pacing is detrimental in patients with reduced cardiac function who require ventricular pacing (VP), and alternatives nowadays are comprised of biventricular pacing (BiVP) and conduction system pacing (CSP). The latter modality is of particular interest in patients with a narrow baseline QRS as it completely avoids, or minimizes, ventricular desynchronization associated with VP. In this article, experts debate whether BiVP or CSP should be used to treat these patients.

Conduction system pacing improves the outcomes on patients with high percentage of ventricular pacing and heart failure with mildly reduced ejection fraction

Aims

This study aimed to investigate the efficacy and safety of CSP in patients with a high percentage of ventricular pacing and heart failure with HFmrEF.

Methods

Patients who underwent CSP for HFmrEF and ventricular pacing >40% were consecutively enrolled from January 2018 to May 2021. All participants were followed up at least 12 months. Clinical data including cardiac performance and lead outcomes were compared before and after the procedure. Left ventricular ejection fraction (LVEF) was measured using the biplane Simpson's method. HFmrEF was defined as heart failure with the LVEF ranging from 41%-49%.

Results

CSP was successfully performed in 64 cases (96.97%), which included 16 cases of left bundle branch pacing (LBBP) and 48 cases of His bundle pacing (HBP). After a mean of 23.12 ± 8.17 months follow-up, NYHA classification (P < 0.001), LVEF (42.45 ± 1.84% vs. 49.97 ± 3.57%, P < 0.001) and left ventricular end diastolic diameter (LVEDD) (55.59 ± 6.17 mm vs. 51.66 ± 3.48 mm, P < 0.001) improved significantly. During follow-up, more than half (39/64,60.9%) of patients returned to normal LVEF and LVEDD with complete reverse remodeling. The pacing threshold in LBBP was lower (0.90 ± 0.27 V@0.4 ms vs. 1.61 ± 0.71 V@0.4 ms, P < 0.001) than that in HBP. No perforation, electrode dislodging, thrombosis or infection was observed during follow-up.

Conclusions

CSP could improve the clinical outcomes in patients with HFmrEF and a high percentage of ventricular pacing. LBBP might be a better choice because of its feasibility and safety, especially in patients with infranodal atrioventricular block.

Adverse effects of right ventricular pacing on cardiac function: prevalence, prevention and treatment with physiologic pacing

Right ventricular (RV) pacing is the main treatment modality for patients with advanced atrioventricular (AV) block. Chronic RV pacing can cause cardiac systolic dysfunction and heart failure (HF). In this review, we discuss studies that have shown deleterious effects of chronic RV pacing on systolic cardiac function causing pacing-induced cardiomyopathy (PiCM), heart failure (HF), HF hospitalization, atrial fibrillation (AF) and cardiac mortality. RV apical pacing is the most widely used and studied. Adverse effects of RV pacing appear to be directly related to pacing burden and are worse in patients with pre-existing left ventricular (LV) dysfunction. Chronic RV pacing is also associated with heart failure with preserved ejection fraction (HFpEF). Mechanisms, risk factors, clinical and echocardiographic features, and strategies to minimize RV pacing-induced cardiac dysfunction are discussed in light of the latest data. Studies on biventricular (Bi-V) pacing upgrade in patients who develop RV PiCM, use of alternate RV pacing sites, de novo Bi-V pacing, and physiologic pacing using HIS bundle pacing (HBP) and left bundle area (LBBA) pacing in patients with an anticipated high RV pacing burden are discussed.

Optimal effectiveness of heart failure management - an umbrella review of meta-analyses examining the effectiveness of interventions to reduce (re)hospitalizations in heart failure

Heart failure (HF) is a major health concern, which accounts for 1-2% of all hospital admissions. Nevertheless, there remains a knowledge gap concerning which interventions contribute to effective prevention of HF (re)hospitalization. Therefore, this umbrella review aims to systematically review meta-analyses that examined the effectiveness of interventions in reducing HF-related (re)hospitalization in HFrEF patients. An electronic literature search was performed in PubMed, Web of Science, PsycInfo, Cochrane Reviews, CINAHL, and Medline to identify eligible studies published in the English language in the past 10 years. Primarily, to synthesize the meta-analyzed data, a best-evidence synthesis was used in which meta-analyses were classified based on level of validity. Secondarily, all unique RCTS were extracted from the meta-analyses and examined. A total of 44 meta-analyses were included which encompassed 186 unique RCTs. Strong or moderate evidence suggested that catheter ablation, cardiac resynchronization therapy, cardiac rehabilitation, telemonitoring, and RAAS inhibitors could reduce (re)hospitalization. Additionally, limited evidence suggested that multidisciplinary clinic or self-management promotion programs, beta-blockers, statins, and mitral valve therapy could reduce HF hospitalization. No, or conflicting evidence was found for the effects of cell therapy or anticoagulation. This umbrella review highlights different levels of evidence regarding the effectiveness of several interventions in reducing HF-related (re)hospitalization in HFrEF patients. It could guide future guideline development in optimizing care pathways for heart failure patients.

Conduction system pacing vs. biventricular pacing in patients with ventricular dysfunction and AV block

BACKGROUND

It is unknown whether His-Purkinje conduction system pacing (HPCSP), as either His bundle or left bundle branch pacing, could be an alternative to cardiac resynchronization therapy (BiVCRT) for patients with left ventricular dysfunction needing ventricular pacing due to atrioventricular block. The aim of the study is to compare the echocardiographic response and clinical improvement between HPCSP and BiVCRT.

METHODS

Consecutive patients who successfully received HPCSP were compared with a historical cohort of BiVCRT patients. Patients were 1:1 matched by age, LVEF, atrial fibrillation, renal function and cardiomyopathy type. Responders were defined as patients who survived, did not require heart transplantation and increased LVEF ≥5 points at 6-month follow-up.

RESULTS

HPCSP was successfully achieved in 92.5% (25/27) of patients. During follow-up, 8% (2/25) of HPCSP patients died and 4% (1/25) received a heart transplant, whereas 4% (1/25) of those in the BiVCRT cohort died. LVEF improvement was 10% ± 8% HPCSP versus 7% ± 5% BiVCRT (p = .24), and the percentage of responders was 76% (19/25) HPCSP versus 64% (16/25) BiVCRT (p = .33). Among survivors, the percentage of patients who improved from baseline II-IV mitral regurgitation (MR) to 0-I MR was 9/11 (82%) versus 2/8 (25%) (p = .02). Compared to those with BiVCRT, patients with HPCSP achieved better NYHA improvement: 1 point versus 0.5 (OR 0.34; p = .02).

CONCLUSION

HPCSP in patients with LVEF ≤45% and atrioventricular block improved the LVEF and induced a response similar to that of BiVCRT. HPCSP significantly improved MR and NYHA functional class. HPCSP may be an alternative to BiVCRT in these patients. (Figure 1. Central Illustration). [Figure: see text].

Clinical outcomes of upgrade to versus de novo cardiac resynchronization therapy in mild heart failure patients with atrioventricular block

BACKGROUND

Indication for de novo cardiac resynchronization therapy (CRT) has been recommended in mild heart failure (HF) patients with left ventricular (LV) ejection fraction (LVEF) <50% and atrioventricular block (AVB). In contrast, the indication of CRT upgrade from right ventricular pacing (RVP) has been limited to severe HF patients with LVEF≤35% and AVB. This study examined LV volumetric responses and clinical outcomes in mild HF patients with AVB who underwent CRT upgrade, compared with those of de novo CRT patients.

METHODS

This retrospective study focused on patients with CRT due to AVB, mild HF at New York Heart Association class II and LVEF<50%. A total of 58 patients were divided into two groups: (1) 27 patients with CRT upgrade from RVP>40% (Upgrade group, UG), and (2) 31 patients with de novo CRT implantation (De novo group, DG). The echocardiographic assessment was performed at baseline and six months after CRT. The study endpoint was a combined endpoint with total mortality, HF hospitalization, or ventricular tachyarrhythmia events.

RESULTS

At six months after CRT, the LV end-systolic volume (LVESV) was significantly reduced in both groups (from 144.3±39.4 mL to 111.1±33.5 mL in UG, p<0.01; from 134.5±36.6 mL to 123.5±45.6 mL in DG, p<0.05); however, a significant improvement in LVEF was obtained in UG but not in DG (from 31.7±6.8% to 39.7±8.5% in UG, p<0.01; from 34.2±7.3% to 36.0±9.7% in DG, p=0.15). Consequently, the changes in LVESV and LVEF were significantly greater in UG than in DG. During the follow-up of 989 days, the survival rate for the composite events were similar between both groups (p=0.18).

CONCLUSIONS

LV reverse remodeling was significantly greater in UG than DG, and the incidence of clinical composite events at mid-term follow-up was equivalent between UG and DG. CRT upgrade could be an acceptable indication in mild HF patients dependent on RVP.

Cardiomyopathy Induced by Artificial Heart Stimulation

With the advent of cardiac pacemakers more than 60 years ago, the era of artificial cardiac pacing began, which changed the natural history of symptomatic bradycardias, significantly increasing the survival especially of patients with complete atrioventricular block.

Cardiomiopatia Induzida por Estimulação Cardíaca Artificial

Com o advento dos marcapassos cardíacos há mais de 60 anos, iniciou-se a era da estimulação cardíaca artificial, que mudou a história natural das bradicardias sintomáticas, aumentando significativamente a sobrevida principalmente dos pacientes portadores de bloqueio atrioventricular total.

Cardiomyopathy Induced by Artificial Heart Stimulation

With the advent of cardiac pacemakers more than 60 years ago, the era of artificial cardiac pacing began, which changed the natural history of symptomatic bradycardias, significantly increasing the survival especially of patients with complete atrioventricular block.

Cardiomiopatia Induzida por Estimulação Cardíaca Artificial

Com o advento dos marcapassos cardíacos há mais de 60 anos, iniciou-se a era da estimulação cardíaca artificial, que mudou a história natural das bradicardias sintomáticas, aumentando significativamente a sobrevida principalmente dos pacientes portadores de bloqueio atrioventricular total.

Incidence and predictors of pacemaker-induced cardiomyopathy with comparison between apical and non-apical right ventricular pacing sites

BACKGROUND

Asynchronous activation of left ventricle (LV) due to chronic right ventricular (RV) pacing has been known to predispose to LV dysfunction. The predictors of LV dysfunction remain to be prospectively studied. This study was designed to follow up patients with RV pacing to look for development of pacing-induced cardiomyopathy (PiCMP), identify its predictors and draw comparison between apical vs non-apical RV pacing sites.

METHODS

Three hundred sixty-three patients undergoing dual-chamber and single-chamber ventricular implants were enrolled and followed up. Baseline clinical parameters; paced QRS duration and axis; RV lead position by fluoroscopy; LV ejection fraction (LVEF) by Simpson's method on transthoracic echocardiography (TTE); intraventricular dyssynchrony (septal-posterior wall contraction delay) and interventricular dyssynchrony (aortopulmonary ejection delay) on TTE were recorded. The patients were followed up at 6-12 monthly interval with estimation of LVEF and pacemaker interrogation at each visit. Pacemaker-induced cardiomyopathy (PiCMP) was defined as a fall in ejection fraction of 10% as compared to the baseline LVEF. Patients developing PiCMP were compared to other patients to identify predictors.

RESULTS

The mean age of study population was 59.8 years, 68.3% being males. Fifty-one percent and 49% patients underwent VVIR and DDDR pacemaker implantation, respectively. After attrition, 254 patients were analysed. PiCMP developed in 35 patients (13.8%) over a mean follow-up of 14.5 months. After multivariate analysis, burden of ventricular pacing > 60% [HR 4.26, p = 0.004] and interventricular dyssynchrony (aortopulmonary ejection delay > 40 msec) [HR 3.15, p = 0.002] were identified as predictors for PiCMP in patients undergoing chronic RV pacing. There was no effect of RV pacing site (apical vs non-apical) on incidence of PiCMP [HR 1.44, p = 0.353).

CONCLUSIONS

Incidence of PiCMP with RV pacing was found to be 13.8% over a mean follow-up of 14.5 months. Burden of right ventricular pacing and interventricular dyssynchrony were identified as the most important predictors for the development of PiCMP. Non-apical RV pacing site did not offer any benefit in terms of incidence of PiCMP over apical lead position.

Efficacy, Safety, and Performance of Isolated Left vs. Right Ventricular Pacing in Patients with Bradyarrhythmias: A Randomized Controlled Trial

Background

Considering the potential deleterious effects of right ventricular (RV) pacing, the hypothesis of this study is that isolated left ventricular (LV) pacing through the coronary sinus is safe and may provide better clinical and echocardiographic benefits to patients with bradyarrhythmias and normal ventricular function requiring heart rate correction alone.

Objective

To assess the safety, efficacy, and effects of LV pacing using an active-fixation coronary sinus lead in comparison with RV pacing, in patients eligible for conventional pacemaker (PM) implantation.

Methods

Randomized, controlled, and single-blinded clinical trial in adult patients submitted to PM implantation due to bradyarrhythmias and systolic ventricular function ≥ 0.40. Randomization (RV vs. LV) occurred before PM implantation. The main results of the study were procedural success, safety, and efficacy. Secondary results were clinical and echocardiographic changes. Chi-squared test, Fisher's exact test and Student's t-test were used, considering a significance level of 5%.

Results

From June 2012 to January 2014, 91 patients were included, 36 in the RV Group and 55 in the LV Group. Baseline characteristics of patients in both groups were similar. PM implantation was performed successfully and without any complications in all patients in the RV group. Of the 55 patients initially allocated into the LV group, active-fixation coronary sinus lead implantation was not possible in 20 (36.4%) patients. The most frequent complication was phrenic nerve stimulation, detected in 9 (25.7%) patients in the LV group. During the follow-up period, there were no hospitalizations due to heart failure. Reductions of more than 10% in left ventricular ejection fraction were observed in 23.5% of patients in the RV group and 20.6% of those in the LV group (p = 0.767). Tissue Doppler analysis showed that 91.2% of subjects in the RV group and 68.8% of those in the LV group had interventricular dyssynchrony (p = 0.022).

Conclusion

The procedural success rate of LV implant was low, and the safety of the procedure was influenced mainly by the high rate of phrenic nerve stimulation in the postoperative period.

Midrange ejection fraction as a risk factor for deterioration of cardiofunction after permanent pacemaker implantation

PURPOSE

To determine whether the midrange ejection fraction (mrEF) is associated with increased risk of deterioration of cardiac function (DCF) after dual chamber permanent pacemaker (PPM) implantation.

METHODS

We performed a prospective cohort study of relevance in patients with EF ≥ 40% and indications for PPMs. Patient characteristics were recorded at baseline and 1 day, 1 month, 3 months, and 6 months after PPM implantation with leads placed in the right ventricular apex. These included clinical symptoms, signs, biochemical parameters, BNP, echocardiography and ECG parameters, and pacing-related parameter changes. The patients were followed-up for 6 months. Univariate and multivariable Cox regression analyses were performed.

RESULTS

A total of 879 patients were included, aged 35 to 88 years (mean age 67.2 ± 9.6); a total of 81 patients (9.2%) developed DCF after PPM implantation, including LVEF < 40% (57 cases) and increased NYHA class (24 cases). Cox models demonstrated that age ≥ 75 years (HR 2.273 [95% CI, 1.541-3.626]), OMI (HR 2.078 [95% CI, 1.275-3.604]), mrEF (HR 2.762 [95% CI, 1.558-4.769]), moderate mitral regurgitation (HR 2.819 [95% CI, 1.604-4.153]), and right ventricular pacing ≥ 50% (HR 2.311 [95% CI, 1.478-3.937]) were strong predictors for DCF, and NT-proBNP > 1000 ng/L and paced QRS duration ≥ 180 ms were also the independent predictors of DCF.

CONCLUSIONS

MrEF was associated with increased risk of deterioration of cardiac function after PPM implantation. Moderate mitral regurgitation and increased NT-proBNP levels are also potential independent predictors for deterioration of cardiac function after PPM implantation.

Prognostic Implications of QRS Duration in Third-Degree Atrioventricular Block Patients with Heart Failure Treated with Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) improves heart function and prognosis in third-degree atrioventricular block (AVB) patients with heart failure (HF). However, it is still unclear how to screen for appropriate patients before implantation. This study aimed to evaluate the value of using QRS duration to predict CRT efficacy.This study enrolled a total of 72 third-degree AVB patients with HF who received CRT implantation. The patients were divided into Groups A (QRS duration < 120 ms, 33 cases), B (120 ms ≤ QRS duration < 150 ms, 22 cases), and C (QRS duration ≥ 150 ms, 17 cases) according to their baseline QRS duration. The effects of different QRS durations on CRT efficacy were analyzed.The CRT response rate were 30.3%, 50.0%, and 76.5% in Groups A, B, and C, respectively (P = 0.008). The patients in the 3 groups showed significant changes in left ventricular (LV) end-diastolic volume, LV end-systolic volume, and LV ejection fraction over the baseline values at 12 months after the implantation (P < 0.05), with the greatest change observed in Group C. Survival analysis indicated statistically significant differences among Groups A, B, and C (P = 0.024). Multivariate logistic regression analysis suggested that QRS duration was an independent prognostic factor for CRT efficacy. Baseline QRS duration was associated with improved myocardial remodeling and reductions in the incidence rates of primary endpoint events.QRS ≥ 150 ms is an effective predictor of postoperative outcome in patients with third-degree AVB and HF treated with CRT.

Heart failure and right ventricular pacing - how to avoid the need for cardiac resynchronization therapy

INTRODUCTION

Heart failure (HF) is a common finding in patients with pacemakers implanted for bradycardia, with cross-sectional and longitudinal studies contributing to the growing consensus that right ventricular pacing can cause adverse cardiac remodeling and left ventricular systolic dysfunction increasing the risk of hospitalization and death. An unselected approach using cardiac resynchronization therapy from the time of first implant in patients with heart block has produced equivocal results. Contemporary research has therefore begun to focus on the stratification of patients' risk of pacemaker-associated impairment to permit focused, personalized management.

AREAS COVERED

The present review will describe the incidence and relevance of HF in the pacemaker population and discuss current management options for such patients.

EXPERT COMMENTARY

At present there are few contemporary data to guide the identification of patients with and at risk of pacemaker-associated cardiac remodeling and dysfunction. Emphasis must be placed on precise and personalized treatment approaches which currently remain under-investigated due to a number of challenges, for example, small sample sizes, limited clarity on programmed settings, and short follow-up periods.

A cohort study of cardiac resynchronization therapy in patients with chronic Chagas cardiomyopathy

Aims

Cardiac resynchronization therapy (CRT) is an established procedure for patients with heart failure. However, trials evaluating its efficacy did not include patients with chronic Chagas cardiomyopathy (CCC). We aimed to assess the role of CRT in a cohort of patients with CCC.

Methods and results

This retrospective study compared the outcomes of CCC patients who underwent CRT with those of dilated (DCM) and ischaemic cardiomyopathies (ICM). The primary endpoint was all-cause mortality and the secondary endpoints were the rate of non-advanced New York Heart Association (NYHA) class 12 months after CRT and echocardiographic changes evaluated at least 6 months after CRT. There were 115 patients in the CCC group, 177 with DCM, and 134 with ICM. The annual mortality rates were 25.4%, 10.4%, and 11.3%, respectively (P < 0.001). Multivariate analysis adjusted for potential confounders showed that the CCC group had a two-fold [hazard ratio 2.34 (1.47-3.71), P < 0.001] higher risk of death compared to the DCM group. The rate of non-advanced NYHA class 12 months after CRT was significantly higher in non-CCC groups than in the CCC group (DCM 74.0% vs. ICM 73.9% vs. 56.5%, P < 0.001). Chronic Chagas cardiomyopathy and ICM patients had no improvement in the echocardiographic evaluation, but patients in the DCM group had an increase in left ventricular ejection fraction and a decrease in left ventricular end-diastolic diameter.

Conclusion

This study showed that CCC patients submitted to CRT have worse prognosis compared to patients with DCM and ICM who undergo CRT. Studies comparing CCC patients with and without CRT are warranted.

Cardiac resynchronization therapy improves left ventricular remodeling and function compared with right ventricular pacing in patients with atrioventricular block

Right ventricular pacing (RVP) exerts a detrimental effect on left ventricular (LV) remodeling. In patients with atrioventricular block (AVB) that require ventricular pacing, the effect of biventricular pacing (BiVP) versus RVP on LV remodeling and function has not been comprehensively assessed in a meta-analysis. Electric databases MEDLINE and Cochrane Library were retrieved for randomized controlled trials (RCT) comparing RVP and BiVP in patients with AVB. Data on left ventricular ejection fraction (LVEF) and LV volumes were analyzed, stratified by different time points. Eleven RCTs were included in the final analysis. There was a significant reduction of LV end-systolic volume in BiVP compared with RVP, at 3, 6, 12, and 24 months follow-up (P < 0.05 for all). BiVP was associated with a decreased LV end-diastolic volume in comparison to RVP at 3, 6, and 12 months. Compared with RVP, BiVP had a higher LVEF at all follow-up visits, with mean difference of 5.91, 3.29, 3.9, 6.66, and 8.69% at 3, 6, 12, 24, and beyond 24 months follow-up, respectively. The results were not significantly changed in sensitivity analysis after removal of studies with mean baseline LVEF < 50% or excluding studies with ablation-induced AVB. In patients with AVB and bradycardia that require ventricular pacing, BiVP is superior to RVP in improving LV remodeling and function.

Rationale and design of the BUDAPEST-CRT Upgrade Study: a prospective, randomized, multicentre clinical trial

Aims

There is lack of conclusive evidence from randomized clinical trials on the efficacy and safety of upgrade to cardiac resynchronization therapy (CRT) in patients with implanted pacemakers (PM) or defibrillators (ICD) with reduced left ventricular ejection fraction (LVEF) and chronic heart failure (HF). The BUDAPEST-CRT Upgrade Study was designed to compare the efficacy and safety of CRT upgrade from conventional PM or ICD therapy in patients with intermittent or permanent right ventricular (RV) septal/apical pacing, reduced LVEF, and symptomatic HF.

Methods and results

The BUDAPEST-CRT study is a prospective, randomized, multicentre, investigator-sponsored clinical trial. A total of 360 subjects will be enrolled with LVEF ≤ 35%, NYHA functional classes II–IVa, paced QRS ≥ 150 ms, and a RV pacing ≥ 20%. Patients will be followed for 12 months. Randomization is performed in a 3:2 ratio (CRT-D vs. ICD). The primary composite endpoint is all-cause mortality, a first HF event, or less than 15% reduction in left ventricular (LV) end-systolic volume at 12 months. Secondary endpoints are all-cause mortality, all-cause mortality or HF event, and LV volume reduction at 12 months. Tertiary endpoints include changes in quality of life, NYHA functional class, 6 min walk test, natriuretic peptides, and safety outcomes.

Conclusion

The results of our prospective, randomized, multicentre clinical trial will provide important information on the role of cardiac resynchronization therapy with defibrillator (CRT-D) upgrade in patients with symptomatic HF, reduced LVEF, and wide-paced QRS with intermittent or permanent RV pacing.

Clinical trials.gov identifier

NCT02270840.

Clinical outcomes with biventricular versus right ventricular pacing in patients with atrioventricular conduction defects

There have been increasing concerns about the unexpected effects of right ventricular (RV) pacing. We aimed to systematically evaluate the effect of biventricular (BiV) versus RV pacing on clinical events in patients with impaired AV conduction. We searched PubMed, EMBASE, and Cochrane Library for studies comparing BiV pacing with RV pacing in patients with AV block, through April 2017. We selected randomized controlled trials (RCTs) reporting data on mortality, hospitalization for heart failure (HF), and/or 6-min walk distance (6MWD). A total of 12 RCTs were finally included. Pooled analysis suggested that BiV pacing was associated with a significantly reduced all-cause mortality in contrast to RV pacing (risk ratio (RR) = 0.77, 95% confidence interval (CI) 0.62 to 0.95, I² = 9.6%). BiV pacing, compared with RV pacing, significantly reduced the rate of HF hospitalization (RR = 0.74, 95% CI 0.59 to 0.93, I² = 10.1%). Sensitivity analyses by excluding studies with AV nodal ablation showed that BiV pacing still had a lower mortality and non-significant reduced HF hospitalization. Patients in BiV and RV pacing mode had a similar 6WMD at follow-up (mean difference = 4.99 m, 95% CI - 11.34 to 21.33 m, I² = 0%). Meta-regression analysis showed that the effect size of all-cause mortality or HF hospitalization was not significantly associated with mean LVEF value at baseline. In patients with impaired AV conduction that need frequent ventricular pacing, BiV pacing was associated with reduced mortality and hospitalization for HF, compared with traditional RV pacing mode.

Right Ventricular Pacing and Cardiac Resynchronization Devices

Long-term right ventricular pacing is associated with electrical and mechanical dyssynchrony and ultimately development of pacing-induced cardiomyopathy (PICM) in a subset of patients. Patients with a high degree of pacing burden and reduced left ventricular (LV) function prior to pacemaker implantation are at the greatest risk for developing PICM. Cardiac resynchronization therapy (CRT) has an established role in the treatment of patients with LV systolic heart failure and intraventricular delay and has been used to successfully treat PICM. This review evaluates predictors for PICM, as well as highlights the role for CRT in prevention and treatment in high risk patients.

Chronic Right Ventricular Pacing in the Heart Failure Population

Purpose of Review

We review the trials that have demonstrated potentially harmful effects from right ventricular (RV) apical pacing as well as reviewing the evidence of alternative RV pacing sites and cardiac resynchronization therapy (CRT) for patients who have heart failure and atrioventricular (AV) block.

Recent Findings

The role of CRT in patients with AV block and impaired left ventricular function remains an important consideration. The BLOCK HF trial demonstrated better outcomes with CRT pacing over RV pacing in patients with left ventricular systolic dysfunction (LVSD) and AV block who were expected to have a high RV pacing burden, but failed to demonstrate a mortality benefit.

Summary

CRT seems to have a beneficial effect on left ventricular reverse remodeling, systolic function, and clinical outcomes in patients with New York Heart Association (NYHA) functional class I–III heart failure, moderate to severe LVSD, and AV block compared to RV pacing. However, it is less clear whether there is a similar benefit from CRT in patients with a high percentage of RV pacing who have normal or mild LVSD in the treatment of AV block.

Long-Term Impact of Right Ventricular Pacing on Left Ventricular Systolic Function in Pacemaker Recipients With Preserved Ejection Fraction: Results From a Large Single-Center Registry

Background

There is limited evidence of long‐term impact of right ventricular pacing on left ventricular (LV) systolic function in pacemaker recipients with preserved LV ejection fraction (LVEF). The objective of the study was to evaluate the outcome and echocardiographic course of baseline preserved LVEF in a large cohort of pacemaker recipients with respect to pacing indication and degree of right ventricular pacing.

Methods and Results

We enrolled 991 patients (73±10 years, 54% male) with baseline normal (>55%) LVEF (n=791) or mildly reduced (41–55%) LVEF (n=200) who had paired echocardiographic data on LV systolic function recorded at implantation and last follow‐up. According to pacing indication, patients were divided into atrioventricular block group A (n=500) and sinus node disease group B (n=491). Main outcome measures were all‐cause mortality and deterioration of LV function ≥2 LVEF categories at last follow‐up. Patients were followed for an average of 44 months. Death from any cause occurred in 166 (17%), and deterioration of LV function ≥2 LVEF categories in 56 (6%) patients. There was no significant difference in outcome between group A and group B either in patients with normal LVEF or in those with mildly reduced LVEF. Mean percentage of right ventricular pacing was not predictive of outcome.

Conclusions

In a large cohort of pacemaker recipients with predominantly normal LVEF, clinically relevant LV dysfunction develops rather infrequently. No significant difference in all‐cause mortality and development of severe LV dysfunction is observed between patients with atrioventricular block and sinus node disease. Accordingly, de novo biventricular pacing cannot be recommended for patients with preserved LVEF.

Feasibility and Acute Hemodynamic Effect of Left Ventricular Septal Pacing by Transvenous Approach Through the Interventricular Septum

BACKGROUND

Left ventricular septal (LVS) pacing reduces ventricular dyssynchrony and improves cardiac function relative to right ventricular apex (RVA) pacing in animals. We aimed to establish permanent placement of an LVS pacing lead in patients using a transvenous approach through the interventricular septum.

METHODS AND RESULTS

Ten patients with sinus node dysfunction scheduled for dual-chamber pacemaker implantation were prospectively enrolled. A custom pacing lead with extended helix was introduced via the left subclavian vein and, after positioning against the right ventricular septum (RVS) using a preshaped guiding catheter, driven through the interventricular septum to the LVS. The acute hemodynamic effect of RVA, RVS, and LVS pacing was evaluated by invasive LVdP/dtmax measurements. The lead was successfully delivered to the LVS in all patients. Procedure time and fluoroscopy time shortened with experience. QRS duration was shorter during LVS pacing (144 ± 20 ms) than during RVA (172 ± 33 ms; P = 0.02 versus LVS) and RVS pacing (165 ± 17 ms; P = 0.004 versus LVS). RVA and RVS pacing reduced LVdP/dtmax compared with baseline atrial pacing (-7.1 ± 4.1% and -6.9 ± 4.3%, respectively), whereas LVS pacing maintained LVdP/dtmax at baseline level (1.0 ± 4.3%; P = 0.001 versus RVA and RVS). R-wave amplitude and pacing threshold were 12.2 ± 6.7 mV and 0.5 ± 0.2 V at implant and remained stable during 6-month follow-up without lead-related complications.

CONCLUSIONS

Permanent placement of an LVS pacing lead by transvenous approach through the interventricular septum is feasible in patients. LVS pacing preserves acute left ventricular pump function. This new pacing method could serve as an alternative and hemodynamically preferable approach for antibradycardia pacing.

Outcomes Related to First-Degree Atrioventricular Block and Therapeutic Implications in Patients With Heart Failure

The prevalence of first-degree atrioventricular block in the general population is approximately 4%, and it is associated with an increased risk of atrial fibrillation. Cardiac pacing for any indication in patients with first-degree heart block is associated with worse outcomes compared with patients with normal atrioventricular conduction. Among patients with heart failure, first-degree atrioventricular block is present in anywhere between 15% and 51%. Data from cardiac resynchronization therapy studies have shown that first-degree atrioventricular block is associated with an increased risk of mortality and heart failure hospitalization. Recent studies suggest that optimization of atrioventricular delay in patients with cardiac resynchronization therapy is an important target for therapy; however, the optimal method for atrioventricular resynchronization remains unknown. Understanding the role of first-degree atrioventricular block in the treatment of patients with heart failure will improve medical and device therapy.

Deterioration of left ventricular systolic function in extended Pacing to Avoid Cardiac Enlargement (PACE) trial: the predictive value of early systolic dyssynchrony

AIMS

Biventricular (BiV) pacing was superior to right ventricular apical (RVA) pacing at extended follow-up in the Pacing to Avoid Cardiac Enlargement (PACE) trial. Early pacing-induced systolic dyssynchrony (DYS) might be related to mid-term result. However, it remains unknown whether early pacing-induced DYS can predict long-term reduction of left ventricular (LV) systolic function.

METHODS AND RESULTS

Patients with standard pacing indications and normal LV ejection fraction (LVEF) were randomized either to BiV (n = 89) or RVA (n = 88) pacing. Seventy-four patients in the RVA group and 72 in the BiV pacing group completed follow-up longer than 2 years. Serial echocardiography was performed with DYS assessed by tissue Doppler imaging, and the early pacing-induced DYS was defined as >33 ms by using standard deviation of the time to peak systolic velocity (Dyssynchrony Index) in a 12-segment model of LV at 1 month. There were 46 (32%) patients having early pacing-induced DYS that was more prevalent in the RVA pacing group than that in the BiV pacing group (50.7 vs. 12.3%, χ(2) = 25.1, P < 0.001) despite the similar DYS between the two groups at baseline (30 ± 13 vs. 26 ± 11 ms, P = 0.051). At a median follow-up of 4.8 years, patients developing early DYS had lower LVEF (53.2 ± 9.4 vs. 60.9 ± 8.0%, P < 0.001) and larger LV end-systolic volume (40.3 ± 23.7 vs. 29.3 ± 13.4 mL, P < 0.001) than those without DYS. Significant EF reduction (defined as ≥5%) occurred in 71.7% (33 in 46) of patients with DYS, but only in 30% (30 in 100) in those without DYS (χ(2) = 22.4, P < 0.001). Further analysis showed that both DYS at 1 month [odds ratio (OR): 3.113, P = 0.013] and RVA pacing (OR: 7.873, P < 0.001) independently predicted the deterioration of LV systolic function with pacing period of 4.8 years.

CONCLUSION

Early pacing-induced DYS is a significant predictor of reduction of LV systolic function for long-term pacing, which could be prevented by BiV pacing at relatively long-period follow-up.

CLINICAL TRIAL REGISTRATION

Centre for Clinical Trials number, CUHK_CCT00037 (URL: http://www.cct.cuhk.edu.hk/Registry/publictrialrecord.aspx?trialid=CUHK_CCT00037).

Cardiac resynchronization therapy is appropriate for all patients requiring chronic right ventricular pacing: the pro perspective

Long-term right ventricular pacing has deleterious effects on the left ventricle (LV). The risk of pacemaker-induced cardiomyopathy (PICM) seems to be lower in patients with a normal LV ejection fraction (LVEF). Patients developing PICM respond favorably to a cardiac resynchronization therapy upgrade, suggesting that the dysfunction is partially reversible. Biventricular pacing has emerged as a treatment and/or prevention of PICM. Cumulative pacing greater than 40% of the time is considered the most important risk factor for PICM. No organizational guidelines exist for preventive biventricular pacing. The decision to pursue biventricular pacing should be individualized.

Co-Morbidities and Cardiac Resynchronization Therapy: When Should They Modify Patient Selection?

Cardiac resynchronization therapy (CRT) improves symptoms, reduces heart failure related hospitalizations and death in selected patients with heart failure. Based on thousands of patients enrolled in major clinical landmark trials, current guidelines describe in relatively precise terms which cardiac patients should receive a device. However, clinical trials often excluded sicker patients leaving clinicians with the dilemma of how to treat real-life patients with major co-morbidities, frailty, and increasing age, who are otherwise candidates for CRT implantation. This review investigates results from clinical trials and available observational data on the influence of co-morbidities on CRT benefit in order to provide better insight of when and why co-morbidities should modify patient selection for CRT.

The changing landscape of cardiac pacing

A number of trials have shown that irrespective of baseline QRS duration, left ventricular (LV) dysfunction and heart failure are more common in patients with right ventricular (RV) than in those with biventricular (BiV) pacing. By contrast, preliminary results of the BIOPACE trial (follow-up 5.6 years) yielded a disappointing comparison of RV vs. BiV pacing. Pacemaker-induced cardiomyopathy (PIC) may occur in patients with normal and abnormal LV ejection fractions (LVEF) and tends to occur if there is RV pacing more than 40 % of the time. Yet, some pacemaker-dependent patients do not develop LV dysfunction. PIC can be improved in about two thirds of patients by upgrading to a BiV system and the results are comparable to de novo BiV pacing in patients with a wide QRS complex. The findings of the BLOCK HF trial (2013) suggested that patients requiring pacing virtually 100 % of the time might benefit from BiV pacing irrespective of the LVEF (< 50 %), manifestations of heart failure, QRS duration, or functional class. These characteristics would generate many patients for BiV pacing. However, these recommendations should now be weighed against a more conservative approach based on the recently announced results of the BIOPACE trial. Organizational guidelines recommend BiV pacing for bradycardia irrespective of QRS duration for patients with LVEF < 35 %. At this time, BiV pacing for antibradycardia therapy (irrespective of QRS duration) has to be individualized in the setting of a normal or decreased LVEF (> 35 %) and according to the expected percentage of RV pacing. The benefit of BiV pacing should be considered against procedural complications, which are more frequent than with traditional RV pacing.

Left ventricular three-dimensional quadripolar lead acute clinical study: the LILAC study

AIMS

This multicenter acute clinical study was designed to verify novel three-dimensional (3D) quadripolar lead designs that can achieve ≤2.5 V average pacing capture threshold (PCT) not only at the apex, but also at the base of the left ventricle with phrenic nerve stimulation (PNS) avoidance for cardiac resynchronization.

METHODS

During the implant procedure, up to two different left ventricular investigational leads were introduced and tested in the same target coronary vein based on the coronary sinus venogram in a wedged and unwedged position. Adverse events were collected in 30 days following the procedure.

RESULTS

Eighty-seven leads were tested in 50 patients. When the best performing spiral electrode was chosen from each lead testing, the average of the best PCT on spiral in a wedged position was similar to the unwedged position (1.7 ± 1.5 V vs 1.9 ± 1.5 V, P = ns) and was similar to the wedged tip electrode average PCT (1.7 ± 1.5 V vs 1.6 ± 1.6 V, P = ns). In the majority of patients (89-96%), pacing was achievable in a mid-basal ventricular location without PNS.

CONCLUSIONS

This acute study demonstrated that a 3D quadripolar spiral lead design can achieve acceptable PCTs and avoid PNS without repositioning the lead at implant in the vast majority of patients. It also demonstrated that this lead design can achieve mid-basal ventricular stimulation with low PCT and good acute stability.

The role of biventricular pacing in the prevention and therapy of pacemaker-induced cardiomyopathy

Right ventricular (RV) pacing produces well-known long-term deleterious effects not only on already compromised, but also on the normal left ventricle (LV). The activation pattern mimicks that of left bundle branch block, with delayed activation of the LV free wall, and results in electrical and mechanical dyssynchrony. Long-term mandatory (100%) RV pacing, increases LV dimensions and decreases the ejection fraction. Many of these negative effects of pacing can be overcome by biventricular pacing. In this review, we describe the characteristics of pacemaker-induced cardiomyopathy, its incidence, and the use of cardiac resynchronization therapy (CRT) for its therapy and prevention. The gaps in the current organizational guidelines for using CRT in the treatment of bradycardia are identified, and goals for future research are discussed.

Chronic right ventricular apical pacing: adverse effects and current therapeutic strategies to minimize them

The permanent cardiac pacemaker is the only effective therapy for patients with symptomatic bradycardia and hundreds of millions are implanted worldwide every year. Despite its undisputed clinical benefits, the last two decades have drawn much attention to the negative effects associated with long-term pacing of the right ventricle (RV). Experimental and clinical studies have shown that RV pacing produces ventricular dyssynchrony, similar to that of left bundle branch block, with consequent detrimental effects on cardiac structure and function, with adverse clinical outcomes such as atrial fibrillation, heart failure and death. Although clinical evidence largely comes from subanalyses of pacemaker and implantable cardiac defibrillator studies, there is strong evidence that patients with reduced left ventricular function are at high risk of suffering from the detrimental effects of long-term RV pacing. Biventricular pacing in cardiac resynchronization therapy devices can prevent ventricular dyssynchrony and has emerged as an attractive option in this patient group with promising results and more clinical studies underway. Moreover, there is evidence that specific pacemaker algorithms that minimize RV pacing can reduce the negative effects of RV stimulation on cardiac function and may also prevent clinical deterioration. The extent of the long-term clinical effects of RV pacing in patients with normal ventricular function and how to prevent this are less clear and subject to future investigation.

The importance of avoiding unnecessary right ventricular pacing in clinical practice

Symptomatic bradycardia is effectively treated with the implantation of a cardiac pacemaker. Although a highly successful therapy, during recent years there has been a focus on the negative effects associated with long-term pacing of the apex of the right ventricle (RV). It has been shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block, with subsequent detrimental effects on cardiac structure and function, and in some cases adverse clinical outcomes such as atrial fibrillation, heart failure and death. There is substantial evidence that patients with reduced left ventricular function (LVEF) are at particular high risk of suffering the detrimental clinical effects of long-term RV pacing. The evidence is, however, incomplete, coming largely from subanalyses of pacemaker and implantable cardiac defibrillator studies. In this group of patients with reduced LVEF and an expected high amount of RV pacing, biventricular pacing (cardiac resynchronization therapy) devices can prevent the negative effects of RV pacing and reduce ventricular dyssynchrony. Therefore, cardiac resynchronization therapy has emerged as an attractive option with promising results and more clinical studies are underway. Furthermore, specific pacemaker algorithms, which minimize RV pacing, can also reduce the negative effects of RV stimulation on cardiac function and may prevent clinical deterioration.