Biventricular pacing during cardiac magnetic resonance imaging

AIMS

We aimed to assess the effect of cardiac resynchronization on left ventricular (LV) function, volumes, geometry, and mechanics in order to demonstrate reverse remodelling using cardiac magnetic resonance (CMR) with resynchronization on.

METHODS AND RESULTS

New York Heart Association (NYHA) Class II-III patients on optimal medical therapy with LV ejection fraction (LVEF) ≤35%, and complete LBBB with broad QRS (>150 ms) were prospectively recruited. Cardiac magnetic resonance examination was performed at baseline and at 6-month follow-up, applying both biventricular and AOO pacing. The following data were measured: conventional CMR parameters, remodelling indices, global longitudinal, circumferential, radial strain, global dyssynchrony [mechanical dispersion (MD) defined as the standard deviation of time to peak longitudinal/circumferential strain in 16 LV segments], and regional dyssynchrony (maximum differences in time between peak septal and lateral transversal displacement). Thirteen patients (64 ± 7 years, 38% male) were enrolled. Comparing the baseline and follow-up CMR parameters measured during biventricular pacing, significant increase in LVEF, and decrease in LV end-diastolic volume index (LVEDVi) and LV end-systolic volume index (LVESVi) were found. Left ventricular remodelling indices, global longitudinal, circumferential, and radial strain values showed significant improvement. Circumferential MD decreased (20.5 ± 5.5 vs. 13.4 ± 3.4, P < 0.001), while longitudinal MD did not change. Regional dyssynchrony drastically improved (362 ± 96 vs. 104 ± 66 ms, P < 0.001). Applying AOO pacing resulted in an immediate deterioration in LVEF, LVESVi, circumferential strain, global and regional dyssynchrony.

CONCLUSION

Cardiac magnetic resonance imaging during biventricular pacing is feasible and enables a more precise quantification of LV function, morphology, and mechanics. As a result, it may contribute to a better understanding of the effects of resynchronization therapy and might improve responder rate in the future.

Clinical outcome of left ventricular multipoint pacing versus conventional biventricular pacing in cardiac resynchronization therapy: a systematic review and meta-analysis

Cardiac resynchronization therapy (CRT) is an effective treatment for selected patients with systolic heart failure. Unlike conventional biventricular pacing (BIP), the left ventricular multipoint pacing (MPP) can increase the number of left ventricular pacing sites via a quadripolar lead positioned in the coronary sinus. This synthetic study was conducted to integratively and quantitatively evaluate the clinical outcome of MPP in comparison with BIP. We systematically searched the databases of EMBASE, Ovid medline, and Cochrane Library through May 2018 for studies comparing the clinical outcome of MPP with BIP in the patients who accepted CRT. Hospitalization for reason of heart failure, left ventricular eject fraction (LVEF), CRT response, all-cause morbidity, and cardiovascular death rate was collected for meta-analysis. A total of 11 studies with 29,606 participants were included in this meta-analysis. Compared with BIP group, MPP decreased heart failure hospitalization (OR, 0.41; 95% CI, 0.33 to 0.50; P < 0.00001), improved LVEF (mean difference, 4.97; 95% CI, 3.11 to 6.83; P < 0.00001), increased CRT response (OR, 3.64; 95% CI, 1.68 to 7.87; P = 0.001), and decreased all-cause morbidity (OR, 0.41; 95% CI, 0.26-0.66; P = 0.0002) and cardiovascular death rate (OR, 0.21; 95% CI, 0.11-0.40; P < 0.00001). The published literature demonstrates that MPP was more effective than BIP in the heart failure patients who accepted cardiac resynchronization therapy.

Spanish Pacemaker Registry. 16th Official Report of the Spanish Society of Cardiology Working Group on Cardiac Pacing (2018)

INTRODUCTION AND OBJECTIVES

This report describes the result of the analysis of the implanted pacemakers reported to the Spanish Pacemaker Registry in 2018.

METHODS

The analysis is based on the information provided by the European Pacemaker Identification Card and supplier-reported data on the overall number of implanted pacemakers.

RESULTS

Information was received from 90 hospitals, with a total of 12 148 cards, representing 31% of the estimated activity. Use of conventional and resynchronization pacemakers was 825 and 77 units per million people, respectively. The mean age of the patients receiving an implant was 78.3 years, and 54% of the devices were implanted in people aged> 80 years. A total of 77.1% were first implants and 21.6% corresponded to generator exchanges. Bicameral sequential pacing was the most frequent pacing mode but was less frequently used in patients aged> 80 years and in women. Single chamber VVI/R pacing was used in 28% of patients with sick sinus syndrome and in 24.7% of those with atrioventricular block, despite being in sinus rhythm.

CONCLUSIONS

The total consumption of pacemaker generators in Spain increased by 1.2% compared with 2017, mainly due to an 8.7% increase in cardiac resynchronization therapy with pacemaker generators. Selection of pacing mode was directly influenced by age and sex.

Atrial fibrillation incidence and impact of biventricular pacing on long-term outcome in patients with heart failure treated with cardiac resynchronization therapy

Background

In patients with cardiac resynchronization therapy (CRT), atrial fibrillation (AF) is associated with an unfavorable outcome and may cause loss of biventricular pacing (BivP). An effective delivery of BivP of more than 98% of all ventricular beats has been shown to be a major determinant of CRT-success.

Methods

At a Swedish tertiary referral center, data was retrospectively obtained from patient registers, medical records and preoperative electrocardiograms. Data regarding AF and BivP during the first year of follow-up was assessed from CRT-device interrogations. No intra-cardiac electrograms were studied. Kaplan-Meier curves and Cox-regression analyses adjusted for age, etiology of heart failure, left ventricular ejection fraction, left bundle branch block and NYHA class were performed to assess the impact of AF and BivP on the risk of death or heart transplantation (HTx) at 10-years of follow-up.

Results

Preoperative AF-history was found in 54% of the 379 included patients and was associated with, but did not independently predict death or HTx. The one-year incidence of new device-detected AF was 22% but not associated with poorer prognosis. At one-year, AF-history and BivP≤98%, was associated with a higher risk of death or HTx compared to patients without AF (HR 1.9, 95%CI 1.2–3.0, p = 0.005) whereas AF and BivP> 98% was not (HR 1.4, 95%CI 0.9–2.3, p = 0.14).

Conclusions

In CRT-recipients, AF-history is common and associated with poor outcome. AF-history does not independently predict mortality and is probably only a marker of a more severe underlying disease. BivP≤98% during first-year of CRT-treatment independently predicts poor outcome thus further supporting the use of 98% threshold of BivP, which should be attained to maximize the benefits of CRT.

Quadripolar versus bipolar leads in cardiac resynchronization therapy: An analysis of the National Cardiovascular Data Registry

BACKGROUND

The introduction of quadripolar (QP) cardiac resynchronization therapy (CRT) leads aimed to improve procedural and clinical outcomes.

OBJECTIVE

The National Cardiovascular Data Registry was analyzed to characterize the use as well as the procedural and clinical outcomes of QP leads in comparison with unipolar and bipolar (BP) leads.

METHODS

We evaluated data on 175,684 procedures reported between September 1, 2010, and December 31, 2015. Clinical outcomes were analyzed using Centers for Medicare & Medicaid Services claims data.

RESULTS

Among all CRT device implants, there was a drop in reported lead placement failure from 6.04% to 5.21% (P < .0001 for trend) and a drop in the reported diaphragmatic stimulation rates from 0.07% to 0.01% (P < .007 for trend) between the last quarters of 2010 and 2015. No significant difference in procedural complication rates between QP and BP leads occurred (1.34% and 1.39%, respectively; P = .50). Among patients linked to Centers for Medicare & Medicaid Services claims data, no statistically significant difference in the combined primary outcome of death, congestive heart failure admission, device malfunction, and reoperation between BP and QP leads was observed (34.15 and 34.19 events per 100 patient-years, respectively; P = .89).

CONCLUSION

Since the introduction of QP leads, there was a reduction in CRT lead placement failure rates and a reduction in diaphragmatic stimulation rates. However, no statistically significant difference in long-term clinical outcomes between BP and QP leads was observed in elderly patients undergoing CRT implantation.

Multisite pacing via a quadripolar lead for cardiac resynchronization therapy

Cardiac resynchronization therapy is challenging. Up to 40% of patients are non-responder. Multisite pacing via a quadripolar lead, also called multipoint/multipole pacing (MPP), is a debated alternative. In this review, we summarize evidence in the literature, tips and pitfalls related to MPP programming, and the different algorithms of MPP in different manufacturers.

Cardiac resynchronization therapy reprogramming to improve electrical synchrony in patients with existing devices

BACKGROUND

Optimal programming of cardiac resynchronization therapy (CRT) has not yet been fully elucidated. A novel algorithm (SyncAV) has been developed to improve electrical synchrony by fusion of the triple wavefronts: intrinsic, right ventricular (RV)-paced, and left ventricular (LV)-paced.

METHODS

Consecutive patients at a single tertiary care center with a previously implanted CRT device with SyncAV algorithm (programmable negative AV hysteresis) were evaluated. QRS duration (QRSd) was measured during 1) intrinsic conduction, 2) existing CRT pacing as chronically programmed by treating physician, 3) using the device-based QuickOpt™ algorithm for optimization of AV and VV delays, and 4) ECG-based optimized SyncAV programming. The paced QRSd was assessed and compared to intrinsic conduction and between the different modes of programming.

RESULTS

Of 64 consecutive, potentially eligible patients who underwent assessment, 34 patients who were able to undergo SyncAV programming were included. Mean intrinsic conduction QRSd was 163 ± 24 ms. In comparison, the mean QRSd was 152 ± 25 ms (-11.1 ± 19.0) during existing CRT pacing, 160 ± 25 ms (-4.1 ± 25.2) using the QuickOpt™ algorithm and 138 ± 23 (-24.9 ± 17.2) using ECG-based optimized SyncAV programming. SyncAV optimization resulted in significant reductions in QRSd compared to existing CRT pacing (P = 0.02) and QuickOpt™ (P < 0.001). Of the 32% of patients who did not have QRS narrowing with existing CRT, 72% experienced QRS narrowing with SyncAV.

CONCLUSION

ECG-based atrio-ventricular delay optimization using SyncAV significantly improved electrical synchrony in patients with a previously implanted CRT. Further studies are needed to assess the impact on long-term outcomes.

His-bundle Pacing to Left Bundle Branch Pacing: Evolution of His-Purkinje Conduction System Pacing

His-bundle pacing (HBP) constitutes an excellent alternative to right ventricular pacing. Recently, several studies have reported on the success and efficacy of HBP in patients with left bundle branch block requiring cardiac resynchronization therapy. Nonetheless, HBP may not always be feasible due to high capture thresholds or disease in the distal His bundle. The present report discusses the utility and feasibility of pacing in the left bundle branch area located distal to the site of conduction block.

Association of body mass index with cardiac resynchronization therapy intention and left ventricular lead implantation failure: insights from the NCDR implantable cardioverter-defibrillator registry

BACKGROUND

Cardiac resynchronization therapy with defibrillator (CRT-D) implantation involves left ventricular (LV) lead placement for biventricular pacing and is more complex than implantable cardioverter-defibrillator (ICD)-only implantation. Differences in the prescription of CRT-D versus ICD may result from clinician biases based on patient body habitus, and body habitus may be associated with LV lead implantation failure.

OBJECTIVE

We sought to evaluate whether patient body mass index (BMI) was associated with planned use and implantation failure of CRT-D therapy.

METHODS

We studied all patients enrolled in the National Cardiovascular Data Registry ICD Registry who met standard CRT-D criteria and received either an ICD or CRT-D between 2010 and 2012. BMI was categorized based on World Health Organization classification. Using hierarchical logistic regression, two multivariate models adjusted for patient demographic and clinical characteristics were fit based on the following outcome variables: (1) planned implantation with CRT-D versus ICD and (2) failed versus successful LV lead placement.

RESULTS

Of 337,547 patients, 41,872 met inclusion criteria for the first analysis and 35,186 met criteria for the second analysis. After multivariable adjustment, patients with extreme (BMI > 40 kg/m²) obesity were less likely to receive guideline-concordant CRT-D compared with patients with normal weight (adjusted odds ratio (AOR), 0.86; 95% confidence interval (CI), 0.75-0.99; p = 0.04). Extreme (BMI > 40 kg/m²) obesity was associated with higher odds of failed LV lead placement (AOR, 1.35; 95% CI, 1.07-1.72, p = 0.01).

CONCLUSIONS

Compared with normal weight patients, extremely obese (BMI > 40 kg/m²) CRT-D eligible patients were less likely to be prescribed CRT-D and were at higher odds for failed LV lead placement.

Benefits of Multisite/Multipoint Pacing to Improve Cardiac Resynchronization Therapy Response

This article provides a general overview of the underlying mechanisms that support pacing from more discrete points and/or a wider vector (multisite and multipoint pacing) to improve left ventricular resynchronization. We performed a critical overview of the current literature and to identify some remaining knowledge gaps to spur further research. It was not our goal to provide a systematic review with a comprehensive bibliography, but rather to focus on selected publications that, in our opinion, have either expertly reviewed a specific aspect of cardiac resynchronization therapy or have been landmark studies in the field.

Role of Atrioventricular Junctional Ablation and Cardiac Resynchronization Therapy in Patients with Chronic Atrial Fibrillation

There remains a great deal of uncertainty whether general application of cardiac resynchronization therapy (CRT) to patients with atrial fibrillation (AF) provides any benefit assuming all other eligibility criteria are met. Preliminary observations suggest that performing atrioventricular junction ablation can improve the results of CRT in patients with AF by rendering the patient pacemaker dependent. Ongoing randomized clinical trials may provide more definitive answers in the future.

Transvenous pacing implantation: techniques, tips, and lessons learned along the way

The right ventricular apex has been the traditional site for lead placement in veterinary patients who require permanent cardiac pacing therapy for atrioventricular block and sick sinus syndrome. Implantation of leads in this location is a straightforward procedure that most veterinary cardiologists perform routinely. Pacing at the right ventricular apex, however, has been demonstrated to have long-term deleterious effects on the left ventricular function in numerous patient populations and animal models. Alternative lead placement sites and pacing system configurations have been developed, and the purpose of this review article is not to review the literature or the decision-making process in selecting a specific pacing system but rather to share the experiences of our group with the use of alternative pacing implantation techniques for veterinary patients in need of permanent cardiac pacing.

Spanish Pacemaker Registry. 15th Official Report of the Spanish Society of Cardiology Working Group on Cardiac Pacing (2017)

INTRODUCTION AND OBJECTIVES

This report describes the data reported to the Spanish Pacemaker Registry concerning the activity in cardiac pacing in 2017 in Spain.

METHODS

The analysis is based on the data obtained from the European Pacemaker Identification Card and the information reported by supplier companies related to global number of implanted pacemakers.

RESULTS

Information was received from 106 hospitals, with a total of 12672 cards, representing the 32.1% of the total pacing activity. Conventional pacemaker and resynchronization pacemaker rate was 820 units/million and 26 units/million inhabitants respectively. A total of 333 leadless pacemakers were implanted. The mean age was 77.9 years, predominantly men (58.5%). Most electrodes were bipolar, with active fixation and only 20% had magnetic resonance protection. Atrioventricular block was the most common electrocardiographic disturb. Most patients received bicameral sequential pacing although single chamber VVIR pacing was used in up to 21.8% of patients. Patients older than 80 years benefited less from physiological pacing and resynchronization therapy.

CONCLUSIONS

Total use of pacemaker generators remains stable with respect to 2016. Age is the main factor that influences pacing mode selection, which could be improved in around 22% of patients. Leadless pacing continues to rise.

His Bundle Pacing for Cardiac Resynchronization

Cardiac resynchronization therapy with left ventricular coronary sinus or epicardial pacing is an established therapy for patients with systolic heart failure and intraventricular conduction system delay, particularly left bundle branch block. Despite large-scale randomized trials demonstrating the efficacy of this therapy, clinical and echocardiographic nonresponse rates remain as high as up to 40%. His bundle pacing (HBP) has reemerged as a means to provide physiologic resynchronization in patients with bundle branch block by correcting QRS by direct capture of the His-Purkinje system. This critical appraisal reviews early clinical data, evaluates possible mechanism, and identifies areas for future investigation for HBP in resynchronization.

Implantation of cardiac resynchronization therapy devices using three leads by cephalic vein dissection approach

Aims

Percutaneous subclavian, axillary, and cephalic vein access are all used in conjunction for atrial and ventricular lead implantation, though no standard approach for cardiac resynchronization therapy (CRT) device implantation has been established. We describe an effective and a safe technique for implanting three leads via cephalic vein for CRT pacemaker and/or defibrillator implantations.

Methods and results

A total of 171 consecutive patients undergoing de novo implantation of CRT pacemaker or defibrillator were included. Cephalic vein access was achieved by dissection and direct visualization. If the cephalic vein was inadequate, alternate means of access was determined after outset of the procedure. Procedural success rates and complications were recorded. Of the 171 de novo CRT implant attempts, 169 (98.8%) patients had successful implantation of all 3 leads on the first attempt. Of the 171 procedural attempts, 150 (87.7%) patients had all 3 leads placed via cephalic vein. Overall, complications occurred in 6 of 171 patients (3.5%) including initial and repeat procedures. These complications included seven lead dislodgements, two cases of diaphragmatic stimulation requiring lead revision, and one coronary sinus dissection without pericardial effusion. There were no cases of pneumothorax, pocket haematoma requiring evacuation, or infection.

Conclusion

The triple lead via cephalic vein technique is safe and effective when used as a first approach for CRT device implantation.

Rationale and design of the TRICHAMPION trial: Triple Chamber Pacing in Hypertrophic Obstructive Cardiomyopathy Patients

PURPOSE

Dual-chamber (DDD) pacing has been used for treatment of patients with hypertrophic obstructive cardiomyopathy (HOCM). Due to inconclusive results in prior trials, current guidelines assign DDD pacing a class IIb indication in selected patients. Prior observations indicate that lack of clinical improvement may result from suboptimal effect of DDD pacing with non-physiological AV intervals due to fusion of intrinsic and paced QRS complex.

METHODS

The Triple Chamber Pacing in Hypertrophic Obstructive Cardiomyopathy Patients (TRICHAMPION) trial is a prospective, randomized, single-blinded, multicenter study to investigate the benefit of atrial synchronous biventricular pacing (CRT-P) in highly symptomatic HOCM patients with severe left ventricular outflow tract (LVOT) obstruction who are not candidates for ablative therapies. AV node ablation is used as key tool to optimize AV intervals in patients with QRS fusion. The primary endpoint is the percentage of patients with symptomatic improvement at 12 months, defined as improvement of New York Heart Association functional class, in the Minnesota Living with Heart Failure Questionnaire score and increased cardiopulmonary exercise endurance.

CONCLUSIONS

The aim of the TRICHAMPION trial is to investigate the benefit of optimized atrial synchronous biventricular pacing in absence of QRS fusion in highly symptomatic HOCM patients with severe LVOT obstruction who are not candidates for ablative therapies.

Spanish Pacemaker Registry. 14th Official Report of the Spanish Society of Cardiology Working Group on Cardiac Pacing (2016)

INTRODUCTION AND OBJECTIVES

This report describes the results of analysis of implanted pacemakers reported to the Spanish Pacemaker Registry.

METHODS

The analysis was based on information provided by the European Pacemaker Identification Card.

RESULTS

Information was received from 115 hospitals, with a total of 12 697 cards, representing 32.3% of the estimated activity. Use of conventional and resynchronization pacemakers was 818 and 79 units per million inhabitants, respectively. A total of 200 leadless pacemakers were implanted. The mean age of the patients receiving an implant was 77.8 years, and 52% of devices were implanted in persons older than 80 years. In all, 74.9% were first implants and 23.4% corresponded to generator exchange. Endocardial leads were bipolar, 82.9% with active fixation, and 16.1% had magnetic resonance imaging protection. Most patients received bicameral sequential pacing, although single chamber pacing VVI(R) was used in 26.7% of the patients with sick sinus syndrome and in 23.8% of those with atrioventricular block, despite sinus rhythm.

CONCLUSIONS

Total use of pacemaker generators in Spain has increased by 1.6% compared with 2015. Most implanted leads have active fixation and less than 20% have magnetic resonance imaging protection. Age and sex directly influenced pacing mode selection, which could be improved in around 32% of patients.

Electrocardiographic patterns in biventricular pacing delivered by second-generation cardiac resynchronization devices

BACKGROUND

With increasing use of cardiac resynchronization therapy (CRT), treating physicians should be familiar with different electrocardiographic (ECG) patterns of left ventricular (LV) lead and biventricular (BiV) pacing. However, there are a few publications on ECG patterns during BiV pacing.

PURPOSE

This study was sought to determine different ECG patterns in patients with BiV pacing.

METHODS

Twelve-lead ECGs during BiV pacing (right ventricular leads at apex and LV leads in one of the lateral coronary veins) were analyzed in 181 consecutive patients (121 male; mean age, 62.0 ± 13.5 years) with advanced heart failure and baseline left bundle branch block pattern after at least 6-month of uncomplicated CRT.

RESULTS

During BiV pacing, 65% of the patients showed a dominant R wave in V1. There was a right axis deviation in 57% in frontal plane. However, a left superior axis emerged in 34% and normal frontal plane axis in 9%. Sequential BiV pacing (73% vs. 58%, P = 0.04) and pacing from posterolateral coronary vein (80% vs. 60%, p = 0.045) were more likely to present with a dominant R wave in V1. In sequential pacing, AV interval was significantly longer in patients with negative complex in V1 than in those with positive complex (124 ± 21 vs. 116 ± 8.0, p = 0.005). A Q/q wave was detected in 85% of patients in lead I and 78% in lead aVL.

CONCLUSIONS

BiV pacing from lateral coronary venous branches and right ventricular apex characteristically presented with dominant R wave in V1, Q/q wave in leads I and aVL, and right or left superior axis. However, a negative complex in V1, QRS axis in other quadrants, and lack of Q/q wave in leads I and aVL did not necessarily indicate a problem.

New insights from a computational model on the relation between pacing site and CRT response

AIMS

Cardiac resynchronization therapy (CRT) produces clinical benefits in chronic heart failure patients with left bundle-branch block (LBBB). The position of the pacing site on the left ventricle (LV) is considered an important determinant of CRT response, but the mechanism how the LV pacing site determines CRT response is not completely understood. The objective of this study is to investigate the relation between LV pacing site during biventricular (BiV) pacing and cardiac function.

METHODS AND RESULTS

We used a finite element model of BiV electromechanics. Cardiac function, assessed as LV dp/dt_max and stroke work, was evaluated during normal electrical activation, typical LBBB, fascicular blocks and BiV pacing with different LV pacing sites. The model replicated clinical observations such as increase of LV dp/dt_max and stroke work, and the disappearance of a septal flash during BiV pacing. The largest hemodynamic response was achieved when BiV pacing led to best resynchronization of LV electrical activation but this did not coincide with reduction in total BiV activation time (∼ QRS duration). Maximum response was achieved when pacing the mid-basal lateral wall and this was close to the latest activated region during intrinsic activation in the typical LBBB, but not in the fascicular block simulations.

CONCLUSIONS

In these model simulations, the best cardiac function was obtained when pacing the mid-basal LV lateral wall, because of fastest recruitment of LV activation. This study illustrates how computer modeling can shed new light on optimizing pacing therapies for CRT. The results from this study may help to design new clinical studies to further investigate the importance of the pacing site for CRT response.

Cardiac Resynchronization Therapy for Heart Failure

Cardiac resynchronization therapy (CRT) has emerged as a valued nonpharmacologic therapy in patients with heart failure, reduced ejection fraction (EF), and ventricular dyssynchrony manifest as left bundle branch block. The mechanisms of benefit include remodeling of the left ventricle leading to decreased dimensions and increased EF, as well as a decrease in the severity of mitral regurgitation. This article reviews the rationale, effects, and indications for CRT, and discusses the patient characteristics that predict response and considerations for nonresponders.