Comparison of right ventricular septal pacing and right ventricular apical pacing in patients receiving cardiac resynchronization therapy defibrillators: the SEPTAL CRT Study

Apical or Septal Right Ventricular Location in Patients Receiving Defibrillation Leads: A Systematic Review and Meta-Analysis

This study reviews the published data comparing the efficacy and safety of apical and septal right ventricle defibrillator lead positioning at 1-year follow-up. Systemic research on Medline (PubMed), ClinicalTrials.gov , and Embase was performed using the keywords "septal defibrillation," "apical defibrillation," "site defibrillation," and "defibrillation lead placement," including implantable cardioverter-defibrillator and cardiac resynchronization therapy devices. Comparisons between apical and septal position were performed regarding R-wave amplitude, pacing threshold at a pulse width of 0.5 ms, pacing and shock lead impedance, suboptimal lead performance, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter, readmissions due to heart failure and mortality rates. A total of 5 studies comprising 1438 patients were included in the analysis. Mean age was 64.5 years, 76.9% were male, with a median LVEF of 27.8%, ischemic etiology in 51.1%, and a mean follow-up period of 26.5 months. The apical lead placement was performed in 743 patients and septal lead placement in 690 patients. Comparing the 2 placement sites, no significant differences were found regarding R-wave amplitude, lead impedance, suboptimal lead performance, LVEF, left ventricular end-diastolic diameter, and mortality rate at 1-year follow-up. Pacing threshold values favored septal defibrillator lead placement ( P = 0.003), as well as shock impedance ( P = 0.009) and readmissions due to heart failure ( P = 0.02). Among patients receiving a defibrillator lead, only pacing threshold, shock lead impedance, and readmission due to heart failure showed results favoring septal lead placement. Therefore, generally, the right ventricle lead placement does not appear to be of major importance.

[Lead placement in cardiac implantable electronic devices]

The implantation of electrodes for cardiac implantable electronic devices (CIED) requires profound technical understanding and precise execution. The positioning of electrodes in the right ventricle and atrium has significant implications for patient safety and the effectiveness of CIED therapy. Particular focus is given to the distinction between apical and septal stimulation in ventricular positioning. Based on current data, this article provides a practice-oriented guide that leads implanters through the individual steps of electrode positioning. The implantation of electrodes for physiological stimulation (cardiac resynchronization therapy, CRT, and conduction system pacing, CSP) is not addressed in this article.

Conduction system pacing: how far are we from the "electrical" bypass?

Conduction system pacing is an alternative practice to conventional right ventricular apical pacing. It is a method that maintains physiologic ventricular activation, based on a correct pathophysiological basis, in which the pacing lead bypasses the lesion of the electrical fibers and the electrical impulse transmits through the intact adjacent conduction system. For this reason, it might be reasonably characterized by the term "electrical bypass" compared to the coronary artery bypass in revascularization therapy. In this review, reference is made to the sequence of events in which conventional right ventricular pacing may cause adverse outcomes. Furthermore, there is a reference to alternative strategies and pacing sites. Interest focuses on the modalities for which there are data from the literature, namely for the right ventricular (RV) septal pacing, the His bundle pacing (HBP), and the left bundle branch pacing (LBBP). A more extensive reference is about the HBP, for which there are the most updated data. We analyze the considerations that limit HBP-wide application in three axes, and we also present the data for the implantation and follow-up of these patients. The indications with their most important studies to date are then described in detail, not only in their undoubtedly positive findings but also in their weak aspects, because of which this pacing mode has not yet received a strong recommendation for implementation. Finally, there is a report on LBBP, focusing mainly on its points of differentiation from HBP.

Estimation of left ventricular activation sequence in patients with heart failure using two-dimensional speckle tracking echocardiography

Evaluation of longitudinal strain (LS) from two-dimensional echocardiography is useful for global and regional left ventricular (LV) dysfunction assessment. We determined whether the LS reflects contraction process in patients with asynchronous LV activation. We studied 144 patients with an ejection fraction ≤ 35%, who had left bundle branch block (LBBB, n = 42), right ventricular apical (RVA) pacing (n = 34), LV basal- or mid-lateral pacing (n = 23), and no conduction block (Narrow-QRS, n = 45). LS distribution maps were constructed using 3 standard apical views. The times from the QRS onset-to-early systolic positive peak (Q-EPpeak) and late systolic negative peak (Q-LNpeak) were measured to determine the beginning and end of contractions in each segment. Negative strain in LBBB initially appeared in the septum and basal-lateral contracted late. In RVA and LV pacing, the contracted area enlarged centrifugally from the pacing site. Narrow-QRS showed few regional differences in strain during the systolic period. The Q-EPpeak and Q-LNpeak exhibited similar sequences characterized by septum to basal-lateral via the apical regions in LBBB, apical to basal regions in RVA pacing, and lateral to a relatively large delayed contracted area between the apical- and basal-septum in LV pacing. Differences in Q-LNpeaks between the apical and basal segments in delayed contracted wall were 107 ± 30 ms in LBBB, 133 ± 46 ms in RVA pacing, and 37 ± 20 ms in LV pacing (p < 0.05, between QRS groups). Specific LV contraction processes were demonstrated by evaluating the LS distribution and time-to-peak strain. These evaluations may have potential to estimate the activation sequence in patients with asynchronous LV activation.

Results of Using Various Conduction System Pacing Options in Patients with Bradyarrhythmia

Chronic right ventricular myocardial pacing causes an asynchronous pattern of left ventricular activation, reduces left ventricular ejection fraction (LVEF), and may be associated with worsening of clinical outcomes in the long term. Although with the emergence of algorithms that minimize ventricular pacing it became possible to reduce the percentage of paced complexes in patients with sinus node dysfunction, permanent ventricular pacing is still inevitable in patients with high-degree atrioventricular (AV) block. The use of permanent conduction system pacing is a promising method for preserving the physiological activation of the ventricular myocardium and preventing the development of heart failure due to ventricular dyssynchrony. The aim. To analyze the immediate and long-term results of the use of conduction system pacing in patients with indications for permanent ventricular pacing. Materials and methods. This study included 18 patients with indications for permanentventricular pacing who were operated at the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine in the period from 01/01/2013 to 12/31/2022, in whom permanent conduction system pacing was used. There were 17 patients with bradyarrhythmias, of these 16 (88%) suffered from high-degree AV block (including 1 patient with Frederick’s syndrome and 1 (5%) patient with atrial ϐibrillation with slow ventricular response) and 1 (5%) patient with ischemic cardiomyopathy with left bundle branch block and ϐirstdegree AV block with indications for cardiac resynchronization therapy. The mean age of the patients was 55 ± 16 years (8 men, 10 women), LVEF at the time of the intervention was 56.42 ± 9.13 %, end diastolic volume 130.2 ± 23.8 ml, end systolic volume 55.1 ± 17.7 ml, diameter of the left atrium 4.01 ± 0.6 cm. The average QRS width before implantation was 116.5 ± 27.7 ms. In 6 (33%) patients, a special delivery system (С304-L69, Medtronic in 1 patient [5%], C315HIS in 5 [27%] patients) and 4.1F active ϐixation lead Medtronic 3830 Select Secure (69 or 74 cm) were used; in other cases (66%) standard 6F leads with active ϐixation and a lumen for a stylet without a delivery system were used. Results. The average follow-up period after implantation of pacemaker was 36.35 ± 29.65 months. During the observation period, LVEF was 57.07 ± 5.38 %, end diastolic volume111.5 ± 18.09 ml, end systolic volume 49.5 ± 13.4 ml, diameter of the left ventricle 3.9 ± 0.5 cm. The mean duration of paced QRS was 119.1 ± 10.09 ms. In 6 patients (33%), it was possible to demonstrate a change in the QRS width when the amplitude of ventricular stimulation was reduced, with 2 variants of transitions: 1) 4 (22%) patients with a transition from non-selective His bundle pacing (NSHBP) to selective His bundle pacing (SHBP), in 2 (11%) of these patients with a transition from SHBP with correction of right bundle branch block (RBBB) to SHBP without correction of RBBB, and then loss of capture of the myocardium of the ventricles; 2) 2 patients (11%) with a transition from NSHBP to myocardial septal ventricular pacing and further with a decrease in amplitude to the loss of capture of the myocardium of the ventricles. One (5%) patient with complete heart block had permanent non-selective left bundle branch area pacing. The other 11 (61%) patients met the criteria for parahisian pacing without visible transitions with a change in the amplitude of ventricular pacing. The average global longitudinal strain was -17.6 ± 2.7 %. The average interval from the stimulus to the peak of the R-wave in lead V6, which indicated the time of left ventricular activation, was 73.2 ± 8.7 ms. Pacing parameters were standardly set according to the primary indications, but with correction of the amplitude of ventricular stimulation relative to the thresholds of pacing of the conduction system. AV delay was corrected for the latency from the stimulus to the onset of the QRS in SHBP or for the duration of the “pseudodelta” wave in NSHBP which in both cases was the duration of the H-V interval. There were no complications in the acute or long-term postoperative period. Conclusions. Conduction system pacing is a challenge in the practice of cardiologist for treating life-threatening bradyarrhythmias and heart failure, but at the same time it is a safe method that provides physiological electrical and mechanical activation of the myocardium of the ventricles, that allows to effectively avoid the consequences of dyssynchrony due to permanent myocardial ventricular pacing.

Meshless Electrophysiological Modeling of Cardiac Resynchronization Therapy—Benchmark Analysis with Finite-Element Methods in Experimental Data

Computational models of cardiac electrophysiology are promising tools for reducing the rates of non-response patients suitable for cardiac resynchronization therapy (CRT) by optimizing electrode placement. The majority of computational models in the literature are mesh-based, primarily using the finite element method (FEM). The generation of patient-specific cardiac meshes has traditionally been a tedious task requiring manual intervention and hindering the modeling of a large number of cases. Meshless models can be a valid alternative due to their mesh quality independence. The organization of challenges such as the CRT-EPiggy19, providing unique experimental data as open access, enables benchmarking analysis of different cardiac computational modeling solutions with quantitative metrics. We present a benchmark analysis of a meshless-based method with finite-element methods for the prediction of cardiac electrical patterns in CRT, based on a subset of the CRT-EPiggy19 dataset. A data assimilation strategy was designed to personalize the most relevant parameters of the electrophysiological simulations and identify the optimal CRT lead configuration. The simulation results obtained with the meshless model were equivalent to FEM, with the most relevant aspect for accurate CRT predictions being the parameter personalization strategy (e.g., regional conduction velocity distribution, including the Purkinje system and CRT lead distribution).

Risk factors of pacing dependence and cardiac dysfunction in patients with permanent pacemaker implantation

AIMS

Right ventricular pacing (RVP) dependence could impair left ventricular ejection fraction (LVEF). This study aimed to illuminate the relationship between RVP proportion and LVEF, as well as disclosing independent predictors of RVP dependence.

METHODS AND RESULTS

Patients indicated for permanent pacemaker implantation were included (2016-2020). The ventricular pacing lead was placed in right ventricular apex or septum. Pacing mode programming followed universal standard. Electrocardiographic, echocardiographic, and serological parameters were collected. RVP dependence was defined according to its influence on LVEF. This study was of case-control design. Included patients were matched by potentially confounding factors through propensity score matching. A total of 1183 patients were included, and the mean duration of follow-up was 24 months. Percentage of RVP < 80% hardly influenced LVEF; however, LVEF tended to decrease with higher RVP proportion. High degree/complete atrioventricular block (AVB) [odds ratio (OR) = 5.71, 95% confidence interval (CI): 3.66-8.85], atrial fibrillation (AF) (OR = 2.04, 95% CI: 1.47-2.82), percutaneous coronary intervention (PCI) (OR = 2.89, 95% CI: 1.24-6.76), maximum heart rate (HR_max ) < 110 b.p.m. (OR = 2.74, 95% CI: 1.58-4.76), QRS duration > 120 ms (OR = 2.46, 95% CI: 1.42-4.27), QTc interval > 470 ms (OR = 2.01, 95% CI: 1.33-3.05), and pulmonary artery systolic pressure (PASP) > 40 mmHg (OR = 1.93, 95% CI: 1.46-2.56) were proved to predict RVP dependence.

CONCLUSIONS

High RVP percentage (>80%) indicating RVP dependence significantly correlates with poor prognosis of cardiac function. High degree/complete AVB, AF, ischaemic aetiology, PCI history, HR_max  < 110 b.p.m., QRS duration > 120 ms, QTc interval > 470 ms, and PASP > 40 mmHg were verified as independent risk factors of RVP dependence.

[ESC guidelines 2021 on cardiac pacing and cardiac resynchronization therapy : What's new?]

The new European Society of Cardiology (ESC) guidelines on cardiac pacing and cardiac resynchronization therapy were presented together with the new ESC heart failure guidelines at the ESC congress in September. The new document includes detailed sections on patient evaluation and clinical assessment, implantation, minimizing complications and patient follow-up. The guidelines have been updated and expanded particularly on the approach to reflex syncope, the indications after transcatheter aortic valve implantation (TAVI) and the perioperative management. The indications for cardiac resynchronization therapy (CRT) are now in line with the simultaneously published ESC heart failure guidelines. New physiological forms of stimulation and leadless pacing are now included in the guidelines.

Automated Localization of Focal Ventricular Tachycardia From Simulated Implanted Device Electrograms: A Combined Physics-AI Approach

Background: Focal ventricular tachycardia (VT) is a life-threating arrhythmia, responsible for high morbidity rates and sudden cardiac death (SCD). Radiofrequency ablation is the only curative therapy against incessant VT; however, its success is dependent on accurate localization of its source, which is highly invasive and time-consuming. Objective: The goal of our study is, as a proof of concept, to demonstrate the possibility of utilizing electrogram (EGM) recordings from cardiac implantable electronic devices (CIEDs). To achieve this, we utilize fast and accurate whole torso electrophysiological (EP) simulations in conjunction with convolutional neural networks (CNNs) to automate the localization of focal VTs using simulated EGMs. Materials and Methods: A highly detailed 3D torso model was used to simulate ∼4000 focal VTs, evenly distributed across the left ventricle (LV), utilizing a rapid reaction-eikonal environment. Solutions were subsequently combined with lead field computations on the torso to derive accurate electrocardiograms (ECGs) and EGM traces, which were used as inputs to CNNs to localize focal sources. We compared the localization performance of a previously developed CNN architecture (Cartesian probability-based) with our novel CNN algorithm utilizing universal ventricular coordinates (UVCs). Results: Implanted device EGMs successfully localized VT sources with localization error (8.74 mm) comparable to ECG-based localization (6.69 mm). Our novel UVC CNN architecture outperformed the existing Cartesian probability-based algorithm (errors = 4.06 mm and 8.07 mm for ECGs and EGMs, respectively). Overall, localization was relatively insensitive to noise and changes in body compositions; however, displacements in ECG electrodes and CIED leads caused performance to decrease (errors 16-25 mm). Conclusion: EGM recordings from implanted devices may be used to successfully, and robustly, localize focal VT sources, and aid ablation planning.

Right ventricular lead location and outcomes among patients with cardiac resynchronization therapy: A meta-analysis

BACKGROUND

Cardiac resynchronization therapy (CRT) has been demonstrated to improve heart failure (HF) symptoms, reverse LV remodeling, and reduce mortality and HF hospitalization (HFH) in patients with a reduced left ventricular (LV) ejection fraction (LVEF). Prior studies examining outcomes based on right ventricular (RV) lead position among CRT patients have provided mixed results. We performed a systematic review and meta-analysis of randomized controlled trials and prospective observational studies comparing RV apical (RVA) and non-apical (RVNA) lead position in CRT.

METHODS

Our meta-analysis was constructed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews and meta-analyses. We searched EMBASE and MEDLINE. Eligible studies reported on at least one of the following outcomes of interest: all-cause mortality, the composite endpoint of death and first HFH hospitalization, change in LVEF, New York Heart Association (NYHA) class improvement, and change in LV end systolic volume (LVESV). We performed meta-analysis summaries using a DerSimonian-Laird random-effects model and conservatively used the Knapp-Hartung approach to adjust the standard errors of the estimated model coefficients.

RESULTS

We included nine studies representing a total of 1832 patients. Of those, 1318 (72%) patients had RVA lead placement and 514 (28%) had RVNA lead placement. The mean age of patients was 65.5 ± 4.4 years, and they were predominantly men (69%-97%). There was no statistically significant difference in all-cause mortality by RVA vs. RVNA (OR = 0.77, 95% CI 0.32-1.89; I2 = 16.7%, p = 0.31), or in the combined endpoint of all-cause mortality and first HFH (OR 0.88, 95% CI 0.62-1.25; I2 = 0%, p = 0.84). Also, there was no difference between RVA and RVNA for NYHA class improvement (OR = 1.03, 95% CI 0.9-1.17; I2 = 0%, p = 0.99), change in LVEF (mean difference (MD) = 1.33, 95% CI -1.45 to 4.10; I2 = 47%; p = 0.093), and change in LVESV (MD = -1.11, 95% CI -3.34 to 1.12; I2 = 0%; p = 0.92).

CONCLUSION

This meta-analysis shows that in CRT pacing, RV lead position does not appear to be associated with clinical outcomes or LV reverse remodeling. Further studies should focus on the relationship of RV lead vis-à-vis LV lead location, and its clinical importance.

Prevention of non-response to cardiac resynchronization therapy: points to remember

Cardiac resynchronization therapy (CRT) is an important and effective therapy for end-stage heart failure. Non-response to CRT is one of the main obstacles to its application in clinical practice. There is no uniform consensus or definition of CRT “response.” Clinical symptoms, ventricular remodeling indices, and cardiovascular events have been reported to be associated with non-responders. To prevent non-response to CRT, three aspects should be thoroughly considered: preoperative patient selection, electrode implantation, and postoperative management. Preoperative selection of appropriate patients for CRT treatment is an important step in preventing non-response. Currently, the CRT inclusion criteria are mainly based on the morphology of QRS waves in deciding ventricular dyssynchrony. Echocardiography and cardiac magnetic resonance are being explored to predict nonresponse to CRT. The location of left ventricular electrode implantation is a current hot spot of research; it is important to identify the location of the latest exciting ventricular segment and avoid scars. Cardiac magnetic resonance and ultrasonic spot tracking are being progressively developed in this field. Some new techniques such as His Bundle pacing, endocardial electrodes, and novel sensors are also being investigated. Postoperative management of patients is another essential step towards preventing non-response; it mainly focuses on the treatment of the disease itself and CRT program control optimization. CRT treatment is just one part of the overall treatment of heart failure, and multidisciplinary efforts are needed to improve the overall outcome.

Multipoint Pacing with Fusion-optimized Cardiac Resynchronization Therapy: Using It All to Narrow QRS Duration

Adaptive atrioventricular (AV)-shortening algorithms have achieved QRS duration (QRSd) narrowing in traditional cardiac resynchronization therapy (CRT) patients. Multipoint pacing (MPP) has also demonstrated benefit in this population. An additional site of activation via intrinsic conduction of the septum may further contribute to CRT; however, the incorporation of all strategies together has yet to be explored. We therefore developed and tested a method combining MPP-CRT and controlled septal contribution to create a multifuse pacing (MFP) technique, establishing four ventricular activation sites for CRT patients using measurements from intracardiac electrograms (EGMs) and incorporating an AV-delay shortening algorithm (SyncAV™; Abbott Laboratories, Chicago, IL, USA) to narrow the QRSd. Patients in sinus rhythm with an AV conduction time of less than 350 ms were included in this analysis and were further stratified by strictly defined left bundle branch block (sLBBB) or nonspecific intraventricular conduction delay (IVCD). EGM-based measurements to determine the QRS septal onset to right ventricular (RV) time (SRAT) and the left ventricular (LV) to RV pacing conduction time were collected and applied to a formula to facilitate MFP. QRSd was compared between before and after programming. A total of 22 patients (19 men and three women) with similar baseline characteristics were compared (all values in mean ± standard deviation). The overall baseline QRSd of 153.31 ± 24.60 ms was decreased to 115.31 ± 16.31 ms after MFP programming (p < 0.0001). The measured SRAT was 59.40 ± 28.49 ms, resulting in a negative AV offset of −20.0 ± 24.97 ms. Patients in the sLBBB group (n = 7) were aged 67.8 ± 13.3 years and had a QRSd of 168.85 ± 27.29 ms that decreased to 113 ± 16.69 ms for a reduction of 55.42 ± 19.3 ms or 32.1% (p = 0.0003). In the IVCD group (n = 15), the baseline QRSd of 146.06 ± 20.29 ms was decreased to 116 ± 16.66 ms for a reduction of 30.07 ± 16.41 ms or 20.62% (p = 0.0001). When comparing the sLBBB and IVCD groups, the sLBBB group was favored by a reduction of 25.35 ms (p = 0.00046). Ultimately, MFP achieved statistically significant reductions in QRSd in all patients tested in this analysis. The benefit was also significantly better in the sLBBB group as compared with in the IVCD group.

Cardiac Stimulation in the Third Millennium: Where Do We Head from Here?

Over the years, pacemakers have evolved from a life-saving tool to prevent asystole to a device to treat heart rhythm disorders and heart failure, aiming at improving both cardiac function and clinical outcomes. Cardiac stimulation nowadays aims to correct the electrophysiologic roots of mechanical inefficiency in different structural heart diseases. This has led to awareness of the concealed risks of customary cardiac pacing that can inadvertently cause atrioventricular and inter-/intra-ventricular dyssynchrony, and has promoted the development of new pacing modalities and the use of stimulation sites different from the right atrial appendage and the right ventricular apex. The perspective of truly physiologic pacing is the leading concept of the continued research in the past 30 years, which has made cardiac stimulation procedure more sophisticated and challenging. In this article, we analyze the emerging evidence in favor of the available strategies to achieve an individualized physiologic setting in bradycardia pacing.

Pacing devices to treat bradycardia: current status and future perspectives

Introduction: Cardiac stimulation evolved from life-saving devices to prevent asystole to the treatment of heart rhythm disorders and heart failure, capable of remote patient and disease-progression monitoring. Cardiac stimulation nowadays aims to correct the electrophysiologic roots of mechanical inefficiency in different structural heart diseases.Areas covered: Clinical experience, as per available literature, has led to awareness of the concealed risks of customary cardiac pacing, that can inadvertently cause atrio-ventricular and inter/intra-ventricular dyssynchrony. New pacing modalities have emerged, leading to a new concept of what truly represents 'physiologic pacing' beyond maintenance of atrio-ventricular coupling. In this article we will analyze the emerging evidence in favor of the available strategies to achieve an individualized physiologic setting in bradycardia pacing, and the hints of future developments.Expert opinion: 'physiologic stimulation' technologies should evolve to enable an effective and widespread adoption. In one way new guiding catheters and the adoption of electrophysiologic guidance and non-fluoroscopic lead implantation are needed to make His-Purkinje pacing successful and effective at long term in a shorter procedure time; in the other way leadless stimulation needs to upgrade to a superior physiologic setting to mimic customary DDD pacing and possibly His-Purkinje pacing.

Second European Society of Cardiology Cardiac Resynchronization Therapy Survey: the Italian cohort

AIM

Adherence to guidelines was not homogeneous in Europe, according to the survey on cardiac resynchronization therapy conducted in 2008-2009. The aim of our study was to compare the results in the Italian and European cohorts of the Second European Cardiac Resynchronization Therapy Survey.

METHODS

Patients' characteristics, procedural data and follow-up were collected. Italian records were compared with European countries.

RESULTS

Italian hospitals enrolled 526 patients. The italian cohort was older (71.6 ± 9.5 vs. 68.4 ± 10.8; P < 0.00001), had less severe NYHA class (>II 47.2 vs. 59.6%; P < 0.00001), higher ejection fraction (30.3 ± 7.4 vs. 28.4 ± 8.2%; P < 0.00001), and less atrial fibrillation prevalence (34.4 vs. 41.2%; P = 0.00197) than the European cohort. Italian patients were more frequently hospitalized for heart failure in the previous year (51.9 vs. 46.2%; P = 0.01118) and had lower mean QRS duration (151 ± 26 vs. 157 ± 27 ms; P < 0.0001). CRT-D were more often implanted in Italian patients (79.3 vs. 69.3%; P < 0.00001). The complication rate was similar (4.6% vs. 5.6%; ns). The rate of use of ACEi/ARBs in Italy was lower than in Europe (77.2 vs. 86.9%; P < 0.00001). Patients were followed up in the implantation centre (92.1 vs. 86%; P = 0.00014), but rarely with remote monitoring (25.9 vs. 30%; P = 0.04792).

CONCLUSION

The survey demonstrates important similarities as well as substantial differences regarding most of the aspects evaluated. Efforts to implement adherence to guidelines will be endorsed in Italy.

Merits of Different Ventricular Lead Locations on Left Ventricular Myocardial Strain and Dyssynchrony in Patients with Cardiac Resynchronization Therapy

BACKGROUND

The idea behind cardiac resynchronization therapy (CRT) is to pace both ventricles resulting in a synchronized electro-mechanical coupling of the left ventricle (LV), meaning every effort should be made to improve the percentage of CRT responders.

OBJECTIVES

This study aimed at demonstrating the short-term effect of right ventricular apical (RVA) and mid-septal (RVS) lead locations combined with different LV lead positions on LV myocardial strain, dyssynchrony, and clinical outcomes.

METHODS

We examined 60 patients with indication for CRT before and after 6 months of implantation for clinical outcome and CRT response (6-min walk test [6MWT], NYHA class, decrease in left ventricular end systolic volume [LVESV] by >15%), dyssynchrony, and myocardial strain.

RESULTS

After 6 months of follow-up, the two RV lead locations represented a significant improvement in 6MWT, left ventricular ejection fraction, and LVESV in comparison to baseline values, but no significant difference was found between both groups. With regards to NYHA class improvement, p values were insignificant between the groups (0.44 and 0.88) at baseline and 6 months after implantation, respectively. The mean 6MWT was 273.8 m in the RVA group compared to 279.0 m in the RVS group (p = 0.84) at baseline. After 6 months of CRT implantation, the 6MWT mean was 326.5 m in the RVA group compared to 316.2 m in the RVS group (p = 0.74). The posterolateral cardiac vein site showed a significant improvement when combined with RVS location in interventricular and intraventricular dyssynchrony, global longitudinal strain, global circumferential strain, and apical circumferential strain (p = 0.01 0.032, 0.02, 0.005, and 0.049), respectively.

CONCLUSION

RVS is not inferior and provides a good alternative to RVA pacing in short-term follow-up. However, the QRS duration, myocardial strain, and dyssynchrony varies depending on RV and LV stimulation sites. Long-term morbidity and mortality outcomes according to LV lead location in coronary sinus need more assessment.

Comparison of measures of ventricular delay on cardiac resynchronization therapy response

BACKGROUND

Left ventricular (LV) pacing at sites of prolonged LV delay (QLV) or at long interventricular delay (right ventricle [RV]-LV) is strongly associated with cardiac resynchronization therapy (CRT) response. QLV and RV-LV have been independently evaluated, but little is known regarding the interrelationship between these measures or of delay to the RV.

OBJECTIVE

The purpose of this study was to evaluate the relationship between measures of electrical delay on CRT response in the SMART-AV (SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy) trial.

METHODS

In 419 patients, QLV and RV-LV were measured. CRT response was defined as a >15% reduction in LV end-systolic volume from implant to 6 months. The correlation between QLV and RV-LV and the clinical variables associated with the difference between QLV and RV-LV (QRV) were determined. Multivariable logistic regression was used to analyze the association between these measures on CRT response. A machine learning algorithm was used to construct a classification tree to predict response to CRT.

RESULTS

The cohort was 66% male (age 66 ± 11 years), 75% had left bundle branch block; and QRS was 150 ± 25 ms. QLV and RV-LV were highly correlated (R² = 0.71). A longer QRV was observed among patients with right bundle branch block, ischemic cardiomyopathy, and increased QRS. In a multivariable model including QLV, RV-LV, and other known predictors of CRT response, RV-LV, but not QLV, remained associated with CRT response (odds ratio 1.13; 95% confidence interval 1.02-1.26; P = .017). Combining the 2 measures achieved better prediction of CRT response in the group with intermediate RV-LV.

CONCLUSION

RV-LV is a better predictor of CRT response than QLV. There is incremental value in using both measurements or QRV in certain subpopulations.

Differential effect with septal and apical RV pacing on ventricular activation in patients with left bundle branch block assessed by non-invasive electrical imaging and in silico modelling

Purpose

It is uncertain whether right ventricular (RV) lead position in cardiac resynchronization therapy impacts response. There has been little detailed analysis of the activation patterns in RV septal pacing (RVSP), especially in the CRT population. We compare left bundle branch block (LBBB) activation patterns with RV pacing (RVP) within the same patients with further comparison between RV apical pacing (RVAP) and RVSP.

Methods

Body surface mapping was undertaken in 14 LBBB patients after CRT implantation. Nine patients had RVAP, 5 patients had RVSP. Activation parameters included left ventricular total activation time (LVtat), biventricular total activation time (VVtat), interventricular electrical synchronicity (VVsync), and dispersion of left ventricular activation times (LVdisp). The direction of activation wave front was also compared in each patient (wave front angle (WFA)). In silico computer modelling was applied to assess the effect of RVAP and RVSP in order to validate the clinical results.

Results

Patients were aged 64.6 ± 12.2 years, 12 were male, 8 were ischemic. Baseline QRS durations were 157 ± 18 ms. There was no difference in VVtat between RVP and LBBB but a longer LVtat in RVP (102.8 ± 19.6 vs. 87.4 ± 21.1 ms, p = 0.046). VVsync was significantly greater in LBBB (45.1 ± 20.2 vs. 35.9 ± 17.1 ms, p = 0.01) but LVdisp was greater in RVP (33.4 ± 5.9 vs. 27.6 ± 6.9 ms, p = 0.025). WFA did rotate clockwise with RVP vs. LBBB (82.5 ± 25.2 vs. 62.1 ± 31.7 ^op = 0.026). None of the measurements were different to LBBB with RVSP; however, the differences were preserved with RVAP for VVsync, LVdisp, and WFA. In silico modelling corroborated these results.

Conclusions

RVAP activation differs from LBBB where RVSP appears similar.

Trial registration

(ClinicalTrials.gov identifier: NCT01831518)

Electronic supplementary material

The online version of this article (10.1007/s10840-019-00567-2) contains supplementary material, which is available to authorized users.

Electrocardiographic optimization techniques in resynchronization therapy

Cardiac resynchronization therapy (CRT) is a cornerstone of therapy for patients with heart failure, reduced left ventricular (LV) ejection fraction, and a wide QRS complex. However, not all patients respond to CRT: 30% of CRT implanted patients are currently considered clinical non-responders and up to 40% do not achieve LV reverse remodelling. In order to achieve the best CRT response, appropriate patient selection, device implantation, and programming are important factors. Optimization of CRT pacing intervals may improve results, increasing the number of responders, and the magnitude of the response. Echocardiography is considered the reference method for atrioventricular and interventricular (VV) intervals optimization but it is time-consuming, complex and it has a large interobserver and intraobserver variability. Previous studies have linked QRS shortening to clinical response, echocardiographic improvement and favourable prognosis. In this review, we describe the electrocardiographic optimization methods available: 12-lead electrocardiogram; fusion-optimized intervals (FOI); intracardiac electrogram-based algorithms; and electrocardiographic imaging. Fusion-optimized intervals is an electrocardiographic method of optimizing CRT based on QRS duration that combines fusion with intrinsic conduction. The FOI method is feasible and fast, further reduces QRS duration, can be performed during implant, improves acute haemodynamic response, and achieves greater LV remodelling compared with nominal programming of CRT.

Optimization of Lead Placement in the Right Ventricle During Cardiac Resynchronization Therapy. A Simulation Study

Patients suffering from heart failure and left bundle branch block show electrical ventricular dyssynchrony causing an abnormal blood pumping. Cardiac resynchronization therapy (CRT) is recommended for these patients. Patients with positive therapy response normally present QRS shortening and an increased left ventricle (LV) ejection fraction. However, around one third do not respond favorably. Therefore, optimal location of pacing leads, timing delays between leads and/or choosing related biomarkers is crucial to achieve the best possible degree of ventricular synchrony during CRT application. In this study, computational modeling is used to predict the optimal location and delay of pacing leads to improve CRT response. We use a 3D electrophysiological computational model of the heart and torso to get insight into the changes in the activation patterns obtained when the heart is paced from different regions and for different atrioventricular and interventricular delays. The model represents a heart with left bundle branch block and heart failure, and allows a detailed and accurate analysis of the electrical changes observed simultaneously in the myocardium and in the QRS complex computed in the precordial leads. Computational simulations were performed using a modified version of the O'Hara et al. action potential model, the most recent mathematical model developed for human ventricular electrophysiology. The optimal location for the pacing leads was determined by QRS maximal reduction. Additionally, the influence of Purkinje system on CRT response was assessed and correlation analysis between several parameters of the QRS was made. Simulation results showed that the right ventricle (RV) upper septum near the outflow tract is an alternative location to the RV apical lead. Furthermore, LV endocardial pacing provided better results as compared to epicardial stimulation. Finally, the time to reach the 90% of the QRS area was a good predictor of the instant at which 90% of the ventricular tissue was activated. Thus, the time to reach the 90% of the QRS area is suggested as an additional index to assess CRT effectiveness to improve biventricular synchrony.

Influence of the Right Ventricular Lead Location on Ventricular Arrhythmias in Cardiac Resynchronization Therapy

Background:

The influence of different right ventricular lead locations on ventricular arrhythmias (VTA) in patients with a cardiac resynchronization therapy (CRT) is not clear. This study aimed to evaluate the influence on VTA in patients with a CRT when right ventricular lead was positioned at the right ventricular middle septum (RVMS) and the right ventricular apical (RVA).

Methods:

A total of 352 patients implanted with a CRT-defibrillator (CRT-D) between May 2012 and July 2016 in the Department of Cardiology of Anhui Provincial Hospital were included. Two-year clinical and pacemaker follow-up data were collected to evaluate the influence of the right ventricular lead location on VTA. Patients were divided into the RVMS group (n = 155) and the RVA group (n = 197) based on the right ventricular lead position. The VTA were compared between these two groups using a Kaplan-Meier curve and Cox multivariate analysis.

Results:

When the left ventricular lead location was not considered, RVMS and RVA locations did not affect VTA. However, the subgroup analysis results showed that when the left ventricular lead was positioned at the anterolateral cardiac vein (ALCV), the RVMS group had an increased risk of ventricular arrhythmias and appropriate defibrillation (hazard ratio [HR] = 3.29, P = 0.01 and HR = 4.33, P < 0.01, respectively); when the left ventricular lead was at the posterolateral cardiac vein (PLCV), these risks in the RVMS group decreased (HR = 0.45, P = 0.02 and HR = 0.33, P < 0.01, respectively), and when the left ventricular lead was at the lateral cardiac vein, there was no difference between the two groups. In regard to inappropriate defibrillation, there was no significant difference among all these groups.

Conclusions:

When the left ventricular lead was positioned at ALCV or PLCV, the right ventricular lead location was associated with VTA and appropriate defibrillation after CRT. Greater distances between leads not only improved cardiac function but also may reduce the risk of VTA.

Association between implantable cardioverter-defibrillator therapy and different lead positions in patients with cardiac resynchronization therapy

Aims

To evaluate the impact of different right and left ventricular lead positions (RV-LP and LV-LP) on the risk of therapy for ventricular tachycardia/ventricular fibrillation in patients with a cardiac resynchronization therapy device (CRT-D).

Methods and results

We performed a large nationwide cohort study on patients in Denmark receiving a CRT-D device from 2008 to 2012 from the Danish Pacemaker and implantable cardioverter defibrillator (ICD) registry. Lead positions were registered during the implantation and categorized as anterior/lateral/posterior and basal/mid-ventricular/apical for the LV-LP, and as apical/non-apical for the RV-LP. Appropriate and inappropriate therapies were registered during follow-up via remote monitoring or at device interrogations. Time to event was summarized with Kaplan-Meier plots, and competed risk regression analysis was used to calculate adjusted hazard ratios (aHR) with 95% confidence intervals (CI). Following variables were included in the analysis: gender, age, heart failure aetiology, New York heart association class, left ventricular ejection fraction, QRS duration, indication (secondary or primary prophylactic), RV-LP, LV-LP, and antiarrhythmic therapy. We included 1643 patients [mean age 68 (±10) years, 1343 (83%) men]. After a mean of 2.0 years, 322 (20%) patients received appropriate and 66 (4%) patients received inappropriate therapy. The aHR for appropriate therapy with a non-apical RV-LP was 0.70 95% CI (0.55-0.87, P = 0.002) as compared with an apical. We observed no significant association between appropriate therapy and LV-LP in left anterior oblique or right anterior oblique views or inappropriate therapy between any lead positions.

Conclusion

An apical RV-LP is associated with an increased risk of appropriate therapy for ventricular tachyarrhythmia in patients with a CRT-D device.

Long-Term Outcomes of Cardiac Resynchronization Therapy Using Apical Versus Nonapical Left Ventricular Pacing

Background Experimental evidence indicates that left ventricular ( LV ) apical pacing is hemodynamically superior to nonapical LV pacing. Some studies have shown that an LV apical lead position is unfavorable in cardiac resynchronization therapy. We sought to determine whether an apical LV lead position influences cardiac mortality after cardiac resynchronization therapy. Methods and Results In this retrospective observational study, the primary end point of cardiac mortality was assessed in relation to longitudinal (basal, midventricular, or apical) and circumferential (anterior, lateral, or posterior) LV lead positions, as well as right ventricular (apical or septal), assigned using fluoroscopy. Lead positions were assessed in 1189 patients undergoing cardiac resynchronization therapy implantation over 15 years. After a median follow-up of 6.0 years (interquartile range: 4.4-7.7 years), an apical LV lead position was associated with lower cardiac mortality than a nonapical position (adjusted hazard ratio: 0.74; 95% confidence interval, 0.56-0.99) after covariate adjustment. There were no differences in total mortality or heart failure hospitalization. Death from pump failure was lower with apical than nonapical positions (adjusted hazard ratio: 0.69; 95% confidence interval, 0.51-0.94). Compared with a basal position, an apical LV position was also associated with lower risk of sudden cardiac death (adjusted hazard ratio: 0.34; 95% confidence interval, 0.13-0.93). No differences emerged between circumferential LV lead positions or right ventricular positions with respect to any end point. Conclusions In recipients of cardiac resynchronization therapy, an apical LV lead position was associated with better long-term cardiac survival than a nonapical position. This effect was due to a lower risk of pump failure and sudden cardiac death.

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy

INTRODUCTION

Cardiac resynchronization therapy (CRT) has emerged as one of the few effective treatments for heart failure. However, up to 50% of patients derive no benefit. Suboptimal left ventricle (LV) lead position is a potential cause of poor outcomes while targeted lead deployment has been associated with enhanced response rates. Image-fusion guidance systems represent a novel approach to CRT delivery, allowing physicians to both accurately track and target a specific location during LV lead deployment.

AREAS COVERED

This review will provide a comprehensive evaluation of how to define the optimal pacing site. We will evaluate the evidence for delivering targeted LV stimulation at sites displaying favorable viability or advantageous mechanical or electrical properties. Finally, we will evaluate several emerging image-fusion guidance systems which aim to facilitate optimal site selection during CRT.

EXPERT COMMENTARY

Targeted LV lead deployment is associated with reductions in morbidity and mortality. Assessment of tissue characterization and electrical latency are critical and can be achieved in a number of ways. Ultimately, the constraints of coronary sinus anatomy have forced the exploration of novel means of delivering CRT including endocardial pacing which hold promise for the future of CRT delivery.

Rational and design of EuroCRT: an international observational study on multi-modality imaging and cardiac resynchronization therapy

Aims

Assessment of left ventricular (LV) volumes and ejection fraction (LVEF) with cardiac imaging is important in the selection of patients for cardiac resynchronization therapy (CRT). Several observational studies have explored the role of imaging-derived LV dyssynchrony parameters to predict the response to CRT, but have yielded inconsistent results, precluding the inclusion of imaging-derived LV dyssynchrony parameters in current guidelines for selection of patients for CRT.

Methods

The EuroCRT is a large European multicentre prospective observational study led by the European Association of Cardiovascular Imaging. We aim to explore if combing the value of cardiac magnetic resonance (CMR) and echocardiography could be beneficial for selecting heart failure patients for CRT in terms of improvement in long-term survival, clinical symptoms, LV function, and volumes. Speckle tracking echocardiography will be used to assess LV dyssynchrony and wasted cardiac work whereas myocardial scar will be assessed with late gadolinium contrast enhanced CMR. All data will be measured in core laboratories. The study will be conducted in European centres with known expertise in both CRT and multimodality cardiac imaging.

Clinical and echocardiographic response of apical vs nonapical right ventricular lead position in CRT: A meta-analysis

Background

Traditionally the right ventricular (RV) pacing lead is placed in the RV apex in cardiac resynchronization therapy (CRT). It is not clear whether nonapical placement of the RV lead is associated with a better response to CRT. We aimed to perform a meta‐analysis of all randomized controlled trials (RCTs) that compared apical and nonapical RV lead placement in CRT.

Methods

We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for studies and performed meta‐analysis using random effects model. Our main outcome measures were all‐cause mortality, composite of death and heart failure hospitalization, improvement in ejection fraction (EF), left ventricle end‐diastolic volume (LVEDV), left ventricle end‐systolic volume (LVESV), and adverse events.

Results

Seven RCTs with a total population of 1641 patients (1199 apical and 492 nonapical) were included in our meta‐analysis. There was no difference in all‐cause mortality (5% vs 4.3%, odds ratio (OR) = 0.86; 95% confidence interval (CI) 0.45‐1.64; P = .65; I² = 11%) and a composite of death and heart failure hospitalization (14.2% vs 12.9%, OR = 0.92; 95% CI: 0.61‐1.38; P = .68; I² = 0) between apical and nonapical groups. No difference in improvement in EF (Weighted mean difference (WMD) = 0.37; 95% CI: −2.75‐3.48; P = .82; I² = 68%), change in LVEDV (WMD = 3.67; 95% CI: −4.86‐12.20; P = .40; I² = 89%) and LVESV (WMD = −1.20; 95% CI: −4.32‐1.91; P = .45; I² = 0) were noted between apical and nonapical groups. Proportion of patients achieving >15% improvement in EF was similar in both groups (OR = 0.85; 95% CI: 0.62‐1.16; P = .31; I² = 0).

Conclusion

In patients with CRT, nonapical RV pacing is not associated with improved clinical and echocardiographic outcomes compared with RV apical pacing.

Avoiding non-responders to cardiac resynchronization therapy: a practical guide

Over two decades after the introduction of cardiac resynchronization therapy (CRT) into clinical practice, ∼30% of candidates continue to fail to respond to this highly effective treatment of drug-refractory heart failure (HF). Since the causes of this non-response (NR) are multifactorial, it will require multidisciplinary efforts to overcome. Progress has, thus far, been slowed by several factors, ranging from a lack of consensus regarding the definition of NR and technological limitations to the delivery of therapy. We critically review the various endpoints that have been used in landmark clinical trials of CRT, and the variability in response rates that has been observed as a result of these different investigational designs, different sample populations enrolled and different means of therapy delivered, including new means of multisite and left ventricular endocardial simulation. Precise recommendations are offered regarding the optimal device programming, use of telemonitoring and optimization of management of HF. Potentially reversible causes of NR to CRT are reviewed, with emphasis on loss of biventricular stimulation due to competing arrhythmias. The prevention of NR to CRT is essential to improve the overall performance of this treatment and lower its risk-benefit ratio. These objectives require collaborative efforts by the HF team, the electrophysiologists and the cardiac imaging experts.

Predicting Clinical and Echocardiographic Response After Cardiac Resynchronization Therapy With a Score Combining Clinical, Electrocardiographic, and Echocardiographic Parameters

The L₂ANDS₂ score was previously found to be able to assess the probability of left ventricular (LV) remodeling. We sought to evaluate this score in terms of clinical outcomes: 275 patients with heart failure, from 2 centers, implanted with a cardiac resynchronization therapy (CRT) device were followed at least 2 years after implantation. Baseline clinical, electrocardiographic, and echocardiographic characteristics including left bundle branch block, age >70 years, nonischemic etiology, LV end-diastolic diameter <40 mm/m², and septal flash by echocardiography were integrated in 4 scoring systems. Nonresponse to CRT was LV reverse remodeling <15% at 6 months' follow-up and/or occurrence of major cardiovascular event (cardiovascular death or transplantation or assistance) during a clinical follow-up of at least 2 years. Ninety-seven patients (36%) demonstrated nonresponse to CRT. The L₂ANDS₂ score demonstrated the best predictive value (C statistic of 0.783) for predicting absence of LV reverse remodeling and/or occurrence of major cardiovascular event during the 2 years follow-up compared with other scoring systems that do not include septal flash. A L₂ANDS₂ score ≤4 was associated with a worse outcome (38% survival vs 81% survival, hazard ratio 4.19, 95% CI 2.70 to 6.48, p <0.0001). In conclusion, the L₂ANDS₂ score is able to assess the probability of nonresponse to CRT in terms of no reverse LV remodeling and/or major cardiovascular event at long-term follow-up. Integrating septal flash in a scoring system adds value over left bundle branch block only.