Biventricular pacing

Recent Advances in Cardiac Resynchronization Therapy: Current Treatment and Future Direction

Cardiac Resynchronization Therapy (CRT) has been established as a major component of heart failure management, resulting in a significant reduction in patient morbidity and death for patients with increased QRS duration, low left ventricular ejection fraction (LVEF), and high risk of arrhythmias. The ability to synchronize both ventricles, lower heart failure hospitalizations, and optimize clinical outcomes are some of the attractive characteristics of biventricular pacing, or CRT. However, the high rate of CRT non-responders has led to the development of new modalities including leadless CRT pacemakers (CRT-P) and devices focused on conduction system pacing (CSP). This comprehensive review aims to present recent findings from CRT clinical trials and systematic reviews that have been published that will likely guide future directions in patient care.

Is interventional technique better than the traditional over-the-wire method for left ventricular lead implantation in cardiac resynchronization therapy?

Background

Interventional cardiac resynchronization therapy (I-CRT) for left ventricular lead (LVL) placement works as a supplement to traditional (over-the-wire) cardiac resynchronization therapy (T-CRT). It has been argued that I-CRT is a time-consuming and complicated procedure.

Objective

The purpose of this study was to investigate differences in procedure-related, perioperative, postoperative, and clinical endpoints between I-CRT and T-CRT.

Methods

This single-center, retrospective, cohort study included all consecutive patients receiving a CRT-pacemaker/defibrillator between January 1, 2012, and August 31, 2018. Patients underwent T-CRT from January 1, 2012, to June 1, 2015, and I-CRT from January 1, 2016, to August 31, 2018. We obtained data from patient record files, fluoroscopic images, and the Danish Pacemaker and ICD Register. Data were analyzed using Wilcoxon rank-sum/linear regression for continuous variables and the Pearson χ2/Fisher exact for categorical variables.

Results

Optimal LVL placement was achieved in 82.7% of the I-CRT group and 76.8% of the T-CRT group (P = .015). In the I-CRT group, 99.0% of LVLs were quadripolar vs 55.3% in the T-CRT group (P <.001). Two or more leads were used during the procedure in 0.7% and 10.5% of all cases in the I-CRT and T-CRT groups, respectively (P <.001). Total implantation time was 81.0 minutes in the I-CRT group and 83.0 minutes in the T-CRT group (P = .41). Time with catheters in the coronary sinus was 45.0 minutes for the I-CRT group vs 37.0 minutes in the T-CRT group, respectively (P <.001).

Conclusion

I-CRT did not prolong total implantation time despite longer time with catheters in the coronary sinus. I-CRT allowed more optimal LVL placement, wider use of quadripolar leads, and use of fewer leads during the procedure.

His-Purkinje system pacing versus biventricular pacing in clinical efficacy: a systematic review and meta-analysis

BACKGROUND

His-Purkinje system pacing (HPSP), including his-bundle pacing (HBP) and left bundle branch area pacing (LBBaP), imitates the natural conduction of the heart as an alternative to biventricular pacing (BVP) in cardiac resynchronization therapy (CRT). However, the feasibility and efficacy of HPSP were currently only evidenced by studies with a limited sample size, so this study aimed to provide a comprehensive assessment through a systematic review and meta-analysis.

METHODS

In order to compare the clinical outcomes associated with HPSP and BVP in patients for CRT, PubMed, EMBASE, Cochrane Library and Web of Science database were searched from inception to April 10, 2023. Clinical outcomes of interest including QRS duration (QRSd), left ventricular (LV) function and New York Heart Association (NYHA) functional classification, pacing threshold, echocardiographic and clinical response, hospitalization rate of HF and all-cause mortality were also extracted and summarized for meta-analysis.

RESULTS

A total of 13 studies (ten observational studies and three randomized studies) involving 1,121 patients were finally included. The patients were followed up for 6-27 months. Compared with BVP, CRT patients treated by HPSP presented shorter QRSd [mean difference (MD): -26.23 ms, 95% confidence interval (CI): -34.54 to -17.92, P < 0.001, I² = 91%], greater LV functional improvement with increased left ventricular ejection fraction (LVEF) (MD: 6.01, 95% CI: 4.81 to 7.22, P < 0.001, I² = 0%), decreased left ventricular end-diastolic dimension (LVEDD) (MD: -2.91, 95% CI: -4.86 to -0.95, P = 0.004, I² = 35%), and more improved NYHA functional classification (MD: -0.45, 95% CI: -0.67 to -0.23, P < 0.001, I² = 70%). In addition, HPSP was more likely to have higher echocardiographic [odds ratio (OR): 2.76, 95% CI: 1.74 to 4.39, P < 0.001, I² = 0%], clinical (OR: 2.10, 95% CI: 1.16 to 3.80, P = 0.01, I² = 0%) and super clinical (OR: 3.17, 95% CI: 2.09 to 4.79, P < 0.001, I² = 0%) responses than BVP, and a lower hospitalization rate of HF (OR: 0.34, 95% CI: 0.22 to 0.51, P < 0.001, I² = 0%), while presented no difference (OR: 0.68, 95% CI: 0.44 to 1.06, P = 0.09, I² = 0%) in all-cause mortality compared with BVP. With threshold change taking into account, BVP was less stable than LBBaP (MD: -0.12 V, 95% CI: -0.22 to -0.03, P = 0.01, I² = 57%), but had no difference with HBP (MD: 0.11 V, 95% CI: -0.09 to 0.31, P = 0.28, I² = 0%).

CONCLUSION

The present findings suggested that HPSP was associated with greater improvement of cardiac function in patients with indication for CRT and was a potential alternative to BVP to achieve physiological pacing through native his-purkinje system.

Troubleshooting the difficult left ventricular lead placement in cardiac resynchronization therapy: current status and future perspectives

INTRODUCTION

Cardiac resynchronization therapy (CRT) is an important option in modern cardiac implantable electronic device (CIED) treatment. Techniques for left ventricular (LV) lead placement in the coronary sinus and its tributaries are neither well described nor studied systematically, despite attention regarding where to place the LV lead.

AREAS COVERED

This review presents specialized tools and techniques to overcome some of the most common problems encountered in LV lead placement in CRT. These tools and techniques are termed Interventional-CRT (I-CRT), as they share technology with other interventional procedures. The main principle in I-CRT, compared to the traditional Over-The-Wire technique, is to add better support for delivery of the LV lead through dedicated inner catheters that also allows more flexibility with use of more guidewires and better imaging with direct venography in the target vein.

EXPERT OPINION

Even though CRT is an established therapeutic option, there are still many challenges in the implementation of the therapy. The cornerstone should be an ease of delivering the CRT and specifically implantation of the LV lead. Therefore, knowledge of the principles in I-CRT, as I-CRT could make implantation simpler in general and easier to reach the optimal LV pacing site.

Outcomes of Left Bundle Branch Area Pacing for Cardiac Resynchronization Therapy: An Updated Systematic Review and Meta-analysis

BACKGROUND

Real-world data on the use of left bundle branch area pacing (LBBAP) as an alternative novel pacing strategy to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT) remains scarce. We aimed to investigate the outcomes of LBBAP as an alternative to BVP as a method of CRT.

METHODS

Electronic databases were searched for studies on the use of LBBAP as CRT and studies that compared LBBAP with BVP. The main outcomes examined were changes in New York Heart Association classification, left ventricular end-diastolic diameter, left ventricular ejection fraction, and paced QRS duration post CRT device implantation.

RESULTS

Our meta-analysis included 8 nonrandomized studies with a total of 527 patients who underwent LBBAP as CRT. In studies with a BVP comparison group, patients with LBBAP had a greater reduction in paced QRS (mean difference [MD], 27.91 msec; 95% confidence interval [CI], 22.33-33.50), and a greater improvement in New York Heart Association class (MD, 0.59; 95% CI, 0.28-0.90) and left ventricular ejection fraction (MD, 6.77%; 95% CI, 3.84-9.71). Patients with underlying left bundle branch block appeared to benefit the most from LBBAP compared with patients without underlying left bundle branch block.

CONCLUSIONS

LBBAP might be a reasonable option for patients who meet indications for CRT, particularly in those who have limited anatomy or do not benefit from CRT. Randomized trials are needed to compare LBBAP with BVP for CRT and to identify which populations might benefit the most from LBBAP.

The Many Faces of Heart Failure

Heart failure is a heterogeneous clinical syndrome stemming from cardiac overload and injury that leads to considerable morbidity and mortality. This review highlights the many faces of heart failure, a major and growing public health problem, including its causes, classification, underlying pathophysiology, and variable progression. An individualized, patient-centered treatment approach that focuses on guideline-directed pharmacologic and device therapies is required for optimal management of this complex syndrome.

The arterial baroreflex effectiveness index in risk stratification of chronic heart failure patients who are candidates for cardiac resynchronization therapy

INTRODUCTION

Baroreflex function is an independent marker of prognosis in heart failure (HF). However, little is known about its relation to response to cardiac resynchronization therapy (CRT). The aim of this study is to assess arterial baroreflex function in HF patients who are candidates for CRT.

METHODS

The study population consisted of 25 patients with indication for CRT, aged 65±10 years, NYHA functional class ≥III in 52%, QRS width 159±15 ms, left ventricular ejection fraction (LVEF) 29±5%, left ventricular end-systolic volume (LVESV) 150±48 ml, B-type natriuretic peptide (BNP) 357±270 pg/ml, and peak oxygen consumption (peak VO2) 18.4±5.0 ml/kg/min. An orthostatic tilt test was performed to assess the baroreflex effectiveness index (BEI) by the sequence method. This group was compared with 15 age-matched healthy individuals.

RESULTS

HF patients showed a significantly depressed BEI during tilt (31±12% vs. 49±18%, p=0.001). A lower BEI was associated with higher BNP (p=0.038), lower peak VO2 (p=0.048), and higher LVESV (p=0.031). By applying a cut-off value of 25% for BEI, two clusters of patients were identified: lower risk cluster (BEI >25%) QRS 153 ms, LVESV 129 ml, BNP 146 pg/ml, peak VO2 19.0 ml/kg/min; and higher risk cluster (IEB ≤25%) QRS 167 ms, LVESV 189 ml, BNP 590 pg/ml, peak VO2 16.2 ml/kg/min.

CONCLUSIONS

Candidates for CRT show depressed arterial baroreflex function. Lower BEI was observed in high-risk HF patients. Baroreflex function correlated closely with other clinical HF parameters. Therefore, BEI may improve risk stratification in HF patients undergoing CRT.

Biventricular Pacemakers in Patients With Heart Failure

Patients with heart failure may benefit from implantation of a biventricular pacemaker. This article discusses the indications for biventricular pacemaker implantation and the assessment of patients with biventricular pacemakers. Biventricular pacemakers require more assessments than do traditional single- or dual-chamber pacemakers.

The characteristics and outcome of infective endocarditis involving implantable cardiac devices

Infection of implantable cardiac electronic devices in particular lead endocarditis (cardiac device infective endocarditis (CDIE)) is an emerging problem with significant morbidity, mortality and health care costs. The epidemiology is characterised with advanced age and health care association in cases presenting within 6 months of implantation. Risk factors include those of the patient, the procedure and the device. Staphylococcal species predominate as the causative organisms. Diagnosis is reliably made by blood cultures and transesophageal echocardiography. Complications include pulmonary and systemic emboli, persistent bacteremia and concomitant valvular involvement. Management includes complete device removal and prolonged antimicrobial therapy. With long-term follow-up to 1 year, the mortality of CDIE is as high as 23 %. It is associated with patient co-morbidities and concomitant valvular involvement and may be prevented by device removal during index admission.

Resynchronization: considering device-based cardiac therapy in older adults

Cardiac resynchronization therapy (CRT) is a device-based treatment available to select individuals with systolic heart failure (HF), a large proportion of whom are aged 65 and older. As the field of CRT advances, together with shifting demographics and expanded indications for implantation, there is a need for practitioners caring for older adults to understand what is and is not known about the use of CRT specifically in this population. Clinical trials demonstrating benefits for severe and mild HF have uncertain generalizability to older adults. Other studies demonstrate that device-related complications may be more common with CRT than with simpler devices and more common in older adults. CRT clinical trials also may not adequately capture outcomes and concerns specific to older adults, including quality of life and end-of-life care experiences. Informed decision-making by clinicians, policy-makers, and patients will require greater understanding of the use and outcomes of CRT in older persons.

Prognostic Estimation of Advanced Heart Failure With Low Left Ventricular Ejection Fraction and Wide QRS Interval

Background and Objectives

Cardiac resynchronization therapy (CRT) has been known to improve the outcome of advanced heart failure (HF) but is still underutilized in clinical practice. We investigated the prognosis of patients with advanced HF who were suitable for CRT but were treated with conventional strategies. We also developed a risk model to predict mortality to improve the facilitation of CRT.

Subjects and Methods

Patients with symptomatic HF with left ventricular ejection fraction ≤35% and QRS interval >120 ms were consecutively enrolled at cardiovascular hospital. After excluding those patients who had received device therapy, 239 patients (160 males, mean 67±11 years) were eventually recruited.

Results

During a follow-up of 308±236 days, 56 (23%) patients died. Prior stroke, heart rate >90 bpm, serum Na ≤135 mEq/L, and serum creatinine ≥1.5 mg/dL were identified as independent factors using Cox proportional hazards regression. Based on the risk model, points were assigned to each of the risk factors proportional to the regression coefficient, and patients were stratified into three risk groups: low- (0), intermediate-(1-5), and high-risk (>5 points). The 2-year mortality rates of each risk group were 5, 31, and 64 percent, respectively. The C statistic of the risk model was 0.78, and the model was validated in a cohort from a different institution where the C statistic was 0.80.

Conclusion

The mortality of patients with advanced HF who were managed conventionally was effectively stratified using a risk model. It may be useful for clinicians to be more proactive about adopting CRT to improve patient prognosis.

Outpatient management of pediatric heart failure

The management of heart failure in children is becoming a specialized discipline within pediatric cardiology. Unlike the treatment of heart failure in adults, for which an extensive body of literature supports current treatment regimens, management of heart failure in children is largely guided by extrapolation from adult studies and expert opinion. This review focuses on the current state-of-the-art with respect to the outpatient management of heart failure in children.

Managing drugs and devices in patients with permanent ventricular assist devices

Patients will be considered for destination mechanical circulatory support device (MCSD) implantation when all other organ-saving treatment options have failed and they are not eligible for heart transplantation. Current medical evidence suggests that only for those patients who are inotrope-dependent and therefore likely have a 1-year survival probability without MCSD implantation of less than 50%, MCSD intervention will add to survival and quality-of-life benefit. Suitable candidates for MCSD are those patients who have a high risk of dying from heart failure but acceptable noncardiac risk. Evaluation of patients for MCSD requires a systematic and critical review of all organ systems and of the psychosocial situation. Specifically, right ventricular function and risk of right ventricular failure should be evaluated before planning destination MCSD implantation. Treatment will focus on prompt recovery from MCSD implantation, maintaining optimal treatment for heart failure, and preventing/treating MCSD complications, including infection, bleeding, coagulopathy, right heart failure, and device dysfunction. MCSD programs should be organized as an advanced heart failure center directed by specialized heart failure cardiologists, surgeons expert at implant and management of MCSD, specialized nurses, social workers, psychologists, financial experts, and physical therapists. MCSD practice is based on a patient-centered theory, with an appropriate understanding of the respective roles of the physician and the patient during their iterative encounters in which the patient is an autonomous person making responsible personal health decisions while the health care team is providing continued expert and empathic counseling about various options, based on systematic outcomes research (eg, by participation in the Interagency Registry for Mechanically Assisted Circulatory Support - MCSD database ).

Management of end-stage heart failure: a perspective on the Arab Gulf states

The ever expanding epidemic of end-stage heart failure represents one of the greatest challenges of modern cardiovascular medicine. With medical treatments hampered by significant limitations, physicians caring for patients with advanced heart disease have turned to cardiac transplantation and durable mechanical circulatory assist devices as definitive therapies. These advanced therapeutic modalities are not widely available outside the United States and Europe, but nevertheless offer enormous potential for patients in the Arab Gulf suffering from end-stage heart failure. This review will discuss the management of end-stage heart failure in the Gulf States, with an emphasis on therapies best utilized within a framework of regional cooperation and coordination.

Evidence-based treatment of chronic heart failure

The past two decades have seen a knowledge explosion in the field of cardiovascular diseases, in general, and in the understanding of chronic heart failure (HF) as a complex neurohumoral syndrome in particular. A new staging system for chronic HF has been developed within the last decade to facilitate the evidence-based prescription of medications and medical devices for each of its four stages. The burden of care for patients with chronic HF is substantially provided in primary care settings. Primary care physicians need to understand the underlying pathophysiology of chronic HF, the elements of its evaluation and treatment by stage, and when referral is necessary.

Biventricular pacing does not affect microvolt T-wave alternans in heart failure patients

BACKGROUND

Microvolt T-wave alternans (MTWA) is a valuable tool for stratification of patients at risk for sudden death and has recently been approved for this purpose by Medicare. Although right atrial (RA) pacing has been applied for MTWA testing, the effects of other pacing modalities on MTWA have not been systematically studied. Accordingly, it is unknown whether biventricular (BiV) pacing might influence MTWA test results.

OBJECTIVE

This study sought to investigate effects of BiV pacing in comparison with other pacing modalities.

METHODS

Congestive heart failure patients (n = 30) receiving cardiac resynchronization therapy were included, and a systematic step-up pacing protocol was performed via the implanted cardioverter-defibrillator.

RESULTS

Of the overall 120 MTWA tests performed, 67 (56%) were nonnegative. Nonnegative MTWA test results were observed in 18 patients (60%) during RA stimulation, whereas 17 (57%), 15 (50%), and 17 test results (57%) were nonnegative during right ventricular (RV), left ventricular (LV), and BiV pacing, respectively. Seven (23%) patients were MTWA negative for all pacing sites. Results of MTWA assessment during RA pacing were concordant with results obtained with RV pacing in 25 (83%) patients (kappa = 0.66, P = .0003), to LV pacing in 21 (70%) patients (kappa = 0.4, P = .025), and to BiV pacing in 25 (83%) patients (kappa = 0.66, P = .0003). Positive and negative predictive values of nonnegative MTWA test results obtained during RA pacing for a similar result obtained with RV pacing were 88% and 76%. Respective values were similar for other pacing modalities (80% and 60% for LV; 88% and 76% for BiV pacing).

CONCLUSION

There is a high level of concordance between MTWA test results obtained during RA pacing and other pacing modalities, and MTWA assessment seems not to be influenced by BiV stimulation in congestive heart failure patients. In general, BiV pacing does not seem to affect an arrhythmogenic substrate as detected by MTWA testing.

Cardiac resynchronization therapy

About 30% of patients with left ventricular systolic dysfunction also have ventricular conduction delays (prolonged QRS duration greater than 0.12 second) most frequently seen as left bundle branch block. This intraventricular conduction delay causes nonsynchronous ventricular activation between the right ventricle and the left ventricle (or dyssychrony), compromising cardiac function. Cardiac resynchronization therapy, or biventricular pacing, is a recent intervention for ventricular dyssychrony that incorporates 3 leads for pacing the right atrium and simultaneous pacing of the right ventricle and left ventricle. Left ventricular lead placement can be difficult to implant because of coronary venous anatomy and can require longer procedure time for the patient. Restoring ventricular synchrony has been shown to decrease septal wall dyskinesis, decrease mitral regurgitation, increase left ventricular filling time, decrease pulmonary capillary wedge pressure, and reverse ventricular modeling.