Cardiac resynchronization therapy in heart failure patients: tough road but clear future

Sex Specific Outcomes With Cardiac Resynchronization Therapy in Patients With Symptomatic Heart Failure Having Reduced Left Ventricular Ejection Fraction: A Systematic Review and Meta-Analysis

Cardiac resynchronization therapy (CRT) has emerged instrumental in managing heart failure. Notably, there is a lack of evidence of CRT efficacy among both sexes. Thus, this meta-analysis focuses on the long-term benefits of CRT in both sexes. PubMed, The Cochrane Library and clinicaltrials.gov were searched for articles from 2010 to 2024. ROB2 was used to assess risk of bias of RCTs. Newcastle Ottawa Scale was used for quality appraisal of cohorts. Meta-analysis was conducted on Revman 5.4. Out of 2722 articles, only 9 RCTs and 18 cohorts were included. Our results demonstrated that females had a significantly lower risk of composite outcomes compared to males in both RCTs (RR 0.80; 95% CI [0.68, 0.94], P = .006) and cohorts (RR 0.76; 95% CI [0.63, 0.92], P = .004). Results were similar for all-cause mortality. For heart failure hospitalization, only cohorts showed a significant lesser risk in females (RR 0.78; 95% CI [0.65, 0.93], P = .006). Left ventricular ejection fraction improved significantly in females but no differences were observed for NYHA class improvement. Males showed a 31% lower survival rate. However future trials are needed to highlight this variation.

The Role of Cardiac Resynchronization Therapy in Heart Failure: A Narrative Review

Introduction

Structural and functional cardiac defects leading to inadequate tissue oxygenation is known as Heart failure (HF) which is characterized by extensive morbidity and mortality. Pathophysiology of HF involves systolic and diastolic dysfunction, neurohormonal dysregulation, and imbalance in inflammatory mediators which complicates treatment further. Cardiac resynchronization therapy (CRT) is an approach used for restoring ventricular synchrony and enhancing mechanical efficiency. This study discusses various key points of CRT and its uses in HF and discusses challenges and future implications.

Methods

An extensive review of the literature was conducted with evidence from several databases like Medline, PubMed Central, and Embase. Preference was given to articles published after 2010, but relevant articles even pre-2010 were included. Mendeley was used as a reference manager for formatting.

Results

Functional improvements and an enhanced quality of life across a diverse range of patients have been demonstrated using CRT. This has significantly impacted the mortality rates of patients with HF. This manuscript conducted a comparative analysis various hallmark clinical trials conducted in lieu of CRT, across many years (2002, 2003, 2004, 2005, 2017, 2018, 2020). All trials have noted the supremacy of CRT compared to pharmaceutical treatment or other therapeutic methods. Majority of the trial participants had an LVEF of ≤ 35%, a QRS duration of ≤ 150 ms, and were categorized as NYHA class II-IV before initiation of CRT and, posttreatment, LVEF was improved significantly. The main advantages noted were functional improvements, such as enhanced quality of life and reduced mortality.

Conclusion

There have been multiple efforts undertaken to address the challenges in CRT, which include a reduction in the rates of nonresponding patients and using alternative adjunctive therapies like defibrillators. These have been shown to improve outcomes among HF patients. Although CRT is noted to be very efficient, some challenges like technological limitations, uncertainty regarding optimal pacing, and nonresponding patients, exist. Ongoing research aims to further develop and revolutionize HF care and improve patient outcomes across the world by refining patient selections and CRT efficacy.

The Prognostic Role of Global Longitudinal Strain and NT-proBNP in Heart Failure Patients Receiving Cardiac Resynchronization Therapy

BACKGROUND

We aimed to evaluate whether baseline GLS (global longitudinal strain), NT-proBNP, and changes in these after cardiac resynchronization therapy (CRT) can predict long-term clinical outcomes and the echocardiographic-based response to CRT (defined by 15% relative reduction in left ventricular end-systolic volume).

METHODS

We enrolled 143 patients with stable ischemic heart failure (HF) undergoing CRT-D implantation. NT-proBNP and echocardiography were obtained before and 6 months after. The patients were followed up (median: 58 months) for HF-related deaths and/or HF hospitalizations (primary endpoint) or HF-related deaths (secondary endpoint).

RESULTS

A total of 84 patients achieved the primary and 53 the secondary endpoint, while 104 patients were considered CRT responders and 39 non-responders. At baseline, event-free patients had higher absolute GLS values (p < 0.001) and lower NT-proBNP serum levels (p < 0001) than those achieving the primary endpoint. A similar pattern was observed in favor of CRT responders vs. non-responders. On Cox regression analysis, baseline absolute GLS value (HR = 0.77; 95% CI, 0.51-1.91; p = 0.002) was beneficially associated with lower primary endpoint incidence, while baseline NT-proBNP levels (HR = 1.55; 95% CI, 1.43-2.01; p = 0.002) and diabetes presence (HR = 1.27; 95% CI, 1.12-1.98; p = 0.003) were related to higher primary endpoint incidence.

CONCLUSIONS

In HF patients undergoing CRT-D, baseline GLS and NT-proBNP concentrations may serve as prognostic factors, while they may predict the echocardiographic-based response to CRT.

Transcriptional response of the heart to vagus nerve stimulation

Heart failure is a major clinical problem, with treatments involving medication, devices, and emerging neuromodulation therapies such as vagus nerve stimulation (VNS). Considering the ongoing interest in using VNS to treat cardiovascular disease, it is important to understand the genetic and molecular changes developing in the heart in response to this form of autonomic neuromodulation. This experimental animal (rat) study investigated the immediate transcriptional response of the ventricular myocardium to selective stimulation of vagal efferent activity using an optogenetic approach. Vagal preganglionic neurons in the dorsal motor nucleus of the vagus nerve were genetically targeted to express light-sensitive chimeric channelrhodopsin variant ChIEF and stimulated using light. RNA sequencing of the left ventricular myocardium identified 294 differentially expressed genes (false discovery rate < 0.05). Qiagen Ingenuity Pathway Analysis (IPA) highlighted 118 canonical pathways that were significantly modulated by vagal activity, of which 14 had a z score of ≥2/≤-2, including EIF-2, IL-2, integrin, and NFAT-regulated cardiac hypertrophy. IPA revealed the effect of efferent vagus stimulation on protein synthesis, autophagy, fibrosis, autonomic signaling, inflammation, and hypertrophy. IPA further predicted that the identified differentially expressed genes were the targets of 50 upstream regulators, including transcription factors (e.g., MYC and NRF1) and microRNAs (e.g., miR-335-3p and miR-338-3p). These data demonstrate that the vagus nerve has a major impact on the myocardial expression of genes involved in the regulation of key biological pathways. The transcriptional response of the ventricular myocardium induced by stimulation of vagal efferents is consistent with the beneficial effect of maintained/increased vagal activity on the heart.NEW & NOTEWORTHY This experimental animal study investigated the immediate transcriptional response of the ventricular myocardium to selective stimulation of vagal efferent activity. Vagal stimulation induced significant transcriptional changes in the heart involving the pathways controlling autonomic signaling, inflammation, fibrosis, and hypertrophy. This study provides the first direct evidence that myocardial gene expression is modulated by the activity of the autonomic nervous system.

Comparative cost analysis of implanting devices in different cardiac resynchronization therapeutic strategies

BACKGROUND

Cardiac resynchronization therapy (CRT) is an established treatment option for heart failure patients. However, the implementation of triple-chamber pacemakers can be cost-prohibitive. His-Purkinje system pacing (HPSP) can also enable cardiac resynchronization, and it can be achieved with relatively inexpensive conventional pacemakers.

HYPOTHESIS

This article aims to comparatively evaluate the cost of implanting devices in different CRT strategies to provide meaningful guidance for clinical decision-making by electrophysiologists.

METHODS

Data was collected on the prices, designed life, and price/designed life of multiple mainstream models of CRT-P, CRT-D, dual-chamber pacemakers, and single-chamber pacemakers that were sold in the Chinese market in 2022. The prices, designed lives, and price/designed life of different pacemaker models were then compared.

RESULTS

The costs of CRT-P and CRT-D (13008.44 ± 2752.30 USD and 22043.36 ± 3676.25 USD) were significantly higher than those of conventional pacemakers (dual-chamber: 11142.39 ± 4273.85 USD and single-chamber: 5634.28 ± 2032.80 USD) (p < .05). Additionally, the price/designed life of conventional pacemakers (dual-chamber: 839.63 ± 258.62 US dollar/year and single-chamber: 435.86 ± 125.44 US dollar/year) was significantly better than that of CRT-P and CRT-D (1386.91 ± 266.73 and 2585.53 ± 520.27 US dollar/year, respectively) (p < .05).

CONCLUSION

Conduction system pacing (CSP)-based CRT is more cost-effective than BVP-based CRT. Furthermore, CSP-based CRT can achieve cardiac resynchronization with conventional pacemakers and may be a good option for HF patients who do not need defibrillation.

Left bundle branch area pacing: A promising modality for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is recognized as the first-line management for patients with heart failure (HF) and conduction disorders. As a conventional mode for delivering CRT, biventricular pacing (BVP) improves cardiac function and reduces HF hospitalizations and mortality, but there are still limitations given the high incidence of a lack of response rates. Alternative pacing methods are needed either for primary or rescue therapy. In recent years, conduction system pacing (CSP) has emerged as a more physiological pacing modality for simultaneous stimulation of the ventricles, including His bundle pacing (HBP) and left bundle branch pacing (LBBP). CSP activates the His-Purkinje system, allowing normal ventricular stimulation. However, HBP is technically challenging with a relatively low success rate, high pacing threshold, and failure to correct distal conduction abnormalities. Therefore, LBBP stands out as a novel ideal physiological pacing modality for CRT. Several non-randomized studies compared the feasibility and safety of LBBP with BVP and concluded that LBBP is superior to BVP for delivering CRT with a narrower QRS and greater improvements in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class. Concurrently, some studies showed lower and stable pacing thresholds and greater improvement of B-type natriuretic peptide (BNP) levels, as well as better mechanical synchronization and efficiency. LBBP ensures better ventricular electromechanical resynchronization than BVP. In this review, we discuss current knowledge of LBBP, compare LBBP with BVP, and explore the potential of LBBP to serve as an alternative primary therapy to realize cardiac resynchronization.

Clinical study on the treatment of chronic heart failure with a novel D-shant atrium shunt device

BACKGROUND

Atrial septal shunt devices might improve hospitalizations and also prognosis in heart failure with increased pulmonary pressures due to left heart diseases. In recent years, atrial shunt devices have been used for the treatment of chronic heart failure, but there remains a lack of clinical experience. This study aimed to analyse the therapeutic effect of a novel type of atrial shunt on chronic heart failure.

METHODS AND RESULTS

From May 2020 to September 2020, six patients who were diagnosed with chronic heart failure and completed percutaneous D-shant atrium shunt device implantation in the Department of Cardiovascular Surgery, Union Hospital, were retrospectively included. The shunt location was evaluated by echocardiography and digital subtraction angiography. Heart function was evaluated by New York Heart Association functional class. Echocardiography was used to measure the diameter of the new chamber and ventricle, and to evaluate the degree of mitral and tricuspid regurgitation. Before operation and 6 months after operation, left atrial end-diastolic volume, right atrial end-diastolic volume, left ventricular end-diastolic volume, and right ventricular end-diastolic volume were measured by magnetic resonance imaging. Left ventricular ejection fractions and right ventricular ejection fractions were calculated. Haemodynamic indexes of right heart catheterization and clinical cardiac function indexes were collected and compared before and 6 months after shunt implantation. All six patients completed percutaneous shunt device implantation. Echocardiography and digital subtraction angiography showed that the shunt device was correctly positioned and unobstructed in all patients. Echocardiography revealed that the left ventricular diameter decreased significantly from 6.40 ± 0.57 mm to 5.03 ± 0.73 mm (P < 0.05). There was an obvious decrease in mitral regurgitation. Magnetic resonance imaging showed a reduction in the volume of the left ventricle (182.00 ± 27.02 mL vs. 125.75 ± 16.11 mL, P < 0.05). Cardiac catheter examination showed the mean left atrium pressure or pulmonary capillary wedge pressure decreased postoperatively (31.83 ± 11.55 vs. 18.00 ± 5.51 mmHg, P < 0.05). There was also obvious improvement in clinical indicators of cardiac function at 6 months after implantation.

CONCLUSIONS

This novel D-shant atrium shunt device revealed maintained good function, no dislodgement and no paradoxical emboli. After implantation, functional mitral regurgitation in all patients with heart failure with reduced ejection fraction improved.

Short QRS Duration After His-Purkinje Conduction System Pacing Predicts Left Ventricular Complete Reverse Remodeling in Patients With True Left Bundle Branch Block and Heart Failure

Objective

This study aimed to explore the outcomes of His-Purkinje conduction system pacing (HPCSP) and to screen the predictors of left ventricular (LV) complete reverse remodeling in patients with true left bundle branch block (LBBB) and heart failure with reduced ejection fraction (HFrEF).

Methods

Patients who underwent HPCSP for true LBBB and HFrEF from April 2018 to August 2020 were consecutively enrolled. All participants were followed up for at least 1 year. Thrombosis, infection, lead dislodgement, perforation, and other complications were observed after HPCSP. Clinical data, including echocardiographic parameters, electrocardiogram measurements, and cardiac function, were assessed before and after the procedure.

Results

A total of 46 patients were enrolled. HPCSP was successfully deployed in 42 cases (91.30%), which included 37 cases with His bundle pacing (HBP) and 5 cases with left bundle branch pacing (LBBP). The QRS duration decreased significantly (169.88 ± 19.17 ms vs. 113.67 ± 20.68 ms, P < 0.001). Left ventricular end-systolic volume (LVESV) (167.67 ± 73.20 ml vs. 85.97 ± 62.24 ml, P < 0.001), left ventricular end-diastolic diameter (LVEDD) (63.57 ± 8.19 mm vs. 55.46 ± 9.63 mm, P = 0.003) and left ventricular ejection fraction (LVEF) (26.52 ± 5.60% vs. 41.86 ± 11.56%, P < 0.001) improved dramatically. Complete reverse remodeling of the LV with normalized LVEF and LVEDD was found in nearly half of the patients (45.24%). A short QRS duration after HPCSP was a strong predictor of normalized LVEF and LVEDD (P < 0.001). The thresholds increased markedly in two patients approximately 6 months after HBP. No patients died during the total follow-up period of 20.07 ± 6.45 months.

Conclusion

Complete reverse remodeling of the LV could be found in nearly half of the patients with HFrEF and true LBBB after HPCSP, and the short QRS duration after HPCSP was a strong predictor.

Effectiveness of multipoint cardiac resynchronizing therapy in heart failure: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Cardiac resynchronization therapy is an important validated technique for patients with dyssynchrony and heart failure. However, the response rate to conventional resynchronization is approximately 50%; therefore, new techniques and schedules have emerged. This study aimed to evaluate the different clinical and echocardiographic variables of conventional versus multipoint cardiac resynchronization therapy.

RESEARCH DESIGN AND METHOD

A systematic review was conducted of randomized clinical trials in the PubMed, Cochrane, and Embase databases on cardiac resynchronization intervention with multipoint stimulation clinical and echocardiographic outcomes evaluated before and 3 months after the intervention.

RESULTS

Three studies (N = 139) were ultimately selected, and 100% of patients had a New York Heart Association functional class of II-IV, QRS > 120 ms, and a left ventricular ejection fraction < 35%. Significantly greater improvement was observed in the functional class of patients who underwent multipoint versus conventional therapy. The final systolic volume and ejection fraction improved in the multipoint group, but the difference was not statistically significant.

CONCLUSIONS

The literature lacks sufficient randomized controlled studies to enable conclusions regarding cardiac resynchronization therapy responses using different strategies. Moreover, the improvement in functional class in the multipoint pacing group involved few patients and had slight statistical relevance.