What Are the Expectations for Cardiac Resynchronization Therapy? A Validation of Two Response Definitions

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.

Predictors of functional mitral regurgitation improvement in patients with left bundle branch block treated with left bundle branch area pacing

BACKGROUND

Functional mitral regurgitation (FMR) and its severity are associated with adverse outcomes in heart failure patients. This study aims to analyze the predictors of FMR improvement after successful left bundle branch area pacing (LBBAP) in patients with LVEF < 50% and complete left bundle branch block (CLBBB).

METHODS

Consecutive patients with LVEF < 50% and CLBBB who underwent successful LBBAP from July 2018 to July 2023 were retrospectively identified. Significant MR was defined as regurgitation of moderate severity or greater. Patients with significant FMR were included in the analysis. FMR improvement (FMRI) was defined as a reduction of at least one grade in regurgitation severity compared to baseline at 3 months or longer follow-up.

RESULTS

Among the 81 identified patients, 42 patients with significant FMR preoperatively were included. After LBBAP, QRS duration significantly shortened from 170.6 ± 18.8 ms to 114.5 ± 20.2 ms (p < .001). Significant FMR improves in approximately 76.2%, and the patients were divided into an FMRI group (n = 32) and a non-FMRI group (n = 10). Univariate analysis showed that absence of persistent atrial fibrillation, typical CLBBB, and left atrium diameter at baseline were associated with improvement of FMR after LBBAP. Of these variables, only absence of persistent atrial fibrillation remains an independent predictor in the multivariate model (OR 12.436, p = .009).

CONCLUSION

LBBAP is able to improve FMR in heart failure patients who had CLBBB with LVEF < 50%. Meanwhile, the absence of persistent atrial fibrillation is an independent predictor of FMR improvement.

Harmonizing Heartbeats: The Mosaic of Cardiac Resynchronization Therapy Responders-A Comprehensive Exploration of Diverse Criteria and Predictors

Background: Heart failure (HF) remains a challenging healthcare issue necessitating innovative therapies like cardiac resynchronization-defibrillation therapy (CRT-D). However, the definition of a CRT-D response lacks uniformity, impeding effective clinical evaluation. This study explores diverse CRT-D responder definitions encompassing functional, echocardiographic and laboratory criteria. Materials & Methods: A single-center study involving 132 CRT-D patients scrutinized responder criteria including NYHA stage, LVEF increase and proBNP decrease. Statistical analyses such as Kaplan-Meier curves and Cox hazard regression were employed to evaluate responder characteristics and survival outcomes. Results: Responder rates varied across criteria, revealing nuanced patient profiles. CRT-D responders defined by NYHA decrease, LVEF increase or proBNP decrease exhibit improved survival rates after 2 and 3 years (p < 0.050). Young age, absence of recent myocardial infarction and normal right ventricular echocardiographic parameters emerge as predictors for positive response. In part, drug-based HF therapy correlates with increased responder rates. Cox regression identified LVEF ≥ 5% and proBNP decrease ≥ 25% as independent predictors of extended survival. Conclusions: CRT-D responder definitions exhibit considerable variability, emphasizing the need for a nuanced patient-centered approach. Factors like right ventricular function, drug therapy, atrial fibrillation and renal function influence responses. This study enriches our understanding of CRT-D response and contributes to the foundation for personalized HF management.

Outcomes of cardiac resynchronization therapy in congenital heart disease: A meta-analysis and systematic review

INTRODUCTION

Cardiac resynchronization therapy (CRT) is a standard treatment for patients with heart failure with reduced ejection fraction. However, there is still a gap of evidence in congenital heart disease (CHD) patients regarding resynchronization therapy.

METHODS

We performed a meta-analysis and systematic review of CHD patients who received CRT implantation. We comprehensively searched the databases of MEDLINE, EMBASE, and Cochrane database from inception to June 2023. Studies that reported response rate to CRT, total mortality rate, change in QRS duration, change in left ventricular ejection fraction, and change in New York Heart Association functional class were included.

RESULTS

A total of 14 studies were included in the study. There were 10 studies that reported response rates after implantation. The overall response rate to CRT in CHD patients was 68% (95% confidence interval [CI] 61%-75%, I2 32%). The response rates in patients with systemic right ventricle (RV), systemic left ventricle (LV), and single ventricle were 58% (95% CI 46%-70%, I2 0%), 80% (95% CI 74%-86% I2 14%), and 67% (95% CI 49%-80% I2 0%). Response to CRT in systemic RV was inferior to systemic LV with an odds ratio of 0.38 (95% CI 0.15-0.95, I2 38%). The total mortality rate from seven studies was 12% (95% CI 8%-18%, I2 55%). The parameters which represented ventricular dyssynchrony improved after CRT implantation.

CONCLUSION

The overall response rate to CRT in CHD was 68%. Patients with systemic RV had a lower response rate to CRT when compared to patients with systemic LV. The total mortality rate after CRT implantation was 12%.

Predictors of Higher Frequency of Atrial Fibrillation in Patients with Cardiac Resynchronization Therapy

Background and Objectives: Cardiac resynchronization therapy (CRT) is one of the effective therapeutic options in the treatment of systolic heart failure (HF) with persistent symptoms. This prospective study was designed to determine whether CRT with biventricular pacing would reduce the risk of development of atrial fibrillation (AF) and to identify predictors for AF occurrence. Materials and Methods: The study population consisted of 126 patients, with a mean age of 63.8 ± 9.1 years, who were eligible for CRT with biventricular pacing. Inclusion criteria were left ventricular ejection fraction (LVEF) ≤ 35%, QRS duration ≥ 130 msec, and persistent HF symptoms of New York Heart Association (NYHA) II or III, despite optimal drug therapy. Patients were followed for a period of 24 months and were evaluated through clinical, electrocardiographic, and echocardiographic examination at baseline (prior to CRT implantation), as well as at 6 and 24 months post-implantation. At the end of follow-up, patients were divided into clinical responders and non-responders based on the following criteria: decrease in NYHA class ≥ I, increase in LVEF ≥ 10%, and reduction in QRS duration ≥ 20 msec. Results: At follow-up, CRT was associated with a significant increase in LVEF (20.6 ± 6.9% pre-implantation, 32.9 ± 9.3% 24 months after implantation; p < 0.001), reduction in left ventricular end-diastolic and end-systolic diameters, and decrease in QRS duration (167.6 ± 14.3 msec pre-implantation, 131.7 ± 11.7 msec 24 months after implantation; p < 0.001), while left atrial (LA) diameter was slightly increased (p = 0.070). The frequency of AF occurrence increased after two years of follow-up (52.4% to 56.9%, p < 0.001). Significant predictors of AF occurrence in our study population were response to CRT-AF more frequent in non-responders (B = 8.134; p < 0.001), LA diameter-AF more frequent with larger LA diameter (B = 0.813; p < 0.001), and coronary sinus (CS) lead position-AF more frequent with posterolateral in comparison with lateral CS lead position (B = 5.159; p = 0.005). Conclusions: The results of our study provide new data on AF predictors in patients with HF subjected to CRT. There remains a permanent need for new predictors, which might help in patient selection and improvement in response rate.

Cardiac reverse remodelling by imaging parameters with recent changes to guideline medical therapy in heart failure

Recently established heart failure therapies, including sodium glucose co-transporter 2 inhibitors, angiotensin-neprilysin inhibitors, and cardiac resynchronization therapy, have led to both clinical and structural improvements. Reverse remodelling describes the structural and functional responses to therapy and has been shown to correlate with patients' clinical response, acting as a biomarker for treatment success. The introduction of these new therapeutic agents in addition to advances in non-invasive cardiac imaging has led to an expansion in the evaluation and the validation of cardiac reverse remodelling. Methods including volumetric changes as well as strain and myocardial work have all been shown to be non-invasive end-points of reverse remodelling, correlating with clinical outcomes. Our review summarizes the current available evidence on reverse remodelling in heart failure by the non-invasive cardiac imaging techniques, in particular transthoracic echocardiography.

Role of monocytes and dendritic cells in cardiac reverse remodelling after cardiac resynchronization therapy

BACKGROUND AND AIMS

Monocytes and dendritic cells (DC) are both key inflammatory cells, with recognized effects on cardiac repair. However, there are distinct subsets of monocytes with potential for beneficial or detrimental effects on heart failure (HF) pathogenesis. The connection between reverse cardiac remodelling, the potential anti-inflammatory effect of cardiac resynchronization therapy (CRT) and monocytes and DC homeostasis in HF is far from being understood. We hypothesized that monocytes and DC play an important role in cardiac reverse remodelling and CRT response. Therefore, we aimed to assess the potential role of baseline peripheral levels of blood monocytes and DC subsets and their phenotypic and functional activity for CRT response, in HF patients. As a secondary objective, we aimed to evaluate the impact of CRT on peripheral blood monocytes and DC subsets, by comparing baseline and post CRT circulating levels and phenotypic and functional activity.

METHODS

Forty-one patients with advanced HF scheduled for CRT were included in this study. The quantification and phenotypic determination of classical (cMo), intermediate (iMo) and non-classical monocytes (ncMo), as well as of myeloid (mDC) and plasmacytoid DC (pDC) were performed by flow cytometry in a FACSCanto™II (BD) flow cytometer. The functional characterization of total monocytes and mDC was performed by flow cytometry in a FACSCalibur flow cytometer, after in vitro stimulation with lipopolysaccharide from Escherichia coli plus interferon (IFN)-γ, in the presence of Brefeldina A. Comparisons between the control and the patient group, and between responders and non-responders to CRT were performed.

RESULTS

Compared to the control group, HF population presented a significantly lower frequency of pDC at baseline and a higher proportion of monocytes and mDC producing IL-6 and IL-1β, both before and 6-months after CRT (T6). There was a remarkable decrease of cMo and an increase of iMo after CRT, only in responders. The responder group also presented higher ncMo values at T6 compared to the non-responder group. Both responders and non-responders presented a decrease in the expression of CD86 in all monocyte and DC populations after CRT. Moreover, in non-responders, the increased frequency of IL-6-producing DC persisted after CRT.

CONCLUSION

Our study provides new knowledge about the possible contribution of pDC and monocytes subsets to cardiac reverse remodelling and response to CRT. Additionally, CRT is associated with a reduction on CD86 expression by monocytes and DC subsets and in their potential to produce pro-inflammatory cytokines, contributing, at least in part, for the well described anti-inflammatory effects of CRT in HF patients.

Outcomes following cardiac resynchronisation therapy in older people

INTRODUCTION

Older patients may be less likely to receive cardiac resynchronisation therapy (CRT) for the management of heart failure. We aimed to describe the differences in clinical response, complications, and subsequent outcomes following CRT implantation compared to younger patients.

METHODS

We conducted a retrospective cohort study of unselected, consecutive patients implanted with CRT devices between March 2008 and July 2017. We recorded complications, symptomatic and echocardiographic response, hospitalisation for heart failure, and all-cause mortality comparing patients aged <70, 70-79 and ≥ 80 years.

RESULTS

Five hundred and seventy-four patients (median age 76 years [interquartile range 68-81], 73.3% male) received CRT. At baseline, patients aged ≥80 years had worse symptoms, were more likely to have co-morbidities, and less likely to be receiving comprehensive medical therapy, although left ventricular function was similar. Older patients were less likely to receive CRT-defibrillators compared to CRT-pacemakers. Complications were infrequent and not more common in older patients. Age was not a predictor of symptomatic or echocardiographic response to CRT (67.2%, 71.2% and 62.6% responders in patients aged <70, 70-79 and ≥ 80 years, respectively; P = 0.43), and time to first heart failure hospitalisation was similar across age groups (P = 0.28). Ten-year survival was lower for older patients (49.9%, 23.9% and 6.8% in patients aged <70, 70-79 and ≥ 80 years, respectively; P < 0.001).

CONCLUSIONS

The benefits of CRT on symptoms and left ventricular function were not different in older patients despite a greater burden of co-morbidities and less optimal medical therapy. These findings support the use of CRT in an ageing population.

Special Issue: Latest Advances in Delivery and Outcomes of Cardiac Resynchronization Therapy and Conduction System Pacing

Cardiac Resynchronization Therapy (CRT) is an established technique to improve morbidity and mortality in selected heart failure patients [...].

Cardiac Resynchronization Therapy and Left Atrial Remodeling: A Novel Insight?

Cardiac resynchronization therapy (CRT) restores ventricular dyssynchrony, improving left ventricle (LV) systolic function, symptoms, and outcome in patients with heart failure, systolic dysfunction, and prolonged QRS interval. The left atrium (LA) plays tremendous roles in maintaining cardiac function, being often inflicted in various cardiovascular diseases. LA remodeling implies structural-dilation, functional-altered phasic functions, and strain and electrical-atrial fibrillation remodeling. Until now, several important studies have approached the relationship between LA and CRT. LA volumes can predict responsiveness to CRT, being also associated with improved outcome in these patients. LA function and strain parameters have been shown to improve after CRT, especially in those who were positive responders to it. Further studies still need to be conducted to comprehensively characterize the impact of CRT on LA phasic function and strain, and, also, in conjunction with its impact on functional mitral regurgitation and LV diastolic dysfunction. The aim of this review was to provide an overview of current available data regarding the relation between CRT and LA remodeling.

Fifteen-Year Differences in Indications for Cardiac Resynchronization Therapy in International Guidelines-Insights from the Heart Failure Registries of the European Society of Cardiology

Cardiac resynchronization therapy (CRT) applied to selected patients with heart failure (HF) improves their prognosis. In recent years, eligibility criteria for CRT have regularly changed. This study aimed to investigate the changes in eligibility of real-life HF patients for CRT over the past fifteen years. We reviewed European and North American guidelines from this period and applied them to HF patients from the ESC-HF Pilot and ESC-Long-Term Registries. Taking into consideration the criteria assessed in this study (including all classes of recommendations i.e., class I, IIa and IIb, as well as patients with AF and SR), the 2013 (ESC) guidelines would have qualified the most patients for CRT (266, 18.3%), while the 2015 (ESC) guidelines would have qualified the least (115, 7.9%; p-value for differences between all analyzed papers <0.0001). There were only 26 patients (1.8%) who would be eligible for CRT using the class I recommendations across all of the guidelines. These results demonstrate the variability in recommendations for CRT over the years. Moreover, this data indicates underuse of this form of pacing in HF and highlights the need for more studies in order to improve the outcomes of HF patients and further personalize their management.

Hemodynamic Effects of Sacubitril/Valsartan in Patients with Reduced Left Ventricular Ejection Fraction Over 24 Months: A Retrospective Study

Background

The effects of sacubitril/valsartan in patients with chronic heart failure with reduced ejection fraction (HFrEF) were recently reported. However, the hemodynamic impact of this well-established treatment in patients with HFrEF has been poorly systematically researched.

Aim

We aimed to investigate the hemodynamic effects of sacubitril/valsartan among patients with HFrEF.

Methods

Between 2016 and 2020, we retrospectively collected data for patients with HFrEF treated at the University Medical Center Mannheim, Germany. Data for 240 patients with HFrEF were available. We systematically analyzed echocardiographic parameters, all-cause hospitalization, and congestion rate.

Results

The left ventricular ejection fraction (LVEF) improved from a median (minimum; maximum) of 28% (3; 65) before initiation of sacubitril/valsartan to a median of 34% (13; 64) at 24-month follow-up (p < 0.001). Systolic pulmonary atrial pressure (PAPsys) decreased from a median of 30 mmHg (13; 115) to 25 mmHg (20; 80) at 24-month follow-up (p = 0.005). The median (minimum; maximum) tricuspid annular plane systolic excursion improved from 17 mm (3; 31) at baseline to 20 mm (9; 30) at 12-month follow-up (p = 0.007). The incidence of severe and moderate mitral, tricuspid, and aortic valvular insufficiency improved after treatment. Hospitalization and congestion rates reduced at 24-month follow-up. The mortality rate in echocardiographic and functional nonresponders was higher than in responders (12.1 vs. 5.2%; p = 0.1 and 11.3 vs. 3.1%; p = 0.01, respectively).

Conclusion

Follow-up 24 months after starting treatment with sacubitril/valsartan revealed sustained improvements in echocardiographic parameters, including LVEF, PAPsys, and cardiac valvular insufficiency. Rates of all-cause hospitalization and congestion had decreased significantly at follow-up. The mortality rate was higher in echocardiographic and functional nonresponders.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40256-022-00525-w.

Prognostic value of the MELD-XI score in patients undergoing cardiac resynchronization therapy

Aims

Multi‐organ dysfunction was recently reported to be a common condition in patients with heart failure (HF). The Model for End‐stage Liver Disease eXcluding International normalized ratio (MELD‐XI) score reflects liver and kidney function. The prognostic relevance of this score has been reported in patients with a variety of cardiovascular diseases who are undergoing interventional therapies. However, the relationship between the severity of hepatorenal dysfunction assessed by the MELD‐XI score and the long‐term clinical outcomes of HF patients receiving cardiac resynchronization therapy (CRT) has not been evaluated.

Methods and results

Clinical records of 283 patients who underwent CRT implantation between March 2003 and October 2020 were retrospectively evaluated (mean age 67 ± 12, 22.6% female). Blood samples were collected before CRT implantation. Patients were divided into three groups based on tertiles of the MELD‐XI score: first tertile (MELD‐XI = 9.44, n = 95), second tertile (9.44 < MELD‐XI < 13.4, n = 94), and third tertile (MELD‐XI ≥ 13.4, n = 94). The primary endpoint was all‐cause mortality. Compared with the other groups, the third tertile group exhibited significantly older age, higher prevalence of diabetes mellitus and hypertension, lower haemoglobin level, and higher N‐terminal pro‐brain natriuretic peptide level (all P < 0.05). The functional CRT response rate was also significantly lower in the third tertile group (P = 0.011). During a median follow‐up of 30 months (inter‐quartile range, 9–67), 105 patients (37.1%) died. Kaplan–Meier analysis revealed that patients with a higher MELD‐XI score had a greater risk of all‐cause mortality (log‐rank test: P < 0.001). Even after adjustment for clinically relevant factors and a conventional risk score, the MELD‐XI score was still associated with mortality (adjusted hazard ratio: 1.04, 95% confidence interval: 1.00–1.07, P = 0.014, and adjusted hazard ratio: 1.04, 95% confidence interval: 1.01–1.09, P = 0.005, respectively). A higher MELD‐XI score was associated with a greater risk of all‐cause mortality than a lower MELD‐XI score regardless of whether a pacemaker or defibrillator was implanted (log‐rank test: P = 0.010 and P < 0.001, respectively).

Conclusions

Impaired hepatorenal function assessed by the MELD‐XI score was associated with older age, higher prevalence of multiple co‐morbidities, severity of HF, lower CRT response rates, and subsequent all‐cause mortality in HF patients undergoing CRT implantation. These results suggest that the MELD‐XI score can provide additional prognostic information and may be useful for improving risk stratification in this population.

Cardiac resynchronization therapy: Current status and near-future prospects

Cardiac resynchronization therapy (CRT) has been established as a standard treatment for heart failure. The effectiveness of CRT has been shown in many clinical trials and realized in actual clinical practice. Nevertheless, underutilization of CRT is a major problem in the treatment of heart failure. One factor leading to underutilization is the existence of CRT non-responders. CRT non-response has been discussed for approximately 20 years, since CRT was introduced. Since the beginning, the CRT non-response rate has been reported to be 30%. However, we are now undergoing a major transformation in the thinking about CRT response. First, heart failure is a progressive disease. Like many medications for heart failure, CRT does not cure the underlying disease of heart failure. Considering the natural course of heart failure, it is easy to understand that there will definitely be non-responders. There might have been misunderstandings about how to determine CRT response. Although CRT is a treatment for heart failure, it does not cure heart failure or myocardial tissue damage. Instead, by correcting conduction disorders and dyssynchrony, it modifies factors that exacerbate heart failure, which contributes to improvement. In addition, it is important to realize that pacing is the only treatment for correcting conduction disorders. Thus, in theory, CRT is an essential treatment for heart failure at any stage, regardless of severity, when it is accompanied by conduction disorder. Here, we consider the current state of CRT and the causes of underutilization. Returning to the origin of CRT, reconsidering the effects of CRT and the thinking about response, and spreading a new way of thinking will lead to the proper utilization of CRT.

Prognostic importance of the Controlling Nutritional Status (CONUT) score in patients undergoing cardiac resynchronisation therapy

Aims

Malnutrition is common and associated with worse clinical outcomes in patients with heart failure (HF). The Controlling Nutritional Status (CONUT) score is an integrated index for evaluating diverse aspects of the complex mechanism of malnutrition. However, the relationship between the severity of malnutrition assessed by the CONUT score and clinical outcomes of HF patients receiving cardiac resynchronisation therapy (CRT) has not been fully clarified.

Methods

Clinical records of 263 patients who underwent pacemaker or defibrillator implantation for CRT between March 2003 and October 2020 were retrospectively evaluated. The CONUT score was calculated from laboratory data obtained before CRT device implantation. Patients were divided into three groups: normal nutrition (CONUT scores 0–1, n=58), mild malnutrition (CONUT scores 2–4, n=132) and moderate or severe malnutrition (CONUT scores 5–12, n=73). The primary endpoint was all-cause mortality.

Results

The moderate or severe malnutrition group had a lower body mass index, more advanced New York Heart Association functional class, higher Clinical Frailty Scale score, lower levels of haemoglobin and higher levels of N-terminal probrain natriuretic peptide (all p<0.05). In the moderate or severe malnutrition group, the CRT response rate was significantly lower than for the other two groups (p=0.001). During a median follow-up period of 31 (10–67) months, 103 (39.1%) patients died. Kaplan-Meier analysis revealed that the moderate or severe malnutrition group had a significantly higher mortality rate (log-rank p<0.001). A higher CONUT score and CONUT score ≥5 remained significantly associated with all-cause mortality after adjusting for previously reported clinically relevant factors and the conventional risk score (VALID-CRT risk score) (all p<0.05).

Conclusions

A higher CONUT score before CRT device implantation was strongly associated with HF severity, frailty, lower CRT response rate and subsequent long-term all-cause mortality.