Cardiac resynchronization therapy in chronic heart failure with moderately reduced left ventricular ejection fraction: Lessons from the Multicenter InSync Randomized Clinical Evaluation MIRACLE EF study

Left Ventricular Ejection Fraction and the Future of Heart Failure Phenotyping

Heart failure (HF) is a complex syndrome traditionally classified by left ventricular ejection fraction (LVEF) cutpoints. Although LVEF is prognostic for risk of events and predictive of response to some HF therapies, LVEF is a continuous variable and cutpoints are arbitrary, often based on historical clinical trial enrichment decisions rather than physiology. Holistic evaluation of the treatment effects for therapies throughout the LVEF range suggests the standard categorization paradigm for HF merits modification. The multidisciplinary Heart Failure Collaboratory reviewed data from large-scale HF clinical trials and found that many HF therapies have demonstrated therapeutic benefit across a large range of LVEF, but specific treatment effects vary across that range. Therefore, HF should practically be classified by association with an LVEF that is reduced or not reduced, while acknowledging uncertainty around the precise LVEF cutpoint, and future research should evaluate new therapies across the continuum of LVEF.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Clinical Outcomes of Permanent Left Bundle Branch Area Pacing in Patients With Left Bundle Branch Block and Left Ventricular Ejection Fraction >35 vs. ≤35%

Aims

The present study aimed to compare the effects of left bundle branch area pacing (LBBAP) on cardiac function and clinical outcomes in patients with left bundle branch block (LBBB) and left ventricular ejection fraction (LVEF) >35 vs. ≤35%.

Methods and Results

Thirty-six consecutive patients with LBBB and LVEF <50% were enrolled. All patients were followed up for a mean of 6 months. The successful LBBAP was defined as a paced QRS complex presented as right bundle branch block (RBBB) morphology and QRSd < 130 ms. Echocardiography parameters, pacing parameters and clinical outcomes were collected. The successful LBBAP was achieved in 77.8% of all cases (28/36). In LVEF > 35% group (70 ± 8 years, 9 male), the success rate was 81.0% (17/21). QRSd significantly decreased from 174 ± 23 ms to 108 ± 13 ms (P < 0.001). The pacing threshold and R-wave amplitude were 0.6 ± 0.2 V @ 0.5 ms and 12 ± 7 mV, respectively. In LVEF ≤ 35% group (69 ± 5 years, 9 male), the success rate was 73.3% (11/15) with QRSd decreasing from 188 ± 25 ms to 107 ± 11 ms (P < 0.001). The hyperresponders to LBBAP (functional recovery and LVEF ≥ 50%) in LVEF > 35% group was 52.9%, which were almost twice of that in LVEF ≤ 35% group (33.3%). Whether patients had LBBAP or left ventricular septal pacing (LVSP), patients in the LVEF > 35% group showed significantly lower incidence of heart failure hospitalizations or death from any cause (hazard ratio in LVEF > 35% group, 0.22; 95%CI, 0.06 to 0.75, P = 0.011).

Conclusions

LBBAP can significantly shorten the QRSd and improve cardiac function in LBBB patients with either LVEF > 35 or ≤ 35%. LBBAP should be considered as an effective therapy for preventing the deterioration of cardiac function in early-stage heart failure patients with LBBB and LVEF > 35%.

Heart failure with mid-range or mildly reduced ejection fraction

Left ventricular ejection fraction (EF) remains the major parameter for diagnosis, phenotyping, prognosis and treatment decisions in heart failure. The 2016 ESC heart failure guidelines introduced a third EF category for an EF of 40-49%, defined as heart failure with mid-range EF (HFmrEF). This category has been largely unexplored compared with heart failure with reduced EF (HFrEF; defined as EF <40% in this Review) and heart failure with preserved EF (HFpEF; defined as EF ≥50%). The prevalence of HFmrEF within the overall population of patients with HF is 10-25%. HFmrEF seems to be an intermediate clinical entity between HFrEF and HFpEF in some respects, but more similar to HFrEF in others, in particular with regard to the high prevalence of ischaemic heart disease in these patients. HFmrEF is milder than HFrEF, and the risk of cardiovascular events is lower in patients with HFmrEF or HFpEF than in those with HFrEF. By contrast, the risk of non-cardiovascular adverse events is similar or greater in patients with HFmrEF or HFpEF than in those with HFrEF. Evidence from post hoc and subgroup analyses of randomized clinical trials and a trial of an SGLT1-SGLT2 inhibitor suggests that drugs that are effective in patients with HFrEF might also be effective in patients with HFmrEF. Although the EF is a continuous measure with considerable variability, in this comprehensive Review we suggest that HFmrEF is a useful categorization of patients with HF and shares the most important clinical features with HFrEF, which supports the renaming of HFmrEF to HF with mildly reduced EF.

Research design considerations for randomized controlled trials of spinal cord stimulation for pain: Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials/Institute of Neuromodulation/International Neuromodulation Society recommendations

ABSTRACT

Spinal cord stimulation (SCS) is an interventional nonpharmacologic treatment used for chronic pain and other indications. Methods for evaluating the safety and efficacy of SCS have evolved from uncontrolled and retrospective studies to prospective randomized controlled trials (RCTs). Although randomization overcomes certain types of bias, additional challenges to the validity of RCTs of SCS include blinding, choice of control groups, nonspecific effects of treatment variables (eg, paresthesia, device programming and recharging, psychological support, and rehabilitative techniques), and safety considerations. To address these challenges, 3 professional societies (Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials, Institute of Neuromodulation, and International Neuromodulation Society) convened a meeting to develop consensus recommendations on the design, conduct, analysis, and interpretation of RCTs of SCS for chronic pain. This article summarizes the results of this meeting. Highlights of our recommendations include disclosing all funding source and potential conflicts; incorporating mechanistic objectives when possible; avoiding noninferiority designs without internal demonstration of assay sensitivity; achieving and documenting double-blinding whenever possible; documenting investigator and site experience; keeping all information provided to patients balanced with respect to expectation of benefit; disclosing all information provided to patients, including verbal scripts; using placebo/sham controls when possible; capturing a complete set of outcome assessments; accounting for ancillary pharmacologic and nonpharmacologic treatments in a clear manner; providing a complete description of intended and actual programming interactions; making a prospective ascertainment of SCS-specific safety outcomes; training patients and researchers on appropriate expectations, outcome assessments, and other key aspects of study performance; and providing transparent and complete reporting of results according to applicable reporting guidelines.

Echocardiographic view and feature selection for the estimation of the response to CRT

Cardiac resynchronization therapy (CRT) is an implant-based therapy applied to patients with a specific heart failure (HF) profile. The identification of patients that may benefit from CRT is a challenging task and the application of current guidelines still induce a non-responder rate of about 30%. Several studies have shown that the assessment of left ventricular (LV) mechanics by speckle tracking echocardiography can provide useful information for CRT patient selection. A comprehensive evaluation of LV mechanics is normally performed using three different echocardioraphic views: 4, 3 or 2-chamber views. The aim of this study is to estimate the relative importance of strain-based features extracted from these three views, for the estimation of CRT response. Several features were extracted from the longitudinal strain curves of 130 patients and different methods of feature selection (out-of-bag random forest, wrapping and filtering) have been applied. Results show that more than 50% of the 20 most important features are calculated from the 4-chamber view. Although features from the 2- and 3-chamber views are less represented in the most important features, some of the former have been identified to provide complementary information. A thorough analysis and interpretation of the most informative features is also provided, as a first step towards the construction of a machine-learning chain for an improved selection of CRT candidates.

Universal definition and classification of heart failure: a report of the Heart Failure Society of America, Heart Failure Association of the European Society of Cardiology, Japanese Heart Failure Society and Writing Committee of the Universal Definition of Heart Failure: Endorsed by the Canadian Heart Failure Society, Heart Failure Association of India, Cardiac Society of Australia and New Zealand, and Chinese Heart Failure Association

In this document, we propose a universal definition of heart failure (HF) as a clinical syndrome with symptoms and/or signs caused by a structural and/or functional cardiac abnormality and corroborated by elevated natriuretic peptide levels and/or objective evidence of pulmonary or systemic congestion. We also propose revised stages of HF as: At risk for HF (Stage A), Pre-HF (Stage B), Symptomatic HF (Stage C) and Advanced HF (Stage D). Finally, we propose a new and revised classification of HF according to left ventricular ejection fraction (LVEF). This includes HF with reduced ejection fraction (HFrEF): symptomatic HF with LVEF ≤40%; HF with mildly reduced ejection fraction (HFmrEF): symptomatic HF with LVEF 41-49%; HF with preserved ejection fraction (HFpEF): symptomatic HF with LVEF ≥50%; and HF with improved ejection fraction (HFimpEF): symptomatic HF with a baseline LVEF ≤40%, a ≥10 point increase from baseline LVEF, and a second measurement of LVEF > 40%.

Universal Definition and Classification of Heart Failure: A Report of the Heart Failure Society of America, Heart Failure Association of the European Society of Cardiology, Japanese Heart Failure Society and Writing Committee of the Universal Definition of Heart Failure

In this document, we propose a universal definition of heart failure (HF) as the following: HF is a clinical syndrome with symptoms and or signs caused by a structural and/or functional cardiac abnormality and corroborated by elevated natriuretic peptide levels and or objective evidence of pulmonary or systemic congestion. We propose revised stages of HF as follows. At-risk for HF (Stage A), for patients at risk for HF but without current or prior symptoms or signs of HF and without structural or biomarkers evidence of heart disease. Pre-HF (stage B), for patients without current or prior symptoms or signs of HF, but evidence of structural heart disease or abnormal cardiac function, or elevated natriuretic peptide levels. HF (Stage C), for patients with current or prior symptoms and/or signs of HF caused by a structural and/or functional cardiac abnormality. Advanced HF (Stage D), for patients with severe symptoms and/or signs of HF at rest, recurrent hospitalizations despite guideline-directed management and therapy (GDMT), refractory or intolerant to GDMT, requiring advanced therapies such as consideration for transplant, mechanical circulatory support, or palliative care. Finally, we propose a new and revised classification of HF according to left ventricular ejection fraction (LVEF). The classification includes HF with reduced EF (HFrEF): HF with an LVEF of ≤40%; HF with mildly reduced EF (HFmrEF): HF with an LVEF of 41% to 49%; HF with preserved EF (HFpEF): HF with an LVEF of ≥50%; and HF with improved EF (HFimpEF): HF with a baseline LVEF of ≤40%, a ≥10-point increase from baseline LVEF, and a second measurement of LVEF of >40%.

Cardiac resynchronization therapy in patients with heart failure and moderately reduced ejection fraction: Could it trigger a super-response?

Background/Aim

Despite the well-established benefits of cardiac resynchronization therapy (CRT) in heart failure (HF) patients with left ventricular ejection fraction (LVEF) ≤35%, many patients with less reduced EF remain refractory to optimized medical treatment and at high risk of morbidity and mortality. The objective of the study is to evaluate the effects of CRT in optimally treated patients with New York Heart Association (NYHA) classes II–IV, LVEF of 36–45%, and left bundle branch (LBBB), including clinical, structural and biochemical response.

Methods

A selected group of HF patients have been implanted with CRT-P devices and were followed up for 6 months at 4, 12 and 24 weeks. Clinical assessment included NYHA class, quality of life and 6-min walk distance (6 MWD) test. Echocardiographic assessment included LV dimensions and function and left atrial volume. Serum N-terminal pro b-type natriuretic peptide (NT-ProBNP) was measured at the same intervals.

Results

This prospective single center study included 23 patients. NYHA functional class significantly improved after CRT-P (p < 0.0001), associated with improvement in QOL (p < 0.0001) and 6 MWD, which increased, from 145.7 ± 20.1 m to 219.5 ± 42.2 m (p < 0.0001). Mean QRS duration showed significant shortening from 164.4 ± 13.2 ms to 126.4 ± 13.6 ms (p < 0.0001). CRT induced reverse remodeling with reduction in both left ventricular end diastolic diameter (LVEDD) from 68.95 ± 5.05 mm to 62.8 ± 4.47 mm, p = 0.0002 and left ventricular end systolic diameter (LVESD) from 54.1 ± 4.5 mm to 46.5 ± 4.1 mm, p < 0.0001, and significant increase in LVEF (from 40.3 ± 2.8 to 48.3 ± 4.2 mm, p < 0.0001). The biochemical response to CRT showed significant reduction in serum NT-ProBNP from 1025.6 ± 363.1 pg/ml to 594.9 ± 263.5 pg/ml (p < 0.0001).

Conclusions

Symptomatic HF patients on maximal optimized medical treatment who have LBBB and baseline LVEF 35–45% appeared to derive significant clinical and structural benefit from CRT.

[Heart failure with preserved left ventricular ejection fraction]

Heart failure remains the number one diagnosis among patients receiving inpatient treatment in Germany. Heart failure with preserved ejection fraction (HFpEF) needs to be verified by signs and symptoms of HF, echocardiographic parameters as well as cardiac biomarkers. Based on etiological and pathophysiological considerations, a classification into systolic and diastolic heart failure and later heart failure with reduced ejection fraction (HFrEF) and HFpEF was proposed. The inhomogeneous group of patients with HFpEF accounts for half of all heart failure cases in the population. Effective treatment options are limited. This article discusses which verified treatments may help or may even be harmful. A glimpse is taken into the future and those substances that are in advanced stages of clinical trials are described.

Heart failure with mid-range ejection fraction and with preserved ejection fraction

The annual "heart report" published by the German Heart Foundation (Deutsche Herzstiftung) in December 2017 indicates that heart failure (ICD I50) remains the number one diagnosis of in-hospital-treated patients throughout Germany. For some time, the clinical diagnosis of heart failure has been verified by echocardiographic parameters as well as cardiac biomarkers that assist the clinician to rule in or rule out the presence of a failing heart, when used wisely. By introducing the term "heart failure with mid-range ejection fraction" (HFmrEF), the 2016 European Society of Cardiology (ESC) heart failure guidelines established a third heart failure entity, which was not necessarily seen as an improvement by the heart failure community. Nevertheless, half of all patients suffering from heart failure are now classified as having HFmrEF or heart failure with preserved ejection fraction (HFpEF), but the etiology and treatment options differ substantially. To elucidate this issue, the current review aims to highlight the key findings published to date. This should minimize the confusion that may have been generated by the new term "HFmrEF".

Cardiac Resynchronization Therapy in Preserved to Mildly Reduced Systolic Function

Cardiac resynchronization therapy has been proven to be clearly beneficial for patients with heart failure, a prolonged QRS duration, and a left ventricular ejection fraction ≤35%. Ejection fraction cutoff, however, is arbitrary and very likely excludes many patients who could benefit from cardiac resynchronization. This article describes the major detrimental effects of left bundle branch block and summarizes the data regarding the potential beneficial effects of cardiac resynchronization in patients with a left ventricular ejection fraction greater than 35%.

Long-term outcomes of cardiac resynchronization therapy by left ventricular ejection fraction

AIMS

Despite our prior report suggesting heart failure (HF) risk reduction from cardiac resynchronization therapy with defibrillator (CRT-D) in mild HF patients with higher left ventricular ejection fraction (LVEF > 30%), data on mortality benefit in this cohort are lacking. We aimed to assess long-term mortality benefit from CRT-D in mild HF patients by LVEF > 30%.

METHODS AND RESULTS

Among 1274 patients with mild HF and left bundle branch block enrolled in MADIT-CRT, we analysed long-term effects of CRT-D vs. implantable cardioverter defibrillator (ICD) therapy only, and reverse remodelling to CRT-D (left ventricular end-systolic volume percent change ≥ median at 1 year), on all-cause mortality and HF for the LVEF ≤ 30% and LVEF > 30 subgroups using Kaplan-Meier and Cox analyses. During long-term follow-up, CRT-D vs. ICD was associated with reduction in all-cause mortality in both patients with LVEF > 30% and LVEF ≤ 30% [hazard ratio (HR) 0.47, 95% confidence interval (CI) 0.25-0.85, P = 0.036 vs. HR 0.69, 95% CI 0.49-0.98, P = 0.013, interaction P = 0.261]. The efficacy of CRT-D vs. ICD only to reduce HF was similar in those with LVEF above and below 30% (HR 0.36, 95% CI 0.35-0.61, P < 0.001 vs. HR 0.46, 95% CI 0.35-0.61, P < 0.001; interaction P = 0.342). Patients with CRT-D-induced reverse remodelling had significant mortality reduction when compared to ICD, with either LVEF > 30% or LVEF ≤ 30% (HR 0.17 and 0.39), but no mortality benefit was seen in patients with less reverse remodelling. HF events, however, were reduced in both CRT-D-induced high and low reverse remodelling vs. ICD only, in both LVEF subgroups.

CONCLUSIONS

In MADIT-CRT, left bundle branch block patients with higher LVEF (> 30%) derive long-term mortality benefit from CRT-D when exhibiting significant reverse remodelling.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov ID NCT00180271, NCT01294449, and NCT02060110.

Interatrial shunt devices for heart failure with normal ejection fraction: a technology update

Heart failure with normal ejection fraction (HeFNEF) accounts for ~50% of heart failure admissions. Its pathophysiology and diagnostic criteria are yet to be defined clearly which may hinder the search for effective treatments. The clinical hallmark of HeFNEF is exertional breathlessness, often due to an abnormal increase in left atrial pressure during exercise. Creation of an interatrial communication to offload the left atrium is a possible therapeutic approach. There are two percutaneously delivered devices currently under investigation which are discussed in this review.