Left ventricular ejection fraction for risk stratification in chronic systolic heart failure

Left ventricular ejection fraction: clinical, pathophysiological, and technical limitations

Risk stratification of cardiovascular death and treatment strategies in patients with heart failure (HF), the optimal timing for valve replacement, and the selection of patients for implantable cardioverter defibrillators are based on an echocardiographic calculation of left ventricular ejection fraction (LVEF) in most guidelines. As a marker of systolic function, LVEF has important limitations being affected by loading conditions and cavity geometry, as well as image quality, thus impacting inter- and intra-observer measurement variability. LVEF is a product of shortening of the three components of myocardial fibres: longitudinal, circumferential, and oblique. It is therefore a marker of global ejection performance based on cavity volume changes, rather than directly reflecting myocardial contractile function, hence may be normal even when myofibril's systolic function is impaired. Sub-endocardial longitudinal fibers are the most sensitive layers to ischemia, so when dysfunctional, the circumferential fibers may compensate for it and maintain the overall LVEF. Likewise, in patients with HF, LVEF is used to stratify subgroups, an approach that has prognostic implications but without a direct relationship. HF is a dynamic disease that may worsen or improve over time according to the underlying pathology. Such dynamicity impacts LVEF and its use to guide treatment. The same applies to changes in LVEF following interventional procedures. In this review, we analyze the clinical, pathophysiological, and technical limitations of LVEF across a wide range of cardiovascular pathologies.

Impact of Coronary Artery Disease in Women With Newly Diagnosed Heart Failure and Reduced Ejection Fraction

BACKGROUND

The representation of women in heart failure studies has been inadequate, resulting in a knowledge gap regarding the prognostic impact of coronary artery disease (CAD) on all-cause mortality in women with newly diagnosed heart failure and reduced ejection fraction (HFrEF).

OBJECTIVES

This study aims to assess the prognostic impact of CAD in women with HFrEF.

METHODS

Using the Western Denmark Heart Registry, the authors identified 891 women and 2,403 men referred for first-time coronary angiography because of HFrEF. The authors stratified for presence of CAD, estimated 10-year all-cause mortality, and calculated crude and adjusted HRs (aHRs) with 95% CIs.

RESULTS

The 10-year mortality was 60% in women with CAD and 27% in women without CAD; for men, the corresponding numbers were 54% and 36%. When adjusted for comorbidities, women without CAD had a lower relative 10-year mortality than men without CAD (aHR: 0.73; 95% CI: 0.58-0.91), whereas women with CAD had similar relative mortality as men with CAD (aHR: 1.00; 95% CI: 0.81-1.24) (Pinteraction = 0.037). Assessed by the number of coronary vessels with significant stenosis, CAD extent was associated with mortality for both women (P < 0.01) and men (P < 0.01). However, compared to those without CAD, the aHR was higher for women with any degree of CAD (aHR ranging from 1.61 [95% CI: 1.09-2.38] for diffuse CAD to 2.01 [95% CI: 1.19-3.40] for 3-vessel disease) than for men with 3-vessel disease (aHR: 1.51; 95% CI: 1.19-1.91).

CONCLUSIONS

In patients with newly diagnosed HFrEF, the presence and extent of CAD has significantly greater prognostic impact among women than among men.

Expression of microRNA Predicts Cardiovascular Events in Patients with Stable Coronary Artery Disease

BACKGROUND

 New biomarkers are warranted to identify patients with coronary artery disease (CAD) at high risk of recurrent cardiovascular events. It has been reported that the expression of microRNAs (miRs) may influence the development of CAD.

OBJECTIVES

 We aimed to investigate whether the expression of selected candidate miRs is a predictor of cardiovascular events in a cohort of stable CAD patients.

METHODS

 We performed a single-center prospective study of 749 stable CAD patients with a median follow-up of 2.8 years. We investigated the expression of nine candidate miRs and their relation to cardiovascular events in this cohort. The primary endpoint was the composite of nonfatal myocardial infarction (MI), stent thrombosis (ST), ischemic stroke, and cardiovascular death. The composite of nonfatal MI and ST was analyzed as a secondary endpoint. Furthermore, nonfatal MI, ST, ischemic stroke, and all-cause mortality were analyzed as individual endpoints.

RESULTS

 Employing receiver operating characteristic curves, it was shown that compared with traditional cardiovascular risk factors alone, combining the expression of miR-223-3p with existing traditional cardiovascular risk factors increased the predictive value of ST (area under the curve: 0.88 vs. 0.77, p = 0.04), the primary composite endpoint (0.65 vs. 0.61, p = 0.049), and the secondary endpoint of the composite of nonfatal MI and ST (0.68 vs. 0.62, p = 0.04).

CONCLUSION

 Among patients with CAD, adding miR-223-3p expression to traditional cardiovascular risk factors may improve prediction of cardiovascular events, particularly ST. Clinical trials confirming these findings are warranted.

miR-182-5p combined with brain-derived neurotrophic factor assists the diagnosis of chronic heart failure and predicts a poor prognosis

Objective

Chronic heart failure (CHF) is a general progressive disorder with high morbidity and poor prognosis. This study analyzed the serum expression and clinical value of miR-182-5p and brain-derived neurotrophic factor (BDNF) in CHF patients.

Methods

A total of 82 CHF patients were selected as the study subjects (15 cases in NYHA stage I, 29 cases in stage II, 27 cases in stage III, and 11 cases in stage IV), with another 78 healthy people as the controls. The expression of serum miR-182-5p was detected by RT-qPCR. BDNF expression was measured by ELISA. Furthermore, the Pearson coefficient was used to analyze the correlation of miR-182-5p/BDNF with BNP and LVEF. ROC curve was employed to assess the potential of miR-182-5p or/and BDNF for the diagnosis of CHF. Kaplan–Meier survival curve was implemented to evaluate the prognostic value of miR-182-5p and BDNF.

Results

Serum miR-182-5p level was elevated and BDNF expression was lowered in CHF patients. Serum miR-182-5p in CHF patients was positively-related with BNP and inversely-correlated with LVEF, while serum BDNF was negatively-linked with BNP and positively-correlated with LVEF. ROC curve indicated the diagnostic value of serum miR-182-5p and BDNF for CHF and the diagnostic accuracy of miR-182-5p combined with BDNF was improved. Kaplan–Meier analysis unveiled that miR-182-5p low expression and BDNF high expression could predict the overall survival in CHF patients.

Conclusion

miR-182-5p expression is increased and BDNF level is decreased in CHF patients. miR-182-5p combined with BDNF can assist the diagnosis of CHF and predict a poor prognosis.

Non-Invasive Assessment of Left Ventricle Ejection Fraction: Where Do We Stand?

The left ventricular (LV) ejection fraction (EF) is the preferred parameter applied for the non-invasive evaluation of LV systolic function in clinical practice. It has a well-recognized and extensive role in the clinical management of numerous cardiac conditions. Many imaging modalities are currently available for the non-invasive assessment of LVEF. The aim of this review is to describe their relative advantages and disadvantages, proposing a hierarchical application of the different imaging tests available for LVEF evaluation based on the level of accuracy/reproducibility clinically required.

Biventricular Morphology and Function Reference Values Derived From a Large Sample of Healthy Chinese Adults by Magnetic Resonance Imaging

Background: Quantification of cardiac structure and function is essential for diagnostic interpretation and clinical decision making. We sought to establish cardiovascular magnetic resonance (CMR) reference values of left and right ventricular (LV and RV) morphology and function based on a large sample of healthy Chinese adults. Methods: Five hundred fifty validated healthy Chinese adults (aged 21-70 years; 323 men) free of hypertension, diabetes, and obesity were included in this study. All the subjects were stratified by gender (men and women) and age decades. On cine CMR, measurements of biventricular end-diastolic, end-systolic, and stroke volumes (EDV, ESV, and SV), ejection fraction (EF), and end-diastolic LV wall thickness (LVWT) and mass (LVM) were obtained. Results: Men had greater LVEDV (111.6 ± 19.8 vs. 94.6 ± 15.6 ml), LVESV (36.5 ± 9.8 vs. 28.2 ± 7.9 ml), LVM (121.1 ± 19.9 vs. 86.1 ± 14.5 g), global end-diastolic LVWT (8.1 ± 1.1 vs. 6.7 ± 1.0 mm), RVEDV (128.0 ± 23.6 vs. 101.7 ± 17.0 ml), and RVESV (53.5 ± 13.7 vs. 36.8 ± 8.9 ml), while women had greater LVEF (67.5 ± 5.4 vs. 70.4 ± 5.7%) and RVEF (58.5 ± 5.2 vs. 64.0 ± 5.3%) (all p < 0.001). For both men and women, age was negatively correlated with LVEDV (r = -0.31 and r = -0.32), LVESV (r = -0.37 and r = -0.47), RVEDV (r = -0.31 and r = -0.29), and RVESV (r = -0.33 and r = -0.44), while it was positively correlated with LVEF (r = 0.28 and r = 0.43) and RVEF (r = 0.28 and r = 0.41) (all p < 0.001). Aging was associated with increasing global end-diastolic LVWT and LVM/LVEDV in both sexes (all p < 0.001). Older age was associated with increasing LVM only in women (r = 0.36, p < 0.001), not in men (r = 0.05, p = 0.359). Conclusions: We systematically provide age-, sex-, and body size-specific CMR reference values for biventricular morphology and function based on a large sample of healthy Chinese adults. Biventricular structure and function are significantly associated with age and sex.

Layer-specific strain in patients with heart failure using cardiovascular magnetic resonance: not all layers are the same

BACKGROUND

Global longitudinal strain (GLS), most commonly measured at the endocardium, has been shown to be superior to left ventricular (LV) ejection fraction (LVEF) for the identification of systolic dysfunction and prediction of outcomes in heart failure (HF). We hypothesized that strains measured at different myocardial layers (endocardium = ENDO, epicardium = EPI, average = AVE) will have distinct diagnostic and predictive performance for patients with HF.

METHODS

Layer-specific GLS, layer-specific global circumferential strain (GCS) and global radial strain (GRS) were evaluated by cardiovascular magnetic resonance imaging (CMR) feature tracking in the Alberta HEART study. A total of 453 subjects consisted of healthy controls (controls, n = 77), at-risk for HF (at-risk, n = 143), HF with preserved ejection fraction (HFpEF, n = 87), HF with mid-range ejection fraction (HFmrEF, n = 88) and HF with reduced ejection fraction (HFrEF, n = 58). For outcomes analysis, CMR-derived imaging parameters were adjusted with a base model that included age and N-terminal prohormone of b-type natriuretic peptide (NT-proBNP) to test their independent association with 5-year all-cause mortality.

RESULTS

GLS_EPI distinguished all groups with preserved LVEF (controls - 16.5 ± 2.4% vs. at-risk - 15.5 ± 2.7% vs. HFpEF - 14.1 ± 3.0%, p < 0.001) while GLS_ENDO and all GCS (all layers) were similar among these groups. GRS was reduced in HFpEF (41.1 ± 13.8% versus 48.9 ± 10.7% in controls, p < 0.001) and the difference between GLS_EPI and GLS_ENDO were significantly larger in HFpEF as compared to controls. Within the preserved LVEF groups, reduced GRS and GLS_EPI were significantly associated with increased LV mass (LVM) and LVM/LV end-diastolic volume EDV (concentricity). In multivariable analysis, only GLS_AVE and GRS predicted 5-year all-cause mortality (all ps < 0.05), with the strongest association with 5-year all-cause mortality by Akaike Information Criterion analysis and significant incremental value for outcomes prediction beyond LVEF or GLS_ENDO by the likelihood ratio test.

CONCLUSION

Global strains measured on endocardium, epicardium or averaged across the wall thickness are not equivalent for the identification of systolic dysfunction or outcomes prediction in HF. The endocardium-specific strains were shown to have poorest all-around performance. GLS_AVE and GRS were the only CMR parameters to be significantly associated with 5-year all-cause mortality in multivariable analysis. GLS_EPI and GRS, as well as the difference in endocardial and epicardial strains, were sensitive to systolic dysfunction among HF patients with normal LVEF (> 55%), in whom lower strains were associated with increased concentricity.

Appraisal of Cardiac Ejection Fraction With Liver Disease Severity: Implication in Post-Liver Transplantation Mortality

BACKGROUND AND AIMS

Enhanced sympathetic nervous activation and peripheral vasodilation in end-stage liver disease (ESLD) may limit the importance of left ventricular ejection fraction (LVEF) as an influential prognosticator. We sought to understand the LVEF and cardiac dimensions in ESLD patients in order to define the LVEF threshold to predict all-cause mortality after liver transplantation (LT).

APPROACH AND RESULTS

Data were collected prospectively from the Asan LT Registry between 2008 and 2016, and outcomes were retrospectively reviewed. LVEF, end-diastolic volume index (EDVI), and end-diastolic elastance (Eed) were measured by preoperative echocardiography. Of 2,799 patients, 452 (16.2%) had LVEF ≤ 60%, with 29 (1.0%) having LVEF < 55% and 269 (9.6%) had LVEF ≥ 70%. Over a median of 5.4-year follow-up, 329 (11.8%) patients died: 104 (3.7%) died within 90 days. LVEF (range, 30%-81%) was directly proportionate to Model for End-stage Liver Disease (MELD) scores, an index of liver disease severity, in survivors but showed a fixed flat-line pattern in nonsurvivors (interaction P = 0.004 between groups), with lower EDVI (P = 0.013) and higher Eed (P = 0.001) in the MELD ≥ 20 group. Patients with LVEF ≤ 60% had higher 90-day (13% vs. 7.4%; log rank, P = 0.03) and median 5.4-year (26.7% vs. 16.2%; log rank, P = 0.003) mortality rates in the MELD ≥ 20 group, respectively, compared to those with LVEF > 60%. Specifically, in the MELD > 35 group, median 5.4-year mortality rate was 53.3% in patients with LVEF ≤ 60% versus 24% in those with LVEF > 60% (log rank P < 0.001). By contrast, mortality rates of LVEF ≤ 60% and > 60% were similar in the MELD < 20 group (log rank P = 0.817).

CONCLUSIONS

LVEF ≤ 60% is strongly associated with higher post-LT mortality rates in the MELD ≥ 20 group, indicating the need to appraise both LVEF and liver disease severity simultaneously. Enhanced diastolic elastance with low EDVI provides insights into pathogenesis of low LVEF in nonsurvivors with MELD ≥ 20.

Machine learning for prediction of sudden cardiac death in heart failure patients with low left ventricular ejection fraction: study protocol for a retroprospective multicentre registry in China

INTRODUCTION

Left ventricular ejection fraction (LVEF) ≤35%, as current significant implantable cardioverter-defibrillator (ICD) indication for primary prevention of sudden cardiac death (SCD) in heart failure (HF) patients, has been widely recognised to be inefficient. Improvement of patient selection for low LVEF (≤35%) is needed to optimise deployment of ICD. Most of the existing prediction models are not appropriate to identify ICD candidates at high risk of SCD in HF patients with low LVEF. Compared with traditional statistical analysis, machine learning (ML) can employ computer algorithms to identify patterns in large datasets, analyse rules automatically and build both linear and non-linear models in order to make data-driven predictions. This study is aimed to develop and validate new models using ML to improve the prediction of SCD in HF patients with low LVEF.

METHODS AND ANALYSIS

We will conduct a retroprospective, multicentre, observational registry of Chinese HF patients with low LVEF. The HF patients with LVEF ≤35% after optimised medication at least 3 months will be enrolled in this study. The primary endpoints are all-cause death and SCD. The secondary endpoints are malignant arrhythmia, sudden cardiac arrest, cardiopulmonary resuscitation and rehospitalisation due to HF. The baseline demographic, clinical, biological, electrophysiological, social and psychological variables will be collected. Both ML and traditional multivariable Cox proportional hazards regression models will be developed and compared in the prediction of SCD. Moreover, the ML model will be validated in a prospective study.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University (2017-SR-06). All results of this study will be published in international peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION NUMBER

ChiCTR-POC-17011842; Pre-results.

Impact of left ventricular function on clinical outcomes among patients with coronary artery disease

AIMS

To investigate the clinical relevance of contemporary cut-offs of left ventricular ejection fraction (LVEF) including an intermediate phenotype with mid-range reduced ejection fraction among patients with coronary artery disease undergoing percutaneous coronary intervention.

METHODS AND RESULTS

Patient-level data were summarized from five randomized clinical trials in which 6198 patients underwent clinically indicated percutaneous coronary intervention in different clinical settings. We assessed all-cause mortality as primary endpoint at five-year follow-up. According to the proposed LVEF cut-offs, 3816 patients were included in the preserved LVEF group (LVEF ≥ 50%), 1793 in the mid-range reduced LVEF group (LVEF 40-49%) and 589 patients in the reduced LVEF group (LVEF < 40%). Patients in the reduced LVEF group were at increased risk for the primary outcome of all-cause mortality compared with both, preserved and mid-range LVEF throughout five years of follow-up (adjusted hazard ratio 2.39 (95% confidence interval 1.75-3.28, p < 0.001) and 1.68 (95% confidence interval 1.34-2.10, p < 0.001), respectively). The risk of cardiac death and the composite endpoint of cardiac death, myocardial infarction, or stroke were higher for patients in the reduced LVEF group compared with the preserved and mid-range reduced LVEF groups, but also for the mid-range LVEF compared with preserved LVEF group (adjusted p < 0.05 for all comparisons) throughout five years. Irrespective of clinical presentation at baseline (stable coronary artery disease or acute coronary syndrome), patients with reduced or mid-range LVEF were at increased risk of all-cause mortality and cardiac death up to five years compared with the other group (adjusted p < 0.05 for all comparisons).

CONCLUSION

Patients with reduced LVEF <40% or mid-range LVEF 40-49% in the context of coronary artery disease undergoing clinically indicated percutaneous coronary intervention are at increased risk of all-cause mortality, cardiac death and the composite of cardiac death, stroke and myocardial infarction throughout five years of follow-up. The recently proposed LVEF cut-offs contribute to the differentiation and risk stratification of patients with ischaemic heart disease.

Cardiac Index by Transthoracic Echocardiography (CITE) study

AIMS

Left ventricular ejection fraction (LVEF) is the most frequently used parameter in the assessment of heart failure (HF). Cardiac index (CI) is considered a potential alternative to LVEF despite limited evidence. We aimed to assess and compare the predictive accuracy of LVEF and echocardiographically-assessed CI in HF patients.

METHODS AND RESULTS

A single-centre, retrospective cohort study was conducted in patients hospitalized for acute HF from 2010-2016. Cox proportional hazard models including either LVEF or CI were created to predict all cause death, cardiovascular (CV) death, or first HF-readmission. Of 334 patients included in the analysis, 58.7% exhibited HF with reduced LVEF (HFrEF). Left ventricular ejection fraction did not show correlation with any endpoint, while CI was predictive of HF-readmission in the entire cohort. Both the LVEF-based and CI-based models demonstrated moderate discriminative accuracy when predicting all-cause death, CV death, or HF-readmission. Left ventricular ejection fraction proved to be an independent predictor of CV mortality in HFrEF-patients, while CI was predictive of HF-readmission in the non-HFrEF group.

CONCLUSIONS

Left ventricular ejection fraction seemed to be associated more closely with disease severity in HFrEF, and CI in the non-HFrEF group, in this real-life cohort of elderly HF patients. The LVEF-based and CI-based predictive models have clinically similar predictive accuracy for mortality and HF-readmission, thus CI may be a potential alternative to LVEF in the assessment of left ventricular function. Cardiac index may be an important new tool in the assessment of HF patients with midrange or preserved LVEF.