Pharmacological treatment of heart failure with preserved ejection fraction: a glimpse of light at the end of the tunnel?

The prevalence of coronary microvascular dysfunction (CMD) in heart failure with preserved ejection fraction (HFpEF): a systematic review and meta-analysis

To date, studies on the prevalence of coronary microvascular dysfunction (CMD) in heart failure with preserved ejection fraction (HFpEF) have not been summarized and analyzed as a whole. We conducted this systematic review and meta-analysis to assess the prevalence of CMD in patients with HFpEF. The PubMed, Cochrane, and Embase databases were searched from dates of inception until May 1, 2023. The primary outcome was the prevalence of CMD in patients with HFpEF, and values of CMD prevalence were pooled using a random-effects model. In total, 10 studies involving 1267 patients, including 822 with HFpEF and 445 without HFpEF, were included. The pooled prevalence of CMD in patients with HFpEF was 71% (95% CI, 0.63-0.79). In the subgroup analysis, the prevalence of CMD was 79% (95% CI, 0.71-0.87) by invasive measurement and 66% (95% CI, 0.54-0.77) by noninvasive measurement and 67% (95% CI, 0.52-0.82) with CFR < 2.0 and 75.0% (95% CI, 0.71-0.79) with CFR < 2.5. The prevalence of endothelium-independent CMD and endothelium-dependent CMD was 62% (95% CI, 0.53-0.72) and 50% (95% CI, 0.19-0.81), respectively. The prevalence of CMD was 74% (95% CI = 0.69-0.79) and 66% (95% CI = 0.41-0.90) in prospective and retrospective studies, respectively. Compared with the control group, patients with HFpEF had a significantly lower CFR (MD =  - 1.28, 95% CI =  - 1.82 to - 0.74, P < 0.01) and a higher prevalence of CMD (RR = 2.21, 95% CI = 1.52 to 3.20, P < 0.01). Qualitative analysis demonstrated that CMD might be associated with poor clinical outcomes in patients with HFpEF. In conclusion, this is the first systematic review and meta-analysis of all studies reporting the prevalence of CMD in patients with HFpEF. Our study demonstrates that CMD is common in patients with HFpEF and might be associated with poor clinical outcomes in these patients. Clinicians should attach importance to CMD in the diagnosis and treatment of HFpEF. The number of studies in this field is relatively small. Therefore, more high-quality studies are needed to explore the diagnostic and prognostic value of CMD and the potential role of CMD as a therapeutic target in patients with HFpEF.

Bibliometric and visual analysis of coronary microvascular dysfunction

Background

Coronary microvascular dysfunction (CMD) may play an important role in various cardiovascular diseases, including HFpEF and both obstructive and non-obstructive coronary artery disease (CAD). To date, there has been no bibliometric analysis to summarize this field. Here, we aim to conduct a bibliometric analysis of CMD to determine the current status and frontiers in this field.

Materials and methods

Publications about CMD were taken from the Web of Science Core Collection database (WOSCC). WOSCC's literature analysis wire, the VOSviewer 1.6.16, and CiteSpace 5.1.3 were used to conduct the analysis.

Results

A total of 785 publications containing 206 reviews and 579 articles are included in the sample. The leading authors are Iacopo Olivotto, Paolo G. Camici, and Carl J. Pepine. The most productive institutions are the University of Florence, Cedars Sinai Medical Center, and Harvard University. The most productive countries are the USA, Italy, and England. There are a total of 237 journals that contribute to this field, and the leading journals in our study were the International Journal of Cardiology, the European Heart Journal and the JACC. From 2012 to 2021, the top three most-cited articles focused on the association between HFpEF and CMD. The important keywords are heart failure, hypertrophic cardiomyopathy, chest pain, women, coronary flow reserve (CFR), endothelial dysfunction and prognostic value. "Positron emission tomography" shows the strongest burst strength, followed by "blow flow" and "artery." The keywords that started to burst from 2015 are particularly emphasized, including "heart failure," "coronary flow reserve," and "management."

Conclusion

Studies about CMD are relatively limited, and the largest contribution comes from the USA, Italy and England. More studies are needed, and publications from other countries should be enhanced. The main research hotspots in the CMD field include CMD in patients with HFpEF, sex differences, the new methods of diagnosis for CMD, and the effective treatment of CMD. Attention should be given to CMD in patients with HFpEF, and untangling the association between CMD and HFpEF could be helpful in the development of physiology-stratified treatment for patients with CMD and HFpEF.

Deep Learning Predicts Heart Failure With Preserved, Mid-Range, and Reduced Left Ventricular Ejection Fraction From Patient Clinical Profiles

Background: Left ventricular ejection fraction (LVEF) is the gold standard for evaluating heart failure (HF) in coronary artery disease (CAD) patients. It is an essential metric in categorizing HF patients as preserved (HFpEF), mid-range (HFmEF), and reduced (HFrEF) ejection fraction but differs, depending on whether the ASE/EACVI or ESC guidelines are used to classify HF. Objectives: We sought to investigate the effectiveness of using deep learning as an automated tool to predict LVEF from patient clinical profiles using regression and classification trained models. We further investigate the effect of utilizing other LVEF-based thresholds to examine the discrimination ability of deep learning between HF categories grouped with narrower ranges. Methods: Data from 303 CAD patients were obtained from American and Greek patient databases and categorized based on the American Society of Echocardiography and the European Association of Cardiovascular Imaging (ASE/EACVI) guidelines into HFpEF (EF > 55%), HFmEF (50% ≤ EF ≤ 55%), and HFrEF (EF < 50%). Clinical profiles included 13 demographical and clinical markers grouped as cardiovascular risk factors, medication, and history. The most significant and important markers were determined using linear regression fitting and Chi-squared test combined with a novel dimensionality reduction algorithm based on arc radial visualization (ArcViz). Two deep learning-based models were then developed and trained using convolutional neural networks (CNN) to estimate LVEF levels from the clinical information and for classification into one of three LVEF-based HF categories. Results: A total of seven clinical markers were found important for discriminating between the three HF categories. Using statistical analysis, diabetes, diuretics medication, and prior myocardial infarction were found statistically significant (p < 0.001). Furthermore, age, body mass index (BMI), anti-arrhythmics medication, and previous ventricular tachycardia were found important after projections on the ArcViz convex hull with an average nearest centroid (NC) accuracy of 94%. The regression model estimated LVEF levels successfully with an overall accuracy of 90%, average root mean square error (RMSE) of 4.13, and correlation coefficient of 0.85. A significant improvement was then obtained with the classification model, which predicted HF categories with an accuracy ≥93%, sensitivity ≥89%, 1-specificity <5%, and average area under the receiver operating characteristics curve (AUROC) of 0.98. Conclusions: Our study suggests the potential of implementing deep learning-based models clinically to ensure faster, yet accurate, automatic prediction of HF based on the ASE/EACVI LVEF guidelines with only clinical profiles and corresponding information as input to the models. Invasive, expensive, and time-consuming clinical testing could thus be avoided, enabling reduced stress in patients and simpler triage for further intervention.

Cardiac structural remodeling in hypertensive cardiomyopathy

Heart failure with preserved ejection fraction (HFpEF), which is a primary driver of morbidity and mortality, accounts for approximately half of all heart failure cases. Therefore, it is essential to develop preclinical animal models for HFpEF pharmacological treatment strategies. We created a porcine model of severe hypertension and hyperlipidemia by using a combination of deoxycorticosterone acetate (DOCA, 100 mg kg^-1), Western diet (WD) and angiotensin II infusion. Systolic blood pressure, echocardiography and invasive pressure-volume loop were assessed at baseline, 12 weeks and 18 weeks. A detailed histological assessment was also performed to determine the cardiac structural remodeling. Compared with controls (n=10), hypertensive animals (n=10) showed markedly higher systolic blood pressure (181 vs. 86 mm Hg) at 18 weeks. Concentric remodeling, characterized by a normal chamber size with a thicker wall, was observed in hypertensive animals. Left ventricle diastolic function showed a tendency toward decline, according to the echocardiographic data. Hemodynamic data showed that the end-diastolic pressure-volume relationship was elevated without changes in the end-systolic pressure-volume relationship. Histological results revealed that the fibrotic area in hypertensive animals (P<0.05 vs. controls) and the fibrotic area in the posterior wall of hypertensive animals' left atria were larger than other sites of the left atria (P<0.05 vs. other sites). This model can mimic clinical HFpEF to some degree. We found that the posterior wall of the left atrium is more susceptible to atrial remodeling associated with hypertension compared with other regions of the left atrium.

Outcomes in patients with heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HF-PEF) represents a heterogenous group of patients with HF, more commonly affecting older women, with a history of hypertension and, less commonly, coronary disease, than patients with HF with reduced ejection fraction (HF-REF). Patients with HF-PEF have lower short-term and longer-term mortality than patients with HF-REF. At present, therapeutic interventions that have had proven benefits for patients with HF with reduced EF have not been shown to have similar benefits for patients with HF-PEF and there remains an urgent need for new therapeutic strategies to improve the clinical outcomes for patients with HF-PEF.

Current treatment of heart failure with preserved ejection fraction: should we add life to the remaining years or add years to the remaining life?

According to the ejection fraction, patients with heart failure may be divided into two different groups: heart failure with preserved or reduced ejection fraction. In recent years, accumulating studies showed that increased mortality and morbidity rates of these two groups are nearly equal. More importantly, despite decline in mortality after treatment in regard to current guideline in patients with heart failure with reduced ejection fraction, there are still no trials resulting in improved outcome in patients with heart failure with preserved ejection fraction so far. Thus, novel pathophysiological mechanisms are under development, and other new viewpoints, such as multiple comorbidities resulting in increased non-cardiac deaths in patients with heart failure and preserved ejection fraction, were presented recently. In this review, we will focus on the tested as well as the promising therapeutic options that are currently studied in patients with heart failure with preserved ejection fraction, along with a brief discussion of pathophysiological mechanisms and diagnostic options that are helpful to increase our understanding of novel therapeutic strategies.

Galectin-3 in heart failure with preserved ejection fraction

In the last decades it has been appreciated that many patients with heart failure (HF) suffer from HF with preserved ejection fraction (HFpEF). The diagnosis and treatment of HFpEF is difficult, as we lack specific markers of the disease and no specific treatments have been identified. Galectin-3 has a strong relationship to several aspects of the pathophysiology of HF, especially myocardial fibrosis, the transition from compensated to decompensated HF, and co-morbidities such as renal disease and diabetes. Many of these traits are very commonly observed in patients with HFpEF, and this suggests that galectin-3 may be particularly important and useful in the study of HFpEF. This review summarizes our knowledge of the role of galectin-3 in fibrosis, specifically in experimental models of HF and HFpEF. Galectin-3 may be a marker and also a causal factor, and experimental studies suggested that galectin-3 may be a target for therapy in HFpEF. The detrimental effects of aldosterone may, in part, be conferred via galectin-3, and there are data to suggest that aldosterone blockers are of more benefit in patients with high levels of galectin-3. Furthermore, the relationship of galectin-3 to clinical correlates of developing HFpEF in human subjects is discussed, and the association between increased levels of galectin-3 and new-onset HF and mortality in the general population is highlighted. Additionally, the usefulness of galectin-3 in patients with established HFpEF is described. We conclude that galectin-3 may be useful for early detection, phenotyping, risk stratification, and therapeutic targeting of individuals with early or established HFpEF in which fibrosis is a major contributor to the disease. Finally, we propose areas of further research that should validate the role of galectin-3 in HFpEF.