Turning the Retrospectroscope on Heart Failure With Preserved Ejection Fraction

NOX1 mediates metabolic heart disease in mice and is upregulated in monocytes of humans with diastolic dysfunction

AIMS

Microvascular inflammation plays an important role in the pathogenesis of diastolic dysfunction (DD) and metabolic heart disease. NOX1 is expressed in vascular and immune cells and has been implicated in the vascular pathology of metabolic disease. However, its contribution to metabolic heart disease is less understood.

METHODS AND RESULTS

NOX1-deficient mice (KO) and male wild-type (WT) littermates were fed a high-fat high-sucrose diet (HFHS) and injected streptozotocin (75 mg/kg i.p.) or control diet (CTD) and sodium citrate. Despite similar weight gain and increase in fasting blood glucose and insulin, only WT-HFHS but not KO-HFHS mice developed concentric cardiac hypertrophy and elevated left ventricular filling pressure. This was associated with increased endothelial adhesion molecule expression, accumulation of Mac-2-, IL-1β- and NLRP3-positive cells and nitrosative stress in WT-HFHS but not KO-HFHS hearts. Nox1 mRNA was solidly expressed in CD45+ immune cells isolated from healthy mouse hearts, but was negligible in cardiac CD31+ endothelial cells. However, in vitro, Nox1 expression increased in response to LPS in endothelial cells and contributed to LPS-induced upregulation of Icam-1. Nox1 was also upregulated in mouse bone marrow-derived macrophages in response to LPS. In peripheral monocytes from age- and sex-matched symptomatic patients with and without DD, NOX1 was significantly higher in patients with DD compared to those without DD.

CONCLUSIONS

NOX1 mediates endothelial activation and contributes to myocardial inflammation and remodeling in metabolic disease in mice. Given its high expression in monocytes of humans with DD, NOX1 may represent a potential target to mitigate heart disease associated with DD.

TRANSLATIONAL PERSPECTIVE

In their multifactorial pathogenesis, diastolic dysfunction (DD) and heart failure with preserved ejection fraction (HFpEF) still remain poorly understood. They frequently occur in patients with obesity and metabolic syndrome. Microvascular inflammation and dysfunction have recently been recognized as major driving forces. We show that genetic deletion of Nox1 prevents cardiac inflammation, remodeling and dysfunction in metabolic disease in mice and find NOX1 upregulated in peripheral monocytes of patients with DD. These findings add to our understanding how obesity, inflammation and heart disease are linked, which is a prerequisite to find therapeutic strategies beyond the control of co-morbidities in HFpEF.

The tip of the iceberg: finding patients with heart failure with preserved ejection fraction in primary care. An observational study

Background

Heart failure with preserved ejection fraction (HFpEF) is under-identified in primary care.

Aim

The aim of this study was to determine what information is available in patients' primary care practice records that would identify patients with HFpEF.

Design & setting

Record review in two practices in east of England.

Method

Practices completed a case report form on each patient on the heart failure register and sent anonymised echocardiography reports on patients with an ejection fraction (EF) >50%. Reports were reviewed and data analysed using SPSS (version 25).

Results

One hundred and forty-eight patients on the heart failure registers with mean age 77 +12 years were reviewed. Fifty-three patients (36%) had possible HFpEF based on available information. These patients were older and multimorbid, with a high prevalence of overweight and obesity. Confirmation of diagnosis was not possible as recommended HFpEF diagnostic information (natriuretic peptides, echocardiogram parameters of structural heart disease and diastolic function) was widely inconsistent or absent in these patients.

Conclusion

Without correct identification of HFpEF, patient management may be suboptimal or inappropriate, and lack the needed focus on comorbidities and lifestyle that can improve patient outcomes. This study describes in detail the characteristics of many of the patients who probably have HFpEF in a real-world sample, and the improvements and diagnostic information required to better identify them. Identifying more than the tip of the iceberg that is the HFpEF population will allow the improvement of the quality of their management, the prevention of ineffective health care, and the recruitment of patients into research.