Heart failure with preserved ejection fraction remains a formidable clinical challenge across modern healthcare systems globally. Emerging evidence indicates that systemic metabolic inflammation, coronary microvascular rarefaction, and neurohormonal activation drive this complex clinical syndrome. Therefore, establishing a reliable cardiometabolic HFpEF model is crucial for identifying novel molecular targets and validating therapeutic strategies. Recent experimental findings elucidate how combined metabolic stress and mineralocorticoid excess replicate multi-organ cardiopulmonary phenotypes in vivo.

Architecture of the Cardiometabolic HFpEF Model

Preclinical investigation of preserved ejection fraction has historically suffered from fragmented experimental design. Many historical models relied strictly on acute surgical interventions or non-physiological chemical nitric oxide depletion. However, those approaches failed to mirror human metabolic phenotypes accurately. In addition, global enzyme inhibition severely disrupted baseline vascular biology. To overcome these experimental limitations, investigators established a two-hit cardiometabolic HFpEF model combining genetic leptin receptor deficiency with chronic mineralocorticoid excess.

Specifically, female db/db mice received continuous d-aldosterone infusions via osmotic minipumps for four weeks. This paradigm paired severe obesity and insulin resistance with elevated systemic mineralocorticoid receptor stimulation. Furthermore, the protocol maintained endogenous nitric oxide synthase machinery intact. As a result, the animals developed robust features of human cardiometabolic disease without artificial endothelial disruption. Therefore, this translational platform provides an authentic physiological landscape to assess interconnected cardiac, vascular, and pulmonary responses under tightly controlled laboratory conditions.

Left Ventricular Mechanics and Atrial Stiffening

High-resolution echocardiography revealed striking myocardial structural and functional alterations in aldosterone-exposed diabetic animals. Notably, left ventricular ejection fraction remained preserved throughout the experimental period. However, the animals demonstrated prominent concentric left ventricular hypertrophy alongside elevated wall thickness. In addition, myocardial strain analysis unmasked significant impairments in global longitudinal strain, exposing subclinical systolic fiber dysfunction.

Furthermore, invasive and noninvasive evaluations demonstrated marked left ventricular diastolic impairment. Mitral inflow velocity profiles showed increased left ventricular filling pressures and prolonged isovolumic relaxation times. Consequently, sustained elevation of backward hydrostatic pressure promoted severe left atrial remodeling. Left atrial reservoirs exhibited significantly enlarged chamber dimensions and progressive wall stiffness. Moreover, left atrial conduit function declined noticeably, reflecting profound loss of mechanical compliance. Thus, the model faithfully mirrors human cardiometabolic cardiomyopathy, where elevated left-sided filling pressures trigger progressive biatrial strain and pulmonary venous hypertension.

Pulmonary Congestion and Right Ventricular Decoupling

Secondary pulmonary vascular disease represents a primary driver of functional decline in clinical heart failure. In this experimental model, chronic left-sided venous hypertension rapidly propagated backward into the pulmonary vascular bed. Consequently, aldosterone-treated db/db mice developed substantial pulmonary congestion, evidenced by markedly elevated wet-to-dry lung weight ratios. In addition, invasive right-heart catheterization demonstrated significantly elevated right ventricular systolic pressure and mean pulmonary arterial pressures.

Furthermore, noninvasive vascular markers confirmed significant pulmonary arteriolar remodeling. The ratio of pulmonary artery acceleration time to ejection time decreased substantially. Importantly, sustained pulmonary afterload provoked secondary right ventricular remodeling and mechanical failure. Echocardiographic measurements demonstrated significantly reduced tricuspid annular plane systolic excursion, signifying depressed right ventricular longitudinal contractility. Therefore, the combination of metabolic stress and aldosterone drives biventricular uncoupling. Ultimately, these findings reproduce the vicious hemodynamics observed in advanced human post-capillary pulmonary hypertension.

Vascular Endothelial Dysfunction and Arterial Remodeling

A major strength of this experimental paradigm lies in systemic vascular phenotyping. Thoracic aortic wire myography provided critical functional insights into endothelial and smooth muscle responses. Notably, untreated diabetic mice already showed moderately impaired endothelium-dependent relaxation to acetylcholine stimulation. However, four weeks of mineralocorticoid infusion severely exacerbated this vascular impairment. Therefore, aldosterone acts synergistically with hyperglycemia to accelerate large-vessel endothelial decay.

In contrast, endothelium-independent relaxation induced by the donor sodium nitroprusside remained completely preserved across experimental groups. This crucial divergence indicates that vascular smooth muscle guanylyl cyclase sensitivity remained structurally intact. Furthermore, vascular damage stemmed primarily from severely impaired endothelial nitric oxide bioavailability and heightened vascular reactive oxygen species production. Consequently, systemic macrovascular and microvascular tone becomes pathologically elevated. Thus, the model confirms that neurohormonal activation directly amplifies metabolic endothelial injury in cardiometabolic disease.

Translational Insights for Cardiometabolic Disease Management

The convergence of diabetes, obesity, and hypertension poses an unprecedented clinical challenge across clinical cardiology and primary care. In India, physicians encounter a massive burden of cardiometabolic syndrome occurring at younger ages and lower body mass thresholds. Consequently, cardiometabolic heart failure remains heavily underdiagnosed across outpatient clinics until patients present with severe pulmonary congestion and acute decompensation. Therefore, early identification of systemic microvascular inflammation and diastolic stiffening is essential for clinical practice.

Furthermore, these experimental findings strongly support aggressive multi-pathway neurohormonal and metabolic antagonism. Sodium-glucose cotransporter-2 inhibitors reduce myocardial stretch, improve vascular compliance, and optimize renal hemodynamics. In addition, modern nonsteroidal mineralocorticoid receptor antagonists offer potent vascular and renal protection without inducing severe hyperkalemia. Importantly, combining these cardioprotective agents addresses the dual metabolic and mineralocorticoid insults highlighted by this model. Clinicians must adopt proactive screening strategies to interrupt this destructive cardiopulmonary continuum before irreversible right ventricular failure develops.

Why is the db/db plus aldosterone model valuable for HFpEF research?

Traditional animal models often fail because they disrupt systemic nitric oxide synthase globally. Consequently, they obscure physiological endothelial responses during metabolic injury. In contrast, this cardiometabolic HFpEF model preserves endogenous nitric oxide pathways while combining profound leptin receptor deficiency with mineralocorticoid excess. Therefore, researchers can study how obesity, microvascular inflammation, and systemic neurohormonal activation interact. Ultimately, this approach accelerates translational testing of drug candidates against real-world human pathophysiology.

How does chronic aldosterone exposure exacerbate vascular dysfunction in diabetes?

Aldosterone accelerates vascular stiffening by stimulating mineralocorticoid receptors within vascular endothelial cells and smooth muscle layers. Furthermore, chronic exposure augments oxidative stress, which uncouples endothelial enzymes and reduces vascular nitric oxide bioavailability. In diabetic vasculature already compromised by advanced glycation, aldosterone drastically worsens endothelium-dependent vasodilation. However, smooth muscle responsiveness to exogenous nitrovasodilators remains largely intact. Therefore, targeted mineralocorticoid receptor antagonism provides substantial clinical protection against progressive diabetic vasculopathy.

What clinical implications do these findings have for Indian patients?

South Asian populations face an extraordinary burden of premature diabetes, abdominal obesity, and arterial stiffness. Consequently, Indian clinicians routinely manage heart failure patients presenting with preserved ejection fraction alongside severe pulmonary hypertension. Because aldosterone excess synergizes with metabolic dysregulation, comprehensive therapeutic regimens must extend beyond simple glycemic control. Specifically, early initiation of mineralocorticoid receptor antagonists, SGLT-2 inhibitors, and lifestyle interventions is essential to reduce hospitalizations and mitigate cardiopulmonary morbidity across our communities.

Disclaimer: This content is for informational and educational purposes only and should not be construed as medical advice. Healthcare professionals should make independent treatment decisions based on individual patient assessment. Refer to the latest local and national guidelines for clinical practice.

References

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2. Schiattarella GG, et al. Cardiometabolic heart failure with preserved ejection fraction: from molecular signatures to personalized treatment. Cardiovasc Res. 2025;121(7):981-995.
3. Valero-Munoz M, et al. Murine models of heart failure with preserved ejection fraction: a review of available platforms. J Cardiovasc Pharmacol Ther. 2024;29(2):145-159.