Clinical Research Directory

Chorioretinal Imaging, Vascular Biomarkers, and Ultra-Trail: A Pilot Study

Retinal and choroidal microcirculation is a relevant biomarker of systemic vascular health and lies at the heart of eye-heart interactions. Noninvasive retinal imaging, particularly OCT angiography (OCT-A), now makes it possible to examine retinal and choroidal microvascularization in vivo and to study its relationship with systemic cardiovascular and neurovascular mechanisms. Ultra-endurance activities, such as ultra-trail races, induce significant systemic hemodynamic changes, including dehydration, variations in perfusion pressure, prolonged sympathetic activation, and redistribution of blood flow. These physiological adaptations could lead to acute and reversible changes in retinal and choroidal vascular parameters as measured by retinophotography and OCT angiography. Several studies suggest that intense physical exercise may be accompanied by significant changes in retinal and choroidal microvascular perfusion. In particular, a significant decrease in the vascular density of the superficial retinal plexus has been observed following intense exercise in a healthy population, suggesting a transient change in retinal microcirculation. Similarly, following a marathon, a decrease in the retinal vascular density index (RVDI) has been reported, likely related to exercise-induced vasoconstriction and a transient reduction in retinal blood flow. This decrease may also be exacerbated by the drop in systemic blood pressure and the relative dehydration observed after the race. More broadly, intense endurance exercise is accompanied by cardiovascular and neurohormonal adaptations, particularly through activation of the renin-angiotensin-aldosterone system, which may modulate ocular perfusion. Scott et al. demonstrated, following a 160-km ultramarathon, significant alterations in left ventricular function and a major elevation in NT-pro-BNP, indicating systemic cardiovascular stress that was markedly greater than that observed after a standard marathon. Furthermore, a multi-omics study conducted during the Ultra-Trail du Mont-Blanc (171 km) revealed systemic oxidative stress, marked inflammation with elevated IL-6 levels, and profound metabolic changes affecting red blood cells-mechanisms recognized as being involved in microvascular dysfunction. However, these variations primarily reflect functional changes in perfusion related to hemodynamic status and autonomic tone, rather than true structural microvascular remodeling or angiogenesis. Metrics derived from OCT angiography, such as vascular density or perfusion density, are in fact sensitive to systemic variations in circulating volume, perfusion pressure, and the quality of the acquired signal. In this context, the effects of ultra-endurance exercise on the eye remain poorly characterized. Research in this area is necessary to better understand the acute physiological adaptations of ocular microcirculation and to highlight the value of retinal imaging as a tool for cardiovascular research and prevention within an integrated eye-heart approach.

OCT-A Biomarkers for Cognitive Impairment in Patients With Chronic Atrial Fibrillation

The OCTAF study is a monocentric, cross-sectional pilot study designed to investigate the relationship between retinal microvascular biomarkers and cognitive impairment in patients with atrial fibrillation (AF). Atrial fibrillation is a highly prevalent cardiac arrhythmia associated not only with stroke and cardiovascular complications but also with an increased risk of cognitive decline, even in the absence of overt cerebrovascular events. Current approaches to detect cognitive impairment are often time-consuming and resource-intensive, highlighting the need for simple, non-invasive screening tools. The retina, often described as a "window to the brain," provides a unique opportunity to assess microvascular health, and Optical Coherence Tomography Angiography (OCT-A) allows detailed, non-invasive visualization of retinal blood flow and structure. In this study, 40 patients with AF aged 40 years or older will be recruited at UZ Brussels and stratified according to cognitive status using the Montreal Cognitive Assessment (MoCA), with a score below 26 indicating cognitive impairment. Each participant will undergo a standardized evaluation including a questionnaire capturing demographic characteristics and vascular risk factors, a MoCA cognitive test, and OCT-A imaging of the retina and optic nerve head. The imaging will focus on quantifying vessel density in different retinal layers, including the superficial and deep capillary plexuses and radial peripapillary capillaries, as well as measuring the foveal avascular zone area. The primary objective is to compare these OCT-A parameters between AF patients with and without cognitive impairment. Statistical analyses will be exploratory and performed using regression models to account for potential confounders such as age and cardiovascular risk factors. As a pilot study, the aim is not to establish definitive causal relationships but to assess feasibility, characterize variability, and generate preliminary data that may guide future larger-scale studies. The study is expected to run from late 2025 to September 2026 and will adhere to ethical standards and Good Clinical Practice guidelines. Ultimately, the study seeks to determine whether retinal imaging could serve as a practical and non-invasive tool for early detection of cognitive decline in patients with atrial fibrillation.

Optimal Strategy to Correct Stent underexpAnsion in Resistant Lesions

Percutaneous coronary intervention (PCI) for in-stent restenosis (ISR) accounts for 5-10% of PCI. ISR may be linked to mechanical complications mainly under-expansion (UE), neointimal hyperplasia and/or neoatherosclerosis. International guidelines recommends non-compliant and very-high-pressure balloons, which lead to sub-optimal angiographic and clinical results. Recently, observational studies have suggested the feasibility and safety of intravascular lithotripsy (IVL) in UE treatment. There are no prospective randomised controlled studies comparing intravascular lithotripsy with balloons in ISR with UE.

Coronary Evaluation And Guided Lesion Exploration Using Photon-counting CT and Intracoronary Imaging Techniques

This study evaluates the diagnostic accuracy and limitations of photon-counting computed tomography (PCCT) in characterizing coronary plaque, with comparisons to optical coherence tomography (OCT) and intravascular ultrasound (IVUS). The objective is to assess whether cardiac ultra-high resolution (UHR) PCCT -with its improved spatial resolution and superior soft tissue contrast relative to conventional CT- can serve as a reliable, non-invasive alternative for coronary plaque assessment and support clinical decision-making. A total of 100 patients with either acute or chronic coronary syndrome will be enrolled, including 40 individuals with suspected in-stent restenosis and 10 patients one year post-percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). All participants will undergo invasive coronary angiography based on current European Society of Cardiology guidelines. Cardiac PCCT imaging will be conducted shortly before the angiographic procedure, accompanied by invasive OCT evaluation. Additionally, a subgroup of 10 patients will undergo both OCT and IVUS, allowing for direct comparison across imaging modalities. OCT, regarded as the gold standard for plaque characterization, offers near-histological resolution for identifying plaque features, while IVUS is particularly effective in evaluating plaque burden and volume.