Clinical Research Directory

FFR-Guided Revascularization in Atherosclerotic Renal Artery Stenosis

For patients with atherosclerotic renal artery stenosis, the results of randomized controlled trials published in recent years have failed to demonstrate that renal artery stenting is superior to optimal medical therapy. However, these studies still have limitations. Fractional flow reserve (FFR) has been extensively studied in coronary artery disease, and it has been established that FFR-guided revascularization is superior to both angiography-guided percutaneous coronary intervention and medical therapy alone. Whether FFR can guide interventional treatment in patients with renal artery stenosis and hypertension is currently a hot topic in the field of renal artery stenosis research. Eligible patients meeting the inclusion criteria were enrolled. Pharmacologically induced FFR values were measured as the baseline. Patients with FFR ≥ 0.8 were randomly assigned to either the medical therapy group or the stenting group, while patients with FFR \< 0.8 underwent stent implantation. Changes in eGFR, 24-hour systolic blood pressure, and 24-hour diastolic blood pressure from baseline to 12 months were compared among the groups.

DECisive Intracoronary PHysiology and Imaging in the Evaluation and Reclassification of Non-culprit Lesions in Acute Coronary Syndrome

Despite all advances in diagnostic and therapeutic methods over the past century, ischemic heart disease (IHD) remains a leading cause of mortality and morbidity worldwide. IHD develops as a result of reversible or irreversible impairment of myocardial perfusion in acute or chronic settings. This perfusion abnormality most commonly arises from compromise of epicardial coronary artery patency due to stenosis, occlusion, or vasomotor abnormalities. Structural and/or functional alterations in the microcirculation may also contribute to impaired myocardial perfusion. Conditions in which myocardial perfusion is acutely compromised are classified as acute coronary syndromes (ACS), whereas reversible ischemia developing on a chronic basis is evaluated under the umbrella of chronic coronary syndromes (CCS). In the assessment of epicardial (macrovascular) or microvascular pathologies leading to ischemia in CCS, angiography, a macroscopic lumenographic method, is often insufficient. Intracoronary pressure and flow measurements are required to determine the impact of angiographically detected epicardial lesions on coronary blood flow, perfusion pressure, and consequently myocardial perfusion. These measurements are referred to as invasive intracoronary physiology (IIP). Current guidelines recommend that decisions regarding revascularization of intermediate epicardial lesions should be based on IIP. Revascularization guided by IIP is associated with reduced mortality and morbidity, along with a lower stent burden. IIP can be performed using pressure-based, flow-based, or combined strategies. Recent multinational studies indicate that strategies integrating both flow and pressure parameters achieve better clinical outcomes with fewer interventions and reduced stent implantation compared to pressure-only approaches. Indeed, in cases where coronary flow and flow reserve are preserved, abnormalities in pressure parameters alone may not justify revascularization. Nevertheless, lesions deemed not to be associated with reversible ischemia based on IIP may still pose a risk due to plaque erosion/rupture and subsequent thrombotic cascades that can acutely compromise the lumen. Many acute coronary syndromes arise from lesions that are hemodynamically insignificant (i.e., do not affect flow) and unrelated to reversible ischemia in the CCS setting, but which undergo sudden near-total or total occlusion. The histopathological characteristics of any coronary lesion can be evaluated using intracoronary imaging techniques. Intracoronary Optical Coherence Tomography (IC-OCT) is a high-resolution, real-time imaging modality that quantitatively assesses lipid-rich plaque content, evaluates the thickness and stability of the fibrous cap separating this content from the lumen, and provides detailed information regarding minimal lumen area, lesion morphology, surface characteristics, presence of erosion, and plaque vulnerability to rupture. IC-OCT can identify lesions that are hemodynamically insignificant yet may benefit from revascularization and have the potential to cause ACS. Combined evaluation using IC-OCT and IIP enables an integrated assessment of both the relationship with chronic reversible perfusion impairment and the risk of precipitating ACS for each lesion and coronary segment, thereby facilitating optimal revascularization strategies. Despite the available evidence and guideline recommendations in CCS, the use of IC-OCT and IIP in the context of ACS remains limited due to procedural challenges and variability in practical application. These methods are not routinely recommended in guidelines and, in some cases, are even discouraged. However, the optimal strategy for revascularization of non-culprit lesions in ACS remains uncertain, and no consensus has yet been established. Patients with ACS are at increased risk for recurrent events arising from all coronary lesions. Therefore, accurate evaluation and preventive revascularization strategies for these lesions are expected to provide substantial benefit. Our study aims to reclassify and characterize non-culprit lesions in patients with ACS using combined IC-OCT and IIP assessment.

Dedinje FFR/QFR Registry

Quantitative Flow Ratio (QFR) has shown good diagnostic performance against Fractional Flow Reserve (FFR) in several meta-analyses, comparable or even superior to nonhyperemic pressure ratios. However, the reproducibility of QFR is modest and there is high inter- and intra-observer variability even when fairly experienced but non-core lab operators (at least 150 QFR procedure experience) are performing the analysis. Although smaller studies have demonstrated that non-core analysis and even paramedical user analysis can have good correlation with FFR, the concern about the diagnostic performance of QFR in real-world clinical practice by inexperienced users remains. The primary objective of "Dedinje FFR/QFR Registry" is to determine the feasibility and diagnostic performance of QFR analysis by vendor-certified inexperienced medical users in a real-world setting using FFR as the gold standard. All patients \>18 years old who present to the Institute for Cardiovascular Diseases "Dedinje" and undergo a planned or ad hoc FFR procedure will be asked to participate in the registry. FFR procedure is performed according to the standardized institutional protocol. QFR analysis will be subsequently performed offline according to a standard operating procedure.