Endothelial Function And Ph: Correlations Between Flow-Mediated Dilatation And Invasive Hemodynamic Parameters

Background: Endothelial dysfunction plays a central role in the pathophysiology of pulmonary hypertension (PH), contributing to vascular remodeling, vasoconstriction, and increased pulmonary vascular resistance (PVR). While right heart catheterization (RHC) remains the gold standard for PH diagnosis, its invasive nature underscores the need for noninvasive predictive tools. This study aimed to evaluate the correlation between peripheral endothelial function, assessed noninvasively by brachial artery flow-mediated dilation (FMD), and invasive hemodynamic parameters in patients with suspected PH. Methods: A prospective study was conducted on 95 consecutive outpatients with suspected PH, referred to the Pulmonary Hypertension Ambulatory Clinic at “Policlinico Riuniti” in Foggia, Italy, between February 2021 and June 2023. Patients underwent comprehensive evaluations, including clinical examination, echocardiography, FMD, and RHC. FMD was performed according to established guidelines, and hemodynamic parameters such as systolic pulmonary artery pressure (sPAP), mean pulmonary artery pressure (mPAP), and PVR were measured via RHC. Statistical analyses included Pearson’s correlation, multivariable regression, and stratification based on FMD and peak tricuspid regurgitation velocity (peak TRV). Results: FMD values were inversely correlated with sPAP (r = -0.29, p = 0.016), with a borderline correlation to PVR (r = -0.21, p = 0.78). Multivariable regression confirmed FMD as an independent predictor of sPAP (B = -47, p = 0.02). Stratification by FMD and peak TRV revealed progressively higher sPAP, mPAP, and PVR in patients with impaired FMD and elevated peak TRV (p for trend <0.001). Patients with both impaired FMD and peak TRV had the highest hemodynamic burden, suggesting FMD as a potential noninvasive marker for PH severity. Conclusion: This study demonstrates that FMD, in combination with echocardiographic parameters, can serve as a noninvasive tool for predicting PH severity and guiding patient selection for RHC. The inverse correlation between FMD and sPAP, along with the progressive increase in hemodynamic parameters in patients with impaired FMD, highlights the systemic nature of endothelial dysfunction in PH. These findings support the use of FMD as a cost-effective and reproducible method for risk stratification and monitoring in PH. Further multicenter studies are needed to validate these results and explore the role of FMD in treatment response and disease progression.