Photoplethysmography-Derived Flow-Mediated Dilation as a Non-Invasive Marker of Endothelial Function in Erectile Dysfunction.

Background: Endothelial dysfunction plays a central role in the pathophysiology of erectile dysfunction (ED) and reflects systemic vascular impairment. Photoplethysmography-derived flow-mediated dilation (PPG-FMD) has emerged as a novel, non-invasive approach for assessing endothelial function. This study aimed to investigate the utility of PPG-FMD as a marker of systemic endothelial function in patients with ED without overt coronary artery disease. Methods: In this observational cross-sectional comparative study, patients with vascular ED (n = 24), non-vascular ED (n = 18), and healthy controls (n = 30) were evaluated. Endothelial function was assessed using PPG-FMD. Key parameters, including dilation index, time to maximum dilation, area under the curve, and dilation index slope, were analyzed and compared across groups. Results: PPG-FMD parameters indicated significantly impaired endothelial function in patients with vascular ED compared to both non-vascular ED patients and controls (p < 0.01). Dilation index and area under the curve were significantly reduced in the vascular ED group. Conclusions: These preliminary findings support the presence of systemic endothelial dysfunction in vascular ED and suggest that PPG-FMD-derived parameters may serve as a non-invasive indicator of endothelial function. Further studies incorporating larger cohorts and validation against established endothelial assessment methods are required to determine its clinical applicability.