High Embolic Risk with Orbital Atherectomy for Calcified Peripheral Artery Disease.

PURPOSE: Orbital atherectomy (OA) is used to treat heavily calcified peripheral arterial lesions, aiming to improve vessel compliance and reduce the need for high-pressure angioplasty and stenting. However, clinical data raise concerns regarding distal embolization, vessel injury, and uncertain long-term benefit. This study aimed to evaluate biomechanical and embolic effects of OA in calcified human femoropopliteal arteries (FPAs). METHODS: OA was studied in 10 human FPAs with advanced atherosclerosis and calcification. A pulsatile flow loop approximated FPA hemodynamics. Sequential OA and balloon angioplasty (BA) were performed, followed by μCT to quantify luminal changes. Pressure and flow sensors assessed translesional pressure gradients and flow. Embolic burden was captured via 100 μm filters and quantified using image analysis. Arterial pulsatility was evaluated using duplex ultrasound and optical imaging. RESULTS: OA and BA produced additive luminal gains (0.409 mL) but frequently caused dissections. OA generated substantial embolic debris (mean area 0.386 ± 1.654 mm2), with 90% of arteries releasing fragments ≥ 1 mm and 10% > 5 mm. BA added smaller debris (0.143 ± 0.361 mm2). Translesional pressure gradients decreased in 40% of arteries, showed no improvement in 50%, and worsened in 10%. Net flow improved in 40% of arteries and was unchanged or decreased in 60%. Inner diameter (ID) pulsatility increased from 1.5 ± 0.7% to 2.3 ± 0.5%, while outer diameter pulsatility remained unchanged. CONCLUSIONS: OA improves lumen volume and ID-based pulsatility but consistently produces large emboli and vessel wall injury. These findings provide mechanistic support for the high embolic complication rates and mixed long-term clinical outcomes, emphasizing the importance of embolic protection and careful patient selection.