Abstract
BACKGROUND: Orbital atherectomy (OA) operates via high-speed elliptical crown rotation, enabling focal plaque modification through controlled forward and backward movement. AIMS: This study aimed to identify the anatomical conditions that optimise OA effectiveness on nodular calcium within curved lesions, using in vitro models to allow quantitative assessment of the debulked volume. METHODS: Forty stenotic vessel models containing nodular calcium were created with varying anatomical parameters: two calcium positions (inner vs outer curve), two curvature radii (CR: 10 mm or 20 mm), and two bending angles (BA: 100° or 60°). Each model underwent OA with the Diamondback 360 Coronary OA System, using two 30-second low-speed passes and one 30-second high-speed pass. Microcomputed tomography was performed pre- and post-ablation to measure the calcium volume reduction, maximum depth, and width. RESULTS: Ablation was significantly greater for nodular calcium on the inner curve compared to that on the outer curve (6.6±0.4 mm³ vs 2.7±0.4 mm³; p<0.0001). Among models with calcium on the inner curve, CR20/BA60 showed the highest volume reduction (8.3±1.4 mm³). For models with calcium on the outer curve, CR20/BA100 resulted in the greatest ablation (5.2±0.9 mm³). Ablation depth, more than width, correlated with the total ablated volume. CONCLUSIONS: Nodular calcium located on the inner curve is more effectively treated with OA. The combination of curvature radius and the bending angle significantly influences procedural efficiency, underscoring the importance of lesion anatomy in OA planning.