Effect of orbital atherectomy in calcified coronary artery lesions as assessed by optical coherence tomography.

OBJECTIVES: We sought to assess plaque modification and stent expansion following orbital atherectomy (OA) for calcified lesions using optical coherence tomography (OCT).

BACKGROUND: The efficacy of OA for treating calcified lesions is not well studied, especially using intravascular imaging in vivo.

METHODS: OCT was performed preprocedure, post-OA, and post-stent (n = 58). Calcium modification after OA was defined as a round, concave, polished calcium surface. Calcium fracture was complete discontinuity of calcium.

RESULTS: Comparing pre- vs post-OA OCT (n = 29), calcium area was significantly decreased post-OA (from 3.4 mm2 [2.4-4.7] to 2.9 mm2 [1.9-3.9], P < 0.001). Poststent percent calcium fracture (calcium fracture length/calcium length) correlated with post-OA percent calcium modification (calcium modification length/calcium length) (r = 0.31, P = 0.01). Among 75 calcium fractures in 35 lesions, maximum calcium thickness at the fracture site was greater with vs without calcium modification (0.58 mm [0.50-0.66] vs 0.45 mm [0.38-0.52], P = 0.003). Final optimal stent expansion, defined as minimum stent area ≥6.1 mm2 or stent expansion ≥90% (medians of this cohort) at the maximum calcium angle site, was observed in 41 lesions. Larger post-OA lumen area (odds ratio 2.64; 95% CI 1.21-5.76; P = 0.02) and the presence of calcium fracture (odds ratio 6.77; 95% CI 1.25-36.6; P = 0.03) were independent predictors for optimal stent expansion.

CONCLUSIONS: Calcium modification by OA facilitates poststent calcium fracture even in thick calcium. Greater calcium modification correlated with greater calcium fracture, in turn resulting in better stent expansion.