Can FD-OCT Predict the crack in the calcified coronary plaque after balloon angioplasty following rotational atherectomy?

Background: Calcified lesions sometimes cause stent underexpansion which increase the risk of stent thrombosis and target lesion revascularization after percutaneous coronary intervention (PCI). Rotational atherectomy (RA) plays an important role to facilitate the dilation or stenting of these lesions. Optical coherence tomography (OCT) is a new imaging modality that visualize calcium component without signal attenuation. The aim of this study was to examine the effects of RA and subsequent balloon angioplasty on calcified coronary plaques using OCT. Methods: From October 2011 to December 2012, a total of 17 calcified lesions requiring RA in patients with CAD were interrogated by FD-OCT. In all patients, OCT images just after atherectomy and after balloon angioplasty (before stent implantation) were analyzed to assess calcium component. The thickness of the calcium component was measured at its thinnest part. The arc, thickness of the calcium component, and the lumen area in each segment as determined by OCT were measured at 1-mm intervals. The incidence of calcium cracks after balloon angioplasty following RA was also assessed by OCT. Results: A total of 328 segments in 17 lesions were analyzed. Calcium cracks were observed in 138 segments (42%) in 14 patients (82%). The segment with calcium cracks after angioplasty had smaller lumen area (3.39±1.43 vs 3.92±1.78 mm2, P<0.001), larger calcium arc (290±78 vs 164±64 degree, P<0.001), and thinner calcium thickness (0.61±0.31 vs 1.03±0.42 mm, P<0.001) than those without cracks. Receiver-operating characteristic curve analysis revealed that the optimal threshold of lumen area, calcium arc, and calcium thickness to predict crack after angioplasty were 3.14mm2, 210degrees, and 0.70mm, respectively. Conclusion: FD-OCT is effective for evaluating plaque characteristics in calcified coronary lesions. Smaller lumen area, larger calcium arc, and thinner calcium thickness were associated with calcium cracks after balloon angioplasty following rotational atherectomy.