Optical Coherence Tomography Compared with IVUS, optical coherence tomography has greater resolution (10 to 20 micronmeter axially) but more limited depth of imaging (1 to 1.5 mm).504,505 Unlike IVUS, optical coherence tomography requires that the artery be perfused with saline solution or crystalloid during image acquisition and therefore does not permit imaging of ostial lesions. Clinical studies have shown low optical coherence tomography complication rates,506,507 similar to those of IVUS.508 The excellent resolution of optical coherence to- mography permits detailed in vivo 2-dimensional imaging of plaque morphological characteristics (eg, calcification, lipid, thrombus, fibrous cap thickness, and plaque ulceration or rupture)508 510 and evaluation of the arterial response to stent implantation (eg, stent strut neointimal thickness and appo- sition)511 513 and may be of value in clinical research. The appropriate role for optical coherence tomography in routine clinical decision making has not been established. 5.5. Adjunctive Therapeutic Devices 5.5.1. Coronary Atherectomy: Recommendations Class IIa 1. Rotational atherectomy is reasonable for fibrotic or heavily calcified lesions that might not be crossed by a balloon catheter or adequately dilated before stent implantation.514,515 (Level of Evidence: C) Class III: NO BENEFIT 1. Rotational atherectomy should not be performed routinely for de novo lesions or in-stent resteno- sis.516 519 (Level of Evidence: A) Rotational atherectomy in RCTs was associated with higher rates of MACE at 30 days and no reduction in restenosis. It has a limited role in facilitating the dilation or stenting of lesions that cannot be crossed or expanded with PCI.520,521 Devices for directional coronary atherectomy are no longer marketed in the United States. 5.5.2. Thrombectomy: Recommendation Class IIa 1. 