Histologic findings in specimens obtained by percutaneous directional coronary atherectomy.

Percutaneous directional coronary atherectomy is a second-generation, catheter-based technique for the treatment of coronary artery disease that provides a unique opportunity to study tissue obtained from coronary artery stenoses. We reviewed the histologic findings in 131 coronary atherectomy specimens from 116 patients, including 79 primary lesions and 52 restenosis lesions that developed after a prior coronary intervention. Although atherosclerotic plaque was seen in 95% of cases, an important observation was the finding of deep arterial wall components in the majority of patients, including media in 61% and adventitia in 31%. Despite the relatively common finding of deep wall components, this was not associated with acute clinical complications. Intimal hyperplasia was seen in 64% of cases, including 96% of restenosis lesions. However, intimal hyperplasia was also seen in 45% of primary lesions. The intimal hyperplasia in primary and restenosis lesions was histologically identical and was characterized by cells that showed staining for vimentin and muscle-specific actin, consistent with a myogenous and/or myofibroblastic phenotype. Restenosis was seen in 29 of 94 lesions (31%) with angiographic follow-up an average of 6.3 months after atherectomy. The risk of restenosis was not significantly related to the vessel treated, the nature of the lesion treated (ie, primary v restenosis lesion), or any of the histologic features evaluated. In conclusion, (1) deep arterial wall components are commonly observed in coronary atherectomy specimens without acute complications and (2) intimal hyperplasia is a sensitive, but not specific, marker for restenosis lesions.