Histopathological Correlates of Early Arterial Recoil following Directional Coronary Atherectomy

Abstract

Elastic recoil has been implicated in the pathophysiology of restenosis after conventional balloon angioplasty alone. Directional atherectomy may attenuate arterial recoil by removing the internal elastic lamina and medial smooth muscle cells and altering the vessel wall architecture. This study sought to evaluate early recoil after directional atherectomy and its relation with excision of deep arterial wall structures. We prospectively evaluated the correlation of the histopathologic evidence of media or adventitia as assessed in the atheroma retrieved during the procedure with the early changes in minimal lumen diameter after directional atherectomy followed by adjunct balloon dilatation in 50 consecutive cases. Recoil was assessed by routinely performed 1- and 15-min postprocedure angiograms, and patients were divided into two groups according to the absence (group I, n = 26) or presence (group II, n = 24) of recoil. The mean changes in minimal luminal diameter between 1 and 15 min was +0.22 mm in group I and –0.14 mm in group II. The absence of recoil was strongly associated with evidence of media tissue in the pathologic analysis as compared with cases with recoil (42 vs. 18%, respectively; p = 0.02). Similarly, retrieval of adventitia was seen exclusively in the group without recoil (15 vs. 0%; p = 0.06). Vessels that underwent recoil had significantly larger reference and immediate postprocedure minimal luminal diameters (3.62 ± 0.57 and 3.02 ± 0.45 mm, respectively) as compared with arteries with no recoil (3.28 ± 0.35 and 2.75 ± 0.43 mm, respectively; p < 0.05 for both). Therefore, early luminal changes, likely related to elastic recoil, correlated with excision of deep wall structures during directional atherectomy. Arteries that showed recoil were larger, possibly due to thicker muscular layer and/or larger plaque burden as compared with arteries that did not recoil. Thus, optimal tissue debulking during directional atherectomy appears to attenuate recoil, providing an additional insight into the mechanism of action of this percutaneous revascularization device.