Comparative quantitative angiographic analysis of directional coronary atherectomy and balloon coronary angioplasty

Abstract

An attempt to assess the “utility” of directional atherectomy was made using a new quantitative angiographic index. This index can be subdivided into an initial gain component and a restenosis component. The initial gain index is the ratio between the gain in diameter during intervention and the theoretically achievable gain (i.e., reference diameter). The restenosis index is the ratio between the decrease at follow-up and the initial gain during the procedure. The net result at long-term follow-up is characterized by the utility index, which is the ratio between the final gain in diameter at follow-up and what theoretically could have been achieved. For this purpose, 30 coronary artery lesions were selected from a consecutive series of successfully dilated primary angioplasty lesions and were matched with the initial 30 successfully treated primary atherectomy lesions. Matching by location of stenosis and reference diameter resulted in 2 comparable groups with identical preprocedural stenosis characteristics. Atherectomy resulted in an increase in minimal luminal diameter 2 times larger than angioplasty (1.53 vs 0.77 mm; p < 0.0001). However, at follow-up there was a significant decrease in minimal luminal diameter and a significant increase in percent diameter stenosis in the groups with atherectomy and angioplasty (1.69 ± 0.58 vs 1.57 ± 0.58 mm, p = not significant [NS], and 37 ± 18 vs 47 ± 18%, p = NS, respectively). The decrease in minimal luminal gain was more pronounced in the group with atherectomy than in that with angioplasty (0.92 ± 0.69 vs 0.35 ± 0.51 mm; p = 0.0005). Consequently, directional atherectomy resulted in a significantly higher initial gain ratio than did balloon angioplasty (0.84 vs 0.41, p < 0.00001). At follow-up, restenosis and utility ratios were comparable in both groups (0.56 vs 0.62, p = NS, and 0.29 vs 0.23, p = NS, respectively). In matched groups, directional atherectomy is a very effective device with a substantially better initial result than that with balloon angioplasty. However, it appears to be a potent stimulator of the restenosis process, because at follow-up this initial favorable result is lost, and the minimal luminal diameter is comparable to that after balloon angioplasty. Thus, the final utility of directional coronary atherectomy is not significantly different from that of conventional balloon angioplasty.