Are residual stenoses after excimer laser angioplasty and coronary atherectomy due to inefficient or small devices? Comparison with balloon angioplasty.

Objectives: The purpose of this study was to determine whether residual stenoses after excimer laser angioplasty and atherectomy were due to inefficient tissue ablation/removal or to undersized devices.
Background: Significant residual stenoses are commonly observed after use of laser and atherectomy devices. It is not known whether these residual stenoses are due to inefficient or undersized devices.
Methods: To determine the relative contribution of these factors, the minimal lumen diameter, percent diameter stenosis and normal reference diameter were measured immediately before and after coronary interventions in 696 lesions, including transluminal extraction atherectomy, high speed mechanical rotational atherectomy, excimer laser angioplasty and conventional balloon angioplasty. The ratio of the diameter of the device to the normal reference diameter (D/A, a measure of device sizing) and the ratio of the residual lumen diameter after use of the device to the device diameter (RLD/D, a measure of the efficiency of lumen enlargement) were calculated.
Results: Baseline diameter stenoses were similar for all interventions. The percent diameter stenoses were greater immediately after extraction atherectomy (60 +/- 21%), rotational atherectomy (54 +/- 23%) and excimer laser angioplasty (61 +/- 18%) compared with balloon angioplasty (26 +/- 12%, p < 0.001). The D/A ratio was smaller after extraction atherectomy (0.63 +/- 0.14), rotational atherectomy (0.59 +/- 0.17) and excimer laser angioplasty (0.51 +/- 0.11) compared with balloon angioplasty (1.05 +/- 0.13, p < 0.001). The RLD/D ratio was similar after extraction atherectomy (0.73 +/- 0.24) and balloon angioplasty (0.71 +/- 0.11) but was greater after rotational atherectomy (0.92 +/- 0.16, p < 0.001) and excimer laser angioplasty (0.85 +/- 0.30, p < 0.01) compared with balloon angioplasty.
Conclusions: Residual stenoses after extraction atherectomy, rotational atherectomy and excimer laser angioplasty were more severe than after balloon angioplasty but were due to undersized devices (low D/A ratio), not to inefficient devices (low RLD/D ratio). Rotational atherectomy and excimer laser angioplasty were more efficient (higher RLD/D) than balloon angioplasty, whereas extraction atherectomy and balloon angioplasty were similar.