Mechanism of high-speed rotational atherectomy and adjunctive balloon angioplasty revisited by quantitative coronary angiography: Edge detection versus videodensitometry

High-speed rotational coronary atherectomy (RA) is primarily used to treat complex lesions. Quantitative angiographic analysis of such complex lesions by edge detection is often unsuitable, whereas videodensitometry, measuring vessel dimensions independently of the target stenosis contours, may offer potential advantages. To gain insight into the operative mechanism of RA and to study the agreement between the two quantitative angiographic methods in measuring the minimal luminal cross-sectional area, the edge detection and videodensitometry techniques were applied to coronary angiograms of 21 lesions in 19 patients with symptoms who underwent successful RA and balloon angioplasty (BA). Obstruction diameter as determined by edge detection increased from 1.00 ± 0.31 mm before intervention to 1.35 ± 0.29 mm after RA (p < 0.001) and further increased to 1.74 ± 0.33 mm after adjunctive BA (p < 0.001). The mean between-method difference (edge detection minus videodensitometry) was 0.34 mm² before intervention, 0.13 mm² after RA, and 0.09 mm² after adjunctive BA (not significant). The standard deviation of the differences decreased from ±0.87 mm² before intervention to ±0.80 mm² after RA (not significant) and increased after BA significantly to ±1.21 mm² (p < 0.05). Thus edge detection and videodensitometry provided equivalent immediate angiographic results after RA and adjunctive BA. The good agreement after RA may reflect the operative mechanism of RA, which by ablation of noncompliant plaque material yields a circular symmetric lumen with smooth surface. The increased dispersion of the between-method differences observed after adjunctive BA presumably results from dissections, plaque ruptures, and loss of luminal smoothness after balloon dilatation.