Intravascular ultrasound assessment of the effects of rotational atherectomy in calcified coronary artery lesions

We sought to clarify intravascular ultrasound (IVUS) features of rotational atherectomy (RA) of calcified lesions. IVUS was performed post-RA and post-stent in 38 lesions and analyzed every 1 mm. Pre-intervention IVUS was performed when the IVUS catheter crossed the lesion (n = 11). Calcium Index was average calcium angle multiplied by calcium length. We compared lowest (n = 13), middle (n = 13), and highest (n = 12) Calcium Index tertiles. Reverberations (multiple reflections from calcium) with a concave-shaped lumen in the post-RA IVUS were considered to represent RA-related calcium modification. Newly visible perivascular tissue through a previously solid arc of calcium in the post-stent IVUS was also evaluated. Comparing the pre and post-RA IVUS, maximum reverberation angle, and length increased significantly after RA (angle, from 45° [31, 67] to 96° [50, 148], p = 0.003; length, from 4.0 mm [2.0, 6.0] to 8.0 mm [4.0, 14.0], p = 0.005). In the post-RA IVUS, reverberations had a larger angle in the middle and highest Calcium Index tertiles (lowest, 91° [64, 133]; middle, 135° [107, 201]; highest, 150° [93, 208], p = 0.03). Post-stent newly visible perivascular tissue was more frequent in the middle and highest Calcium Index tertiles (lowest, 30.8%; middle, 69.2%; highest, 75.0%, p = 0.049). Minimum stent area was similar after calcium modification by RA irrespective of the severity of the Calcium Index (lowest, 6.7 mm2 [5.7, 8.9]; middle, 5.6 mm2 [4.9, 6.8]; highest, 6.7 mm2 [5.9, 8.2], p = 0.2). Greater calcium modification by RA occurs in severely calcified lesions with smaller lumen diameters to mitigate against stent underexpansion.