Relationship Between Thickness of Calcium on Optical Coherence Tomography and Crack Formation After Balloon Dilatation in Calcified Plaque Requiring Rotational Atherectomy

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Background:Target lesion calcification is known to influence percutaneous coronary intervention. We evaluated the effects of rotational atherectomy (RA) and subsequent balloon angioplasty on calcified coronary lesions using optical coherence tomography (OCT).Methods and Results:Thirty-seven calcified lesions in 36 patients were treated with RA followed by balloon angioplasty and stent implantation. In all patients, serial OCT images obtained after RA, after balloon angioplasty, and after stent implantation were analyzed at 1-mm intervals. The arc and thickness of the calcium component were measured after RA. The formation of calcium cracks was assessed after balloon angioplasty. A total of 625 segments were analyzed. The formation of calcium crack after balloon angioplasty was associated with greater stent cross-sectional area (7.38±1.92 vs. 7.13±1.68 mm², P=0.035) as well as greater lumen gain (3.89±1.53 vs. 3.40±1.46 mm², P<0.001). Segments with calcium cracks after angioplasty had a larger median calcium arc (360°, IQR, 246–360° vs. 147°, IQR, 118–199°, P<0.001) and a thinner calcium thickness (0.53±0.28 vs. 1.02±0.42 mm, P<0.001) than those without. The optimal thresholds of calcium arc and calcium thickness for the prediction of cracks were 227° and 0.67 mm, respectively.Conclusions:Larger calcium arc and thinner calcium thickness were associated with formation of calcium crack. Presence of calcium crack was the important determinant of optimal stent expansion. (Circ J 2016; 80: 1413–1419)