The relationship between coronary plaque characteristics and small embolic particles during coronary Stent implantation

Objectives We investigated the relationship between coronary plaque components and small embolic particles during stenting and examined the influence on the coronary microcirculation. Background In vivo tissue characterization of atherosclerotic plaques was introduced by the Virtual Histology intravascular ultrasound (VH-IVUS) system (Volcano Therapeutics, Inc., Rancho Cordova, California). Methods The study consisted of 44 patients who underwent elective coronary stenting. Plaque characteristics were identified with VH-IVUS, and small embolic particles liberated during stenting were detected as high-intensity transient signals (HITS) with a Doppler guidewire. Coronary flow velocity reserve (CFVR) was also measured before and after stenting. Results Patients were divided into the tertiles according to the HITS counts: the lowest, HITS < 5 (n = 16); the middle, 5 to 12 (n = 15); and the highest, > 12 (n = 13). Dense calcium and necrotic core area identified with VH-IVUS were significantly larger in the highest tertile (lowest vs. middle vs. highest; dense calcium: 0.2 +/- 0.3 mm(2) VS. 0.3 +/- 0.6 mm(2) VS. 0.8 +/- 0.7 mm(2), p = 0.007; necrotic core: 0.5 +/- 0.4 mm(2) VS. 0.9 +/- 0.9 mm(2) VS. 1.8 +/- 1.0 mm(2), p < 0.001, respectively). Multivariate logistic regression analysis revealed only necrotic core area was an independent predictor of high HITS counts (odds ratio 4.41, p = 0.045). Furthermore, there was a significant negative correlation between the HITS count and CFVR after stenting (r = -0.35, p = 0.017). Conclusions The necrotic core component identified with VH-IVUS is related to liberation of small embolic particles during coronary stenting, which results in the poorer recovery of CFVR.