Tong Shi-fei

e0474 Effect of plaque distribution to biomechanical

Introduction we presume that the plaque vulnerability of mildly lesions will be related to its intrinsic structural features and biomechanical characteristics. However, very little is known about their relationship between structural features and plaque vulnerability and about effect of biomechanical characteristics and plaque behaviour on vulnerable plaque. It is well known that coronary angiography (CAG) cannot accurately determine lesion morphology because it only shows the silhouette of the contrast materiel passing through the stenotic lesions. In recent years, intravascular ultrasound (IVUS) has evolved as a valuable adjunct to angiography. IVUS allows precise tomographic measurement of lumen area and plaque size, distribution and, to some extent, composition. Therefore, IVUS provide us likelihood for study on structural features and biomechanics characteristics in angiographic mildly stenosis in vivo. Materials and methods In 42 patients of angiographic intermediate coronary stenosis (diameter stenosis 40%-60%), IVUS imaging was performed and intracoronary pressure was recorded. The patients were classified as either unstable plaques group (n=30) or stable plaques group (n=12) by IVUS image. The biomechanical properties (distensibility index and stiffness) of coronary artery were calculated and the plaque behaviour during cardiac cycle was determined. Results There was no significant difference in percent area stenosis between eccentric plaque group and concentric plaque group (53.9±8.9% vs 58.4±9.8%, p>0.05). The coronary distensibility index in unstable plaques was significantly greater than it was in stable plaques (2.1±0.3 vs 1.2±0.2 mm Hg-1, p<0.01), but stiffness β for stable plaques was significantly greater than it was for unstable plaques (8.1±1.3 vs 29.4±7.2, p<0.01). The change of plaque area during cardiac cycle (plaque distensibility) in unstable plaque group was greater than it was in stable plaque group (0.52±0.22 mm2 vs 0.24±0.19 mm2, p<0.01). Positive remodelling occurred more frequently with unstable plaques than with stable plaques (63% vs 8%, p<0.01). Conclusion High coronary artery distensibility and high plaque distensibility during the cardiac cycle in eccentric lesions will likely increase plaque vulnerability.

e0373 Intravascular ultrasound study on angiographic contrast materiel drain-lagged coronary segments

Introduction To investigate the structural characteristics and its clinical significant of angiographic contrast materiel drain-lagged coronary segments. Materials and methods 23 segments coronary arteries in 20 patients with angiographic contrast materiel drain-lagged were performed by intravascular ultrasound (IVUS) imaging. The characteristics of the plaques and reference segments were analysed. Percent area stenosis and remodelling index were calculated. Results External elastic membrane cross-sectional area in angiographic contrast materiel drain-lagged segments greater than reference segments (17.04±3.86 mm2 vs 14.35±3.62 mm2, p<0.01). Lesions had greater lumen area compared with reference (13.72±2.38 mm2 vs 11.86±2.57 mm2, p<0.01). Lesions had a soft plaque and minor stenosis (percent area stenosis 19.48%±5.23%) and positive remodelling was more frequent (20/23, 87%) in lesions. Conclusion Posimentive remodelling and minor atherosclerosis plaque in coronary segments are the causes of angiographic contrast materiel drain-lagged. This lesion has structural characteristics of unstable plaque.

e0688 Intravascular Ultrasound Criteria for the Assessment of the Functional Significance of Intermediate Coronary Artery Stenosis

Introduction In recent years, intravascular ultrasound (IVUS) has evolved as a valuable adjunct to angiography. IVUS allows precise tomographic measurement of lumen area and plaque size, distribution and, to some extent, composition. It is essential in clinic decision making. Myocardial fractional flow reserve (FFRmyo) is a special index of the functional severity of coronary stenosis. Although the application of FFRmyo to assess intermediate coronary lesion is widely performed in some centers in developed countries, its use in China was lagged. Because it is relatively expensive to measure FFRmyo, it will be beneficial to save the expenses and to short operation time if CAG and IVUS criteria could be clinically used as tools to discriminate functional significant of intermediate stenosis. Materials and methods In 46 lesions of intermediate severity (eg, 40% to 60% diameter stenosis) we assessed 1. by pressure wire: myocardial fractional flow reserve (FFRmyo, index of functional significance), and 2. by IVUS: minimal lumen cross-sectional area (MLA) and percent area stenosis at the lesion site. Receiver operating characteristic curve analysis was performed to establish the best cut-off values of IVUS indexes (ie, MLA and percent area stenosis) that were most predictive of FFRmyo<0.75. Results FFRmyo in 46 lesions of angiographic intermediate stenosis (49±11%) was significantly lower than it was in angiographic normal artery (0.83±0.15 vs 0.97±0.02, p<0.01). 14 lesions (30%) were functionally critical (eg, FFRmyo<0.75). By regression analysis, percent area stenosis had a significant inverse correlation with FFRmyo (r=−0.68, p<0.01). MLA showed a significant positive relation with FFRmyo (r=0.63, p<0.01). By receiver operating characteristic analysis, we identified a IVUS area stenosis ≥65% (sensitivity 100%, specificity 72%), a minimal lumen cross-sectional area ≤4 mm2 (sensitivity 93%, specificity 77%) to be the best cut-off values to fit with FFRmyo<0.75. Conclusion IVUS area stenosis ≥65% and minimal lumen cross-sectional area ≤4 mm2 reliably identified functionally critical intermediate coronary stenosis.