| Objective: Unheralded sudden death and acute myocardial infarction are common presentations of coronary atherosclerosis. Most events are related to thrombotic occlusion at the site of non–flow limiting atherosclerotic plaques in epicardial coro- nary arteries. Histopathological studies have retrospectively sug- gested that plaque composition is a crucial determinant of the propensity of atherosclerotic lesions to rupture. Therefore, the acute coronary thrombi has ruptured thin-cap fibroatheroma (TCFA) lesions as a substrate. the purpose of our study has been to assess plaque characterization in the patients of acute coronary syndrome(ACS) when compared with the patients of stable angina pectoris(SAP). All of the subjects was determined by intravascular ultrasound (IVUS) radiofrequency(RF) data analysis.Methods: Consecutive patients admitted for coronary catheterizeation were eligible for IVUS interrogation of at least 30 mm of length in a non- branching coronary segment with an angiographically non-obstructive (<50%) de novo lesion, in a non- target vessel suitable for IVUS interrogation. Patients with lesions located in proximal (but not ostial) and mid segments of a coronary artery were included. Patients with stable angina or acute coronary syndromes (ACS) were included. Acute coro- nary syndrome patients encompassed patients presenting with unstable angina, non-ST segment elevation MI, or ST segment elevation MI. Acute Myocardial Infarction (AMI) was diagnosed by an increase in the creatine kinase MB level to more than two- fold the nor- mal limit. Major exclusion criteria included hemodynamically unstable, coronary anatomy that precluded safe IVUS examination or severe angiographic calcification. The institutional ethic committee approved the study protocol and informed written consent was obtained from all patients.IVUS-VH uses spectral analysis of IVUS radiofrequency data to build tissue maps that are correlated with a specific spectrum of the radiofrequency signal and assigned colour codes fibrous (labelled green), fibrolipidic (labelled greenish-yellow), necrotic core (labelled red) and calcium (labelled white). IVUS- VH data was acquired using a continuous pullback (EagleEye TM 20 MHz Volcano Therapeutics), by a dedicated IVUS- VH console (Volcano Therapeutics, Rancho Cordova, CA). The IVUS VH data were stored on a CD/DVD. Data acquisition was ECG-gated and recorded during the automated withdrawal of the catheter using a mechanical pullback device (Volcano Therapeutics, Rancho Cordova, CA) at a pullback speed of 1 mm/s. Cine runs, before and during contrast injection, were performed to define the position of the IVUS catheter before the pullback was started. Compositional and geometric data were expressed as mean percentages for the ROI. To assess the stenosis severity of the lesions, we report the mean external elastic membrane(EEM) area obstruction {[(EEM area-Lumen area)/EEM area]×100}.Statistic analysis: Discrete variables are presented as counts and percentages. Continuous variables are presented as mean±SD. We looked for correlations between the percent- ages of the 4 different plaque components and RI using univariate Pearson correlation coefficients. Differences in means among groups were analyzed by 2-samplet test or by 1-way analysis of variance. A P value of <0.05(2-sided) was considered to indicate statistical significance. Statistical analyses were performed with use of SPSS software version13.0 (SPSS Inc, Chicago, IL).Results: Mean percentage of the different plaque components were 4.02±2.3%, calcium; 43.42%±20.56%, fibrous; 33.85%±13.68%, fibrolipidic; and 18.00%±10.1%, lipid core. Mean lipid core percentage was significantly larger in patients with ACS when compared with patients with SAP (25.78%±6.3 vs 9.11%±4.90% p<0.001). In addition, patients with SAP showed more fibrotic vessels(59.66%±16.87% vs 49.07%±10.2%, p<0.001). There was no significant difference for either mean calcium (4.37%±2.4%vs 5.12%±3.0% p=0.225) or fibrolipidic (24.94%±9.4% vs 5.82%±13.6%, P=0.731) percentages in nonculprit vessels, conversely, mean calcium percentage was significantly larger in non–flow limiting segment of culprit vessels(5.51%±3.29% vs 3.57%±2.1% p=0.003). In addition, there was a positive correlation between lipid core and RI (r=0.847, p<0.001) and an negative correlation between fibrous tissue and RI (r=-0.946, p<0.001) were also significant.Conclusions: There are significantly difference in plaque characterization of nonculprit lesions using spectral analysis of IVUS RF data. percentage of lipid core was significantly larger in patients with ACS, Conversely, SAP showed more fibrotic content. In vivo plaque composition and morphology assessed by spectral analysis of IVUS radio frequency data were related to coronary artery remodeling. |
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