Ubiquitous atherosclerosis in coronary arteries without angiographically significant stenosis

Intravascular ultrasound comparison of left main coronary artery disease between white and Asian patients

We assessed the ethnic differences in coronary atherosclerosis lesion morphology between white and Asian patients. Our hypothesis was that left main coronary artery (LMCA) disease was more focal and less complex in Asian than in Western white patients. We studied 99 Asian patients (Japan and South Korea) and 99 matched control United States white patients with a stable clinical presentation and >30% LMCA angiographic diameter stenosis by visual estimation. The matching parameters included age, gender, and diabetes mellitus. The vessel and lumen areas and calcium arc were analyzed every 0.5 mm and normalized for analysis length. Overall, 75.1% of the patients were men and 34.1% had diabetes. The patient age was 68.0 ± 10 years, with no differences between the Asian and white patients. The Asian patients had a lower prevalence of hyperlipidemia than the white patients (41.4% vs 81.8%; p <0.0001) and were smaller in size, and the white patients were more obese (body mass index 23.7 ± 2.6 vs 27.6 ± 4.1 kg/m(2), p <0.0001). The Asian patients had a smaller lumen area (5.2 ± 1.8 vs 6.2 ± 14 mm(2); p <0.0001), larger vessel area (20.0 ± 4.9 vs 18.4 ± 4.4 mm(2); p <0.0001), and larger plaque burden (72 ± 10 vs 64 ± 12%: p <0.0001) at the minimum lumen site and over the entire LMCA length. The white patients had more calcification, whether assessed by the maximum arc (82° ± 74° vs 49° ± 45°; p <0.0001) or total length (3.6 ± 3.2 vs 2.1 ± 2.1 mm; p <0.0001). In conclusion, after matching well-known risk factors, there appeared to be ethnic differences in coronary atherosclerosis morphology between Asian and white patients, at least as it affected LMCA morphology.

The maximum necrotic core area is most often located proximally to the site of most severe narrowing: a virtual histology intravascular ultrasound study

Previous angiographic studies have shown that almost two-thirds of vulnerable plaques are located in non-obstructive lesions. Possibly, the maximum necrotic core (Max NC) area is not always identical to the site of most severe stenosis. Therefore, the purpose of this study was to evaluate the potential difference in location between the maximum necrotic core area and the site of most severe narrowing as assessed by virtual histology intravascular ultrasound (VH IVUS). Overall, 77 patients (139 vessels) underwent VH IVUS. The Max NC site was defined as the cross section with the largest necrotic core area per vessel. The site of most severe narrowing was defined as the minimum lumen area (MLA). Per vessel, the distance from both the Max NC site and MLA site to the origo of the coronary artery was evaluated. In addition, the presence of a virtual histology-thin cap fibroatheroma (VH-TCFA) was assessed. The mean difference (mm) between the MLA site and Max NC site was 10.8 ± 20.6 mm (p < 0.001). Interestingly, the Max NC site was located at the MLA site in seven vessels (5%) and proximally to the MLA site in 92 vessels (66%). Importantly, a higher percentage of VH-TCFA was demonstrated at the Max NC site as compared to the MLA site (24 vs. 9%, p < 0.001). In conclusion, the present findings demonstrate that the Max NC area is rarely at the site of most severe narrowing. Most often, the Max NC area is located proximal to the site of most severe narrowing.

Intravascular ultrasound assessment of the association between spatial orientation of ruptured coronary plaques and remodeling morphology of culprit plaques in ST-elevation acute myocardial infarction

The aim of this study was to assess the association between the spatial location of plaque rupture and remodeling pattern of culprit lesions in acute anterior myocardial infarction (MI). Positive remodeling suggests a potential surrogate marker of plaque vulnerability, whereas plaque rupture causes thrombus formation followed by coronary occlusion and MI. Intravascular ultrasound (IVUS) can determine the precise spatial orientation of coronary plaque formation. We studied 52 consecutive patients with acute anterior MI caused by plaque rupture of the culprit lesion as assessed by preintervention IVUS. The plaques were divided into those with and without positive remodeling. We divided the plaques into three categories according to the spatial orientation of plaque rupture site: myocardial (inner curve), epicardial (outer curve), and lateral quadrants (2 intermediate quadrants). Among 52 plaque ruptures in 52 lesions, 27 ruptures were oriented toward the epicardial side (52%), 18 toward the myocardial side (35%), and 7 in the 2 lateral quadrants (13%). Among 35 plaques with positive remodeling, plaque rupture was observed in 21 (52%) on the epicardial side, 12 (34%) on the myocardial side, and 2 (6%) on the lateral side. However, among 17 plaques without positive remodeling, plaque rupture was observed in 6 (35%), 6 (35%), and 5 (30%), respectively (p = 0.047). Atherosclerotic plaques with positive remodeling showed more frequent plaque rupture on the epicardial side of the coronary vessel wall in anterior MI than those without positive remodeling.

Correlation of atherosclerosis between different topographic sites is highly dependent on the type of hyperlipidemia

There is a surprising paucity of studies that provide quantitative correlative data on the extent of atherosclerosis between different topographic sites. The impact of cardiovascular risk factors is dependent on the vascular bed, which underlies site-selective effects on progression of atherosclerosis. Therefore, the intraindividual correlation of atherosclerosis between different topographic sites may be dependent on the specific cardiovascular risk profile. The focused objective of the current study is to evaluate whether the correlation of the extent of atherosclerosis between different topographic sites is dependent on the type of hyperlipidemia. Atherosclerosis was quantified at four different topographic locations in the aorta of rabbits with type II or type III hyperlipidemia. Correlation coefficients and semi-partial correlation coefficients adjusted for plasma lipoproteins and sex were determined to compare the degree of atherosclerosis at different topographic sites. Semi-partial correlations adjusted for total plasma cholesterol, plasma triglycerides, and sex of the intima/media ratio between different topographic sites were highly dependent on the type of hyperlipidemia. E.g., the semi-partial correlation coefficient between the intima/media ratio at the level of the ascending aorta and at the level of the descending thoracic aorta was 0.87 (p < 0.0001) in the model of type II hyperlipidemia and was only 0.10 (p = NS) in the model of type III hyperlipidemia. This divergent pattern was also observed for other intersite correlations. Semi-partial Pearson correlation coefficients were very similar to unadjusted Pearson correlation coefficients. Correlation of atherosclerosis between different topographic sites may vary importantly in relation to the type of hyperlipidemia.

Effect of intravascular ultrasound-guided adjuvant high-pressure non-compliant balloon post-dilation after drug-eluting stent implantation

Drug-eluting stent (DES) expansion characteristics after aggressive high-pressure post-dilation using a non-compliant (NC) balloon have not been fully investigated. We evaluated 58 patients with native coronary lesions treated with DESs [24 paclitaxel eluting stents (PES) and 34 sirolimus-eluting stents (SES)]. After post-dilation (12-14 atm) using a stent-mounted semi-compliant balloon to reduce stent edge injury, adjuvant high-pressure post-dilation using NC balloon was performed within the stents. Stent size, stent length, and NC balloon size were selected based on preinterventional intravascular ultrasound (IVUS) assessment. Stent underexpansion was defined according to criteria of the Multicenter Ultrasound Stenting in Coronaries (MUSIC) study as a minimal stent cross-sectional area <90% of the average reference lumen area. Resultant endpoint was to obtain optimal stent expansion. Serial changes of stent expansion and stent symmetry were calculated in each group. After stent-mounted semi-compliant balloon post-dilation, both stents could not achieve adequate percent stent expansion (PES 73 ± 18% vs. SES 67 ± 9%, p = 0.38). After high-pressure post-dilation using an NC balloon, percent stent expansion was 97 ± 14% in PES and 91 ± 13% in SES, respectively (p = 0.25). Axial stent symmetry indices also significantly improved in both groups. Although radial stent symmetry indices improved significantly in PES group, those in the SES group had no significant changes. Finally, frequency of stent underexpansion significantly reduced, 87-20% in PES and 92-15% in SES, respectively (p = 0.01) without any significant stent edge injury. DES expansion improved safely after adjuvant high-pressure post-dilation using an NC balloon under IVUS guidance.

The S447X variant of lipoprotein lipase gene is inversely associated with severity of coronary artery disease

Hyperlipidemia is a major risk factor for coronary artery disease (CAD). Lipoprotein lipase (LPL) is an important enzyme in lipoprotein metabolism. S447X polymorphism of the LPL gene has been implicated in the pathogenesis of CAD. Carriers of X447 allele were reported to have lower triglyceride and higher high-density lipoprotein cholesterol levels as well as a reduced risk of CAD. We hypothesized that S447X gene polymorphism might have a protective effect for CAD. A total of 178 subjects (mean age 42.97 ± 6.5 years) who underwent coronary angiography for clinical indications were included in the study. The patients had been referred for evaluation of chest pain and/or abnormal stress tests, and were selected consecutively. Gensini scores were used to assess the severity of CAD; 97 patients were diagnosed with angiographically proven CAD, and 81 subjects did not display significant CAD (≥ 70%) angiographically. Genotyping of LPL S447X polymorphism was performed by real-time polymerase chain reaction amplification and fluorescent probe melting point analysis on the light cycler. The minor allele frequencies of LPL 447X allele were 11.1% and 6.2% among subjects without CAD compared with CAD subjects (P = 0.081) and 447X allele had favorable effects on lipid levels among CAD patients; 447X homozygotes and heterozygotes displayed lower total cholesterol (171 ± 37 vs 208 ± 48 mg/dl, P = 0.02), lower triglycerides (121 ± 72 vs 184 ± 86 mg/dl, P = 0.02), lower low-density lipoprotein cholesterol (102 ± 27 vs 129 ± 39 mg/dl, P = 0.03). Gensini scores were significantly lower among the heterozygotes and homozygotes of LPL 447X allele than in the LPL S447 homozygotes (15 ± 23 vs 25 ± 30, P = 0.048). S447X polymorphism of LPL gene may have a protective role for the severity of CAD. The beneficial effects of S447X polymorphism of the LPL gene may be through its favorable effects on lipid levels.