Background: The purpose of the present study was to determine the differences in integrated backscatter (IB) values between a new IB intravascular ultrasound (IB-IVUS) mode for peripheral artery and the previous mode for coronary arteries for the tissue characterization of plaques.

Methods: A cross-validation study was performed with the 40 patients divided into a training study to determine the difference in IB value and the most appropriate correction for ultrasound signal attenuation between the mode for coronary and peripheral arteries (n = 20) and a testing study to validate the similarity of the images (n = 20). Comparison between the findings of IB-IVUS and angioscopy was performed in 10 patients.

Results: In the training study, 57 cross sections were subjected to the comparison. The IB value of +4.5 dB was the most appropriate setting compared with the mode for coronary arteries. The slope of regression lines were 1.00 in the measurement of lipid area and 1.00 in the measurement of fibrous area. The most appropriate correlation for ultrasound signal attenuation was +3.0 dB/mm. In the testing study, the slopes of regression lines in the measurement of lipid and fibrous areas were excellent in 20 cross sections (1.00 and 1.02, respectively) based on the settings that were determined in the training study. In the comparison with angioscopy, thickness of fibrous cap was associated with the color of plaques in peripheral arteries.

Conclusions: The IB-IVUS system with the new mode for peripheral arteries provides high diagnostic accuracy for the analysis of tissue characteristics of plaques.

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Purpose: Low body mass index (BMI) is strongly associated with an increased long-term risk of cardiovascular events. However, there is no evidence of relationship between BMI and the degree of coronary atherosclerosis, and we evaluated the relationship using multivessel angioscopic observation.

Methods: A total of 89 patients with coronary artery disease who underwent angioscopic examination were analyzed. The patients were divided into four categories according to BMI levels: underweight: <20 kg/m² (n = 7); normal weight: 20 to <25 kg/m² (n = 40); overweight: 25 to <28 kg/m² (n = 27); and obese: >28 kg/m² (n = 15). The number of yellow plaques (NYP) through the observed coronary artery was counted and the color of each plaque was defined as grade 1 (light yellow), grade 2 (yellow), or grade 3 (intense yellow). The NYP per vessel and the maximum yellow grade (MYG) were compared between the four different groups of BMI.

Results: The severity of coronary atherosclerosis was significantly different: NYP per vessel (2.10 ± 1.16 vs. 1.53 ± 0.91 vs. 1.33 ± 0.79 vs. 1.10 ± 0.93, p = 0.024) and MYG (2.57 ± 0.54 vs. 2.25 ± 0.87 vs. 1.96 ± 0.90 vs. 1.93 ± 1.03, p = 0.046). Multivariate regression analysis showed that BMI (p = 0.024) independently correlate with the NYP per vessel.

Conclusions: Coronary atherosclerosis in underweight patients was more advanced than normal and overweight patients. Low BMI was independently related to progressive coronary atherosclerosis and that might be a characteristic of vulnerable patients.

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In recent years, neoatherosclerosis and very late stent thrombosis in the extended follow-up period after baremetal stent (BMS) implantation have been recognized. We experienced a case of in-stent restenosis (ISR) detected in a BMS implanted 14 years prior. An 86-year-old man who had a history of BMS implantation because of angina pectoris in the proximal left anterior descending coronary artery (LAD) 14 years previously was referred to our hospital because of worsening chest pain on exertion for 1 month. A coronary angiogram revealed severe stenosis in the previously implanted BMS. Seven days later, percutaneous coronary intervention (PCI) for the LAD lesion was performed. Prior to intervention, intravascular ultrasound (IVUS), optical coherence tomography (OCT), and intracoronary angioscopy were performed, which showed diffuse heterogeneous plaque throughout the stent, various types of imaging in plaques including thrombi and fibrous plaque, and yellow plaques with respective imaging devices. We deployed two drug-eluting stents to cover all the plaque using a filter device in order to protect from distal embolism, and verified the good result by final angiography. From observations obtained with intravascular coronary imaging modalities in this case and knowledge that some past studies revealed, this case was considered as an acute coronary syndrome since neoatherosclerosis rupture in the BMS lesion happened in the extended follow-up period. Therefore we emphasize that physicians have to follow patients who have undergone BMS implantation carefully, even if ISR is not detected in the post early phase.

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The second-generation drug-eluting stent (DES) reportedly has an antithrombotic effect. An 80-year-old man with acute myocardial infarction (AMI) underwent primary percutaneous coronary intervention. He received both a bare-metal stent (BMS) and a DES at that time, and underwent intravascular ultrasound and coronary angioscopy in the acute and subacute phases. Thrombi were detected in both the BMS and DES in the acute phase. However, thrombus was only detected in the BMS in the subacute phase. It is important to consider the extent of thrombus formation in acute treatment. Therefore, residual thrombus should be evaluated with an intravascular imaging in the chronic phase to help reduce the risk of not only stent thrombosis but also other adverse cardiac events.

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Implantation of metallic stents in the atherosclerotic lesions resolved the lumen stenosis or obstruction of a coronary artery and myocardial ischemia. The phenomenon of transformation of proliferating neointima into atheromatous intima is now recognized as neoatherosclerosis that can lead to stent failure including restenosis or thrombosis at the late phase after stent implantation. Although neoatherosclerosis in the second-generation drugeluting stent (DES) had been found by the proper signal patterns of optical coherence tomography, there is no certification by direct visualization using angioscopy. An 85-year-old woman with dyslipidemia and hypertension, chronic kidney disease admitted to our hospital suffered from recurrent angina pectoris of effort. She had a history of successful stent implantation for stable angina pectoris two years ago. Cobalt chromium everolimus-eluting stent was implanted into the mid left anterior descending artery. Coronary angiography showed focal restenosis in the stent segment. Coronary angioscopy identified intense yellow plaque at the same lesion. In this case, late stent failure presented as restenosis in the second-generation EES was caused by neoatherosclerosis. To the best of our knowledge, this is the first report of neoatherosclerosis in the second-generation everolimus eluting stent validated by angioscopy.

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