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It has been reported that coronary vasa vasorum is associated with plaque vulnerability, and low-echoic structures in grayscale intravascular ultrasound (IVUS) are consistent pathologically with vasa vasorum. However, the association of low-echoic structures with plaque composition and no-reflow phenomenon during percutaneous coronary intervention (PCI) is unclear. We investigated plaque composition in virtual histology IVUS (VH-IVUS) and no-reflow phenomenon during PCI of low-echoic structures.A total of 106 lesions being treated by VH-IVUS before PCI were included in this study. Low-echoic structure was defined as a small tubular structure exterior to media without a connection to the vessel lumen in ≥ 3 consecutive crosssectional IVUS images. Lesions with low-echoic structures were found in 42% (45/106).Lesions with low-echoic structures were more prevalent in acute coronary syndrome (ACS) patients (53% [24/45] versus 20% [12/61], P < 0.001), had more positive remodeling (49% [22/45] versus 21% [13/61], P = 0.003), a larger number of VH-IVUS derived thin-cap fibroatheromas (VH-TCFAs) (0.64 ± 0.53 versus 0.05 ± 0.22, P < 0.001), more VH-TCFAs with a baseline plaque burden of 70% or more and minimal luminal area of 4.0 mm(2) or less (29% [13/45] versus 2% [1/61], P < 0.001), and more frequent no-reflow phenomenon after stent implantation and more final TIMI flow grade 0/1/2 (38% [17/45] versus 5% [3/61], P < 0.001; 9% [4/45] versus 0% [0/61], P = 0.03) than lesions without low-echo structures.Lesions with low-echoic structures in grayscale IVUS had high plaque vulnerability and were more prevalent in ACS patients, positive remolding, and VH-TCFAs, and they had more frequent no-reflow phenomenon during PCI than lesions without low-echoic structures.

Lesions with spotty calcification was highly vulnerable in VH-IVUS. Spotty or intermediate plaque calcification without angiographic calcification was more vulnerable than those with angiographic calcification. Extensive plaque calcification with angiographic calcification had more dense calcium than those without angiographic calcification.

In patients with ST-segment elevation myocardial infarction (STEMI), it is unclear if combined assessment of left ventricular end-diastolic pressure (LVEDP) and left ventricular ejection fraction (LVEF) improves prediction of major adverse cardiac events (MACE). We analyzed data from 266 STEMI patients who underwent successful percutaneous coronary intervention and subsequent left ventriculography (LVG). Patients were divided into 4 groups, as follows: Group 1, LVEDP < 21 mmHg and LVEF ≥ 55%; Group 2, LVEDP < 21 mmHg and LVEF < 55%; Group 3, LVEDP ≥ 21 mmHg and LVEF ≥ 55%; and Group 4, LVEDP ≥ 21 mmHg and LVEF < 55%. Multivariate Cox proportional hazards analysis was used to determine if LVEDP and LVEF were associated with MACE (including cardiac death, non-fatal myocardial infarction, and heart failure requiring hospitalization). Change in LV parameters was assessed in the subset of 183 patients who underwent serial LVG (mean interval 6.3 ± 1.6 months). During a mean follow-up of 43 ± 31 months, 29 patients (10.9%) had a MACE. As compared to Group 1, MACE risk was significantly higher in Group 3 [hazard ratio (HR) 3.26; 95% confidence interval (CI) 1.05-10.0] and Group 4 (HR 3.99; 95% CI 1.44-11.0), but not in Group 2 (HR 0.46, 95% CI 0.54-3.96). In sub-analyses, LV end-systolic volume index after PCI was significantly higher in Group 4 than in the other groups and remained higher during follow-up. Combined LVEDP/LVEF assessment was useful in predicting MACE after successful PCI for STEMI patients and could facilitate risk stratification, as it predicts LV remodeling.

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