Takumi Kimura

Atherosclerotic coronary lesions with inadequate compensatory enlargement have smaller plaque and vessel volumes: observations with three dimensional intravascular ultrasound in vivo

Objective To compare vessel, lumen, and plaque volumes in atherosclerotic coronary lesions with inadequate compensatory enlargement versus lesions with adequate compensatory enlargement. Design 35 angiographically significant coronary lesions were examined by intravascular ultrasound (IVUS) during motorised transducer pullback. Segments 20 mm in length were analysed using a validated automated three dimensional analysis system. IVUS was used to classify lesions as having inadequate (group I) or adequate (group II) compensatory enlargement. Results There was no significant difference in quantitative angiographic measurements and the IVUS minimum lumen cross sectional area between groups I (n = 15) and II (n = 20). In group I, the vessel cross sectional area was 13.3 (3.0) mm2 at the lesion site and 14.4 (3.6) mm2 at the distal reference (p < 0.01), whereas in group II it was 17.5 (5.6) mm2 at the lesion site and 14.0 (6.0) mm2 at the distal reference (p < 0.001). Vessel and plaque cross sectional areas were significantly smaller in group I than in group II (13.3 (3.0)v 17.5 (5.6) mm2, p < 0.01; and 10.9 (2.8) v 15.2 (4.9) mm2, p < 0.005). Similarly, vessel and plaque volume were smaller in group I (291.0 (61.0) v 353.7 (110.0) mm3, and 177.5 (48.4) v 228.0 (92.8) mm3, p < 0.05 for both). Lumen areas and volumes were similar. Conclusions In lesions with inadequate compensatory enlargement, both vessel and plaque volume appear to be smaller than in lesions with adequate compensatory enlargement.

Intravascular Ultrasound-Derived Stent Dimensions as Predictors of Angiographic Restenosis Following Nitinol Stent Implantation in the Superficial Femoral Artery.

Purpose: To identify intravascular ultrasound (IVUS) measurements that can predict angiographic in-stent restenosis (ISR) following nitinol stent implantation in superficial femoral artery (SFA) lesions. Methods: A retrospective review was conducted of 97 patients (mean age 72.9±8.9 years; 63 men) who underwent IVUS examination during endovascular treatment of 112 de novo SFA lesions between July 2012 and December 2014. Self-expanding bare stents were implanted in 46 lesions and paclitaxel-eluting stents in 39 lesions. Six months after stenting, follow-up angiography was conducted to assess stent patency. The primary endpoint was angiographic ISR determined by quantitative vascular angiography analysis at the 6-month follow-up. Variables associated with restenosis were sought in multivariate analysis; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Results: At follow-up, 27 (31.8%) angiographic ISR lesions were recorded. The lesions treated with uncoated stents were more prevalent in the ISR group compared with the no restenosis group (74.1% vs 44.8%, p=0.02). Lesion length was longer (154.4±79.5 vs 109.0±89.3 mm, p=0.03) and postprocedure minimum stent area (MSA) measured by IVUS was smaller (13.9±2.8 vs 16.3±1.6 mm2, p<0.001) in the ISR group. Multivariate analysis revealed that bare stent use (OR 7.11, 95% CI 1.70 to 29.80, p<0.01) and longer lesion length (OR 1.08, 95% CI 1.01 to 1.16, p=0.04) were predictors of ISR, while increasing postprocedure MSA (OR 0.58, 95% CI 0.41 to 0.82, p<0.01) was associated with lower risk of ISR. Receiver operating characteristic analysis identified a MSA of 15.5 mm2 as the optimal cutpoint below which the incidence of restenosis increased (area under the curve 0.769). Conclusion: Postprocedure MSA can predict ISR in SFA lesions, which suggests that adequate stent enlargement during angioplasty might be required for superior patency.

Angioscopy and OCT in repeated in-stent restenosis in saphenous vein graft.

The morphological characteristics of in-stent restenosis (ISR) that occur in multiple layers of stents (stent in stent) are not well described. We used multimodality imaging in a 69-year-old man in whom repeated episodes of restenosis developed in a 9-year-old saphenous vein graft (SVG) to the left

Clinical and pathological characteristics of homogeneous and nonhomogeneous tissue of in-stent restenosis visualized by optical coherence tomography.

BackgroundAlthough it is known that in-stent restenosis (ISR) patterns appear homogeneous or nonhomogeneous by optical coherence tomography (OCT), interpretations of the ISR inflammatory response, of the OCT image, and its pathological implications are unclear. The aim of this study was to use OCT to characterize ISR and its inflammatory index in patients after coronary stenting. MethodsOCT was performed at follow-up in 100 angiographic ISR lesions. ISR lesions were divided into two groups: (a) homogeneous (n=48) and (b) nonhomogeneous (n=52) image groups. We assessed the ISR images produced by OCT for tissue heterogeneity and neo-intimal hyperplasia using the normalized standard deviation of OCT signal-intensity (OCT-NSD) observed in neo-intimal hyperplasia tissue. In some patients with a nonhomogeneous OCT image, we collected pathological tissue. ResultsThe prevalence of drug-eluting stents was 48% in the nonhomogeneous group and 29% in the homogeneous group (P=0.05). The OCT-NSD value in the nonhomogeneous group (0.223±0.019) was significantly higher than that in the homogeneous group (0.203±0.025; P<0.0001). Pathological tissue showed fibrin thrombi with infiltrating macrophage in 12 cases of nonhomogeneous ISR. The area under the receiver operating characteristic curve for the prediction of a nonhomogeneous image was 0.73 for OCT-NSD (95% confidence interval: 0.62–0.83: P<0.0001). The odds ratio for the prediction of a nonhomogeneous image was 3.47 (95% confidence interval: 1.18–10.2: P=0.02) for smoking by logistic regression analysis. ConclusionNonhomogeneous ISR visualized by OCT showed a high OCT-NSD value, which was a useful predictor for nonhomogeneous images. Moreover, the nonhomogeneous ISR image visualized by OCT may show chronic inflammation and fibrin thrombi.

A honeycomb-like structure in the right coronary artery visualized by three-dimensional optical coherence tomography.

A 66-year-old Japanese man with hypertension, diabetes, dyslipidemia, ischemic cardiomyopathy with left ventricular (LV) dysfunction, and sustained ventricular tachycardia was treated with the oral medicine in another hospital from 2011. He was transferred from the satellite hospital to our hospital for catheter treatment of ischemic cardiomyopathy in 2012. Myocardial perfusion imaging (MPI) of this patient indicated previous myocardial infarction at the inferoposterior wall and partial ischemia at the inferior wall after an ergometer stress test (Fig. 1). Coronary angiography showed two significant lesions at the right coronary artery (RCA) and the left circumflex artery (LCX). The distal LCX was occluded and angiographic haziness was present in the middle RCA and the proximal LCX (Fig. 2). Thrombolysis in myocardial infarction (TIMI) grade of the RCA was grade 3. There was no viability at the posterior wall according to MPI and a small perfusion territory of LCX from angiography. Therefore, a percutaneous coronary intervention was performed on the middle RCA. We assessed the segment of haziness by intravascular ultrasound (IVUS) and optical coherence tomography (OCT) before percutaneous coronary intervention. Initially, there were some low echoic lesions that were separated by partitions using IVUS imaging (Fig. 3); as a result, it was considered to be a ruptured plaque or recanalized thrombus. By contrast, OCT imaging indicated a honeycomb-like structure with multiple channels in at least 10 lumens (Fig. 4) (Supplemental digital content 1, http://links.lww.com/ MCA/A27). After contrast enhancement, a complex lesion was shown by OCT, although blood could not be replaced by contrast completely at first. Multiple channels were separated by high signal intensity tissue and each of the lumens was connected in the distal lumen and the proximal lumen. There was no evidence of atherosclerotic changes and lipid pool by OCT. White thrombus characterized as without backscattering protrusions was observed in the distal site of a honeycomb lesion. It was assumed to be spontaneous recanalization of the old thrombus. Finally, this site was treated with an everolimus-eluting stent (Xience Prime 3.5/28mm; Abbott Vascular, Santa Clara, California, USA). Although almost all channels were crushed by the stent, some outside channels remained on OCT imaging (Fig. 5). As expansion and apposition of the stent were good, it was decided that further extension was unnecessary. Furthermore, we performed 3D-OCT imaging of the honeycomb structure using free software (Blender, Ver. 2.5, Amsterdam, the Netherlands). A more detailed structure could be easily observed by actually using 3D animation. According to the 3D image, there was no occluded lumen and almost all lumens were connected to the distal site and the proximal site (Fig. 6).

Surgical Unroofing of Hemodynamically Significant Left Anterior Descending Myocardial Bridges

BACKGROUND Left anterior descending artery myocardial bridges (MBs) range from clinically insignificant incidental angiographic findings to a potential cause of sudden cardiac death. Within this spectrum, a group of patients with isolated, symptomatic, and hemodynamically significant MBs despite maximally tolerated medical therapy exist for whom the optimal treatment is controversial. We evaluated supraarterial myotomy, or surgical unroofing, of the left anterior descending MBs as an isolated procedure in these patients. METHODS In 50 adult patients, we prospectively evaluated baseline clinical characteristics, risk factors, and medications for coronary artery disease, relevant diagnostic data (stress echocardiography, computed tomography angiography, stress coronary angiogram with dobutamine challenge for measurement of diastolic fractional flow reserve, and intravascular ultrasonography), and anginal symptoms using the Seattle Angina Questionnaire. These patients then underwent surgical unroofing of their left anterior descending artery MBs followed by readministration of the Seattle Angina Questionnaire at 6.6-month (range, 2 to 13) follow-up after surgery. RESULTS Dramatic improvements were noted in physical limitation due to angina (52.0 versus 87.1, p < 0.001), anginal stability (29.6 versus 66.4, p < 0.001), anginal frequency (52.1 versus 84.7, p < 0.001), treatment satisfaction (76.1 versus 93.9, p < 0.001), and quality of life (25.0 versus 78.9, p < 0.001), all five dimensions of the Seattle Angina Questionnaire. There were no major complications or deaths. CONCLUSIONS Surgical unroofing of carefully selected patients with MBs can be performed safely as an independent procedure with significant improvement in symptoms postoperatively. It is the optimal treatment for isolated, symptomatic, and hemodynamically significant MBs resistant to maximally tolerated medical therapy.

Assessment of bioresorbable scaffold with a novel high‐definition 60 MHz IVUS imaging system: Comparison with 40‐MHz IVUS referenced to optical coherence tomography

In vivo assessment of bioresorbable scaffold (BRS) is of growing clinical interest. The novel 60MHz high‐definition intravascular ultrasound (HD‐IVUS) has been developed to overcome the limitations of conventional 40 MHz IVUS. This study aimed to evaluate the performance and limitations of 60 MHz HD‐IVUS compared with 40 MHz IVUS with respect to polymeric‐strut visualization, quantitative and qualitative analysis, and feasibility of high‐speed pullback in the assessment of BRS.

Impact of stent diameter on vascular response after self-expanding paclitaxel-eluting stent implantation in the superficial femoral artery ☆

BACKGROUND The optimal sizing of self-expanding paclitaxel-eluting stents (PES) in the treatment for superficial femoral artery (SFA) lesions is unclear. This study sought to investigate the influence of PES diameter on stent patency in SFA lesions using optical frequency domain imaging (OFDI). METHODS A total of 20 de novo SFA lesions were randomized 1:1 to receive either self-expanding PES with a nominal diameter of 6mm or 8mm. Follow-up angiography and OFDI was scheduled six months after stent implantation, and volumetric OFDI analysis was performed to evaluate vascular response to the stents. Volume index (VI) was defined as the volume divided by the stent length. The primary end point was lumen VI at the 6-month follow-up. Secondary end point was minimum lumen diameter (MLD) by quantitative vascular angiography (QVA) at the follow-up. RESULTS Stent length was 78.0±23.9mm in the 6-mm group and 70.0±23.6mm in the 8-mm group (p=0.46). Baseline QVA data were also similar between the two groups. MLD immediately after stent implantation was similar between the two groups (4.2±0.5mm in the 6-mm group and 3.9±0.5mm in the 8-mm group, p=NS). At the 6-month follow-up, MLD was greater in the 8-mm group compared to the 6-mm group (4.0±1.0mm vs. 3.2±0.4mm, p<0.05). Stent VI was larger in the 8-mm group (28.4±6.7mm3/mm vs. 22.2±1.2mm3/mm, p=0.01). Neointimal VI was similar between the two groups (5.8±2.9mm3/mm vs. 5.2±2.6mm3/mm, p=0.68). Lumen VI was greater in the 8-mm group (23.2±7.6mm3/mm vs. 17.3±2.6mm3/mm, p=0.04). CONCLUSIONS Chronic stent enlargement resulted in greater lumen area after implantation of self-expanding PES with a large diameter at the mid-term follow-up. Stent diameter might be important for stent patency in procedure with PES for SFA lesions.

Impact of Stent Size Selection on Acute and Long-Term Outcomes After Drug-Eluting Stent Implantation in De Novo Coronary Lesions

Background— Although significant undersizing often results in incomplete stent apposition or underexpansion, the possible impact of oversized stent implantation on arterial wall injury has not been systematically investigated with drug-eluting stents. The aim of this study was to investigate the impact of stent oversizing on acute and long-term outcomes after drug-eluting stents implantation in de novo coronary lesions. Methods and Results— Serial (baseline and 6–12 months) coronary angiography and intravascular ultrasound were performed in 2931 lesions treated with drug-eluting stents (355 sirolimus, 846 paclitaxel, 1387 zotarolimus, and 343 everolimus). The percentage of stent oversizing to angiographic reference vessel diameter (RVD) was calculated as (nominal stent diameter–RVD)/RVD×100 (%). Clinical outcomes, including target lesion revascularization and stent thrombosis, were followed for 1 year. Overall, smaller preintervention RVD was associated with higher percentage of stent oversizing (P<0.001). The significant oversizing group underwent less post-dilatation (P=0.002) but achieved greater stent expansion (P<0.001) and less incomplete stent apposition (P<0.001) without increase of edge dissection after procedure. When stratified by vessel size and stent oversizing, progressive decreases of restenosis (P=0.002) and target lesion revascularization rates (P=0.007) were found in favor of larger vessel size and oversized stents. Stent thrombosis was observed the most in small RVD with low percentage of stent oversizing group among the subgroups (P=0.040). Conclusions— The positive impact of stent oversizing was documented on procedural and clinical outcomes. In particular, small vessels treated with smaller stents were associated with greater adverse events, suggesting that aggressive selection of larger stents, with appropriate attention to edge effects, may optimize long-term outcomes, even in drug-eluting stents implantation.

Accuracy of non-invasive stress testing in women and men with angina in the absence of obstructive coronary artery disease

OBJECTIVE While >20% of patients presenting to the cardiac catheterization laboratory with angina have no obstructive coronary artery disease (CAD), a majority (77%) have an occult coronary abnormality (endothelial dysfunction, microvascular dysfunction (MVD), and/or a myocardial bridge (MB)). There are little data regarding the ability of noninvasive stress testing to identify these occult abnormalities in patients with angina in the absence of obstructive CAD. METHODS We retrospectively evaluated 155 patients (76.7% women) with angina and no obstructive CAD who underwent stress echocardiography and/or electrocardiography before angiography. We evaluated Duke treadmill score, heart rate recovery (HRR), metabolic equivalents, and blood pressure response. During angiography, patients underwent invasive testing for endothelial dysfunction (decrease in epicardial coronary artery diameter >20% after intracoronary acetylcholine), MVD (index of microcirculatory resistance ≥25), and intravascular ultrasound for the presence of an MB. RESULTS Stress echocardiography and electrocardiography were positive in 58 (43.6%) and 57 (36.7%) patients, respectively. Endothelial dysfunction was present in 96 (64%), MVD in 32 (20.6%), and an MB in 83 (53.9%). On multivariable logistic regression, stress echo was not associated with any abnormality, while stress ECG was associated with endothelial dysfunction. An abnormal HRR was associated with endothelial dysfunction and MVD, but not an MB. CONCLUSION Conventional stress testing is insufficient for identifying occult coronary abnormalities that are frequently present in patients with angina in the absence of obstructive CAD. A normal stress test does not rule out a non-obstructive coronary etiology of angina, nor does it negate the need for comprehensive invasive testing.