Hiroyuki Kawamori

Feasibility of combined use of intravascular ultrasound radiofrequency data analysis and optical coherence tomography for detecting thin-cap fibroatheroma

AIMS To evaluate the feasibility of the combined use of virtual histology (VH)-intravascular ultrasound (IVUS) and optical coherence tomography (OCT) for detecting in vivo thin-cap fibroatheroma (TCFA). METHODS AND RESULTS In 56 patients with angina, 126 plaques identified by IVUS findings were analysed using both VH-IVUS and OCT. IVUS-derived TCFA was defined as an abundant necrotic core (>10% of the cross-sectional area) in contact with the lumen (NCCL) and %plaque-volume >40%. OCT-derived TCFA was defined as a fibrous cap thickness of <65 microm overlying a low-intensity area with an unclear border. Plaque meeting both TCFA criteria was defined as definite-TCFA. Sixty-one plaques were diagnosed as IVUS-derived TCFA and 36 plaques as OCT-derived TCFA. Twenty-eight plaques were diagnosed as definite-TCFA; the remaining 33 IVUS-derived TCFA had a non-thin-cap and eight OCT-derived TCFA had a non-NCCL (in discord with NCCL visualized by VH-IVUS, mainly due to misreading caused by dense calcium). Based on IVUS findings, definite-TCFA showed a larger plaque and vessel volume, %plaque-volume, higher vessel remodelling index, and greater angle occupied by the NCCL in the lumen circumference than non-thin-cap IVUS-derived TCFA. Conclusion Neither modality alone is sufficient for detecting TCFA. The combined use of OCT and VH-IVUS might be a feasible approach for evaluating TCFA.

Delayed Neointimalization on Sirolimus-Eluting Stents : 6-Month and 12-Month Follow up by Optical Coherence Tomography

BACKGROUND Sirolimus-eluting stents (SES) have incomplete neointimal coverage at 6-month follow up as determined with optical coherence tomography (OCT). The long-term detailed changes of neointima in SES remains to be clarified. METHODS AND RESULTS Serial changes in neointimal coverage of SES from 6 months to 12 months using OCT were examined. Of 21 SES in 13 patients, OCT was used to visualize 2,321 stent struts at 6 months and 2,285 stent struts at 12 months. The frequency of struts without neointimal coverage decreased from 6 months to 12 months (from 10.4 to 5.7%). The frequency of malapposed struts decreased from 6 months to 12 months (from 1.7 to 0.2%). The average thickness of the neointima increased (from 112 +/-123 to 120 +/-130 microm). The frequency of struts located at the side branch orifice without neointima decreased (from 4 out of 17 (24%) to 0 out of 17 (0%)). Complete coverage with neointima was observed in 14% (3 of 21 SES) at 6 months, and 24% (5 of 21 SES) at 12 months. CONCLUSIONS Additional neointimal coverage was observed between 6 and 12 months, with a small increase in the neointimal thickness. The incidence of complete coverage, however, was still low at 12 months. These findings suggest delayed neointimalization on SES.

Natural consequence of post-intervention stent malapposition, thrombus, tissue prolapse, and dissection assessed by optical coherence tomography at mid-term follow-up

Aims We performed this study to clarify natural consequences of abnormal structures (stent malapposition, thrombus, tissue prolapse, and stent edge dissection) after percutaneous coronary intervention (PCI). Methods and results Thirty-five patients treated with 40 drug-eluting stents underwent serial optical coherence tomography (OCT) imaging immediately after PCI and at the 8-month follow-up. Among a total of 73 929 struts in every frame, 431 struts (26 stents) showed malapposition immediately after PCI. Among these, 49 remained malapposed at the follow-up examination. The mean distance between the strut and vessel wall (S–V distance) of persistent malapposed struts on post-stenting OCT images was significantly longer than that of resolved malapposed struts (342 ± 99 vs. 210 ± 49 μm; P <0.01). Based on receiver-operating characteristic curve analysis, an S–V distance ≤260 µm on post-stenting OCT images was the corresponding cut-off point for resolved malapposed struts (sensitivity: 89.3%, specificity: 83.7%, area under the curve = 0.884). Additionally, 108 newly appearing malapposed struts were observed on follow-up OCT, probably due to thrombus dissolution or plaque regression. Thrombus was observed in 15 stents post-PCI. Serial OCT analysis revealed persistent thrombus in 1 stent, resolved thrombus in 14 stents, and late-acquired thrombus in 8 stents. Tissue prolapse observed in 38 stents had disappeared at the follow-up. All eight stent edge dissections were repaired at the follow-up. Conclusion Most cases of stent malapposition with a short S–V distance, thrombus, tissue prolapse, or minor stent edge dissection improved during the follow-up. These OCT-detected minor abnormalities may not require additional treatment.

Optical coherence evaluation of everolimus-eluting stents 8 months after implantation

Objective The aim of this study was to evaluate detailed vessel response after everolimus-eluting stents (EES) implantation in human de novo coronary lesions by optical coherence tomography (OCT). Design, setting and patients Between November 2008 and October 2009, 25 patients (14 men, 65.5±8.6 years) with de novo native coronary artery lesions were implanted with 30 EES, and OCT was performed at 8 months post-implantation. Main outcome measures Neointimal thickness (NIT) on each strut, strut apposition to the vessel wall, the frequency of struts surrounded by low intensity area and the incidence of intra-stent thrombus were analysed. To evaluate the radial unevenness of NIT, the difference between the maximum and minimum NIT (dNT) was calculated for each cross-section. Results At 236±39 days after implantation, there were no major adverse cardiac events, nor target vessel revascularisation. A total of 5931 struts was evaluated by OCT. The median NIT was 80 μm (25th and 75th percentile 50 μm and 140 μm) and average NIT was 100±74 μm. The number of neointima-covered struts was 5834 (98.4%), and 31 (0.52%) struts showed malapposition without neointimal coverage. The number of struts surrounded by low intensity area was 452 (7.62%). Eleven EES (37%) showed full neointimal coverage. No intra-stent thrombus was detected. The average dNT was 108±77 μm. Conclusions Most EES struts were covered with uniform and thin neointima. The frequency of low-intensity neointima was very low, which may be a result of promoted vessel healing. These results may support improved clinical outcomes with EES in clinical trials.

Very late thrombosis of sirolimus-eluting stent due to late malapposition: Serial observations with optical coherence tomography

A 54 years old man underwent directional coronary atherectomy in segment 7 with a partial deep-cut injury. A sirolimus-eluting stent (SES) was implanted at the restenosed post-atherectomy lesion. Six months after SES implantation, intravascular ultrasound (IVUS) examination revealed slight vessel enlargement although there were no malapposed struts. Optical coherence tomography (OCT) revealed partial stent malapposition. Ticlopidine was discontinued 3 months after SES implantation, but aspirin was continued. Twenty-nine months after SES implantation, after discontinuing aspirin for 7 days for colon polypectomy, the patient suffered an acute myocardial infarction at the SES implantation site. IVUS revealed further positive vessel remodeling and slight stent malapposition and OCT revealed extension of the previous stent malapposition and ulcer-like appearance around the stent struts. This case demonstrates that even a small partial SES malapposition that can be detected only by OCT has the potential to enlarge over time and the late malapposition may result in late thrombosis when anti-platelet therapy is discontinued.

Coronary plaque morphology using virtual histology-intravascular ultrasound analysis in hemodialysis patients.

Most dialysis patients have coronary artery disease at the initiation of dialysis therapy and these patients also have marked vascular calcification. Virtual histology–intravascular ultrasound (VH–IVUS) provides coronary tissue maps that are color coded by four major plaque components and facilitate the characterization of coronary plaque composition in vivo. The aim of this study was to identify coronary plaque characteristics in dialysis patients using VH–IVUS. Twenty‐three patients with coronary artery disease were included in this study. Of these, 12 patients had normal renal function or mild renal insufficiency (control group) and 11 patients were receiving maintenance dialysis therapy (hemodialysis group). We performed coronary angiography and VH–IVUS analysis on culprit lesions of all patients in the study. The result of VH–IVUS analysis showed that the hemodialysis group had a greater plaque volume, lower percentage of fibrous plaque, and higher percentage of dense calcium plaque compared with the control group. In addition, the serum phosphate levels were significantly associated with the percentage of necrotic core and dense calcium plaque in all study patients. Our findings suggest that the amount of necrotic core and dense calcium plaques increase significantly in hemodialysis patients, and that disordered mineral metabolism may be associated with coronary plaque morphology.

Feasibility of a novel radiofrequency signal analysis for in-vivo plaque characterization in humans: Comparison of plaque components between patients with and without acute coronary syndrome

BACKGROUND The iMAP™ is a novel intravascular ultrasound (IVUS)-based technology to classify coronary plaque into 4 components. The aim of this study was to evaluate the feasibility of iMAP™ technology by comparing plaque characteristics in patients with and without acute coronary syndrome (ACS and non-ACS). MATERIALS AND METHODS A total of 93 culprit lesions from 87 patients were analyzed using the iMAP™. Each plaque was classified into 4 components with a newly introduced parameter, confidence level (CL). RESULTS iMAP™ analysis of the minimal lumen cross-sectional area (MLA) revealed that ACS lesions had significantly larger lipidic and necrotic areas than non-ACS lesions. Multivariate analysis revealed that the lipidic area at the MLA was an iMAP™ factor independently associated with ACS lesions (odds ratio -1.5, p=0.04). Based on receiver operating characteristic analysis with 4 different CL ranges, the lipidic area at the MLA with 25%-100% CL had the largest area under the curve (0.756), suggesting that 25%-100% is the best CL range for identifying ACS culprit lesions. CONCLUSIONS The feasibility of the novel iMAP™ IVUS system was shown in discriminating culprit lesions in patients with and without ACS. Analyzing with a CL of 25%-100% may be the best option for discriminating lesions.

Impact of the angiographic burden on the incidence of out-of-hospital ventricular fibrillation in patients with acute myocardial infarction

Ventricular fibrillation (VF) is a catastrophic complication of spontaneous (type 1) acute myocardial infarction (AMI). This study sought to clarify the angiographic coronary characteristics related to out-of-hospital VF in AMI patients. We retrospectively reviewed 464 consecutive cases of suspicious AMI, including type 1 AMI, with or without out-of-hospital VF. In addition to patient demographics, proximal left coronary artery (LCA) disease, multivessel disease (MVD), and chronic total occlusion (CTO) were assessed via coronary angiography and compared between patients with and without out-of-hospital VF. Coronary angiography was evaluated for 74 patients with out-of-hospital VF and for 237 without. Male sex (93.2 vs. 83.1%; P = 0.036), Killip class ≥ 2 (89.2 vs. 16.5%; P < 0.001), and ST elevation myocardial infarction (83.8 vs. 66.7%; P = 0.003) were more frequent in the out-of-hospital VF group. The culprit lesions located in the proximal left coronary artery (62.2 vs. 29.5%; P < 0.001), MVD (75.7 vs. 41.8%, P < 0.001), and CTO (43.2 vs. 10.5%, P < 0.001) were more frequently observed in patients with out-of-hospital VF. Multivariate logistic regression analysis identified the culprit lesion located in the proximal LCA [odds ratio (OR) 2.86; 95% confidence interval (CI) 1.34–6.08], the presence of CTO (OR 8.52; 95% CI 3.35–21.65), and MVD (OR 3.69; 95% CI 1.57–8.65) as predictors of out-of-hospital VF. For type 1 AMI patients, advanced disease burden including the culprit lesion located in the proximal LCA and coexistence of CTO or MVD might be associated with out-of-hospital VF.

Sudden Onset of Platypnea-Orthodeoxia Syndrome Caused by Traumatic Tricuspid Regurgitation with Ruptured Chordae Tendineae after Blunt Chest Trauma

An 86-year-old man was admitted our hospital because of sudden onset of dyspnea after blunt chest trauma. Because his oxygen saturation deteriorated from 92% in the supine position to 86% in the sitting position, platypnea-orthodeoxia syndrome was suspected. Transesophageal echocardiography showed severe tricuspid regurgitation (TR) caused by anterior papillary muscle rupture. Furthermore, right-to-left shunt with TR through a patent foramen ovale (PFO) was observed. The diagnosis was therefore platypnea-orthodeoxia syndrome with right-to-left shunt through PFO with shunting exacerbated by acute severe TR after blunt chest trauma. The patient underwent urgent tricuspid valve repair and PFO closure and has remained asymptomatic postoperatively.

A rare case of “subcommissural adhesive aortic stenosis”: Triangular struggle of aortic valve area, hemodynamics, and calcium burden

This report concerns an 83‐year‐old woman with aortic stenosis (AS) who had a history of repetitive hospitalization due to decompensated heart failure. Although her clinical history was compatible with significant AS, findings for aortic valve area, hemodynamics, and valvular calcium burden were discrepant. Multiplanar reconstruction images revealed the membranous structures attached to a subcommissural lesion, which resulted in severe stenosis. The patient had a favorable clinical course after transcatheter aortic valve replacement. This is the first reported case of severe AS due to the subcommissural adhesions, which were successfully visualized by means of echocardiography and computed tomography.