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Objective A high proportion of uncovered stent struts is associated with late stent thrombosis after drug-eluting stent (DES) implantation, which frequently results in myocardial infarction or death. However, the predictors of uncovered stent struts remain unknown. Here, using optical coherence tomography (OCT), we studied the baseline tissue characteristics of the target coronary segment and evaluated their influence on the neointimal coverage of the strut in the chronic phase. Methods We analyzed 118 coronary lesions treated with OCT-guided DES implantation. OCT examinations of target lesions were performed before and after DES implantation, and tissue characteristics were evaluated within 5 mm outer segment of both stent edges. At follow-up, stent strut coverage was assessed within 5 mm inner segment from each stent edge. On the basis of the proportion of uncovered stent struts in the chronic phase, target segments were divided into poorly covered (the highest quartile with % uncovered struts, n=29) and well-covered (the remaining lower quartiles with % uncovered struts, n=89) groups. Results Clinical parameters were similar between the two groups. On baseline OCT images, thin-cap fibroatheroma (TCFA) and large calcification were more frequently observed in the poorly covered group than the well-covered group (10.3 vs. 0.0%, P=0.0032, and 27.6 vs. 9.0%, P=0.017, respectively). Furthermore, multivariable analysis showed TCFA and large calcification at the proximal edge, but not at the distal edge, were predictors of uncover stent struts. Conclusion TCFA and large calcification at the proximal stent edge are strong predictors of uncovered stent struts. OCT is useful for selecting stent landing sites in terms of future occurrence of uncovered stent struts.

Introduction: Takotsubo Cardiomyopathy (TTC) is characterized by transient hypokinesis of the left ventricular (LV) apex and mid-ventricular regions, and hyperkinesis of the LV base, without significant coronary artery stenosis. The precise pathogenic mechanism of TTC remains unknown. Earlier reports assumed that catecholamine excess is involved in the pathogenesis of TTC, from the elevation of plasma catecholamine concentration or by 123I-metaiodobenzylguanidine myocardial scintigraphy. However, there have been no pathological findings that directly support this scenario in human, so far. In this study, we investigated clinical and pathological features in TTC heart including expression of G-protein receptor kinase 2 (GRK2), which is a marker for acute desensitization of β-adrenergic receptors (β-ARs), and compared with those in non-TTC heart. Methods and Results: The clinical and pathological features from 20 TTC patients (TTC group) and non-TTC patients (non-TTC group) were analyzed. In TTC patients, LV biopsy was performed at the acute phase. Non-TTC group of patients consisted of 14 patients with ventricular tachycardia or conduction disorder, who underwent LV biopsy to rule out primary myocardial diseases. Pathological data showed that the contraction band was more frequently observed in TTC than in non-TTC group (p=0.017) (Figure A), and the percentage of interstitial fibrosis area of TTC was higher than that of non-TTC group (12.1±7.7% vs 7.4±3.0%, p=0.036) (Figure B). Moreover, the percentage of GRK2 positive stained area in TTC was greater than in non-TTC group (49.0±17.8% vs 15.7±11.9%, p Conclusions: The present study demonstrates up-regulation of GRK2 for the first time in human TTC, and supports the involvement of catecholamine toxicity in the pathogenesis of TTC.

The thin fibrous cap covering large lipid pool is known as one of the risks for coronary plaque rupture and subsequent acute coronary events. However, little is known about the influence of drug eluting stent (DES) implantation on the tissue characteristics of coronary plaque with lipid accumulation

Objective: In optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI), stent size is usually determined according to the pre-PCI lumen size of either the distal or proximal reference site. However, the effect of the OCT imaging catheter crossing the target lesion on the reference lumen measurements has not been studied. We evaluated changes in the reference lumen size before and after PCI using frequency domain OCT. Methods: For 100 consecutive patients with PCI, mean lumen diameter (LD) and lumen area (LA) were measured at the proximal and distal reference sites before and after coronary stent implantation with OCT. Results: Mean LD and LA of the distal reference site were significantly increased after PCI with stent implantation (2.57 ± 0.6 to 2.62 ± 0.64 mm, p 1.50 mm2. Tissue characteristics were not correlated with changes in reference lumen size. Conclusions: When we select the stent size during OCT-guided PCI, we need to pay attention to the decrease in the luminal measurement of the reference sites, especially in lesions with tight stenosis.

A 63-year-old man was referred to our hospital because of a cardiac tumor. Transthoracic echocardiography revealed a rough, mobile tumor in the dilated right atrium, and transesophageal echocardiography showed that the tumor consisted of small, botryoidal masses. Catheter-based biopsy carried a high risk of embolism. Therefore, we used F-18-fluorodeoxyglucose positron emission tomography (FDG-PET), which revealed an abnormal accumulation in the right cervical lymph nodes, as well as in the heart. We safely performed biopsy of the lymph nodes and diagnosed the patient with primary cardiac lymphoma. We concluded that echocardiography and FDG-PET are useful for selecting an appropriate biopsy site in primary cardiac lymphoma.

Introduction: Inadequate neointimal coverage of the stent struts is one of the risks for late stent thrombosis, especially in DES. Using OCT, we studied the morphological characteristics of coronary segment of both proximal and distal edges, and evaluated their influence on the neointimal coverage of the strut in chronic phase. Methods: Of 111 culprit coronary lesions in 91 patients, baseline OCT tissue characteristics were evaluated at both proximal and distal edges after DES implantation. The second OCT examination was performed on 9.1 months after implantation, and neointimal coverage of struts was assessed within 5mm inner segments from each stent edge. An uncovered strut was defined as having the signal thickness less than 30 μm from the center of strut. Results: Of 10995 apposed stent struts, uncovered struts were detected in 5.3% within distal and 6.8% within proximal edges. For further statistical analysis, edge segments were classified into two categories according to the ratio of uncovered struts, as the poorly-covered group (highest quartile with % uncovered struts), and the well-covered group (the remaining lower quartiles with % uncovered struts). As to OCT tissue characteristic, 1) fibrous plaque was significantly less observed in the poorly-covered group at both distal and proximal edges (p=0.0031 and p=0.0046, respectively). 2) Lipid pool was more frequently observed in the poorly-covered group than the well-covered group at both distal and proximal edges (p=0.0037 and p=0.0061, respectively). 3) Thin-cap fibroatheroma (TCFA) and calcification were also more frequently observed in the poorly-covered group than the well-covered group (p=0.0025 and p=0.0070, respectively) at proximal stent edge. Logistic regression analysis revealed that existence of calcification at proximal edge was an independent predictor for uncovered struts (OR: 5.48, 95%CI: 1.46-23.46, p=0.0119). TCFA at proximal edge was also an independent predictor (p=0.0044). Conclusions: TCFA and calcification at proximal edge were predictors of uncovered struts. Although mechanism should be further elucidated, placement of proximal edge on such tissue characteristics should be avoided.

Introduction: Clinical introduction of percutaneous coronary intervention (PCI) with drug eluting stent has substantially decreased the rate of in-stent restenosis (ISR). However, it is reported that patients with diabetes mellitus (DM) still have higher incidence of restenosis and secondary cardiovascular events than patients without DM. Using intravascular optical coherence tomography (OCT), we evaluated the effect of DM on healing process of coronary artery after everolimus eluting stents (EES) implantation in the comparison with non-DM patients. Methods and Results: We studied 26 DM patients (65.1±11.9y/o) and 59 non-DM patients (68.1±9.4y/o) who received OCT-guided EES implantation. The second OCT examination was performed on 296±71.1 days after implantation (291±74.2days vs. 298±70.3days, p=0.51). OCT cross-sectional images of the second study were examined to determine the condition of neointimal coverage over every strut in 1mm interval (DM; 725 cross-sections and 5742 struts, non-DM; 1482 cross-sections and 12098 struts). In addition, neointimal thickness (NIT) over each strut measured and tissue characteristics were examined. One in-stent restenosis with clinical manifestation was observed in each group. Average NIT was significantly thicker in DM group than in non-DM group (107±99.2μm vs. 92±74.6μm, p Conclusions: EES implanted in DM patients showed acceptable neointimal proliferation and uncovered stent struts similar to non-DM patients, suggesting the mid-term efficacy and safety of EES in DM patients. However, long-term follow-up should be necessary because of the high incidence of unstable neointimal characteristics which might be a substrate for the future development of neoatherosclerosis.

Percutaneous coronary intervention (PCI) with drug eluting stent (DES) has substantially decreased the rate of in-stent restenosis, and improved prognosis of patients with coronary artery disease. However, presence of coronary artery calcification (CAC) increases the rate of long-term adverse events