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Dive into the research topics where Ryota Uemura is active.

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Featured researches published by Ryota Uemura.


Journal of the American College of Cardiology | 2004

Changes in coronary plaque color and morphology by lipid-lowering therapy with atorvastatin: serial evaluation by coronary angioscopy

Masamichi Takano; Kyoichi Mizuno; Shinya Yokoyama; Koji Seimiya; Fumiyuki Ishibashi; Kentaro Okamatsu; Ryota Uemura

OBJECTIVES Changes in coronary plaque color and morphology by statin therapy were evaluated using coronary angioscopy. BACKGROUND Coronary plaque stabilization by statin therapy has not been clarified in humans. METHODS Thirty-one patients with coronary artery disease were divided into either the comparison group (n = 16) or the atorvastatin group (n = 15). Before treatment and 12 months after, the color and complexity of 145 coronary plaques were determined according to angioscopic findings. The yellow score of the plaque was defined as 0 (white), 1 (light yellow), 2 (yellow), or 3 (dark yellow), and its disrupted score was defined as 0 (smooth surface) or 1 (irregular surface) and as 0 (without thrombus) or 1 (with thrombus). In each patient, the mean yellow score and mean disrupted score were calculated. RESULTS Mean low-density lipoprotein cholesterol (LDL-C) decreased by 45% in the atorvastatin group, whereas an increase of 9% was seen in the comparison group. The mean yellow score decreased from 2.03 to 1.13 in the atorvastatin group, whereas it increased from 1.67 to 1.99 in the comparison group. There was a good correlation between the change in the mean yellow score and the change in LDL-C levels (r = 0.81, p < 0.0001). The change in the mean yellow score and mean disrupted score differed significantly between the two groups (p = 0.002 and p = 0.03, respectively). CONCLUSIONS This is the first report clarifying detailed changes in coronary plaque by statin in humans. This study indicated that lipid-lowering therapy changes plaque color and morphology and should then lead to coronary plaque stabilization.


Circulation | 2004

Elevated Troponin T Levels and Lesion Characteristics in Non–ST-Elevation Acute Coronary Syndromes

Kentaro Okamatsu; Masamichi Takano; Shunta Sakai; Fumiyuki Ishibashi; Ryota Uemura; Teruo Takano; Kyoichi Mizuno

Background—Elevated troponin T levels in non–ST-elevation acute coronary syndromes (NSTE-ACS) have been shown to predict an adverse outcome. Furthermore, it has been reported that troponin T could help improve the effectiveness of such new antithrombotic drugs as platelet GPIIb/IIIa antagonists and low-molecular-weight heparins. We hypothesized that such elevated troponin T levels in NSTE-ACS indicate the presence of thrombus at culprit lesions, and this hypothesis was verified through the use of coronary angioscopy. Methods and Results—We studied 57 consecutive patients with NSTE-ACS who underwent preinterventional angioscopy. Before catheterization, we obtained blood samples to determine troponin positivity, and the patients were then classified as either troponin-positive or troponin-negative groups (diagnostic threshold, 0.1 ng/mL). Using angioscopy at the culprit lesions, we examined the presence of coronary thrombus, yellow plaque, and complex plaque. Moreover, we compared the preinterventional angiographic parameters (thrombus and complexity of the culprit lesion, and TIMI flow) between the two groups. Twenty-two patients were troponin-positive and 35 patients were troponin-negative. Univariate analyses indicated that the TIMI flow and the incidence of coronary thrombus detected with angioscopy correlate with the elevated troponin T levels. A multivariate logistic regression analysis showed the presence of coronary thrombus detected with angioscopy to be the only independent factor associated with elevated troponin T levels in patients with NSTE-ACS (odds ratio, 22.1; 95% CI, 2.59 to 188.42; P =0.0046). Conclusions—Using angioscopy, the elevated troponin T levels in NSTE-ACS were confirmed to be strongly associated with the presence of coronary thrombus.


Circulation-cardiovascular Interventions | 2009

Extended Follow-Up by Serial Angioscopic Observation for Bare-Metal Stents in Native Coronary Arteries: From Healing Response to Atherosclerotic Transformation of Neointima

Shinya Yokoyama; Masamichi Takano; Masanori Yamamoto; Shigenobu Inami; Shunta Sakai; Kentaro Okamatsu; Shinichi Okuni; Koji Seimiya; Daisuke Murakami; Takayoshi Ohba; Ryota Uemura; Yoshihiko Seino; Noritake Hata; Kyoichi Mizuno

Background— Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results— Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P <0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P <0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P =0.011). Conclusions— This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing. Received January 29, 2009; accepted April 15, 2009. # CLINICAL PERSPECTIVE {#article-title-2}Background—Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results—Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P<0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P<0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P=0.011). Conclusions—This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing.


Circulation-cardiovascular Interventions | 2009

Extended Follow-Up by Serial Angioscopic Observation for Bare-Metal Stents in Native Coronary Arteries

Shinya Yokoyama; Masamichi Takano; Masanori Yamamoto; Shigenobu Inami; Shunta Sakai; Kentaro Okamatsu; Shinichi Okuni; Koji Seimiya; Daisuke Murakami; Takayoshi Ohba; Ryota Uemura; Yoshihiko Seino; Noritake Hata; Kyoichi Mizuno

Background— Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results— Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P <0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P <0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P =0.011). Conclusions— This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing. Received January 29, 2009; accepted April 15, 2009. # CLINICAL PERSPECTIVE {#article-title-2}Background—Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results—Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P<0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P<0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P=0.011). Conclusions—This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing.


Catheterization and Cardiovascular Interventions | 2002

Visualized plaque debris as a cause of distal embolization after percutaneous coronary intervention in patient with unstable angina.

Shunta Sakai; Kyoichi Mizuno; Masato Tomimura; Jun Tanabe; Koji Seimiya; Masamichi Takano; Shinya Yokoyama; Takayoshi Ohba; Ryota Uemura

Procedural complications of percutaneous transluminal coronary angioplasty for unstable angina are higher than for stable angina. We report a case in which coronary angioscopy proved the dislodgment of a large plaque fragment after Cutting Balloon angioplasty and confirmed our suspicion that plaque fragmentation can cause distal embolization. Cathet Cardiovasc Intervent 2002;55:113–117.


Circulation-cardiovascular Interventions | 2009

Extended Follow-Up by Serial Angioscopic Observation for Bare-Metal Stents in Native Coronary ArteriesCLINICAL PERSPECTIVE: From Healing Response to Atherosclerotic Transformation of Neointima

Shinya Yokoyama; Masamichi Takano; Masanori Yamamoto; Shigenobu Inami; Shunta Sakai; Kentaro Okamatsu; Shinichi Okuni; Koji Seimiya; Daisuke Murakami; Takayoshi Ohba; Ryota Uemura; Yoshihiko Seino; Noritake Hata; Kyoichi Mizuno

Background— Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results— Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P <0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P <0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P =0.011). Conclusions— This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing. Received January 29, 2009; accepted April 15, 2009. # CLINICAL PERSPECTIVE {#article-title-2}Background—Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results—Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P<0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P<0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P=0.011). Conclusions—This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing.


Circulation-cardiovascular Interventions | 2009

Extended Follow-Up by Serial Angioscopic Observation for Bare-Metal Stents in Native Coronary ArteriesCLINICAL PERSPECTIVE

Shinya Yokoyama; Masamichi Takano; Masanori Yamamoto; Shigenobu Inami; Shunta Sakai; Kentaro Okamatsu; Shinichi Okuni; Koji Seimiya; Daisuke Murakami; Takayoshi Ohba; Ryota Uemura; Yoshihiko Seino; Noritake Hata; Kyoichi Mizuno

Background— Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results— Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P <0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P <0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P =0.011). Conclusions— This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing. Received January 29, 2009; accepted April 15, 2009. # CLINICAL PERSPECTIVE {#article-title-2}Background—Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated. Methods and Results—Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and ≥4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P<0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P<0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4±17.3% versus 3.6±4.2%, respectively; P=0.011). Conclusions—This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing.


Journal of the American College of Cardiology | 2003

Are multiple plaque disruptions more common in patients with acute coronary syndrome than in patients with stable ischemic heart disease

Shigenobu Inami; Tomohiro Ogawa; Fumiyuki Ishibashi; Kentaro Okamatsu; Hiroyuki Kamon; Kohji Seimiya; Masamichi Takano; Takayoshi Ohba; Shinya Yokoyama; Ryota Uemura; Atsunobu Nomura; Shunta Sakai; Junko Sano; Kyoichi Mizuno

Background Plaque disruption with or without thrombus plays a key role in acute ccrcnary syndrome(ACS) and sudden progression of coronary lesions. Previous cur study demonstrated that plaque disruptions in culprit lesion is mere ccmmcn in patients with ACS than stable ischemic heart disease(SIHD). We investigated whether the prevalence of plaque disruptions in non ischemic related arteries is different between in patients with ACS and SIHD in living subjects. Methods We performed coronary angioscopy in non ischemic related artery on coronary angiography in 32 patients with ACS and 30 patients with SIHD. Forty-one arteries were explored in each groups. Results At least one plaque disruption was found somewhere other than on the culprit artery I” 31 patients(50%). Plaque disruption was found mere frequently in ACS group(Zlpts.65.6%) than in SIHD group(lOpts.33.3%)(pcO.O01). Conclusion Multiple plaque disruptions were mere ccmmcn in patients with acute ccrcnary syndrome than in patient with stable ischemic heart disease. These results indicate that acute coronary syndrome is not a local vascular accident but a pancoronary process.


Journal of the American College of Cardiology | 2003

Morphologic changes in infarct-related plaque after coronary stent placement: a serial angioscopy study.

Shunta Sakai; Kyoichi Mizuno; Shinya Yokoyama; Jun Tanabe; Takuroh Shinada; Koji Seimiya; Masamichi Takano; Takayoshi Ohba; Masato Tomimura; Ryota Uemura; Takahiro Imaizumi


Japanese Heart Journal | 2003

Unique single coronary artery with acute myocardial infarction: observation of the culprit lesion by intravascular ultrasound and coronary angioscopy.

Masamichi Takano; Koji Seimiya; Shinya Yokoyama; Kentaro Okamatsu; Fumiyuki Ishibashi; Ryota Uemura; Noritake Hata; Kyoichi Mizuno

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Eitaro Kodani

University of Louisville

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