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Dive into the research topics where Myong Hwa Yamamoto is active.

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Featured researches published by Myong Hwa Yamamoto.


Heart and Vessels | 2014

Association between increased epicardial adipose tissue volume and coronary plaque composition

Kennosuke Yamashita; Myong Hwa Yamamoto; Seitarou Ebara; Toshitaka Okabe; Shigeo Saito; Koichi Hoshimoto; Tadayuki Yakushiji; Naoei Isomura; Hiroshi Araki; Chiaki Obara; Masahiko Ochiai

To assess the relationship between epicardial adipose tissue volume (EATV) and plaque vulnerability in significant coronary stenosis using a 40-MHz intravascular ultrasound (IVUS) imaging system (iMap-IVUS), we analyzed 130 consecutive patients with coronary stenosis who underwent dual-source computed tomography (CT) and cardiac catheterization. Culprit lesions were imaged by iMap-IVUS before stenting. The iMAP-IVUS system classified coronary plaque components as fibrous, lipid, necrotic, or calcified tissue, based on the radiofrequency spectrum. Epicardial adipose tissue was measured as the tissue ranging from −190 to −30 Hounsfield units. EATV, calculated as the sum of the fat areas on short-axis images, was 85.0 ± 34.0 cm3. There was a positive correlation between EATV and the percentage of necrotic plaque tissue (R2 = 0.34, P < 0.01), while there was a negative correlation between EATV and the percentage of fibrous tissue (R2 = 0.24, P < 0.01). Multivariate analysis revealed that an increased low-density lipoprotein cholesterol level (β = 0.15, P = 0.03) and EATV (β = 0.14, P = 0.02) were independently associated with the percentage of necrotic plaque tissue. An increase in EATV was associated with the development of coronary atherosclerosis and, potentially, with the most dangerous type of plaque.


Eurointervention | 2017

Characteristics of early versus late in-stent restenosis in second-generation drug-eluting stents: an optical coherence tomography study

Lei Song; Gary S. Mintz; Dong Yin; Myong Hwa Yamamoto; Chee Yang Chin; Mitsuaki Matsumura; Ajay J. Kirtane; Manish Parikh; Jeffrey Moses; Ziad Ali; Richard Shlofmitz; Akiko Maehara

AIMS In-stent restenosis (ISR) is an important cause of drug-eluting stent (DES) failure and target vessel revascularisation. In this study we aimed to evaluate differences between early and late-presenting restenosis in second-generation DES using optical coherence tomography (OCT). METHODS AND RESULTS Overall, 171 cases of second-generation DES ISR with a follow-up OCT minimum lumen area <3.0 mm2 were included: 33.3% of patients (n=57) had early ISR, and 66.7% (n=114) had late ISR (duration from stent implantation >1 year). Minimum stent area (MSA) <4.0 mm2, neointimal thickness <100 µm, and heterogeneous neointimal hyperplasia (NIH) were more prevalent in early ISR, whereas NIH with neoatherosclerosis trended towards being more frequent for late ISR (28.9% vs. 15.8%, p=0.06). Multivariable analysis revealed that duration from implantation >2 years, absence of statin use, and NIH >50% were independent predictors for neoatherosclerosis (all p<0.05). CONCLUSIONS OCT morphological characteristics of second-generation DES ISR differ between early and late presentation. Early ISR was associated with MSA <4.0 mm2, while neoatherosclerosis contributed more commonly to late ISR.


Esc Heart Failure | 2016

Steroid pulse therapy was effective for cardiac sarcoidosis with ventricular tachycardia and systolic dysfunction

Toshitaka Okabe; Tadayuki Yakushiji; Michiaki Hiroe; Yuji Oyama; Wataru Igawa; Morio Ono; Takehiko Kido; Seitaro Ebara; Kennosuke Yamashita; Myong Hwa Yamamoto; Shigeo Saito; Koichi Hoshimoto; Amemiya Kisaki; Naoei Isomura; Hiroshi Araki; Masahiko Ochiai

A 32‐year‐old man presented with palpitation. He was diagnosed with pulmonary sarcoidosis by lung biopsy. The electrocardiogram showed first‐degree atrioventricular block and complete right bundle branch block (CRBBB). We planned to examine laboratory data, echocardiography, Holter monitoring, and gallium‐67 scintigraphy. Before he went through all these exams, he developed ventricular tachycardia. After defibrillation was performed, his electrocardiogram revealed complete atrioventricular block. We observed elevation of serum angiotensin‐converting enzyme levels. In addition, both of gallium‐67 scintigraphy and 18F‐fluorodeoxyglucose positron emission tomography showed abnormal uptake in the ventricular septum. We diagnosed the patient with cardiac sarcoidosis associated with these arrhythmias. We started treatment with methylprednisolone pulse therapy (1 g daily). After 3 days of steroid pulse therapy, we administered prednisolone 30 mg daily. On day 15, electrocardiogram changed from complete atrioventricular block to first‐degree atrioventricular block and CRBBB. He was discharged with no progression with cardiac sarcoidosis for 2 years.


European Journal of Echocardiography | 2016

Morphological assessment of chronic total occlusions by combined coronary computed tomographic angiography and intravascular ultrasound imaging

Myong Hwa Yamamoto; Akiko Maehara; Michael Poon; Jun Guo; Kennosuke Yamashita; Tadayuki Yakushiji; Shigeo Saito; K. Koyama; Gary S. Mintz; Masahiko Ochiai

Aims The relationship between CTO morphology and vessel remodelling is unclear. We described chronic total occlusion (CTO) morphology using coronary computed tomographic angiography (CCTA) combined with intravascular ultrasound (IVUS). Methods and results Pre‐intervention CCTA and IVUS of 130 CTO lesions (128 patients) were evaluated. Based on CCTA, positive CTO lesion remodelling [PR, maximum CTO segment vessel diameter > proximal reference vessel diameter (RVD)] was seen in 44 (33.8%) lesions. In the other 86 lesions without PR, 74 (56.9%) had a minimum CTO segment vessel diameter >50% of the proximal RVD and were classified as non‐PR; 12 (9.2%) lesions had a minimum CTO segment vessel diameter ≤50% of the proximal RVD and were classified as collapse. Comparing the three groups, CTO with PR had the greatest maximum atheroma cross‐sectional area (CSA) while the collapse group had the least atheroma CSA (16.0 mm2 [12.0, 19.4] vs. 9.1 mm2 [6.0, 15.9], P < 0.001). The maximum arc of attenuated plaque was greatest in the PR group (51° [0, 167]); and the maximum arc of calcium was greatest in the non‐PR group (91° [51, 174]). In the collapse group distal to the occluded segment, there was a normal‐appearing vessel by IVUS that corresponded to the collapsed segment by CCTA; its minimum plaque burden was 33.2% [19.9, 38.1] with a smooth concave‐shaped lumen surface, implying that the CCTA collapse segment was not occluded. Conclusion Not all CTOs are the same with regard to lesion remodelling and underlying morphology. The combination of IVUS and CCTA can help to categorize CTO morphology.


International Journal of Cardiology | 2017

Relationship between worsening renal function and long-term cardiovascular mortality in heart failure patients

Toshitaka Okabe; Tadayuki Yakushiji; Takehiko Kido; Yuji Oyama; Wataru Igawa; Morio Ono; Seitaro Ebara; Kennosuke Yamashita; Myong Hwa Yamamoto; Shigeo Saito; Kisaki Amemiya; Naoei Isomura; Hiroshi Araki; Masahiko Ochiai

BACKGROUND Recently several studies showed that worsening renal function (WRF) during hospitalization might be a strong independent predictor of poor prognosis in decompensated heart failure (HF) patients. However, these studies had a relatively short follow-up duration and their data were limited to in-hospital outcomes. Our purpose was to assess the relationship between WRF and long-term cardiovascular mortality in HF patients. METHODS We enrolled decompensated HF patients who were admitted to our hospital between April 2010 and March 2015. WRF was defined as a relative increase in serum creatinine of at least 25% or an absolute increase in serum creatinine ≥0.3mg/dL from the baseline. We assessed the cardiovascular mortality and all-cause mortality in HF patients with WRF (WRF group) and without WRF (no WRF group). RESULTS Among 301 patients enrolled, WRF developed in 118 patients (39.2%). During a median follow-up period of 537days [interquartile range, 304.3 to 1025.8days], cardiovascular mortality and all-cause mortality were significantly higher in the WRF group than in the no WRF group (23.2% vs. 6.1%, P<0.001; 30.3% vs. 14.7%, P<0.001, respectively). In the multivariate Cox proportional hazards model, age and serum B-type natriuretic peptide (BNP) level were associated with both cardiovascular death and all-cause death. However, WRF was not the independent predictor of cardiovascular death (P=0.19) nor all-cause death (P=0.57). CONCLUSIONS WRF was associated with cardiovascular death in patients with HF. Although not an independent predictor, WRF might be one of useful markers to identify patients who should be followed carefully after discharge.


Journal of Cardiology Cases | 2014

Local injection of tissue-plasminogen activator using a pulse spray catheter as a treatment option for proximal deep vein thrombosis: A case report

Toshitaka Okabe; Hiroshi Araki; Tadayuki Yakushiji; Seitaro Ebara; Kennosuke Yamashita; Myong Hwa Yamamoto; Shigeo Saito; Koichi Hoshimoto; Kisaki Amemiya; Naoei Isomura; Chiaki Obara; Masahiko Ochiai

A 24-year-old woman was admitted to our hospital with the diagnosis of pulmonary thromboembolism (PTE) and left common iliac vein thrombosis. She had used low-dose contraceptive pill for dysmenorrhea. Otherwise, her laboratory data did not show any other thrombotic risk factors. Thrombus in the common iliac vein usually requires a permanent inferior vena cava (IVC) filter. However, the use of long-term warfarin should have been avoided for her potential future pregnancy. A retrievable IVC filter was placed and catheter directed thrombolysis was performed for her deep vein thrombosis (DVT). Local injection of monteplase from a pulse spray catheter was performed for 4 days. After the catheter-based treatment, the thrombus resolved and the IVC filter was successfully removed on day 19. The patient was discharged on day 21. Warfarin therapy was discontinued 6 months after discharge. <Learning objective: Urokinase is recommended in the guideline of the Japanese Circulation Society. But the dose is much less than those stated in guidelines overseas. Several studies have shown that tissue-plasminogen activator (t-PA) might be more effective than urokinase. We report a case in which local injection of monteplase, a type of long acting t-PA, for DVT was effective in treating PTE and DVT.>.


PLOS ONE | 2018

Serum zinc concentration in patients with acute myocardial infarction in percutaneous coronary intervention era

Toshitaka Okabe; Tadayuki Yakushiji; Suguru Shimazu; Jumpei Saito; Taro Kimura; Yuji Oyama; Wataru Igawa; Morio Ono; Takehiko Kido; Seitaro Ebara; Kennosuke Yamashita; Myong Hwa Yamamoto; Kisaki Amemiya; Naoei Isomura; Masahiko Ochiai

Introduction There were few studies that investigated the association between serum zinc concentration and acute myocardial infarction (AMI) in percutaneous coronary intervention era. Objective We assessed the relationships between serum zinc concentration, complications, and prognosis in AMI patients after primary percutaneous coronary intervention. Methods We conducted a single-center, prospective, observational study including 50 patients with AMI. We divided patients into two groups (High-zinc group and Low-zinc group) by median serum zinc concentration and compared two groups about clinical outcomes up to 1 year follow up. Results The mean age of patients was 66.2 ± 11.8 years old. Patients in the Low-zinc group had ST-segment elevation more frequently than those in the High-zinc group (96.0% vs. 72.0%, P = 0.02). All-cause mortality at 1 year was similar in both groups (P (log-rank) = 0.33). However, the lengths of hospital stay and in coronary care unit were longer in patients in the Low-zinc group than in those in the High-zinc group (15.6 ± 9.2 days vs. 11.9 ± 2.9 days, P = 0.06; 3.9 ± 2.8 days vs. 2.3 ± 0.8 days, P = 0.01). Multivariate regression analysis showed that low serum zinc concentration was associated with the use of cardiac or respiratory assist devices (adjusted odds ratio, 17.79; 95% CI 1.123 to 1216.5; P = 0.04). Conclusions Although there was no significance difference in mortality in Low-zinc and High-zinc groups, low serum zinc concentration was associated with longer stay in the coronary care unit, and was one of the independent predictors for the use of cardiac or respiratory assist devices.


Esc Heart Failure | 2018

The association between high-dose loop diuretic use at discharge and cardiovascular mortality in patients with heart failure: High-dose loop diuretic use

Toshitaka Okabe; Tadayuki Yakushiji; Takehiko Kido; Yuji Oyama; Wataru Igawa; Morio Ono; Seitaro Ebara; Kennosuke Yamashita; Myong Hwa Yamamoto; Shigeo Saito; Kisaki Amemiya; Naoei Isomura; Masahiko Ochiai

Few studies have reported the impact of high‐dose loop diuretics at discharge on prognosis in Japanese patients with heart failure (HF). Our purpose was to assess the relationship between the dose of loop diuretics at discharge and cardiovascular mortality in patients with HF.


Journal of the American College of Cardiology | 2017

PROCEDURAL CALCIUM FRACTURE AND ITS EFFECT ON STENT EXPANSION ASSESSED BY OPTICAL COHERENCE TOMOGRAPHY

Akiko Fujino; Gary S. Mintz; Kohei Koyama; Mitsuaki Matsumura; Myong Hwa Yamamoto; Dragos Alexandru; Joan Jennings; Patricia Krug; Lyn Santiago; Meghan Murray; Linda Bongiovanni; Fernando Sosa; Elizabeth Haag; Richard Shlofmitz; Akiko Maehara

Background: Severe coronary calcium (Ca) may limit stent expansion. We hypothesized that Ca fracture during stent implantation may mitigate its impact. Methods: Pre-intervention and final optical coherence tomography (OCT) were performed in 196 pts. Maximum superficial Ca angle and minimum Ca


Journal of the American College of Cardiology | 2017

INTRAVASCULAR ULTRASOUND ASSESSMENT OF THE EFFECTS OF ROTATIONAL ATHERECTOMY IN CALCIFIED CORONARY ARTERY LESIONS

Myong Hwa Yamamoto; Sung Sik Kim; Akiko Maehara; Kohei Koyama; Colin Berry; Keith G. Oldroyd; Gary S. Mintz; Margaret McEntegart

Background: Impact of rotational atherectomy (RA) on stent expansion is not fully understood. Method: We compared low, intermediate, and high Ca Index ([maximum superficial Ca angle/360] × [Ca length/lesion length]) tertiles assessed by IVUS of post RA. Reverberations with a concave-shaped lumen

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Akiko Maehara

Columbia University Medical Center

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Gary S. Mintz

Columbia University Medical Center

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Naoei Isomura

National Defense Medical College

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Shigeo Saito

Columbia University Medical Center

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Tadayuki Yakushiji

Columbia University Medical Center

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