Hideki Miyachi

Dr. Hideki Miyachi

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Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 January 2016 in Heart and Vessels
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Journal Article
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HMHideki Miyachi
Hideki Miyachi
ATAtsushi Takagi
Atsushi Takagi
KMKatsumi Miyauchi
Katsumi Miyauchi
MYMasao Yamasaki
Masao Yamasaki
HTHiroyuki Tanaka
Hiroyuki Tanaka
MTMorimasa Takayama
Morimasa Takayama
Limited data exists on ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) managed by a well-organized cardiac care network in a metropolitan area. We analyzed the Tokyo CCU network database in 2009–2010. Of 4329 acute myocardial infarction (AMI) patients including STEMI (n = 3202) and NSTEMI (n = 1127), percutaneous coronary intervention (PCI) was performed in 88.8 % of STEMI and 70.4 % of NSTEMI patients. Mean onset-to-door and door-to-balloon times in STEMI patients were shorter than those in NSTEMI patients (167 vs 233 and 60 vs 145 min, respectively, p < 0.001). Coronary artery bypass graft surgery was performed in 4.2 % of STEMI and 11.4 % of NSTEMI patients. In-hospital mortality was significantly higher in STEMI patients than NSTEMI patients (7.7 vs 5.1 %, p < 0.007). Independent correlates of in-hospital mortality were advanced age, low blood pressure, and high Killip classification, statin-treated dyslipidemia and PCI within 24 h were favorable predictors for STEMI. High Killip classification, high heart rate, and hemodialysis were significant predictors of in-hospital mortality, whereas statin-treated dyslipidemia was the only favorable predictor for NSTEMI. In conclusion, patients with MI received PCI frequently (83.5 %) and promptly (door-to-balloon time; 66 min), and had favorable in-hospital prognosis (in-hospital mortality; 7.0 %). In addition to traditional predictors of in-hospital death, statin-treated dyslipidemia was a favorable predictor of in-hospital mortality for STEMI and NSTEMI patients, whereas hemodialysis was the strongest predictor for NSTEMI patients.

4 October 2022 in JACC: Asia
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Journal Article
Open access
HMHideki Miyachi
Hideki Miyachi
TYTakeshi Yamamoto
Takeshi Yamamoto
MTMorimasa Takayama
Morimasa Takayama
KMKatsumi Miyauchi
Katsumi Miyauchi
MYMasao Yamasaki
Masao Yamasaki
KNKen Nagao
Ken Nagao
The mortality rate of acute myocardial infarction (AMI) has improved dramatically because of reperfusion therapy during the last 40 years; however, recent temporal trends for AMI have not been fully clarified in Japan. The purpose of this study was to elucidate the temporary trend in in-hospital mortality and treatment of AMI for the last decade in the Tokyo Metropolitan area. We enrolled 30,553 patients from the Tokyo Cardiovascular Care Unit Network Registry, diagnosed with AMI from 2007 to 2016, as part of an ongoing, multicenter, cohort study. We analyzed the temporal trends in basic characteristics, treatment, and in-hospital mortality of AMI. The overall emergency percutaneous coronary intervention (PCI) rate significantly increased (P < 0.001). In particular, it remarkably increased in patients older than 80 years of age (58.3% to 70.3%, P < 0.001) and patients with Killip III or IV (Killip III, 46.9% to 65.7%; Killip IV, 65.2% to 76.6%, P < 0.001 for both). The crude and age-adjusted in-hospital mortality remained low (5.2% to 8.2% and 3.4% to 5.5%, respectively) and significantly decreased during the decade (P < 0.001). The in-hospital mortality remarkably decreased in patients older than 80 years of age (17.3% to 12.7%, P < 0.001) and in those with cardiogenic shock (38.5% to 27.3%, P < 0.001). This large cohort study from Tokyo revealed that in-hospital mortality of AMI significantly decreased with the increase in emergency percutaneous coronary intervention rate over the decade, particularly for high-risk patients such as older patients and those with cardiogenic shock.

1 December 2021 in Internal Medicine
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Journal Article
Open access
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YWYukihiro Watanabe
Yukihiro Watanabe
HMHideki Miyachi
Hideki Miyachi
KMKosuke Mozawa
Kosuke Mozawa
KYKenta Yamada
Kenta Yamada
EOEiichiro Oka
Eiichiro Oka
WSWataru Shimizu
Wataru Shimizu
Objective The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on global healthcare systems. Some studies have reported the negative impact of COVID-19 on ST-elevation myocardial infarction (STEMI) patients; however, the impact in Japan remains unclear. This study investigated the impact of the COVID-19 pandemic on STEMI patients admitted to an academic tertiary-care center in Tokyo, Japan. Methods In this retrospective, observational, cohort study, we included 398 consecutive patients who were admitted to our institute from January 1, 2018, to March 10, 2021, and compared the incidence of hospitalization, clinical characteristics, time course, management, and outcomes before and after March 11, 2020, the date when the World Health Organization declared COVID-19 a pandemic. Results There was a 10.7% reduction in hospitalization of STEMI patients during the COVID-19 pandemic compared with that in the previous year (117 vs. 131 cases). During the COVID-19 pandemic, the incidence of late presentation was significantly higher (26.5% vs. 12.1%, p<0.001), and the onset-to-door (241 [IQR: 70-926] vs. 128 [IQR: 66-493] min, p=0.028) and door-to-balloon (72 [IQR: 61-128] vs. 60 [IQR: 43-90] min, p<0.001) times were significantly longer than in the previous year. Furthermore, the in-hospital mortality was higher, but the difference was not significant (9.4% vs. 5.0%, p=0.098). Conclusions The COVID-19 pandemic significantly impacted STEMI patients in Tokyo and resulted in a slight decrease in hospitalization, a significant increase in late presentation and treatment delays, and a slight but nonsignificant increase in mortality. In the COVID-19 era, the acute management system for STEMI in Japan must be reviewed.

24 August 2012 in European Heart Journal
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Journal Article
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HMHideki Miyachi
Hideki Miyachi
SKShin-Ichiro Kumita
Shin-Ichiro Kumita
KTKeiji Tanaka
Keiji Tanaka
An 85-year-old female was referred with chest pain. The electrocardiogram showed ST-elevation in the precordial leads. A routine biological evaluation showed increased troponin T (1.32 ng/mL), total creatine kinase (CK) (687 IU/L), and CKMB (60.0 IU/L). Emergent coronary arteriography showed no stenosis and revealed acetylcholine-inducible spasm of the right coronary artery (RCA). Left ventriculography and transthoracic echocardiography demonstrated remarkable apical ballooning and hyperdynamic contraction of the basal segment (Panel A). Therefore, we diagnosed the patient with Takotsubo cardiomyopathy. 99mTc-sestamibi (MIBI) and 123I-beta-methyl iodophenyl pentadecanoic acid SPECT and 18F-fluorodeoxyglucose (18F-FDG) PET were performed on Days 5 and 6. 123I-beta-methyl iodophenyl pentadecanoic acid images revealed a severely reduced uptake in the apex and a slightly reduced uptake of MIBI in the same region (Panels B and C). These results demonstrated severely impaired fatty acid metabolism rather than myocardial perfusion during the acute phase. The 18F-fluorodeoxyglucose PET image showed an obvious focal FDG accumulation in the apex. (Panel D). In this case, 18F-FDG injection was performed after prolonged fasting, unlike the procedure followed in the standardized glucose loading state. The normal myocardium primarily utilizes free fatty acids in the fasting state, and physiological accumulation of 18F-FDG in the normal myocardium was inhibited. Therefore, high uptake of 18F-FDG in the fasting state suggests an impaired myocardium, including the presence of inflammation. In summary, SPECT/CT and PET/CT fusion imaging revealed increased glucose metabolism probably due to inflammation and a reduction of fatty acid metabolism that was inconsistent with a spastic lesion of the RCA. Transthoracic echocardiography demonstrated complete resolution of left ventricular wall motion within 1 week.

3 June 2024 in Acta Biomaterialia
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Journal Article
Open access
HMHideki Miyachi
Hideki Miyachi
STShuhei Tara
Shuhei Tara
HNHidetaka Nakayama
Hidetaka Nakayama
RHRikako Hama
Rikako Hama
Tadahisa SugiuraTadahisa Sugiura
Tadahisa Sugiura
TSToshiharu Shinoka
Toshiharu Shinoka
Macrophages are the primary cell type orchestrating bioresorbable vascular graft (BVG) remodeling and infiltrate from three sources: the adjacent native vessel, circulating blood, and transmural migration from outer surface of the graft. To elucidate the kinetics of macrophage infiltration into the BVG, we fabricated two different bilayer arterial BVGs consisting of a macroporous sponge layer and a microporous electrospun (ES) layer. The Outer ES graft was designed to reduce transmural cell infiltration from the outer surface and the Inner ES graft was designed to reduce cell infiltration from the circulation. These BVGs were implanted in mice as infrarenal abdominal aorta grafts and extracted at 1, 4, and 8 weeks (n=5, 10, and 10 per group, respectively) for evaluation. Cell migration into BVGs was higher in the Inner ES graft than in the Outer ES graft. For Inner ES grafts, the majority of macrophage largely expressed a pro-inflammatory M1 phenotype but gradually changed to tissue-remodeling M2 macrophages. In contrast, in Outer ES grafts macrophages primarily maintained an M1 phenotype. The luminal surface endothelialized faster in the Inner ES graft; however, the smooth muscle cell layer was thicker in the Outer ES graft. Collagen fibers were more abundant and matured faster in the Inner ES graft than that in the Outer ES graft. In conclusion, compared to macrophages infiltrating from the circulating blood, transmural macrophages from outside promote the acute inflammatory-mediated response for vascular remodeling and subsequent collagen deposition within BVGs. STATEMENT OF SIGNIFICANCE: To elucidate the kinetics of macrophage infiltration into the bioresorbable vascular graft (BVG), two different bilayer arterial BVGs were implanted in mice as infrarenal abdominal aorta grafts. Cell migration into BVGs was higher in the inner electrospun graft which cells mainly infiltrate from outer surface than in the outer electrospun graft which cells mainly infiltrate from the circulating blood. In the inner electrospun grafts, the majority of macrophages changed from the M1 phenotype to the M2 phenotype, however, outer electrospun grafts maintained the M1 phenotype. Collagen fibers matured faster in the Inner electrospun graft. Compared to macrophages infiltrating from the circulating blood, transmural macrophages from outside promote the acute inflammatory-mediated response for vascular remodeling and subsequent collagen deposition within BVGs.

4 January 2022 in Journal of Clinical Medicine
Verified
Journal Article
Open access
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SNSatsuki Noma
Satsuki Noma
HMHideki Miyachi
Hideki Miyachi
IFIsamu Fukuizumi
Isamu Fukuizumi
JMJunya Matsuda
Junya Matsuda
HSHideto Sangen
Hideto Sangen
HTHitoshi Takano
Hitoshi Takano
Background: High coronary thrombus burden has been associated with unfavorable outcomes in patients with ST-segment elevation myocardial infarction (STEMI), the optimal management of which has not yet been established. Methods: We assessed the adjunctive catheter-directed thrombolysis (CDT) during primary percutaneous coronary intervention (PCI) in patients with STEMI and high thrombus burden. CDT was defined as intracoronary infusion of tissue plasminogen activator (t-PA; monteplase). Results: Among the 1849 consecutive patients with STEMI, 263 had high thrombus burden. Moreover, 41 patients received t-PA (CDT group), whereas 222 did not receive it (non-CDT group). No significant differences in bleeding complications and in-hospital and long-term mortalities were observed (9.8% vs. 7.2%, p = 0.53; 7.3% vs. 2.3%, p = 0.11; and 12.6% vs. 17.5%, p = 0.84, CDT vs. non-CDT). In patients who underwent antecedent aspiration thrombectomy during PCI (75.6% CDT group and 87.4% non-CDT group), thrombolysis in myocardial infarction grade 2 or 3 flow rate after thrombectomy was significantly lower in the CDT group than in the non-CDT group (32.2% vs. 61.0%, p < 0.01). However, the final rates improved without significant difference (90.3% vs. 97.4%, p = 0.14). Conclusions: Adjunctive CDT appears to be tolerated and feasible for high thrombus burden. Particularly, it may be an option in cases with failed aspiration thrombectomy.