• myocardial salvage (17 segment model) by SPECT [ Time Frame: 3 day to 6 month ]
  Calculation of score using software in the Core Lab (Tokai University, Department of Radiology). Scoring should be conducted in 17 segments and at 5 grades from 0 to 4 in each segment on the polar map images. The Myocardial salvage (17-segment) was calculated by subtracting the total sum of the 123I-BMIPP and 99mTc-tetrofosmin defect scores in each segment ( ∑123I-BMIPP defect score minus 99mTc-∑tetrofosmin defect score).
• Myocardial Salvage index (17 segment model) by SPECT [ Time Frame: 3 day to 6 month ]
  Salvage index was calculated as follows: Myocardial Salvage index =∑123I-BMIPP defect score minus ∑99mTc-tetrofosmin defect score/ ∑123I-BMIPP defect score × 100 (%).

• Myocardial scar amount assessment by MRI [ Time Frame: 5-9 days and 6 month ]
  All the outcome values will be derived by MRI image assessment. Each variables values will be derived as follows: Myocardial scar amount assessed on Late Short Axis LGE image
• Microvascular obstruction assessment by MRI [ Time Frame: 5-9 days and 6 month ]
  All the outcome values will be derived by MRI image assessment. Each variables values will be derived as follows: Microvascular obstruction on perfusion image and Early Short Axis LGE image
• Myocardial salvage assessment by MRI [ Time Frame: 5-9 days and 6 month ]
  All the outcome values will be derived by MRI image assessment. Each variables values will be derived as follows: Myocardial salvage derived from T2WBB and Late Short Axis LGE images
• Ejection fraction assessment by MRI [ Time Frame: 5-9 days and 6 month ]
  All the outcome values will be derived by MRI image assessment. Each variables values will be derived as follows: Ejection Fraction derived from Cine images
• Gray zone assessment by MRI [ Time Frame: 5-9 days and 6 month ]
  All the outcome values will be derived by MRI image assessment. Each variables values will be derived as follows: Gray zone derived from Late Short Axis LGE images.
• Left ventricular ejection fraction by TF scintigraphy at 6 months [ Time Frame: 5-7 month ]
  99mTc-tetrofosmin (TF) scintigraphy was performed 6 months after the PCI procedure. For the scanning procedure, the 740 MBq of 99mTc-tetrofosmin injected with patient while at rest. ejection fraction (%) based on 99mTc-tetrofosmin QGS data.
• Left ventricular volume (ml) by TF scintigraphy at 6 months [ Time Frame: 5-7 month ]
  99mTc-tetrofosmin (TF) scintigraphy was performed 6 months after the PCI procedure. For the scanning procedure, the 740 MBq of 99mTc-tetrofosmin injected with patient while at rest. Left ventricular volume (ml) based on 99mTc-tetrofosmin QGS data.
• Left ventricular end-diastolic volume (ml) by TF scintigraphy at 6 months [ Time Frame: 5-7 month ]
  99mTc-tetrofosmin (TF) scintigraphy was performed 6 months after the PCI procedure. For the scanning procedure, the 740 MBq of 99mTc-tetrofosmin injected with patient while at rest. Left ventricular end-diastolic volume (ml) based on 99mTc-tetrofosmin QGS data.
• Left ventricular end-systolic volume (ml) by TF scintigraphy at 6 months [ Time Frame: 5-7 month ]
  99mTc-tetrofosmin (TF) scintigraphy was performed 6 months after the PCI procedure. For the scanning procedure, the 740 MBq of 99mTc-tetrofosmin injected with patient while at rest. Left ventricular end-systolic volume (ml) on 99mTc-tetrofosmin QGS data.
• Intra-stent tissue volume by OCT [ Time Frame: at the end of procedure and 1-year ]
  OCT analysis should be conducted by an independent core lab (Kobe University Hospital) before and after stenting at Primary PCI and 1 year after PCI in selected patients. Should be conducted preoperatively, postoperatively and 1 year after operation. For analysis, the required matters (catheter size and target lesion) should be entered into the technician worksheet. The size and length of the stent used should be entered, in particular. In conducting OCI imaging in each medical institution, attention should be paid to the following points, and the requirements should be entered in the given section of technician worksheet: Analysis should be conducted based on the stent length described in the technician worksheet. In the qualitative analysis, the inside of stent and 5 mm to proximal and distal ends of stent should be evaluated at the interval of 0.2 mm. In the quantitative analysis, the inside of stent should be evaluated at the interval of 1.0 mm.
• Myocardial salvage [total perfusion defect (TPD) model] by SPECT [ Time Frame: 3 day to 6 month ]
  Myocardial salvage [total perfusion defect model (TPD)] = (Risk at area: TPD measured by BMIPP 3-9 days after p-PCI) minus (Infarct size: TPD measured by Tc99m-tetrofosmin at 6 months after p-PCI)
• Myocardial salvage index (%) [total perfusion defect (TPD) model] by SPECT [ Time Frame: 3 day to 6 month ]
  Myocardial salvage index (%) [total perfusion defect model (TPD)] = myocardial salvage / Risk at area: TPD measured by BMIPP 3-9 days after p-PCI x 100
• Major adverse cardiovascular events (MACE) at 12 months [ Time Frame: 12 months ]
  Major adverse cardiovascular events (MACE) MACE were defined as all-cause death, myocardial infarction (MI), or target lesion revascularization (TLR).
• Major adverse cardiovascular events (MACE) at 36 months [ Time Frame: 36 months ]
  Major adverse cardiovascular events (MACE) MACE were defined as all-cause death, myocardial infarction (MI), or target lesion revascularization (TLR).
• Major adverse cardiovascular events (MACE) at 60 months [ Time Frame: 60 months ]
  Major adverse cardiovascular events (MACE) MACE were defined as all-cause death, myocardial infarction (MI), or target lesion revascularization (TLR).
• Cardiac death at 12 months [ Time Frame: 12 months ]
  Death was considered to be of cardiac origin unless obvious noncardiac causes could be identified.
• Cardiac death at 36 months [ Time Frame: 36 months ]
  Death was considered to be of cardiac origin unless obvious noncardiac causes could be identified.
• Cardiac death at 60 months [ Time Frame: 60 months ]
  Death was considered to be of cardiac origin unless obvious noncardiac causes could be identified.

The clinical result of catheter treatment in the patients with acute myocardial infarction in these several decades improved because of progress of early reperfusion therapy and stent treatment technique. However, the no-reflow phenomenon is still remaining as a problem, which is involved in a decrease in left ventricular function and worsening of prognosis. It is considered that the no-reflow phenomenon is induced by atherosclerotic and thrombotic emboli, endothelial dysfunction of capillary vessels, free radicals and cytokine. The treatment combining the peripheral protection and thrombus aspiration aiming at prevention of no-reflow is expected to reduce no-reflow and the infarct size and has been conducted on the patients with acute myocardial infarction. However, a lot of randomized studies have been conducted, so far, which do not lead to reduction of infarct size and improvement of survival rate, and the efficacy has not been demonstrated.

Some explanations have been suggested for this phenomenon:

1. The operation method of device is complicated, and it is difficult to acquire the treatment technique.
2. Giant thrombus and solid lesion could not be aspirated effectively.
3. A lot of randomized studies have not focused on the "patients with anterior descending lesion of thrombolysis in myocardial infarction (TIMI) grade 0/1, of which the time from onset to treatment is within 6 hours," considered to have the largest benefit of prevention of no-reflow.

In recent years in Japan, excimer laser coronary angioplasty (ELCA) has been used in the patients with acute coronary syndrome (ACS), and not only debulking of arteriosclerotic lesion but also thrombolytic effect have been reported. In the Camel trial and Utility of Laser for Transcatheter Atherectomy Multicenter Analysis around Naniwa (ULTRAMAN) registry, the efficacy and safety in ACS have been reported, but the infarct size has not been evaluated.

This time in this study, it is considered that verification whether or not ELCA is able to improve the myocardial salvage in anterior ST elevation myocardial infarction (STEMI) using myocardial scintigram (acute-phase BMIPP and chronic-phase TF) will provide the useful information helpful for selection of treatment to medical care staffs and patients for future patients suffering from ACS and will be able to contribute to further improvement of medical science and medical practice.

MRI will be performed twice at 5-9 days and at 6 months post index ST elevation myocardial infarction to assess myocardial damage and functional variables, which details will be described in the following outcome measurement section.

• Experimental: ELCA
  On the antegrade delivery of the laser catheter after wiring, we used safe laser techniques and injected saline before and during the laser procedure at a 0.5 mm/sec catheter advancement rate. Whether to perform a retrograde laser method depended on each operator. After ablation by ELCA, patients undergo balloon dilation via standard techniques, and as appropriate, receive drug-eluting stent deployment.
  Intervention: Device: Excimer laser catheter
• No Intervention: non ELCA
  In non ELCA group, the conventional PCI procedure, including thrombus aspiration, POBA, and stent implantation was performed. The indication for aspiration was at the discretion of the physician based on angiographic, intravascular ultrasound, or optical coherence tomography/Optical Frequency-Domain Imaging.

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Inclusion Criteria:

• Patients to whom PCI treatment for anterior STEMI is indicated [Main selection criteria]
• First-episode anterior STEMI patients within 6 hours of onset that satisfy electrocardiogram criteria
• Patients who are 21 years of age or older at the time of consent acquisition
• Patient who the patient himself agreed in writing

Exclusion Criteria:

• Patients presenting cardiac shock at the time of visit
• Patients whose target lesions are left main trunk, circumflex, right coronary artery, distal anterior descending branch
• Patients who have TIMI 2, 3 at the initial imaging
• Patients with a reference vessel diameter of 2.5 mm or less
• Patients determined to lack consent ability for mental or other reasons
• Patient who is judged inappropriate by research researcher or research sharing doctor

The inclusion and exclusion criteria for the MRI will follow the main study, but in addition, will exclude following conditions.

• Atrial fibrillation subject at the timing of MRI scan
• Internally implanted devices such as pacemakers or ICDs
• Subject that is allergic to Gadolinium,
• Subject with claustrophobia
• Pregnancy