the MCCE vs EGD Trial

Inclusion Criteria: subjects are patients older than 18 years old with: 1. the diagnosis of ACS as defined by symptoms of chest pain or shortness-of-breath, abnormal electrocardiogram and positive enzyme, requiring coronary intervention 2. new-onset anaemia as defined by Hb\<11 g/dL on admission blood taking Exclusion Criteria: 1. History of active haematological disease including hemoglobinopathies such as thalassemia, Myelodysplastic syndromes, haematological malignancy, aplastic anaemia, or autoimmune haemolytic anaemia. 2. Patients with known active gastrointestinal malignancy. 3. Contraindications for CE: suspected or known gastrointestinal obstruction, stenosis, fistula, diverticula, presence of gastrointestinal obstruction symptoms such as pain or dysphagia; inoperative conditions or refusal to undergo abdominal surgery if required; history of laparotomy, gastric or bowel surgery; presence of metallic implants that is not MRI conditional. 4. Contraindications for EGD: Possible gastrointestinal perforation, medically unstable patients, patient with known pharyngeal diverticulum, and patients with recent head and neck trauma. 5. Inability to take 1-month DAPT such as non-deferrable surgery within 1 months, severe allergy or hypersensitivity reaction to aspirin or P2Y12 inhibitors, or patients in whom 1 months DAPT is not indicated. 6. Patients whose life-expectancy is less than 6 months. 7. Patients who are pregnant or lactating. 8. Patients who are unable to give informed consent. 9. Patients who are in active heart failure or fluid-overload state. 10. Patients who have chronic renal failure as defined by estimated glomerular filtration rate \<15 ml/min/1.73m2.