1 Step 1: Assessment and diagnosis In patients arriving at the emergency room with acute chest pain, the first step is to immediately assess the condition and identify the fatal disease causing the chest pain. 1.1 If the patient has life-threatening signs and symptoms (including: sudden syncope or dyspnea, blood pressure <90/60 mmHg, heart rate >100 beats/min, bilateral pulmonary rales), immediately establish intravenous access, administer oxygen, and stabilize vital signs; 1.2 Complete the first ECG and physical examination within 5 minutes (mainly pay attention to the presence or absence of jugular venous filling, the consistency of bilateral pulmonary breath sounds, the presence or absence of bilateral pulmonary rales 1.3 Complete blood gas analysis, myocardial biochemical markers, renal function, routine blood count, bedside chest X-ray and bedside echocardiography; 1.4 Take medical history (including the time of this chest pain episode, history of previous chest pain, history of previous heart disease, history of history of diabetes mellitus and hypertension, history of previous medication); 2 Step 2: After the above tests, enter the green channel immediately according to the maximum possible diagnosis. 2.1 Definitive diagnosis of myocardial infarction a. STEMI treatment: As soon as the diagnosis is clear, aspirin 0.3 chewable and clopidogrel tablets 0.3 oral are given, while the cardiology PCI team is notified of the availability of medical and nursing staff. The goal is to minimize the time to reperfusion therapy, save lives, and improve prognosis. the ACC/AHA recommended time window for starting thrombolytic therapy is within 30 minutes of onset, and the D2B time window is within 90 minutes of onset. The current recommendations for early reperfusion therapy for STEMI are: if seen within 3 hours of onset, both thrombolysis and emergency PCI are options, and if seen after 3 hours of onset, emergency PCI is the recommended treatment of choice. b. Diagnosis and treatment of UA/NSTEMI: The key to its treatment is early diagnosis of ACS, accurate risk stratification, early identification of high-risk patients, different treatment plans according to different risk stratification, and immediate admission to CCU. 2.2 Initial diagnosis does not confirm the diagnosis of ACS, but may be ACS. a. For patients with normal ECG and troponin at the time of consultation, repeat observation of ECG or troponin changes after 6 hours. or troponin changes after 6 hours. If the patient has persistent chest pain, or requires nitroglycerin for relief, this is a high risk and early and continuous review of ECG and troponin is recommended. b. If the patient has dynamic changes in ST-T on the ECG or elevated troponin or hemodynamic abnormalities suggestive of UA or NSTEMI, please follow the UA/NSTEMI procedure described above. c. If the patient has no ST-T changes on ECG or no troponin elevation 6 to 12 hours after the visit or 6 to 12 hours after chest pain, it suggests that the patient is at low or intermediate risk for recent non-fatal myocardial infarction or death. For risk stratification, please use the TIMI score or GRACE score. a) For low-risk patients, if there is no other clear cause of chest pain, a stress test or coronary CT (coronary CTA) can be performed within 72 hours of discharge and followed up on an outpatient basis. b) For intermediate-risk patients, it is recommended to consult a cardiologist and perform a cardiac stress test or coronary CTA before discharge. Since the main clinical causes of fatal chest pain include pulmonary embolism, aortic coarctation and coronary artery disease, it is necessary to complete screening for all three diseases in one CTA examination for low- and intermediate-risk patients with ACS, which is known as triple imaging of chest pain (TRIPLE-RULE-OUT CT, TRO CT). 2.3 Exclusion of ACS, immediate chest pain triple CT examination, and diagnosis of aortic coarctation aneurysm The first step is sedation, analgesia, oxygenation, and establishment of intravenous access ↓ Control of blood pressure and heart rate mainly by intravenous drugs, such as sodium nitroprusside and uradil ↓ Further treatment intervention (stent); surgery 2.4 Exclusion of ACS, immediate chest pain triple CT examination, and diagnosis of pulmonary embolism The first step is treatment analgesia, sedation, high concentration of oxygen, establishment of intravenous access, cardiac monitoring ↓ continue to deal with anti-shock, correction of acute right heart failure ↓ causal treatment of anticoagulation, assessment of thrombolytic indications, surgical or interventional embolization, inferior vena cava network