<prompt> Answer this question truthfullyWhat is the first-line treatment for non ST elevation myocardial infarction?  <response>: <reason> Class I 1. The history, physical examination, 12 lead ECG, and initial cardiac biomarker tests should be integrated to assign patients with chest pain into 1 of 4 categories: a non cardiac diagnosis, chronic stable angina, possible ACS, and definite ACS. Level of Evidence: C 2. Patients with probable or possible ACS but whose initial 12 lead ECG and cardiac biomarker levels are normal should be observed in a facility with cardiac monitoring e.g., chest pain unit or hospital telemetry ward, and repeat ECG or continuous 12-lead ECG monitoring and repeat cardiac biomarker measurements should be obtained at predetermined, specified time intervals. Level of Evidence: B 3. In patients with suspected ACS in whom ischemic heart disease is present or suspected, if the follow-up 12 lead ECG and cardiac biomarkers measurements are normal, a stress test exercise or pharmacological to provoke ischemia should be performed in the ED, in a chest pain unit, or on an outpatient basis in a timely fashion within 72 h as an alternative to inpatient admission. Low-risk patients with a negative diagnostic test can be managed as outpatients. Level of Evidence: C 4. In low-risk patients who are referred for outpatient stress testing, precautionary appropriate pharmacotherapy e.g., ASA, sublingual NTG, andor beta blockers should be given while awaiting results of the stress test. Level of Evidence: C 5. Patients with definite ACS and ongoing ischemic symptoms, positive cardiac biomarkers, new ST-segment deviations, new deep T-wave inversions, hemodynamic abnormalities, or a positive stress test should be admitted to the hospital for further management. Admission to the critical care unit is recommended for those with active, ongoing ischemiainjury or hemodynamic or electrical instability. Otherwise, a telemetry step-down unit is reasonable. Level of Evidence: C 6. Patients with possible ACS and negative cardiac biomarkers who are unable to exercise or who have an abnormal resting ECG should undergo a pharmacological stress test. Level of Evidence: B 7. Patients with definite ACS and ST-segment elevation in leads V7 to V9 due to left circumflex artery occlusion should be evaluated for immediate reperfusion therapy. Level of Evidence: A 8. Patients discharged from the ED or chest pain unit should be given specific instructions for activity, medications, additional testing, and follow-up with a personal physician. Level of Evidence: C Class IIa 1. In patients with suspected ACS with a low or intermediate probability of CAD, in whom the follow up 12 lead ECG and cardiac biomarkers measurements are normal, performance of a non invasive coronary imaging test i.e., Cardiac Coronary CT Angiography is reasonable as an alternative to stress testing. Level of Evidence: B 