What is the initial management of a patient presenting with chest pain and suspected acute coronary syndrome?

Initial Management of Chest Pain Suspected to be Acute Coronary Syndrome

Patients with suspected ACS and high-risk features (continuing chest pain >20 minutes, severe dyspnea, syncope/presyncope, or palpitations) should be transported immediately to the emergency department by emergency medical services, where a 12-lead ECG must be obtained within 10 minutes of arrival. 1, 2

Immediate Triage and Risk Assessment

High-Risk Features Requiring Emergency Transport

• Chest pain or discomfort lasting more than 20 minutes at rest 1, 2
• Hemodynamic instability 1
• Recent syncope or presyncope 1
• Severe dyspnea or palpitations 1

Lower-Risk Presentations

• Patients with less severe symptoms may be evaluated in an ED, chest pain unit, or appropriate outpatient facility capable of performing ECG and troponin measurements 1

Critical First 10 Minutes: ECG and Vital Signs

Obtain a 12-lead ECG within 10 minutes of presentation to differentiate STEMI from non-ST-elevation ACS. 2, 3

• Check vital signs including consciousness, respiration, blood pressure, and heart rate 2
• Establish intravenous access for medication administration 2
• Monitor cardiac rhythm continuously to detect life-threatening arrhythmias 2

ECG Interpretation for Risk Stratification

• ST-segment elevation indicates complete coronary occlusion requiring immediate reperfusion therapy (door-to-balloon time <90 minutes for PCI or door-to-needle time <30 minutes for fibrinolysis) 2, 3
• ST-segment depression, T-wave inversion, or normal ECG requires further assessment with cardiac biomarkers 2, 3
• STEMI accounts for approximately 30% of ACS cases, while non-ST-elevation ACS accounts for 70% 3

Immediate Pharmacological Management

Antiplatelet Therapy

Administer aspirin 162-325 mg (chewed) immediately unless contraindicated. 2, 4

• For non-ST-elevation ACS with high-risk features, add clopidogrel 300 mg loading dose followed by 75 mg daily 4, 5
• High-risk features include recurrent ischemia, elevated troponin, hemodynamic instability, major arrhythmias, or diabetes 4

Pain Management

• Provide sublingual nitroglycerin for ongoing chest pain (may repeat every 5 minutes for maximum of 3 doses) 2
• Administer intravenous morphine titrated to pain severity if pain is unrelieved by nitroglycerin 2

Beta-Blocker Therapy

• Consider intravenous metoprolol if tachycardia or hypertension is present and no contraindications exist 2
• For confirmed myocardial infarction, initiate metoprolol tartrate injection 5 mg IV at 2-minute intervals for three doses (total 15 mg), followed by oral metoprolol 50 mg every 6 hours starting 15 minutes after the last IV dose 6

Anticoagulation

• Administer low molecular weight heparin (enoxaparin) or unfractionated heparin for high-risk non-ST-elevation ACS 4

Laboratory Assessment

Draw blood samples immediately for cardiac troponin (preferably high-sensitivity troponin), complete blood count, and basic metabolic panel. 2, 3

• High-sensitivity troponin is the preferred test to evaluate for NSTEMI 3
• Do not delay treatment while waiting for cardiac biomarker results—initial management should be based on clinical presentation and ECG findings 2

Differential Diagnosis to Consider

Life-Threatening Cardiovascular Causes

• Aortic dissection 1
• Expanding aortic aneurysm 1
• Pulmonary embolism 1
• Pericarditis 1

Other Causes

• Pulmonary: pneumonia, pleuritis, pneumothorax 1
• Gastrointestinal: GERD, esophageal spasm, peptic ulcer, pancreatitis, biliary disease 1
• Musculoskeletal: costochondritis, cervical radiculopathy 1

Reperfusion Strategy Based on ECG

For STEMI

Primary PCI within 120 minutes reduces mortality from 9% to 7%. 3

• If PCI within 120 minutes is not possible, administer fibrinolytic therapy (alteplase, reteplase, or tenecteplase at full dose for patients <75 years; half dose for patients ≥75 years) 3
• Transfer to PCI-capable facility within 24 hours after fibrinolysis 3

For High-Risk NSTE-ACS

Prompt invasive coronary angiography and revascularization within 24-48 hours reduces mortality from 6.5% to 4.9%. 3

Critical Pitfalls to Avoid

• Do not delay reperfusion therapy with consultation delays—these are associated with increased mortality 2
• Recognize atypical presentations: approximately 40% of men and 48% of women present with nonspecific symptoms such as dyspnea rather than classic chest pain 3
• Women and elderly patients frequently present with atypical symptoms including dyspnea, fatigue, or nausea 2
• Do not administer fibrinolytic therapy to patients presenting >24 hours after symptom onset unless continuing ischemic pain with ST-segment elevation is present 2
• Balance bleeding risk against antithrombotic benefit, particularly in elderly patients or those with renal impairment 4
• Consider echocardiography to assess left ventricular function and rule out other cardiovascular causes of chest pain 2