What is the initial management for an adult patient with chest pain and no known medical history?

Initial Management of Chest Pain in Adults with No Known Medical History

Obtain a 12-lead ECG within 10 minutes of patient contact and administer aspirin 160-325 mg (chewed) immediately unless contraindicated, while simultaneously activating emergency medical services for transport to the emergency department. 1, 2

Immediate Actions (First 10 Minutes)

ECG Acquisition and Interpretation

• Acquire and interpret a 12-lead ECG within 5-10 minutes to identify ST-segment elevation myocardial infarction (STEMI), ST-segment depression, T-wave inversions, or other ischemic changes 1, 2, 3
• If ST-segment elevation ≥1 mm in contiguous leads is present, immediately activate STEMI protocols with door-to-balloon time <90 minutes (preferred) or door-to-needle time <30 minutes for thrombolysis 2
• If initial ECG is nondiagnostic but clinical suspicion remains high, obtain supplemental leads V7-V9 to detect posterior myocardial infarction 1, 2
• Perform serial ECGs if symptoms persist, change, or clinical condition deteriorates 1

Immediate Pharmacotherapy

• Administer aspirin 160-325 mg orally (chewed, not swallowed) as soon as possible unless contraindicated by known allergy or active gastrointestinal bleeding 1, 2, 4
• Provide sublingual nitroglycerin 0.4 mg every 5 minutes (up to 3 doses) unless systolic blood pressure <90 mmHg or heart rate <50 or >100 bpm 2, 4
• Administer intravenous morphine 4-8 mg with additional 2 mg doses every 5 minutes for pain relief, as pain increases sympathetic activation and myocardial oxygen demand 2, 5
• Provide supplemental oxygen 2-4 L/min if patient is breathless, has heart failure features, or oxygen saturation is low 2

Emergency Transport

• Transport by emergency medical services (EMS) rather than private vehicle for all patients with suspected acute coronary syndrome (ACS) or life-threatening chest pain 1, 2, 6
• Pre-hospital ECG acquisition and aspirin administration by trained EMS personnel reduces mortality and in-hospital delay time 2
• Never delay transfer to the emergency department for troponin testing in office settings when ACS is suspected 1, 2, 6

Risk Stratification Framework

High-Risk Features Requiring Immediate CCU Admission

• Prolonged ongoing rest pain (>20 minutes) with associated diaphoresis, dyspnea, nausea, or syncope 2, 6
• Hemodynamic instability (systolic blood pressure <90 mmHg, heart rate >130 or <40 bpm) 1, 2
• ST-segment changes on ECG (elevation or depression) 1, 2
• New T-wave inversions or new arrhythmias 1
• Signs of acute heart failure (crackles, S3 gallop, jugular vein distension) 1, 2

Intermediate-Risk Features

• Rest angina >20 minutes that has resolved 2
• Age >70 years 2, 6
• Diabetes mellitus 2, 6
• Prior history of myocardial infarction or known coronary artery disease 2

Essential Diagnostic Testing

Cardiac Biomarkers

• Measure high-sensitivity cardiac troponin (hs-cTn) as soon as possible after presentation in all patients with suspected ACS 1, 2, 3
• High-sensitivity troponin is the preferred biomarker because it enables more rapid detection or exclusion of myocardial injury and increases diagnostic accuracy 1
• Obtain serial troponin measurements at presentation and 10-12 hours after symptom onset to identify abnormal values and rising or falling patterns indicative of acute myocardial injury 1
• Clinicians must be familiar with the 99th percentile upper reference limit that defines myocardial injury for the troponin assay used at their institution 1
• Creatine kinase myocardial (CK-MB) isoenzyme and myoglobin are not useful for diagnosis of acute myocardial injury with availability of troponin 1

Chest Radiography

• Obtain a chest radiograph to evaluate for other potential cardiac, pulmonary, and thoracic causes of symptoms including aortic dissection, pulmonary embolism, pneumothorax, and pneumonia 1

Critical History Elements to Document

Pain Characteristics

• Exact location and radiation pattern (retrosternal with radiation to left arm, neck, or jaw suggests ACS) 2, 3
• Quality of pain: pressure, squeezing, gripping, heaviness, or tightness suggests ischemia; sharp, stabbing, fleeting, or pleuritic pain suggests non-ischemic causes 3
• Onset pattern: anginal pain builds gradually over several minutes, not instantaneously 3
• Duration and timing relative to presentation 3

Associated Symptoms That Increase ACS Likelihood

• Dyspnea or shortness of breath 3
• Diaphoresis, nausea, vomiting 3
• Lightheadedness, presyncope, or syncope 3
• Palpitations 3

Cardiovascular Risk Factors

• Age and sex 3
• Diabetes mellitus, hypertension, hyperlipidemia 3
• Smoking history 3
• Family history of premature coronary artery disease 3

Special Population Considerations

Women

• Women are at high risk for underdiagnosis of ACS and may present with atypical symptoms including isolated dyspnea, nausea, fatigue, arm pain, jaw pain, neck pain, back pain, or epigastric discomfort without classic chest pain 2, 3, 6
• Emphasize accompanying symptoms rather than relying solely on classic chest pain presentation 3, 6

Older Adults (≥75 Years)

• May present with atypical symptoms including isolated dyspnea, syncope, acute delirium, or unexplained falls without classic chest pain 2, 3, 6
• Consider ACS in elderly patients with any of these presentations even without chest pain 2, 3

Patients with Diabetes

• More likely to present with vague abdominal symptoms, confusion, or isolated dyspnea 3
• Higher risk for silent ischemia 3

Disposition Algorithm

If STEMI Identified on ECG

• Immediate reperfusion therapy is mandatory 2
• Primary percutaneous coronary intervention (PCI) preferred with door-to-balloon time <90 minutes 2
• Fibrinolytic therapy with door-to-needle time <30 minutes if PCI unavailable 2
• Pre-hospital thrombolysis reduces mortality by 17%, with 23 lives saved per 1000 per hour of earlier treatment 2

If Troponin Elevated Without ST-Elevation (NSTEMI/Unstable Angina)

• Admit to coronary care unit with continuous cardiac monitoring 2
• Initiate dual antiplatelet therapy 2
• Urgent coronary angiography ideally within hours for recurrent ischemia, major arrhythmias, or signs of acute heart failure 2

If Normal ECG and Negative Initial Troponin

• Transfer to chest pain unit or emergency department for observation 10-12 hours after symptom onset 1, 2
• Repeat troponin at 10-12 hours after symptom onset 1
• The risk of patients discharged without correctly diagnosing ACS is 20-30% without proper observation 1

Critical Pitfalls to Avoid

Diagnostic Errors

• Do not use nitroglycerin response as a diagnostic tool for ACS, as esophageal spasm and other conditions may also respond 3, 6
• Do not assume young age excludes ACS, as it can occur in adolescents without traditional risk factors 3, 6
• Sharp, pleuritic pain does not exclude ACS, as pericarditis and atypical presentations can occur 3
• Avoid the term "atypical chest pain" and instead describe chest pain as cardiac, possibly cardiac, or noncardiac to prevent misinterpretation 3

Management Errors

• Never delay transfer to the emergency department for additional history-taking or troponin testing in office settings if clinical evidence of ACS or life-threatening causes is present 1, 2, 3, 6
• Physical examination contributes minimally to diagnosing myocardial infarction unless shock is present 2
• Patients with normal ECG still require biochemical marker testing and careful observation, as pulmonary embolism, aortic dissection, acute pericarditis, and pneumothorax are life-threatening conditions that may present with normal ECG 1

Medication Safety

• Rapid intravenous administration of morphine may result in chest wall rigidity 5
• Have naloxone injection and resuscitative equipment immediately available when administering morphine 5
• Do not administer nitroglycerin if systolic blood pressure <90 mmHg, heart rate <50 or >100 bpm, or if patient has taken medications for erectile dysfunction within 24-48 hours 4

Life-Threatening Differential Diagnoses to Consider

Acute Aortic Syndromes

• Sudden-onset tearing or ripping pain with radiation to the back 3
• Blood pressure differential between arms 3

Pulmonary Embolism

• Sudden dyspnea and pleuritic chest pain, particularly with risk factors (recent surgery, immobilization, malignancy) 1, 3

Tension Pneumothorax

• Sudden onset of unilateral chest pain with dyspnea, tracheal deviation, absent breath sounds 1

Pericarditis with Tamponade

• Sharp pain worsening with inspiration and lying supine 3
• Signs of cardiogenic shock, jugular vein distension, respiratory distress 1
• Rapid transfer to center with ultrasound-guided pericardiocentesis capability is mandatory 1