What is the differential diagnosis for a young patient presenting with left-sided chest pain, cough, and sudden tachycardia?

Differential Diagnosis for Young Patient with Left-Sided Chest Pain, Cough, and Sudden Tachycardia

In a young patient presenting with left-sided chest pain, cough, and sudden tachycardia, pulmonary embolism must be considered first given that tachycardia and dyspnea occur in >90% of PE cases, followed by pneumothorax (which presents with unilateral chest findings), community-acquired pneumonia (including severe necrotizing forms like PVL-positive MRSA), acute coronary syndrome (which can occur in young patients without typical risk factors), pericarditis, and myocarditis. 1

Immediately Life-Threatening Causes to Rule Out

Pulmonary Embolism

• Tachycardia is present in >90% of PE patients, combined with dyspnea, and chest pain may occur with inspiration or at rest 1
• Physical examination reveals tachycardia, tachypnea, and potentially accentuated P2 heart sound 1
• The combination of sudden tachycardia with pleuritic chest pain in a young patient makes PE a critical diagnosis that cannot be missed 2, 3

Pneumothorax

• Presents with dyspnea and pain on inspiration, with unilateral absence of breath sounds on the affected side 1
• Left-sided chest pain with sudden onset strongly suggests this diagnosis 1
• Primary spontaneous pneumothorax characteristically causes acute chest pain and occurs in young patients without underlying lung disease 4

Acute Coronary Syndrome

• Can occur at rest without exertion, particularly in unstable angina or NSTEMI, presenting with diaphoresis, tachypnea, tachycardia, hypotension, crackles, S3, or mitral regurgitation murmur 2
• The examination may be completely normal in uncomplicated cases, which is a critical pitfall 1
• Young patients without traditional risk factors can still develop ACS, and atypical presentations are common 3

Serious Infectious/Inflammatory Causes

Community-Acquired Pneumonia (Including PVL-Positive MRSA)

• Fever, localized chest pain (may be pleuritic), friction rub, regional dullness to percussion, and egophony characterize pneumonia 1
• PVL-positive Staphylococcus aureus must be considered in severe community-acquired pneumonia presenting with septic shock, tachycardia, and unilateral lung consolidation 1
• This organism causes life-threatening invasive infection with rapid progression to multi-organ failure, particularly in previously healthy young patients 1
• Initial empirical antibiotic therapy should include MRSA coverage when severe pneumonia is suspected 1

Pericarditis

• Sharp, pleuritic chest pain that worsens when supine and improves when leaning forward, with friction rub on examination and fever 1, 3
• Tachycardia may be present as a compensatory response to reduced cardiac output 1

Myocarditis

• Fever, chest pain, heart failure signs, and S3 gallop characterize myocarditis 1, 2
• Can present similarly to ACS in young patients and should be strongly considered when infection symptoms accompany cardiac findings 3

Critical Diagnostic Approach

Immediate Actions Required

• Obtain ECG within 10 minutes of presentation and cardiac troponin as soon as possible 2
• Perform focused cardiovascular examination specifically assessing for pulse differentials, heart sounds (S3, friction rub, murmurs), unilateral breath sounds, and signs of respiratory distress 1
• Obtain chest radiograph to evaluate cardiac silhouette, pulmonary infiltrates, pneumothorax, and mediastinal width 2

Key Physical Examination Findings to Differentiate

• Unilateral absence of breath sounds indicates pneumothorax 1
• Regional dullness to percussion with egophony suggests pneumonia 1
• Friction rub can indicate either pericarditis or pneumonia 1
• Diaphoresis, S3 gallop, or new mitral regurgitation murmur suggests ACS 1

Critical Pitfalls to Avoid

• Do not assume a normal examination excludes ACS, as uncomplicated myocardial infarction may have no abnormal physical findings 1, 2
• Do not use nitroglycerin relief as a diagnostic criterion for myocardial ischemia, as esophageal spasm and other conditions also respond to nitroglycerin 2, 3
• Do not delay transfer to the emergency department for troponin or diagnostic testing if ACS is suspected 2
• In young patients presenting with severe community-acquired pneumonia and septic shock, consider PVL-positive MRSA and initiate empirical MRSA coverage immediately 1