How should a patient presenting with chest pain radiating to the left arm be evaluated and managed?

Evaluation and Management of Chest Pain Radiating to Left Arm

A patient presenting with chest pain radiating to the left arm requires immediate evaluation for acute coronary syndrome (ACS) with a 12-lead ECG obtained within 10 minutes of presentation and immediate cardiac troponin measurement, as this presentation pattern represents a potentially life-threatening condition requiring urgent risk stratification and treatment. 1

Immediate Actions (First 10 Minutes)

• Obtain 12-lead ECG within 10 minutes to distinguish between ST-elevation myocardial infarction (STEMI) and non-ST-elevation ACS (NSTE-ACS), as this determines the entire treatment pathway and directly impacts mortality. 1, 2

• Draw cardiac troponin immediately (preferably high-sensitivity troponin), with repeat measurement at 1-2 hours using rapid rule-in/rule-out protocols, as elevated troponin above the 99th percentile upper reference limit confirms myocardial infarction. 1, 3, 4

• Administer aspirin 162-325 mg immediately unless contraindicated or already taken, as this reduces mortality in ACS. 5

• Consider sublingual nitroglycerin if systolic blood pressure >90 mmHg, though relief of pain with nitroglycerin is not diagnostic and occurs in only 35% of patients with active coronary artery disease. 1, 5

Clinical Assessment and Risk Stratification

Recognize the Typical Presentation

Chest pain radiating to the left arm is a classic presentation of ACS, characterized by retrosternal pressure or heaviness that may be intermittent (lasting several minutes) or persistent (>20 minutes at rest suggests possible MI). 1, 4

Additional high-risk features that increase ACS likelihood include:

• Diaphoresis (observed sweating) - has 95% specificity and likelihood ratio of 5.18 for ACS, making it one of the most powerful clinical predictors. 3, 5, 6
• Pain radiating to both arms - increases odds of AMI by 2.69-fold. 6
• Vomiting - increases odds of AMI by 3.50-fold. 6
• Central chest pain - increases odds of AMI by 3.29-fold. 6

Important Clinical Pitfalls

Do not dismiss this presentation as low-risk - while pain radiating specifically to the left arm alone has limited diagnostic value (likelihood ratio 1.36), the combination of chest pain with left arm radiation warrants full cardiac evaluation. 6, 7

Atypical presentations are common in elderly patients, women, and those with diabetes, chronic kidney disease, or dementia, who may present with epigastric pain, dyspnoea alone, or indigestion-like symptoms without classic chest pain. 1

Relief with nitroglycerin is NOT diagnostic - it occurs in 41% of patients without active coronary artery disease and should never be used as a criterion to rule out ACS. 1

ECG Interpretation and Immediate Management

If STEMI is Present (Persistent ST-Elevation >1mm in Contiguous Leads or New LBBB)

• Activate immediate reperfusion strategy with primary percutaneous coronary intervention (PCI) within 120 minutes, which reduces mortality from 9% to 7%. 1, 2

• If PCI unavailable within 120 minutes, administer fibrinolytic therapy (alteplase, reteplase, or tenecteplase at full dose for age <75 years; half dose for age ≥75 years), followed by transfer for PCI within 24 hours. 2

If NSTE-ACS is Present (ST-Depression, T-Wave Inversion, or Non-Diagnostic ECG)

• Continue with troponin protocol - NSTE-ACS accounts for approximately 70% of ACS cases and includes NSTEMI (with troponin elevation) and unstable angina (without troponin elevation). 1, 2

• High-sensitivity troponin measurements have increased MI detection by 4% absolute and 20% relative, with reciprocal decrease in unstable angina diagnosis. 1

• For high-risk NSTE-ACS patients (elevated troponin, ongoing chest pain >20 minutes, hemodynamic instability, heart failure signs, or high-risk ECG changes), perform invasive coronary angiography within 24-48 hours, which reduces mortality from 6.5% to 4.9%. 1, 2

Physical Examination Priorities

Perform focused cardiovascular examination looking for:

• Signs of heart failure (rales, third heart sound, jugular venous distension) - indicates higher risk and worse prognosis. 1, 4
• Systolic murmur - may indicate ischemic mitral regurgitation (associated with poor prognosis) or aortic stenosis. 1
• Hemodynamic instability (hypotension, narrow pulse pressure, pallor, sweating) - mandates immediate aggressive management. 1

Examine for alternative diagnoses:

• Blood pressure differential between arms suggests aortic dissection. 1
• Chest wall tenderness on palpation (likelihood ratio 0.3) makes AMI less likely but does not exclude it - 7% of patients with reproducible pain on palpation still have ACS. 1, 7

Risk Factors That Increase ACS Likelihood

The following significantly increase probability of NSTE-ACS: 1

• Older age, male gender
• Known coronary artery disease, previous MI
• Diabetes mellitus, hyperlipidemia, hypertension
• Renal insufficiency
• Family history of CAD
• Peripheral or carotid artery disease

Disposition Decision Algorithm

If Troponin Elevated OR ECG Shows Ischemic Changes:

Admit immediately for ACS management per cardiology protocols with consideration for early invasive strategy. 3, 4

If Initial Troponin Negative and ECG Non-Diagnostic:

• Repeat troponin at 1-2 hours using high-sensitivity assay protocols. 1, 5
• If both troponins negative, calculate TIMI or HEART score for risk stratification. 8
• Arrange stress testing or coronary CT angiography either during hospitalization or after discharge based on risk score. 8

If Cardiac Workup Negative:

• Consider alternative diagnoses including pericarditis (friction rub, ECG with diffuse ST elevation), aortic dissection (tearing pain to back, BP differential), pulmonary embolism, esophageal disorders, or musculoskeletal pain. 1, 4

Critical Errors to Avoid

Never delay ECG beyond 10 minutes to obtain chest X-ray or other testing in potentially unstable patients - this causes treatment delays that increase mortality. 3, 5

Never evaluate suspected ACS patients solely by telephone - they require facility-based evaluation with ECG and biomarkers. 5

Never discharge patients with ongoing symptoms - between 2-5% of ACS patients are inappropriately discharged from emergency departments, contributing to preventable mortality. 8

Do not rely on "typical" vs "atypical" symptoms alone - approximately 40% of men and 48% of women with ACS present with nonspecific symptoms, and the diagnostic performance of chest pain characteristics for MI is limited. 1, 2