What is the appropriate management for a patient with chest pain radiating to the shoulder, potentially indicating a myocardial infarction (heart attack)?

Management of Chest Pain Radiating to the Shoulder

Chest pain radiating to the shoulder requires immediate emergency department evaluation with ECG within 10 minutes, as this presentation carries a 2.3-4.7 times increased likelihood of acute coronary syndrome and demands urgent assessment for life-threatening conditions including myocardial infarction, aortic dissection, and pulmonary embolism. 1, 2, 3

Immediate Actions

Prehospital Management

• Call 9-1-1 immediately and transport by ambulance rather than private vehicle or driving to a physician's office 1, 2
• Administer aspirin 162-325 mg orally immediately unless contraindicated or already taken 4, 2
• Give sublingual nitroglycerin (up to 3 doses, 5 minutes apart) if previously prescribed and systolic BP >90 mmHg 1, 4, 2
• Initiate continuous ECG monitoring during transport to detect life-threatening arrhythmias 1

Emergency Department Triage (Within First 10 Minutes)

• Obtain 12-lead ECG within 10 minutes of arrival to identify ST-segment elevation ≥1 mm in contiguous leads or new left bundle branch block 1, 4, 2
• Draw cardiac troponin immediately with repeat measurement at 1-2 hours using rapid rule-in/rule-out protocols 1, 4, 2
• Place patient in environment with continuous ECG monitoring and defibrillation capability 1
• Do not wait for troponin results before initiating reperfusion therapy if ST-elevation is present on ECG 1, 4

Diagnostic Approach

Critical Differential Diagnoses to Rule Out

Acute Coronary Syndrome (Most Common)

• Pain radiating to one or both shoulders increases ACS likelihood 2.3-4.7 fold 3, 5
• Look for associated diaphoresis (95% specificity, LR 5.18 when combined with typical pain) 2
• Exertional pain further increases likelihood (LR 2.06-2.35) 3, 5

Aortic Dissection (Life-Threatening Alternative)

• Obtain CT chest with IV contrast as preferred initial imaging if pain described as "ripping" or "worst pain ever" radiating to back 6
• Check for pulse differentials between extremities (present in 30% of dissections) 6
• Higher risk in patients with hypertension, known aortic valve disease, or connective tissue disorders 6

Pulmonary Embolism

• Consider if pleuritic chest pain, dyspnea, and tachycardia present 6
• CT chest with IV contrast evaluates for both aortic dissection and PE simultaneously 6

ECG Interpretation

• ST-segment elevation ≥1 mm in contiguous leads or new left bundle branch block = STEMI requiring immediate reperfusion therapy 1, 2
• Repeat ECG recordings if initial tracing equivocal, as ECG evolves over time 1
• Consider additional leads V7-V8 for suspected posterior infarction 1

Biomarker Strategy

• Troponin I or T >99th percentile with rising or falling pattern confirms MI 2
• Serial measurements at 0 and 1-2 hours using ESC rapid protocols 2
• Prioritize troponin over CK-MB, especially in patients with potential rhabdomyolysis (e.g., methamphetamine users) 4

Treatment Algorithm

If STEMI Identified (ST-elevation or new LBBB)

1. Primary PCI is preferred if available within 90 minutes of first medical contact 4
2. Administer aspirin 160-325 mg if not already given 4
3. Add P2Y12 inhibitor (clopidogrel) for dual antiplatelet therapy 4
4. Give IV morphine 4-8 mg with additional 2 mg doses every 5 minutes until pain relieved (avoid IM injections) 1
5. Administer oxygen 2-4 L/min if breathless, heart failure features, or oxygen saturation low 1
6. Start IV nitroglycerin for ongoing chest pain unless systolic BP <90 mmHg 4, 2

If Non-ST Elevation ACS Suspected

• Continue aspirin and consider P2Y12 inhibitor based on risk stratification 1
• IV nitroglycerin for ongoing symptoms 4
• Morphine for pain relief 1
• Proceed to risk stratification and consideration of early invasive strategy 1

Special Pharmacologic Considerations

• Avoid beta-blockers in methamphetamine or cocaine-associated MI as they worsen coronary vasoconstriction 4
• Use calcium channel blockers (verapamil preferred) for stimulant-induced vasospasm 4
• Have naloxone available for opioid-induced respiratory depression 1
• Have atropine available for opioid-induced hypotension with bradycardia 1

Critical Pitfalls to Avoid

• Do not dismiss right arm or shoulder radiation as atypical—it carries nearly 3-fold increased ACS likelihood and warrants full evaluation 2, 3, 5
• Do not delay ECG beyond 10 minutes of presentation 1, 2
• Do not wait for troponin results before initiating reperfusion in STEMI—ECG findings alone warrant immediate treatment 1, 4
• Do not evaluate suspected ACS patients solely by telephone—they require facility-based evaluation with ECG and biomarkers 2
• Do not use intramuscular injections for medications—IV route preferred 1
• Do not rely on single troponin measurement—serial measurements essential 4, 2

High-Risk Features Requiring Immediate Intervention

• Chest discomfort at rest >20 minutes 2
• Hemodynamic instability 2
• Recent syncope or presyncope 2
• Severe dyspnea 2
• Signs of shock, pulmonary congestion, heart rate >100 bpm, systolic BP <100 mmHg 1

Special Population Considerations

• Elderly patients may present with atypical symptoms including generalized weakness, stroke, syncope, or altered mental status rather than typical chest pain 1, 6
• Diabetic patients may have atypical presentations due to autonomic dysfunction 1, 6
• Women may present more frequently with atypical chest pain and symptoms 1