Do we start aspirin (acetylsalicylic acid) in a patient with ischemia on electrocardiogram (ECG) but no chest pain and no hypertension?

Aspirin Should Be Started Immediately in Patients with ECG Evidence of Ischemia, Regardless of Chest Pain or Hypertension Status

Yes, aspirin should be initiated immediately (162-325 mg chewed) in any patient with ECG evidence of ischemia, even in the absence of chest pain or hypertension, as this represents acute coronary syndrome requiring immediate antiplatelet therapy. 1

Rationale for Immediate Aspirin Administration

ECG Ischemia Defines Acute Coronary Syndrome

• Patients with ST-segment changes (depression, negative T waves, or pseudonormalization) without persistent ST-elevation constitute acute coronary syndrome and require immediate aspirin 75-150 mg daily as initial medical treatment. 1
• The European Society of Cardiology guidelines explicitly state that once ACS is diagnosed based on ECG changes, aspirin is mandatory regardless of symptom presentation. 1
• ECG evidence of ischemia alone, even without chest pain, qualifies as ACS requiring full antithrombotic therapy. 1

Chest Pain is NOT Required for ACS Diagnosis

• Silent ischemia (ischemia without chest pain) is a well-recognized presentation of ACS that still requires aspirin therapy. 1
• The SWISSI-II study demonstrated that patients with recent MI who had silent ischemia on stress testing still benefited from antiplatelet therapy and revascularization. 1
• Women and elderly patients frequently present with atypical symptoms or no chest pain, yet still require standard ACS treatment including aspirin. 2

Mortality Benefit is Time-Dependent

• Aspirin alone in acute MI confers a 23% relative risk reduction in 35-day mortality (2.4% absolute benefit), comparable to thrombolytic therapy. 1
• The ISIS-2 trial established that aspirin provides mortality benefit regardless of whether reperfusion therapy is administered. 1
• Early aspirin administration is crucial—benefits emerge within 4-24 hours of initiation. 1

Specific Dosing and Administration

Initial Dose

• Administer 162-325 mg of non-enteric-coated aspirin (chewed) immediately upon recognition of ECG ischemia. 1
• Chewing provides more rapid buccal absorption than swallowing. 1
• Prehospital EMS providers should administer aspirin to suspected ACS patients unless contraindicated or already taken. 1

Maintenance Therapy

• Continue aspirin 75-150 mg daily as long-term therapy after the initial loading dose. 1
• High-intensity statin therapy should also be initiated concurrently. 1

Critical Considerations Before Administration

Absolute Contraindications to Check

• Known aspirin hypersensitivity or major gastrointestinal intolerance 1
• Active bleeding or bleeding disorder 1
• Recent use of phosphodiesterase inhibitors (within 24-48 hours) is a contraindication to nitrates, not aspirin 1

Hypertension is NOT a Contraindication

• The absence of hypertension does not preclude ACS diagnosis or aspirin therapy. 1
• Hypotension may actually indicate higher-risk ACS (cardiogenic shock) requiring more aggressive management. 1

Additional Immediate Management Required

Concurrent Therapies to Initiate

• Beta-blocker therapy should be started within 24 hours unless contraindications exist (heart failure, low-output state, risk of cardiogenic shock). 1
• Anticoagulation with LMWH or unfractionated heparin should be initiated. 1
• Clopidogrel (or other P2Y12 inhibitor) should be added for dual antiplatelet therapy. 1
• Nitrates (sublingual or IV) for ongoing ischemia. 1

Risk Stratification Determines Next Steps

• Obtain cardiac troponin levels at presentation and repeat at 6-12 hours to differentiate MI from unstable angina. 1
• High-risk features requiring urgent angiography include: recurrent ischemia, elevated troponins, hemodynamic instability, major arrhythmias, or diabetes. 1
• Even with negative troponins, ECG ischemia warrants observation with serial ECGs and biomarkers. 1

Common Pitfalls to Avoid

Do Not Delay Aspirin for Symptom Confirmation

• Silent ischemia carries similar mortality risk as symptomatic ischemia—do not withhold aspirin based on absence of chest pain. 1
• ECG changes are sufficient to diagnose ACS and mandate aspirin therapy. 1

Do Not Confuse with Primary Prevention

• This scenario represents secondary prevention/acute treatment of active ischemia, not primary prevention. 1
• The risk-benefit ratio strongly favors aspirin when ECG ischemia is present. 1, 3

Ensure Proper ECG Interpretation

• Verify that ECG changes represent true ischemia (ST-depression ≥1mm, T-wave inversions, or dynamic changes). 1
• Bundle branch block or pacemaker rhythm may obscure ischemia—these patients require troponin measurement and echocardiography. 1

Monitor for Complications

• Assess for signs of hemodynamic instability (hypotension, pulmonary rales) requiring more intensive management. 1
• Obtain 12-lead ECG if any recurrence of symptoms during observation period. 1