Can ST elevation in aVR (augmented voltage right) lead be considered as an indicator of type 2 myocardial infarction (MI)?

ST Elevation in aVR and Type 2 Myocardial Infarction

ST elevation in aVR with multilead ST depression should NOT be automatically classified as a Type 2 MI, but rather represents a high-risk ECG pattern that requires urgent—not emergent—cardiac catheterization to determine the underlying etiology, which may include Type 1 MI from severe coronary disease, Type 2 MI from supply-demand mismatch, or non-coronary causes. 1, 2

Understanding the aVR Pattern

The combination of ST elevation in aVR with multilead ST depression (≥8 leads) has historically been associated with left main or proximal left anterior descending coronary artery occlusion, suggesting severe global myocardial ischemia. 1 However, this interpretation has evolved significantly:

• The 2022 ACC Expert Consensus recommends managing STE-aVR with multilead ST depression as NSTE-ACS (non-ST elevation acute coronary syndrome), not as a STEMI equivalent. 1

• The 2013 ACCF/AHA STEMI guidelines explicitly state that fibrinolytic therapy should NOT be administered to patients with ST depression when associated with ST elevation in lead aVR. 1 This reflects recognition that this pattern does not represent a typical acute coronary occlusion requiring emergent reperfusion.

The Critical Evidence on Acute Occlusion

Recent data demonstrates that STE-aVR with multilead ST depression rarely represents an acutely occluded coronary artery:

• In a 2019 study of 99 patients with STE-aVR and multilead ST depression, only 10% had an acutely thrombotic coronary occlusion identified on emergent angiography, and none involved the left main or proximal LAD. 2

• While 59% had severe coronary disease, most maintained intact distal flow, suggesting chronic disease rather than acute occlusion. 2

• Despite the low rate of acute occlusion, this pattern carried a 31% in-hospital mortality compared to 6.2% in typical STEMI patients, indicating high-risk pathophysiology. 2

Type 1 vs Type 2 MI Distinction

The STE-aVR pattern can represent either Type 1 or Type 2 MI, depending on the underlying mechanism:

Type 1 MI (Atherothrombotic)

• Occurs when severe multivessel coronary disease or left main stenosis causes acute plaque rupture or thrombosis. 2
• Requires anticoagulation, antiplatelet therapy, and revascularization. 3

Type 2 MI (Supply-Demand Mismatch)

• Results from conditions causing global myocardial oxygen supply-demand imbalance in the setting of underlying coronary disease. 3
• Common causes include severe anemia, hypotension, tachycardia, drug-induced vasospasm, or sepsis. 3, 4
• Anticoagulation may be contraindicated (e.g., in gastrointestinal bleeding causing severe anemia). 3

Non-MI Causes

• Takotsubo cardiomyopathy can present with transient STE-aVR, representing reversible ischemia of the basal interventricular septum without coronary occlusion. 4
• Other non-coronary causes must be systematically excluded. 3, 5

Recommended Clinical Approach

When encountering STE-aVR with multilead ST depression:

1. Do NOT activate the STEMI protocol for emergent catheterization. 1, 2 This pattern does not meet STEMI criteria and rarely represents acute coronary occlusion requiring immediate reperfusion.

2. Manage as NSTE-ACS per 2014 AHA/ACC guidelines. 1 This involves urgent (not emergent) evaluation with serial troponins, continuous ECG monitoring, and antiplatelet/anticoagulation therapy unless contraindicated.

3. Systematically evaluate for Type 2 MI causes before assuming Type 1 MI:

   • Check hemoglobin for severe anemia. 3
   • Assess hemodynamic status for hypotension or shock. 3
   • Review medications and toxicology for drug-induced vasospasm or tachycardia. 3
   • Consider sepsis, respiratory failure, or other systemic stressors. 3

4. Perform urgent (within hours, not minutes) cardiac catheterization to define coronary anatomy and guide management. 1, 2 The high mortality associated with this pattern (31%) justifies urgent rather than delayed evaluation. 2

5. Withhold anticoagulation if Type 2 MI from bleeding is suspected until the diagnosis is clarified. 3

Key Clinical Pitfalls

• Overreacting to STE-aVR as a STEMI equivalent leads to inappropriate emergent catheterization activation when urgent evaluation is more appropriate. 2, 5

• Under-appreciating the high mortality risk (31%) associated with this pattern can result in delayed evaluation and missed opportunities for intervention. 2

• Failing to consider non-coronary causes such as Takotsubo cardiomyopathy or supply-demand mismatch can lead to inappropriate treatment. 3, 4

• Automatically administering anticoagulation without considering contraindications (e.g., active bleeding) can worsen outcomes in Type 2 MI from hemorrhage. 3