Can ST elevations in leads V2, V3, and V4 still indicate pericarditis or does it suggest a myocardial issue?

ST Elevations in V2-V4: Pericarditis vs. Myocardial Infarction

Yes, ST elevations in leads V2, V3, and V4 can still represent pericarditis, but you must actively exclude anterior STEMI caused by left anterior descending (LAD) artery occlusion, which carries significantly higher mortality risk and requires immediate reperfusion therapy. 1

Critical Distinguishing Features

ECG Patterns That Favor Pericarditis Over STEMI

• Concave ST elevation that is diffuse across multiple non-contiguous lead territories (not just V2-V4 in isolation) strongly suggests pericarditis 2
• PR segment depression in multiple leads, particularly when present alongside ST elevation, is highly specific for pericarditis 2
• ST elevation to T-wave amplitude ratio >0.24 in lead V6 favors pericarditis over myocardial infarction 2
• Absence of reciprocal ST depression in leads opposite to the ST elevation (particularly no depression in inferior leads II, III, aVF when V2-V4 are elevated) suggests pericarditis rather than LAD occlusion 1

ECG Patterns That Favor Anterior STEMI

• Convex (upward) ST elevation with reciprocal ST depression in inferior leads (II, III, aVF) indicates LAD occlusion 1
• ST elevation in V1 through V4-V6 PLUS elevation in leads I and aVL with reciprocal depression in II, III, aVF indicates proximal LAD occlusion above the first septal and diagonal branches—this is an extensive anterior/anterobasal infarction requiring emergent catheterization 1
• Any ST depression in lead aVL when inferior leads show changes is 100% sensitive and specific for differentiating inferior STEMI from pericarditis 3
• QRS complex widening in the lead with maximal ST elevation suggests STEMI even in patients with prior pericarditis 4

Algorithmic Diagnostic Approach

Step 1: Assess ST Elevation Distribution and Morphology

• If ST elevation is isolated to V2-V4 only without involvement of V1, I, or aVL, and without reciprocal changes, consider more distal LAD occlusion or pericarditis 1
• If ST elevation extends to V1, I, and aVL with reciprocal depression in II, III, aVF, this is proximal LAD occlusion—activate catheterization lab immediately 1

Step 2: Look for Pericarditis-Specific Features

• Check for PR depression in multiple leads—this is pathognomonic for pericarditis and does not occur in STEMI 2
• Measure ST/T wave ratio in V6—if >0.24, pericarditis is more likely 2
• Assess ST segment morphology—concave favors pericarditis, convex favors STEMI 2

Step 3: Evaluate for Reciprocal Changes

• Any ST depression in aVL when there is inferior ST elevation is 100% specific for STEMI and rules out pericarditis 3
• Absence of reciprocal changes in a typical coronary distribution favors pericarditis 1

Step 4: Obtain Cardiac Biomarkers and Imaging

• Troponin elevation occurs in both conditions—myopericarditis can cause troponin rise, so this alone does not differentiate 5
• Echocardiography is critical: regional wall motion abnormalities in LAD distribution confirm STEMI, while global dysfunction with pericardial effusion suggests pericarditis 2, 5
• If diagnostic uncertainty persists despite ECG analysis, emergent coronary angiography is warranted to exclude LAD occlusion 5

Common Pitfalls to Avoid

• Do not assume diffuse ST elevation always means pericarditis—myopericarditis can coexist with focal myocardial involvement that requires different management 5
• Pericarditis is listed as a "false positive" ECG pitfall in diagnosing MI, meaning it can mimic STEMI, but the Third Universal Definition emphasizes that ST deviation in pericarditis should be considered in the differential when evaluating ST elevation 1
• Right bundle branch block causes ST-T abnormalities in V1-V3, making ischemia assessment difficult in these leads—however, new ST elevation or Q waves should still raise concern for myocardial ischemia or infarction 1
• Troponin positivity does not exclude pericarditis—myopericarditis commonly causes troponin elevation without coronary occlusion 5
• Serial ECGs are essential—pericarditis evolves through four stages with changing ST-T patterns, while STEMI shows different temporal evolution with Q wave development 5

When Both Conditions Coexist

• Myopericarditis presents with features of both conditions and can be particularly challenging 5, 4
• In cases where pericarditis is known but new focal ST elevation develops in V2-V4, QRS widening in leads with maximal ST elevation helps identify superimposed STEMI 4
• When clinical suspicion for LAD occlusion is high despite pericarditis features, proceed directly to coronary angiography—normal coronary arteries confirm pericarditis as the sole diagnosis 2, 5