Characteristic EKG Findings in Acute Pericarditis
The correct answer is B: Global concave shaped ST elevations are the characteristic EKG finding in acute pericarditis, representing widespread ST-segment elevation in multiple leads (I, II, aVL, aVF, and V3-V6) with a distinctive concave upward morphology. 1
Primary Diagnostic EKG Features
The European Society of Cardiology identifies widespread concave ST-segment elevation as the hallmark EKG sign of acute pericarditis, though these classic changes appear in only approximately 60% of cases. 1, 2 The key distinguishing features include:
ST-Segment Changes
- Concave upward ST elevation in anterior and inferior leads (I, II, aVL, aVF, V3-V6) is the characteristic finding in Stage I acute pericarditis 1, 2
- ST-segment depression occurs in lead aVR (always), frequently in V1, and occasionally in V2 1, 2
- The widespread distribution without reciprocal changes helps differentiate pericarditis from acute coronary syndrome 2
PR-Segment Changes
- PR-segment depression (opposite to P wave polarity) is a characteristic finding that accompanies ST elevation 1, 2
- PR-segment elevation occurs in lead aVR as the reciprocal change 3
- This pattern results from atrial epicardial inflammation creating an atrial injury current 3
Why Other Options Are Incorrect
ST depressions (Option A) are not characteristic of acute pericarditis; instead, ST depression is limited to lead aVR and occasionally V1-V2, while the predominant pattern is ST elevation. 1
T-wave inversions (Option C) occur later in the disease course (Stage III) after the ST segments have normalized, not as the initial characteristic finding. 1
S1Q3T3 pattern (Option D) is associated with acute pulmonary embolism, not pericarditis. [@General Medicine Knowledge]
Important Clinical Caveats
Diagnostic Pitfalls
- A quantitative criterion can help differentiate pericarditis from early repolarization: in lead V6, if the J point is >25% of the height of the T wave apex (using the PR segment as baseline), pericarditis is likely [@2@, 1]
- An ST/T ratio ≥0.25 in V6 has 100% positive and negative predictive value for distinguishing acute pericarditis from normal variant ST elevation [@10@]
- ECG changes may be absent at initial presentation or evolve rapidly during the disease course, so serial ECGs should be performed [@9@, @6@]
Beware of Mimics
- Left circumflex artery occlusion can occasionally produce PR depression with multilead ST elevation and ST depression in aVR, mimicking pericarditis [@8@]
- QRS widening and QT interval shortening in leads with ST elevation suggest STEMI rather than pericarditis [@8@]
- Early repolarization with ST elevation (ERSTE) can present with diffuse ST elevation and even PR depression, but lacks the clinical symptoms of pericarditis 4
Temporal Evolution
The ESC guidelines describe four stages of EKG evolution in acute pericarditis [@2@, 1]:
- Stage I: Widespread concave ST elevation with PR depression
- Stage II (early): ST segments return to baseline, PR remains deviated
- Stage II (late): T waves progressively flatten
- Stage III: Generalized T wave inversions
- Stage IV: ECG returns to pre-pericarditis state
Clinical Integration
ECG is a Class I recommendation (should be performed) in all patients with suspected acute pericarditis. [@1@, @5@, 2] However, only 24.5% of patients with isolated pericarditis demonstrate ECG changes, compared to 60.7% of those with concurrent myocarditis. [@12@] When ECG changes are present, particularly with troponin elevation (occurs in 49% of cases with ST elevation), concurrent myocardial involvement should be suspected. [@6@, @12