ECG findings in Acute Pericarditis

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ECG findings of Acute Pericarditis

Short-Answer Questions

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1. What are the typical ECG changes seen in Stage 1 of acute pericarditis?
– Diffuse ST-segment elevation
– PR segment depression
– Upright T waves
– No reciprocal ST depression (except aVR, V1)
– No Q waves

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2. How can acute pericarditis be distinguished from STEMI on ECG?
– ST elevation is diffuse, not localized to a coronary artery territory
– PR segment depression favors pericarditis
– No reciprocal ST depression except in aVR and V1
– No Q waves in pericarditis
– ST/T ratio > 0.25 in pericarditis

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3. Describe the four ECG stages of acute pericarditis.
– Stage 1: ST elevation + PR depression
– Stage 2: Normalization of ST and PR
– Stage 3: T wave inversion
– Stage 4: ECG returns to baseline
– Changes usually occur over days to weeks

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4. What is the PR segment abnormality seen in pericarditis?
– PR depression in multiple leads
– PR elevation in aVR and V1
– Caused by atrial epicardial inflammation
– Helps differentiate from STEMI
– Resolves as inflammation subsides

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5. Why is the ST elevation in pericarditis called “concave upward”?
– ST segment curves upward like a smile
– Unlike convex (“tombstone”) ST in STEMI
– Suggests non-transmural inflammation
– Diffuse and benign-appearing pattern
– A hallmark of Stage 1 pericarditis

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6. How does pericarditis affect the T wave over time?
– T waves are upright in early stages
– Become inverted in Stage 3
– Follow ST segment normalization
– Do not correlate with ischemia
– Eventually return to baseline

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7. What is the significance of the aVR lead in pericarditis?
– Shows reciprocal PR elevation
– May show ST depression
– A clue to diffuse inflammation
– Helps distinguish from ischemia
– Not a primary diagnostic lead

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8. Which leads typically show the most prominent changes in pericarditis?
– I, II, V5, V6
– Limb and lateral precordial leads
– Reflect pericardial surface inflammation
– ST elevation and PR depression evident
– Diffuse distribution pattern

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9. What ECG finding suggests pericardial effusion rather than pericarditis?
– Low voltage QRS complexes
– Electrical alternans (if tamponade)
– No ST elevation or PR depression
– Alternating QRS amplitude
– Indicates swinging of heart in fluid

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10. When does normalization of ECG occur in pericarditis?
– Over days to weeks
– Stage 2 shows initial resolution
– Stage 3 has T wave inversion
– Stage 4 is complete normalization
– Depends on inflammation control

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Feature	Acute Pericarditis	Notes
Stage 1 (Early)	Diffuse ST elevation (concave) + PR depression	Most diagnostic stage
Stage 2	ST and PR segments normalize	Few days after onset
Stage 3	T wave inversion begins	Occurs after ST normalization
Stage 4 (Late)	ECG returns to baseline	Usually within 2–3 weeks
ST Segment Morphology	Concave upward (“smiling”) ST elevation	Differs from convex ST in STEMI
Distribution of ST Elevation	Diffuse (I, II, aVL, V3–V6)	Not limited to a coronary artery territory
PR Segment Changes	PR depression in most leads; PR elevation in aVR, V1	Reflects atrial epicardial inflammation
T Wave Changes	Upright in early stages; inversion in stage 3	Does not indicate ischemia
Q Waves	Absent	Helps distinguish from STEMI
Reciprocal ST Depression	Typically absent (except in aVR, V1)	A clue against STEMI
Lead aVR	PR elevation ± ST depression	Reciprocal to pericarditis changes elsewhere
Electrical Alternans	Not typical unless pericardial effusion/tamponade present	Suggests effusion > pericarditis
ST/T Ratio in Lead V6	> 0.25	Useful quantitative clue
Evolution Timeline	Stages evolve over days to weeks	In contrast to rapid changes in STEMI
Response to NSAIDs	ECG improves with anti-inflammatory therapy	Diagnostic and therapeutic implication

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