The Correct Answer is B: ST-segment elevation with upward convexity in the precordial leads
ST-segment elevation in acute pericarditis characteristically shows upward CONCAVITY (saddle-shaped), not upward convexity. This is a critical distinguishing feature that helps differentiate pericarditis from acute myocardial infarction, where ST elevations typically demonstrate upward convexity (dome-shaped) 1.
Characteristic ECG Findings in Acute Pericarditis
The 2015 ESC Guidelines and 2004 ESC Guidelines clearly define the typical ECG pattern 2, 1:
Features That ARE Typical (Options A, C, D, E):
Sinus tachycardia (Option A): Common finding due to pain, fever, and inflammatory response
PR-segment depression (Option C): A hallmark sign, with PR deviations opposite to P wave polarity 1
ST-segment elevations in multiple leads not corresponding to vascular distribution (Option D): The widespread, diffuse nature of ST elevation (typically in leads I, II, aVL, aVF, and V3-V6) distinguishes pericarditis from MI, which follows coronary artery territories 1
ST-segment elevation with upward concavity (Option E): This is the classic "saddle-shaped" or concave morphology described in Stage I of acute pericarditis 1
The Atypical Finding (Option B):
Upward convexity is characteristic of acute myocardial infarction, not pericarditis. This morphologic distinction is one of the key ECG features used to differentiate these two conditions 3.
Additional Distinguishing Features
The guidelines emphasize several other ECG characteristics 1:
- ST segment is typically depressed in aVR (and often V1, occasionally V2)
- Absence of reciprocal ST depression (unlike MI)
- Absence of Q waves (unlike MI)
- The ECG evolves through four stages, though not all patients demonstrate all stages
Clinical Pitfall
Important caveat: Classic ECG changes occur in only up to 60% of acute pericarditis cases 2. The diagnosis should not be excluded based solely on ECG findings. According to ESC criteria, acute pericarditis requires at least 2 of 4 criteria: pericarditic chest pain, pericardial rub, new widespread ST-elevation or PR depression on ECG, and pericardial effusion 2.
The ST/T ratio ≥0.25 in leads I, V4, V5, and V6 can help discriminate acute pericarditis from early repolarization and left ventricular hypertrophy patterns 4.