EKG in Pericarditis

Aka: EKG in Pericarditis, Electrocardiogram in Pericarditis

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II. Indication

  1. Suspected Pericarditis

III. Efficacy: Test Sensitivity

  1. Abnormal EKG changes in 90% of Pericarditis cases
  2. All 4 EKG stages seen in <50% of Pericarditis cases
  3. EKG changes are most common in Viral Pericarditis (due to inflammatory response)
  4. EKG changes are frequently absent in Uremic Pericarditis

IV. Differential Diagnosis

  1. Myocardial Infarction
  2. Myocarditis
  3. EKG with Early Repolarization

V. Precautions

  1. Exclude Myocardial Infarction on EKG prior to diagnosing Pericarditis
    1. Overdiagnosis and misdiagnosis of Pericarditis instead of true STEMI is the most significant pitfall
  2. In true Pericarditis (when MI is excluded), EKG changes alone are NOT associated with a worse prognosis
  3. Obtain serial EKGs
    1. EKG in Myocardial Infarction evolves over minutes to hours
    2. EKG in Pericarditis evolves over days

VI. Approach

  1. Step 1: Evaluate for Myocardial Infarction (any positive finding strongly favors MI)
    1. ST depression (outside of V1 or aVR) or
    2. ST Elevation convex upwards (tombstone) or horizontal or
    3. ST Elevation in Lead III more than Lead II
  2. Step 2: Evaluate for Pericarditis (if all 3 EKG criteria above are negative)
    1. Significant down-sloping PR Segment Depression in multiple leads
    2. Pericardial Friction Rub
    3. ST Elevation is concave upwards
    4. No ST Elevation in V1 or aVR (but may have ST depression in these labs)
  3. References
    1. Amal Mattu, MD on EM:Rap TV (EMRAPTV_143_STEMIvsPericarditis)

VII. Findings: General

  1. ST Segment
    1. ST Elevation (not ST depression)
      1. Exclude ST Elevation Myocardial Infarction (STEMI)!
      2. Pericardititis should not cause ST depression except in leads V1 and aVR
      3. ST depression (outside V1, aVR) is Myocardial Ischemia or MI reciprocal change until proven otherwise
    2. Concave upward ("Smiley face")
      1. Similar to Early Repolarization
      2. Contrast with Myocardial Infarction
        1. ST Segment is convex upward or horizontal on EKG in Acute MI
          1. Approach as Myocardial Infarction
        2. ST Segment in Myocardial Infarction may be concave upward
          1. Concave upward appearance does not completely exclude Myocardial Infarction
    3. ST Segment changes are often diffuse (but may be focal)
      1. Diffuse ST Elevation (and PR Depression) is typically seen only in Viral Pericarditis
      2. Contrast with focal changes on EKG in Acute MI
    4. ST Elevation in lead II is typically greater than that in lead III in Pericarditis
      1. Suggests Pericarditis (but does not exclude Myocardial Infarction)
      2. Contrast with ST Elevation in lead III greater than lead II which strongly suggests Myocardial Infarction
    5. ST Segment Elevation to T Wave amplitude ratio (measure in lead V6)
      1. Pericarditis: >0.25
      2. Early Repolarization: <0.25
    6. Absent Reciprocal ST Segment changes
  2. PR Segment
    1. PR Segment Depression (down-sloping) present
      1. More suggestive of Pericarditis if preceding downsloping TP segment
      2. Variable finding (often transient)
      3. Early and transient in Viral Pericarditis
      4. May also be seen in Myocardial Infarction
    2. PR Segment elevation in aVR
      1. May also be seen in Myocardial Infarction
      2. Typically absent in constrictive Pericarditis
  3. Findings typically absent in Pericarditis and suggestive of alternative diagnosis (e.g. Myocardial Infarction)
    1. Pathologic Q Waves
    2. Reciprocal ST Segment changes
  4. Findings on EKG suggestive of large Pericardial Effusion (or Cardiac Tamponade)
    1. Low Voltage (R Wave amplitude <5 mV in limb leads, <10 mV in precordial leads)
    2. Electrical alternans

VIII. Findings: Stage 1 Pericarditis Changes

  1. Timing
    1. Onset: Day 2-3
    2. Duration: Up to 2 weeks
  2. Findings
    1. Diffuse concave upward ST Segment Elevation
    2. ST segment Depression in leads aVR or V1
    3. Concordant T Wave changes
    4. PR Segment Depression in leads II, AVF, and V4-V6

IX. Findings: Stage 2 Pericarditis Changes

  1. Timing
    1. Duration: Days to several weeks
  2. Findings
    1. ST Segment returns to baseline
    2. T Wave flattens

X. Findings: Stage 3 Pericarditis Changes

  1. Timing
    1. Onset: Week 2-3
    2. Duration: Several weeks
  2. Findings
    1. ST Segment returns to baseline
    2. T Wave inverts in leads II, AVF, and V4-V6

XI. Findings: Stage 4 Pericarditis Changes

  1. Timing
    1. Duration: Up to 3 months
  2. Findings
    1. Gradual resolution of T Wave Inversion

XII. References

  1. Klasek and Alblaihed (2023) Crit Dec Emerg Med 37(6): 4-11
  2. Imazio (2022) Heart 108(18): 1474-8 +PMID: 35523541 [PubMed]

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