How to manage ST elevation in cases of benign early repolarization or Right Bundle Branch Block (RBBB)?

Management of ST Elevation in Benign Early Repolarization or RBBB

In cases of ST elevation with benign early repolarization or RBBB, prompt evaluation for true myocardial infarction is essential, with RBBB not hampering ST elevation interpretation; proceed with emergency coronary angiography when clinical suspicion of myocardial ischemia exists despite these conditions. 1

Differentiating Features in Benign Early Repolarization

• Benign early repolarization (BER) typically shows diffuse or widespread ST segment elevation with upward concavity of the initial portion of the ST segment 2, 3
• Additional features include notching or slurring of the terminal QRS complex and concordant T waves of large amplitude 2
• BER is common, occurring in approximately 1% of the general population and up to 48% of emergency department patients with chest pain 3
• More frequently observed in young men, athletes, and individuals of African descent 4

Management Algorithm for ST Elevation in RBBB

1. Initial Assessment: Unlike LBBB, RBBB usually does not hamper interpretation of ST-segment elevation 1
2. ECG Interpretation: ST-segment elevation measured at the J-point should be found in two contiguous leads and meet specific criteria:
   • ≥0.25 mV in men below 40 years
   • ≥0.2 mV in men over 40 years
   • ≥0.15 mV in women in leads V2–V3
   • ≥0.1 mV in other leads 1
3. Decision Point: When persistent ischemic symptoms occur with RBBB, prompt management should be considered regardless of whether the RBBB is previously known 1
4. Intervention: Emergency coronary angiography with a view to primary PCI is recommended when clinical suspicion of ongoing myocardial ischemia exists 1

Management Algorithm for ST Elevation in Benign Early Repolarization

1. Initial Assessment: Compare with previous ECGs when available to determine if the pattern is longstanding 1
2. Clinical Context: Evaluate for presence of chest pain, risk factors, and other symptoms of myocardial ischemia 1
3. ECG Features to Differentiate from STEMI:
   • Upward concavity of the ST segment (vs. convexity in STEMI)
   • Notching or slurring of the terminal QRS complex
   • Concordant T waves of large amplitude 2, 3
4. Additional Testing: If diagnosis remains uncertain:
   • Consider point-of-care troponin testing 1-2 hours after symptom onset 1
   • Consider echocardiography to assess for wall motion abnormalities 1
5. Decision Point: With ongoing suspicion of myocardial ischemia despite medical therapy, emergency coronary angiography is indicated even without diagnostic ST-segment elevation 1

Special Considerations

• Extending ECG Leads: In cases where standard 12-lead ECG is inconclusive, additional posterior leads (V7-V9) may help identify posterior infarction 1
• Serial ECGs: Repeat ECG recordings are often needed to detect dynamic changes that would suggest true myocardial infarction 1
• Risk Stratification: The electrocardiographic territory, degree of J-point elevation, and ST-segment morphology are associated with different levels of risk for subsequent ventricular arrhythmia in BER 4

Pitfalls and Caveats

• Do not rely on symptom relief after nitroglycerin administration to rule out myocardial infarction; this can be misleading 1
• Complete normalization of ST-segment elevation after nitroglycerin, along with complete symptom relief, suggests coronary spasm rather than BER 1
• Patients with myocardial infarction and RBBB have a poor prognosis, necessitating prompt intervention when clinical suspicion exists 1
• While traditionally considered benign, recent evidence suggests that certain patterns of early repolarization may be associated with increased risk of idiopathic ventricular fibrillation 4
• Never delay reperfusion therapy while waiting for cardiac biomarker results when clinical suspicion for STEMI is high 1