What is the management approach for a patient presenting with a right bundle branch block (RBBB) and ST elevation?

Management of Right Bundle Branch Block with ST Elevation

Patients with right bundle branch block (RBBB) and ST elevation should be treated as ST-elevation myocardial infarction (STEMI) cases requiring immediate reperfusion therapy, preferably with primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact.

Diagnostic Considerations

Unlike left bundle branch block (LBBB), RBBB does not typically interfere with the diagnosis of STEMI. Key points to consider:

• ST elevation can still be reliably detected in the presence of RBBB 1
• RBBB with ST elevation represents a high-risk presentation with increased mortality compared to STEMI without bundle branch block 2, 3
• When evaluating a patient with RBBB and ST elevation, it's essential to:
  • Confirm ST elevation meets criteria: ≥0.1 mV in two contiguous leads
  • Rule out Brugada syndrome, which can present with RBBB pattern and ST elevation in V1-V3 but represents a different pathophysiology 4

Immediate Management Algorithm

1. Initial Assessment (0-10 minutes)

   • Obtain 12-lead ECG immediately at first medical contact
   • Administer oxygen if SaO₂ < 90% (not routinely if SaO₂ ≥ 90%) 1
   • Provide pain relief with titrated IV opioids 1
   • Consider mild tranquilizer for anxiety 1

2. Reperfusion Strategy Decision (10-30 minutes)

   • Primary PCI preferred: If PCI-capable facility is available within 90 minutes of first medical contact 1
   • Fibrinolysis: If PCI cannot be performed within 90 minutes and no contraindications exist 1
   • Immediate transfer: For all patients with STEMI and RBBB who present to non-PCI capable facilities 1

3. Special Considerations

   • For cardiogenic shock: Immediate PCI is indicated regardless of time from symptom onset 1
   • For hemodynamic instability: Urgent coronary angiography with intent to perform PCI 1
   • For failed fibrinolysis: Rescue PCI is indicated (ST-segment elevation less than 50% resolved after 90 minutes) 1

Antithrombotic Therapy

• Aspirin: Immediate oral or IV administration 1
• P2Y₁₂ inhibitor: Add ticagrelor or prasugrel (clopidogrel if these are unavailable) 1
• Anticoagulation:
  • For primary PCI: Unfractionated heparin, enoxaparin, or bivalirudin
  • For fibrinolysis: Enoxaparin IV followed by SC (preferred) or weight-adjusted unfractionated heparin 1

Post-Reperfusion Management

1. Monitoring and Assessment

   • Routine echocardiography to assess LV and RV function 1
   • Monitor for arrhythmias, especially given the presence of RBBB
   • Watch for progression to complete heart block, which may require temporary pacing 5

2. Pharmacotherapy

   • Beta-blockers: Indicated for patients with heart failure or LVEF <40% (avoid IV administration in hypotensive patients) 1
   • ACE inhibitors: Start within 24 hours in patients with anterior infarct, heart failure, LV dysfunction, or diabetes 1
   • High-intensity statins: Start as early as possible 1
   • Dual antiplatelet therapy: Continue for 12 months 1

Clinical Pitfalls and Caveats

1. Do not delay reperfusion therapy in patients with RBBB and ST elevation. Unlike LBBB, RBBB does not obscure ST elevation diagnosis 1.

2. Watch for right ventricular involvement in inferior STEMI with RBBB, which requires special management:

   • Maintain right ventricular preload
   • Avoid excessive vasodilators
   • Consider fluid loading if hypotensive
   • Correct atrial fibrillation promptly if it occurs 1

3. Be vigilant for progression to complete heart block, especially in patients with inferior MI and RBBB, which may require temporary pacing 5.

4. RBBB with concomitant ST elevation carries a higher mortality risk than isolated RBBB or isolated ST elevation 3.

5. Distinguish from Brugada syndrome, which can present with RBBB pattern and ST elevation in V1-V3 but requires different management 4.

By following this algorithm, clinicians can provide optimal care for patients with RBBB and ST elevation, recognizing the high-risk nature of this presentation and the need for prompt reperfusion therapy.