What is the management approach for a patient with Right Bundle Branch Block (RBBB) and ST-Elevation Myocardial Infarction (STEMI)?

From the Guidelines

The management of a patient with Right Bundle Branch Block (RBBB) and ST-Elevation Myocardial Infarction (STEMI) should follow standard STEMI protocols, as RBBB should not delay reperfusion therapy. Immediate reperfusion with primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact is the preferred strategy, as outlined in the 2017 AHA/ACC clinical performance and quality measures for adults with ST-elevation and non-ST-elevation myocardial infarction 1. If PCI is not available within 120 minutes, fibrinolytic therapy should be administered within 30 minutes of hospital arrival in eligible patients. Standard STEMI medications should be given, including:

• Aspirin (162-325mg loading dose, then 81mg daily)
• A P2Y12 inhibitor such as ticagrelor (180mg loading, 90mg twice daily) or prasugrel (60mg loading, 10mg daily)
• Anticoagulation with unfractionated heparin (60 IU/kg bolus plus infusion) or bivalirudin
• High-intensity statin therapy Beta-blockers (metoprolol 5mg IV every 5 minutes for 3 doses, then oral therapy) should be given if no contraindications exist, as recommended in the ACC/AHA guideline update for the management of ST-segment elevation myocardial infarction 1. The presence of RBBB in STEMI is associated with higher mortality and risk of complete heart block, so temporary pacemaker placement should be considered, especially with anterior STEMI. Continuous cardiac monitoring is essential as these patients may develop high-degree AV blocks requiring intervention. RBBB can make ECG interpretation challenging, but new ST elevations in the appropriate clinical context should still prompt immediate STEMI management regardless of the underlying RBBB. Key considerations in the management of STEMI include minimizing the time from the onset of symptoms until the initiation of reperfusion therapy, with a goal of fibrinolysis beginning less than 30 minutes from the time of the patient’s first contact with the health care system, or balloon inflation for PCI beginning in less than 90 minutes 1.

From the FDA Drug Label

The COMMIT trial included 45,852 patients presenting within 24 hours of the onset of the symptoms of myocardial infarction with supporting ECG abnormalities (i.e., ST-elevation, ST-depression or left bundle-branch block). Patients were randomized to receive clopidogrel (75 mg once daily) or placebo, in combination with aspirin (162 mg per day), for 28 days or until hospital discharge, whichever came first.

The management approach for a patient with Right Bundle Branch Block (RBBB) and ST-Elevation Myocardial Infarction (STEMI) is not directly addressed in the provided drug labels.

• The COMMIT study included patients with STEMI and supported the use of clopidogrel in combination with aspirin for 28 days or until hospital discharge.
• However, the study did not specifically address the management of patients with RBBB and STEMI.
• The prasugrel label indicates that it is indicated for the reduction of thrombotic cardiovascular events in patients with acute coronary syndrome who are to be managed with percutaneous coronary intervention (PCI), including patients with STEMI.
• But, it does not provide specific guidance on the management of patients with RBBB and STEMI. Therefore, the management approach for a patient with RBBB and STEMI cannot be determined based on the provided information 2, 3.

From the Research

Management Approach for RBBB and STEMI

The management approach for a patient with Right Bundle Branch Block (RBBB) and ST-Elevation Myocardial Infarction (STEMI) involves prompt reperfusion therapy.

• Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy in STEMI, as long as it can be delivered within 90-120 minutes from the patient's first medical contact 4.
• Fibrinolytic therapy (FT) is the recommended choice in patients with an anticipated delay to PCI of >90-120 minutes, presenting early after symptom onset and without contraindications 4.
• The use of antithrombotic agents such as aspirin, bivalirudin, and either prasugrel or ticagrelor is recommended to support primary PCI 5.

RBBB as an Indication for Reperfusion Therapy

RBBB should be considered as a standard indication for reperfusion therapy, similar to left bundle branch block (LBBB) 6.

• Patients with new or presumably new RBBB have a high incidence of cardiogenic shock and in-hospital mortality, highlighting the need for prompt reperfusion therapy 6.
• Primary PCI is frequently performed in patients with RBBB, and restoration of coronary flow may lead to resolution of the conduction delay on the discharge ECG 6.

Transfer for Primary PCI

Transfer for primary PCI does not significantly impact clinical outcomes, including survival and major adverse cardiac events, compared to direct admission to a PCI center 7.

• However, transfer is associated with longer times to reperfusion and first door-to-balloon time, emphasizing the need for efficient transfer protocols 7.