Diagnosis and Management of ST Elevation in RBBB

Diagnostic Principles

The American College of Emergency Physicians suggests that RBBB produces characteristic secondary ST-T abnormalities in leads V1-V3, making it difficult to assess for acute ischemia in the right precordial leads 1
The American Heart Association recommends applying concordance and discordance criteria to identify acute MI in RBBB patients, including ST-segment elevation ≥1 mm concordant with the QRS complex in 2 or more contiguous leads, which is highly specific for acute MI 2
The American College of Cardiology states that ST-segment depression ≥1 mm concordant with the QRS in leads V1-V3 suggests acute MI, and ST-segment elevation ≥5 mm discordant from the major QRS deflection may indicate acute MI, though with lower specificity 2, 3

The American College of Emergency Physicians notes that RBBB patients with acute MI have a 64% increased odds of in-hospital death compared to those without bundle branch block, and recommends immediate action for high-risk features 1
The American Heart Association recommends primary PCI as the preferred strategy for RBBB patients meeting criteria for acute MI, with a first medical contact-to-device time goal ≤90 minutes, and administering fibrinolytic therapy if PCI cannot be performed within 90 minutes 2

The European Society of Cardiology suggests obtaining serial ECGs when clinical suspicion remains high, symptoms persist, or the patient's condition deteriorates, although this is not directly cited, transthoracic echocardiography can identify focal wall motion abnormalities to confirm ongoing ischemia when ECG interpretation is difficult, and high-sensitivity cardiac troponin provides biochemical confirmation 3

The American Heart Association notes that RBBB causes ST-T abnormalities in leads V1-V3 as a secondary repolarization effect, while posterior MI produces ST-segment depression in V1-V3 with a prominent R wave and upright terminal T waves 4, 5
The American College of Cardiology recommends considering RBBB when QRS complexes are wide (≥0.12 seconds) with a characteristic RSR' pattern in V1-V2 4, 5
ST-T abnormalities in leads V1-V3 are expected and common as part of the bundle branch block pattern itself, making it difficult to assess for ischemia in the right precordial leads 4, 5, 6

The European Society of Cardiology states that horizontal ST-segment depression ≥0.05 mV in leads V1-V3, with prominent R waves and upright terminal T waves, is indicative of posterior MI 7, 4, 5
ST elevation ≥0.05 mV in posterior leads V7-V9 confirms the diagnosis of posterior MI 7, 4, 5, 6

The American College of Cardiology recommends that RBBB patients with acute MI receive immediate reperfusion, as they have a 64% increased odds of in-hospital death compared to those without bundle branch block 8
Isolated posterior MI should be treated as a STEMI with immediate reperfusion therapy, according to the European Heart Journal 7