Rate?
Rhythm?
Axis?
Intervals?
QRST?
Interpretation: Sinus bradycardia, Right Axis Deviation, QRS>120, Right bundle branch morphology. No pathologic q waves, good R wave progression, No STE/STD, TWI in V2
The Case:
49-year-old female with a past medical history of anxiety presenting with central sternal chest pressure, which she describes as sharp that started 3 hours prior to arrival. The pain is non-radiating and not associated with exertion, emesis, or diaphoresis, but she does feel like she is going to pass out. She says when she has had panic attacks before, she had chest pain. Vitals were BP 124/72 mmHg, HR 59 bpm, RR 18 bpm, and Spo2 98% on RA.
Discussion: This patient has a RBBB morphology with right axis deviation. RBBB should not give you a RAD unless they also have concomitant right ventricular hypertrophy.
Upon closer inspection the patient has a Left Posterior Fascicular Block (LPFB).
Right axis deviation (RAD)
rS complexes in leads I and aVL
qR complexes in leads II, III and aVF
Prolonged R wave peak time in aVF
Question: What is the significant of chest pain or syncope with a RBBB and LAFB/LPFB?
A bifascicular block is often associated with structural heart disease (50-80%) and issues with the conducting system. In patients with syncope strongly consider admission and cardiology consult given the risk to progression of complete heart block (rate of progression 17% per year in patients with syncope).
A new-onset fascicular block in the context of chest pain is highly associated with proximal LAD occlusion even in the absence of ST-segment changes. However this is typically a LAFB with RBBB. The 2017 European Society of Cardiology STEMI recommendation is to consider a primary PCI strategy [emergent coronary angiography and percutaneous coronary intervention (PCI) if indicated] when persistent ischemic symptoms occur in the presence of left or right bundle branch block.
Our patient had a negative initial troponin but given symptom onset was less than 3 hours we repeated a troponin that resulted at 0.24 with dynamic ST changes. She had a negative CTPE and was given ASA and started on a heparin drip.
Her cardiac catheterization showed coronary vasospasm of her PDA with successful balloon angioplasty but was otherwise negative for occlusion. Her echocardiogram showed mid-region hypokinesis consistent with atypical stress induced cardiomyopathy (Takutsubo’s).
Take away points:
· RBBB in isolation does not produce RAD unless RVH is present
· RBBB with LPFB is considered a bifascicular block with a concern for progression to complete heart block in patients presenting with syncope
· Strongly consider admission and cardiology consult for syncope in the setting of bifascicular block
· New RBBB in the presence of persistent ischemic symptoms is a consideration for PCI
Authored by Alejandro Negrete, MD
Resources:
Larkin J and Buttner R. Left Posterior Fascicular Block (LPFB) [Internet]. Life in the Fast Lane • LITFL. 2021 [cited 2023 Oct 25];Available from: https://litfl.com/left-posterior-fascicular-block-lpfb-ecg-library/
Burns E and Buttner R. Bifascicular Block [Internet]. Life in the Fast Lane • LITFL. 2021 [cited 2023 Oct 25];Available from: https://litfl.com/bifascicular-block-ecg-library/
Buttner R and Cadogan M. OMI: Replacing the STEMI misnomer [Internet]. Life in the Fast Lane • LITFL. 2023 [cited 2023 Oct 25];Available from: https://litfl.com/omi-replacing-the-stemi-misnomer/
Ibanez B and James S. The 2017 ESC STEMI Guidelines, European Heart Journal, Volume 39, Issue 2, 07 January 2018, Pages 79–82, https://doi.org/10.1093/eurheartj/ehx753
Ibanez B, James S, Agewall S, Antunes MJ, Bucciarelli-Ducci C, Bueno H, Caforio ALP, Crea F, Goudevenos JA, Halvorsen S, Hindricks G, Kastrati A, Lenzen MJ, Prescott E, Roffi M, Valgimigli M, Varenhorst C, Vranckx P, Widimský P; ESC Scientific Document Group. 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J. 2018 Jan 7;39(2):119-177. doi: 10.1093/eurheartj/ehx393. PMID: 28886621.