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Cardiology

A Case of Right Bundle Branch Block With Changing Axis

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.

1 Credit CME

JAMA Cardiology

Published Online: November 30, 2022

JAMA Cardiology Clinical Challenge

Article Information and Disclosures

Robert B. King, MD¹;

Ramil Goel, MD^2,3

Author Affiliations

¹Department of Medicine, University of Florida, Gainesville
²Division of Cardiology, University of Florida, Gainesville
³Malcolm Randall VA Medical Center, Gainesville

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A man in his 80s with a history of heart failure with preserved ejection fraction, permanent atrial fibrillation, and coronary artery bypass graft 10 years ago presented with recurrent presyncope and bradycardia. Review of prior physician encounters revealed reports of lightheadedness and electrocardiograms (ECGs) with atrial fibrillation with ventricular rates of 40 to 50 beats per minute. Current medications included carvedilol, 25 mg, twice daily and apixaban, 5 mg, twice daily. An ECG (Figure, A) showed atrial fibrillation with an irregular ventricular rate of around 60 beats per minute, right bundle branch block (RBBB), and left posterior fascicular block (LPFB).

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A man in his 80s with a history of heart failure with preserved ejection fraction, permanent atrial fibrillation, and coronary artery bypass graft 10 years ago presented with recurrent presyncope and bradycardia. Review of prior physician encounters revealed reports of lightheadedness and electrocardiograms (ECGs) with atrial fibrillation with ventricular rates of 40 to 50 beats per minute. Current medications included carvedilol, 25 mg, twice daily and apixaban, 5 mg, twice daily. An ECG (Figure, A) showed atrial fibrillation with an irregular ventricular rate of around 60 beats per minute, right bundle branch block (RBBB), and left posterior fascicular block (LPFB).

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Article Information

Published Online: November 30, 2022. doi:10.1001/jamacardio.2022.4283

Correction: This article was corrected on May 24, 2023, to fix the diagnosis and discuss lead reversal as part of the differential diagnosis.

Corresponding Author: Robert B. King, MD, Department of Medicine, University of Florida, 1600 SW Archer Rd, PO Box 100277, Gainesville, FL 32610-0277 (robert.king@medicine.ufl.edu).

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient for granting permission to publish this information.

References

Rosenbaum MB , Elizari MV , Lazzari JO . Los Hemibloqueos. Editorial Paidós; 1968.

Rosenbaum MB , Elizari MV , Lazzari JO , Nau GJ , Levi RJ , Halpern MS . Intraventricular trifascicular blocks. the syndrome of right bundle branch block with intermittent left anterior and posterior hemiblock. Am Heart J. 1969;78(3):306-317. doi:10.1016/0002-8703(69)90038-6 PubMed Google Scholar Crossref

Kusumoto FM , Schoenfeld MH , Barrett C , et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2019;140(8):e382-e482. doi:10.1161/CIR.0000000000000628 PubMed Google Scholar Crossref

AMA CME Accreditation Information

Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
1.00 credit toward the CME [and Self-Assessment requirements] of the American Board of Surgery’s Continuous Certification program

It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.