What is the cause of the Right Bundle Branch Block (RBBB) in a patient with a history of Coronary Artery Bypass Grafting (CABG) 10 years ago, who presents with chest pain, an electrocardiogram (ECG) consistent with ST-Elevation Myocardial Infarction (STEMI), and prior imaging done 6 years ago?

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Differential Diagnosis for Chest Pain with STEMI and RBBB

  • Single most likely diagnosis
    • B. The STEMI has nothing to do with RBBB (acutely LBBB): This is the most likely diagnosis because the presence of RBBB on an EKG in a patient with a history of CABG and STEMI does not necessarily imply a new or acute cause for the RBBB. The RBBB could be a pre-existing condition, as suggested by imaging done 6 years ago, and the STEMI is a separate acute event. The fact that the RBBB has been consistent with previous imaging indicates it is likely a chronic condition rather than an acute development related to the STEMI.
  • Other Likely diagnoses
    • D. RBBB is often ASx: This option is plausible because many individuals with RBBB are asymptomatic, and the condition may not directly relate to the STEMI or the CABG. The RBBB could be an incidental finding in this context.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • A. CABG can lead to heart block: Although less likely, it's crucial not to miss the possibility that the CABG could have led to a heart block, which might manifest as RBBB. Heart block can be a complication of CABG and needs prompt recognition and management.
    • C. PE can acutely cause RBBB: Pulmonary embolism (PE) is a critical condition that can cause RBBB acutely. Although the primary presentation is STEMI, it's essential to consider PE, especially if there are other suggestive symptoms or signs, as it requires immediate and different management.
  • Rare diagnoses
    • Other rare causes of RBBB, such as cardiac sarcoidosis, Lyme disease, or tumors, are less likely in this context given the provided history and presentation but should be considered if other explanations are ruled out and the clinical picture warrants further investigation.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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