New Right Bundle Branch Block: A Benign Variant or an Ominous Sign?

A gentleman in his 80s presented to the hospital with several hours of ongoing, dull-aching chest pain radiating to his left arm. The initial electrocardiogram (ECG) showed atrial fibrillation (AF), bifascicular block (right bundle branch block (RBBB) and left anterior fascicular block), and concordant 0.5 mm ST-segment elevation in leads V1-V3. The repeated ECGs at one-hour and three-hour intervals showed similar findings. The initial high-sensitivity troponin (HS-troponin) level was 2672.7 ng/L. He was triaged as non-ST-segment elevation acute coronary syndrome (NSTE-ACS). However, his ECGs repeated on the next day showed AF, bifascicular block, and ST-segment elevation in leads V2-V4, I, and augmented vector left (aVL) alongside a significant troponin surge to 25,951 ng/L. The emergency coronary angiogram uncovered severe coronary artery disease that warranted percutaneous coronary intervention (PCI).