Which EKG finding was noted?

• A. Atrial fibrillation
• B. Left bundle branch block
• C. Possible left atrial abnormality
• D. ST elevation

Answer: (C)

Recognizing left atrial abnormality on an ECG centers on the P-wave morphology. Left atrial changes most often show up as a prolonged and often notched P wave in the inferior leads, and a biphasic P wave in V1 with a prominent terminal negative portion. This reflects delayed activation of the left atrium. When these features are present but not clearly diagnostic—perhaps the P-wave duration or notch is near the threshold—the report may say “possible left atrial abnormality” to indicate suspicion without proving a definite enlargement.

This fits better than the other possibilities because those describe distinct rhythm or ischemic issues: atrial fibrillation would show no clear P waves and an irregular rhythm; left bundle branch block presents a wide QRS with a specific ventricular conduction pattern; ST elevation describes an acute change in the ST segment. So the note of a possible left atrial abnormality aligns with subtle P-wave changes suggesting left atrial involvement without a definitive, standalone diagnosis.