Chronological Magnetic Resonance Angiography Demonstration of Spontaneous Posterior Cerebral Artery Recanalization: Unmasking Cardioembolic Stroke and Postprandial Atrial Fibrillation Mislabeled as Dumping Syndrome

Atrial fibrillation (AF) and post-gastrectomy dumping syndrome share overlapping symptoms, such as palpitations, dizziness, and chest discomfort, making them clinically difficult to distinguish. We report a case where anchoring bias led both the patient and clinicians to misattribute postprandial symptoms to dumping syndrome, until a cardioembolic stroke unmasked latent AF. A 63-year-old man with a history of distal gastrectomy performed 5 years prior developed postprandial palpitations, chest discomfort, and dizziness triggered by rapid eating or cold drinks. A prior facility had empirically attributed these episodes to dumping syndrome without cardiac evaluation. Initial electrocardiogram showed normal sinus rhythm. The next day, he developed acute diplopia and ptosis due to left oculomotor nerve palsy. Brain MRI demonstrated a left medial midbrain infarction, and MR angiography (MRA) showed 99% stenosis of the left P1 segment. Transesophageal echocardiography demonstrated left atrial enlargement and decreased left atrial appendage flow velocity with spontaneous echo contrast. Continuous electrocardiographic telemetry post-dinner captured paroxysmal AF, unmasking the arrhythmia. His CHA₂DS₂-VASc and HAS-BLED scores were calculated as 3 and 2, respectively. He was treated with anticoagulants and discharged with mild sequelae (modified Rankin Scale score 1). Follow-up MRA at 3 months showed complete recanalization of the P1 segment. This chronological MRA sequence provided visual proof differentiating cardioembolism from fixed intracranial atherosclerosis.