Asymptomatic Positive Tilt Test with Concurrent Atrial Fibrillation: A Diagnostic Challenge

An elderly male was evaluated for recent-onset recurrent syncope. He has been a diabetic for the last 5 years and is on regular medications. The likely etiology of syncope was thought to be autonomic dysfunction secondary to diabetes, and hence, tilt table testing was done to demonstrate the same. Tilt table testing revealed a vasodepressor-like hypotensive response, favoring the diagnosis of autonomic dysfunction. However, he also developed concomitant atrial fibrillation during the testing, which was not previously diagnosed. He remained asymptomatic during the vasodepressor response and the atrial fibrillation paroxysm, and hence, the cause of syncope was unclear. A Holter study was obtained to quantify the burden of atrial fibrillation. It showed that his syncopal episodes correlated with fast ventricular rate episodes of atrial fibrillation. The occurrence of atrial fibrillation during a vasodepressor response to a tilt table test is rare, and the absence of symptoms despite a positive tilt table response warrants further evaluation for the cause of syncope. He was treated with rate-control therapy for atrial fibrillation, following which his symptoms had resolved.