Atrial fibrillation occurring during head-up tilt testing: Once detected, atrial fibrillation should be monitored, regardless of how it is detected

Background: Atrial fibrillation (AF) often progresses to more sustained forms and increases the risk of ischemic stroke or sinus node dysfunction. However, there have been no data on the clinical outcomes of patients who developed AF during head-up tilt testing (HUT). Objective: The purpose of this study was to evaluate the clinical significance of AF detected during HUT performed for syncope evaluation. Methods: We analyzed incidence, short- and long-term prognosis, and predictors of adverse outcomes of AF detected during HUT, which was performed in 6780 consecutive patients without AF history. Results: Of the 6780 patients, 52 (0.8%) developed AF during passive tilting (n = 5), isoproterenol infusion (n = 32), and recovery phase (n = 15) of HUT, respectively. There was no short-term adverse event: spontaneous sinus conversion occurred in 43 patients (83%) within 48 hours. Over a median follow-up of 34.8 months, 24 patients (46%) had AF recurrence with initial presentation as ischemic stroke (n = 2), sinus node dysfunction requiring pacemaker (n = 10), and AF alone (n = 12). In addition, 19 of 24 recurred AF cases (79.2%) progressed to persistent/permanent forms. The index AF duration was identified as an independent predictor of AF recurrence. Patients with longer AF duration (≥1.0 hour) showed worse prognosis than did those with shorter AF duration (<1.0 hour). Conclusion: The incidence of AF during HUT was ∼0.8%, and short-term prognosis was favorable. However, about half of the cases were complicated by long-term adverse outcomes. Therefore, regular follow-up might be warranted for patients with HUT-induced AF, particularly when AF duration is long.