Clinical determinants of early spontaneous conversion to sinus rhythm in patients with atrial fibrillation.

Background: The current standard of care for acute atrial fibrillation (AF) focuses primarily on immediate restoration of sinus rhythm by cardioversion, although AF often terminates spontaneously.
Objective: To identify determinants of early spontaneous conversion (SCV) in patients presenting at the emergency department (ED) because of AF.
Methods: An observational study was performed of patients who visited the ED with documented AF between July 2014 and December 2016. The clinical characteristics and demographics of patients with and without SCV were compared.
Results: We enrolled 943 patients (age 69 ± 12 years, 47% female). SCV occurred within 3 h of presentation in 158 patients (16.8%). Logistic regression analysis showed that duration of AF <24 h [odds ratio (OR) 7.7, 95% confidence interval (CI) 3.5-17.2, p < 0.001], left atrial volume index <42 ml/m ² (OR 1.8, 95% CI 1.2-2.8, p = 0.010), symptoms of near-collapse at presentation (OR 2.4, 95% CI 1.2-5.1, p = 0.018), a lower body mass index (BMI) (OR 0.9, 95% CI 0.91-0.99, p = 0.028), a longer QTc time during AF (OR 1.01, 95% CI 1.0-1.02, p = 0.002) and first-detected AF (OR 2.5, 95% CI 1.6-3.9, p < 0.001) were independent determinants of early SCV.
Conclusion: Early spontaneous conversion of acute AF occurs in almost one-sixth of admitted patients during a short initial observation in the ED. Spontaneous conversion is most likely to occur in patients with first-onset, short-duration AF episodes, lower BMI, and normal left atrial size.