A Formula for the Stratified Selection of Patients with Paroxysmal Atrial Fibrillation in the Emergency Setting: A Retrospective Pilot Study

Abstract Background: Amiodarone is a commonly used medication in the treatment of atrial fibrillation (AF) of recent onset. Study Objectives: The aim of the study was to identify a possible formula for selecting Emergency Department (ED) patients with paroxysmal AF who will spontaneously restore sinus rhythm (SR), successfully restore SR with the use of loading intravenous (i.v.) amiodarone, or require 24-h maintenance amiodarone infusion. Methods: This retrospective pilot study included 141 patients with recent-onset AF. Patients who did not restore SR spontaneously received i.v. amiodarone (5 mg/kg) within a period of 30 min. In case of no response, an additional dosage of 1000 mg of i.v. amiodarone was administered over a period of 24 h. Binary logistic regression models were used to determine the predictors of spontaneous conversion and the response to amiodarone administration. Results: The formula ([heart rate/systolic blood pressure] + 0.1 × number of past AF incidences) was chosen as the one with the highest combined sensitivity and specificity. This index identified the patients who spontaneously restored SR (cutoff point 1.31 with 78.6% sensitivity and 77.9% specificity), whereas for patients who responded to the loading i.v. amiodarone dose, the use of the index (cutoff point 1.24) exhibited 84.1% sensitivity and 75.3% specificity. Conclusions: This formula may be a useful and reliable bedside diagnostic tool to identify AF patients most likely to spontaneously convert, or respond to loading amiodarone administration in the emergency setting. The use of this index also can assist in patient risk stratification.