Predicting spontaneous conversion to sinus rhythm in symptomatic atrial fibrillation: The ReSinus score

Background: The optimal management of patients presenting to the Emergency Department with hemodynamically stable symptomatic atrial fibrillation remains unclear. We aimed to develop and validate an easy-to-use score to predict the individual probability of spontaneous conversion to sinus rhythm in these patients Methods: This retrospective cohort study analyzed 2426 cases of first-detected or recurrent hemodynamically stable non-permanent symptomatic atrial fibrillation documented between January 2011 and January 2019 in an Austrian academic Emergency Department atrial fibrillation registry. Multivariable analysis was used to develop and validate a prediction score for spontaneous conversion to sinus rhythm during Emergency Department visit. Clinical usefulness of the score was assessed using decision curve analysis Results: 1420 cases were included in the derivation cohort (68years, 57-76; 43% female), 1006 cases were included in the validation cohort (69years, 58-76; 47% female). Six variables independently predicted spontaneous conversion. These included: duration of atrial fibrillation symptoms (<24hours), lack of prior cardioversion history, heart rate at admission (>125bpm), potassium replacement at K⁺ level ≤3.9mmol/l, NT-proBNP (<1300pg/ml) and lactate dehydrogenase level (<200U/l). A risk score weight was assigned to each variable allowing classification into low (0-2), medium (3-5) and moderate (6-8) probability of spontaneous conversion. The final score showed good calibration (p=0.44 and 0.40) and discrimination in both cohorts (c-indices: 0.74 and 0.67)