Procedures around rate control medication and cardioversion
SHOCKS
Rate control strategy was described in the study protocol. For patients in the early cardioversion group, no specific instructions on the administration of rate control medication were given. First choice of treatment for early cardioversion was immediate pharmacological cardioversion. This was preferably performed with flecainide with an infusion scheme of 2 mg/kg body weight (150 mg maximum) in 10 min or until conversion to sinus rhythm occurred. Electrical cardioversion was performed in patients with contraindications to pharmacological cardioversion, as well as in patients with previous or current unsuccessful pharmacological cardioversion. For electrical cardioversion, a maximum of three shocks was performed from a biphasic defibrillator in synchronized mode, with energy set at 200, 360, and 360 J.In the delayed cardioversion group, acute rate control was achieved through the administration of beta blockers (1st choice), calcium channel blockers (2nd choice) or digoxin (3rd choice). The dosage of the rate control medication was titrated based on heart rate, with the goal to achieve a heart rate of <110 bpm. The oral maintenance dose was subsequently determined based on the initial dosage needed to achieve adequate rate control.All data on rate control medication use and adaptation were collected from the electronic patient record. During the index ED visit, medication use at that time was verified and recorded, as were any changes made during this visit. The same applied to the second‐day visit in the delayed cardioversion group. Rate control medication used at index visit included all medication with a start date before the index visit. To determine which rate control medication was used at the start of the follow‐up period, this information was complemented with details on newly started medication, stopped medication or changes in dosages during the index visit in case of early cardioversion, and the index visit and/or the second‐day visit in case of delayed cardioversion.