Exercise stress test in patient with persistent form of atrial fibrillation receiving treatment with Class Ic antiarrhythmic drugs after sinus rhythm restoration

Class Ic antiarrhythmic medications are widely used for rhythm control in patients with atrial fibrillation. Currently, the data regarding the use of exercise testing in patients with normal ejection fractions testing to screen for proarrhythmia and Class I drugs safety is limited. The purpose of our study was to determine the efficacy and utility of bicycleexercise stress test in evaluating outcomes managing atrial fibrillation with Class I antiarrhythmic medications. This prospective study included 35 patients undergoing ECV (electrical cardioversion) for persistent form of AF in the Latvian Centre of Cardiology, Pauls Stradins Clinical University Hospital from September 2019 to June 2020. The patients were asked to perform a stress test before and after receiving therapy with propaphenone or aethacizinum. For safety evaluation blood tests and electrocardiogram were performed.  25 patients (71%) were admitted for ECV by emergency service, while 10 (29%) were referred by a cardiologist or general practitioner. At the baseline 20 patients (57%) received therapy with aethacizinum 50 mg daily and 15 patient (43%) – propapfenone 300 mg daily. No proarrhythmic events were observed during the study. There were no important changes in performed safety tests. The bicycle stress test time increased from a mean of 5.52 minutes to 6.04 minutes (p = 0.005).  With screening, initiation of Class Ic agent is associated with very low rate of proarrhythmia. Bicycle exercise stress testing is an effective and safe, widely used test that should be cperformed in all patients after initiation of Class Ic antiarrhythmic drugs for evaluation of safety and physical activity level changes during threatment.