New-onset perioperative atrial fibrillation in cardiac surgery patients: transient trouble or persistent problem?—Authors' reply. Issue 6 (24th December 2021) - Kawczynski, Michal J; Zeemering, Stef; Gilbers, Martijn; Isaacs, Aaron; Verheule, Sander; Zink, Matthias D; Maesen, Bart; Bramer, Sander; Van Gelder, Isabelle C; Crijns, Harry J G M; Schotten, Ulrich; Bidar, Elham