Miek Hornikx ^* Peter Haemers Linda Stans Tomas Robyns Christophe Garweg Joris Ector Bert Vandenberk Rik Willems²

• University Hospitals Leuven, Leuven, Belgium

Purpose-Reflex syncope is a burdensome disease with considerable repercussion on quality of life. Tilt training is a therapeutic option, but evidence on this topic is scarce and outdated. Hyperventilation is oftentimes associated with reflex syncope. The aim of this study was to evaluate the effectiveness of tilt training in patients with reflex syncope and to study the association between reflex syncope and hyperventilation.-Patients referred for tilt training after a positive tilt test from July 2014-March 2021 were included in a single-center, retrospective registry. Demographic characteristics and outcomes of the program were collected. Response of tilt training on (pre)syncope recurrence and the association with hyperventilation was studied. Results-A total of 173 patients were included. The median age was 27 [17-48] years. Patients needed 2 [1-3] sessions to reach a first negative tilt training. The tilt training program was completed successfully by 65% of patients. An additional 3% had no complaints anymore in daily life, despite remaining symptomatic during tilt training. Other therapy was initiated in 10%. Drop-out of the tilt training occurred in 21% of patients. Presyncope recurred in 21% of patients during a follow-up of 21 [16-23] months.Concomitant hyperventilation was suspected in 24%. Among these patients, 74% were referred for a hyperventilation provocation test, which confirmed the diagnosis in 82%.We report a reasonable success of tilt training in a contemporary cohort of patients. In patients completing the tilt training program, presyncope and syncope recurrence was low. Concomitant hyperventilation seems prevalent in patients with reflex syncope and warrants specific attention and treatment.