Recovery kinetics of oxygen uptake is prolonged in adults with an atrial septal defect and improves after transcatheter closure

Background In adults with an atrial septal defect (ASD) transcatheter closure leads to an improvement of peak oxygen uptake (VO2), but the kinetics of recovery of VO2 after maximal exercise in this patient population and the impact of transcatheter ASD closure have never been investigated. Methods Twenty consecutive patients underwent a maximal cardiopulmonary exercise test both the day before and 6 months after transcatheter ASD closure. For comparison, an age- and sex-matched group consisting of 53 healthy adults was built. The constant decay of VO2, CO2 production (VCO2), minute ventilation (VE), and heart rate (HR), expressed as the first-degree slope of a single linear relation, were calculated for the first minute of recovery. Results Patients with an ASD had a prolonged VO2 slope (P=.0012), VCO2 slope (P=.0003), and VE slope (0.013) when compared with control subjects. Six months after transcatheter ASD closure, significant improvements of VO2 slope (P=.0043) and of VCO2 slope (P=.0022) were recorded, so that no difference was found when compared with those of the control group (P=.1 and P=.06, respectively). The VE slope and HR slope did not change after closure. A significant association between VO2 Slope and peak VO2 in the group of patients with ASD was shown by the Spearman correlation, both before (r=0.67, P=.0012) and after ASD closure (r=0.71, P=.0004). Conclusions A limited cardiopulmonary reserve in adults with no symptom who have an ASD appears to affect not only maximal exercise responses but also the recovery phase. Transcatheter ASD closure induces a significant improvement of the ability of recovering from maximal exercise and eliminates the difference with a healthy population.