Analysis of the recovery phase after maximal exercise in children with repaired tetralogy of Fallot and the relationship with ventricular function

Background Few studies demonstrate delayed recovery after exercise in children and adults with heart disease. We assess the recovery patterns of gas exchange parameters and heart rate (HR) in children with repaired Tetralogy of Fallot (rToF) compared to healthy peers and investigate the correlation with ventricular function and QRS duration. Methods 45 children after rToF and 45 controls performed a maximal incremental cardiopulmonary exercise test. In the subsequent recovery period, patterns of VO ₂, VCO ₂ and HR were analysed. Half-life time (T _1/2) of the exponential decay and drop per minute (Rec _min) were compared between groups. In the rToF group, correlations were examined between the recovery parameters and QRS-duration and ventricular function, described by fractional shortening (FS) and tricuspid annular plane systolic excursion (TAPSE) measured at baseline prior to exercise. Results Recovery of VO ₂ and VCO ₂ was delayed in rToF patients, half-life time values were higher compared to controls (T _1/2VO ₂ 52.51 ±11.29 s vs. 44.31 ± 10.47 s; p = 0.001 and T _1/2VCO ₂ 68.28 ± 13.84 s vs. 59.41 ± 12.06 s; p = 0.002) and percentage drop from maximal value was slower at each minute of recovery (p<0.05). Correlations were found with FS (T _1/2VO ₂: r = -0.517; p<0.001; Rec _1minVO ₂: r = -0.636, p<0.001; Rec _1minVCO ₂: r = -0.373, p = 0.012) and TAPSE (T _1/2VO ₂: r = -0.505; p<0.001; Rec _1minVO ₂: r = -0.566, p<0.001; T _1/2VCO ₂: r = -0.466; p = 0.001; Rec _1minVCO ₂: r = -0.507, p<0.001), not with QRS-duration. No difference was found in HR recovery between patients and controls. Conclusions Children after rToF show a delayed gas exchange recovery after exercise. This delay correlates to ventricular function, demonstrating its importance in recovery after physical activity.