Relation of right ventricular mechanics to exercise tolerance in children after tetralogy of Fallot repair

Background Progressive right ventricular (RV) dysfunction and exercise intolerance are common problems after tetralogy of Fallot (TOF) repair. We investigated RV myocardial deformation and dyssynchrony in children after TOF repair and their association with exercise capacity. Methods Asymptomatic children after TOF repair were investigated by 2-dimensional speckle tracking echocardiography, magnetic resonance, and metabolic exercise study. Patients with RV outflow obstruction were excluded. Peak RV longitudinal strain and strain rate (SR) and dyssynchrony (RV intraventricular delay) were compared with healthy controls. Associations between RV strain, dyssynchrony, and exercise capacity were analyzed. Results Thirty-nine (81%) of 48 TOF patients and 40 healthy controls had adequate RV strain imaging. The TOF patients had moderately dilated RVs and normal RV ejection fraction. Right ventricular peak systolic strain (−23.2% ± 5.1% vs −28.5% ± 8.5%, P P P = .008). Decreased RV strain and SR were associated with increased RV dyssynchrony (strain parameter estimate [PE] 6.31 [2.30], P = .007; SR [PE] 11.32 [3.84], P = .004). Increased RV–left ventricular delay was associated with prolonged QRS duration (PE 0.13 [0.058], P = .03) and reduced RV ejection fraction (PE −2.95 [1.275], P = .02). Reduced RV peak SR was associated with decreased exercise peak oxygen uptake (PE 0.14 [0.07], P = .04). Conclusions After repair of TOF, asymptomatic children have reduced RV deformation in association with RV dyssynchrony and reduced exercise tolerance.