We explored the effect of dobutamine stress and its possible clinical implications in different groups of asymptomatic patients with chronic right ventricular (RV) pressure overload due to congenital heart disease. Forty-seven asymptomatic and minimally symptomatic patients with chronic RV pressure overload were studied: 24 patients with systemic right ventricles (16 surgically corrected transposition of the great arteries (TGA) (Mustard or Senning), 8 congenitally corrected TGA), 23 patients with chronic pressure overloaded subpulmonic right ventricles, and 11 age- and sex-matched healthy volunteers. Magnetic resonance imaging (MRI) was performed both at baseline and during dobutamine stress to determine RV volumes and ejection fraction. At baseline, RV ejection fraction in patients with surgically corrected TGA was significantly lower than in controls (58 +/- 10% vs 70 +/- 8%, p = 0.02). During dobutamine stress, RV ejection fraction increased significantly in controls and patient groups except for patients with pressure overloaded subpulmonic right ventricles. RV stroke volume increased in controls (21 +/- 21%, p = 0.008); RV stroke volume remained unchanged in patients with congenitally corrected TGA and surgically corrected TGA (2 +/- 17%, p = NS; -8 +/- 29%, p = NS). A significant RV stroke volume decrease was observed in patients with subpulmonic right ventricles (-15 +/- 16%, p = 0.0002). The changes in RV stroke volume were accompanied by a significant decrease in RV end-diastolic volume (-13 +/- 14%, p = 0.001) in patients with subpulmonic right ventricles and in patients with surgically corrected TGA (-23 +/- 16%, p = 0.0001). In controls and in patients with congenitally corrected TGA there was no change in RV end-diastolic volume (3 +/- 15%, p = NS; -5 +/- 11%, p = NS). There is a clear heterogeneity in response to MRI dobutamine stress between different groups of patients with chronic RV pressure overload. Our data suggest impaired filling in surgically corrected TGA and decreased contractility in patients with chronic pressure overloaded subpulmonic right ventricles. Dobutamine stress MRI may facilitate follow-up of RV (dys)function in patients with chronic RV pressure overload due to congenital heart disease.
