Myocardial Blood Flow in Patients With Transposition of the Great Arteries

BACKGROUND: Dysfunction of the morphologic systemic right ventricle (RV) is a sequela in long-term survivors with transposition of the great arteries (TGA) after atrial switch operation (AtSO). Impairment of myocardial blood flow (MBF) and coronary flow reserve (CFR) are hypothesized as predisposing factors. METHODS AND RESULTS: The study group comprised 20 patients after AtSO (22.7 ± 5.03 years) and 15 individuals with congenitally corrected transposition (ccTGA) (30.6 ± 19.4 years). MBF was quantified by positron emission tomography; controls for coronary flow were 11 healthy volunteers (26.2 ± 5.1 years). Exercise capacity, ventricular mass, function and end-diastolic volume assessed by coronary magnetic resonance (CMR), hemodynamic parameters assessed by cardiac catheterization and echocardiography, and B-type natriuretic peptide levels correlated with MBF. At rest, MBF did not differ between patients and healthy volunteers (MBFrestml·100 g(-1)·min(-1); ccTGA: 75 ± 14 vs. AtSO: 73 ± 16 vs. controls: 77 ± 15; NS). After vasodilatation, MBF increased significantly, but was significantly lower in ccTGA and AtSO groups compared with controls (MBFstressml·100 g(-1)·min(-1); ccTGA: 198 ± 38 vs. AtSO: 167 ± 46 vs. controls 310 ± 74; P<0.001). In ccTGA, CFR correlated significantly with clinical, CMR, echocardiographic and hemodynamic parameters, but for AtSO patients no significant correlation could be calculated. CONCLUSIONS: In patients with ccTGA, maximal coronary blood flow is attenuated and significantly correlated with ventricular function, whereas dysfunction of the morphologic systemic RV after AtSO is a multifactorial problem.