Myocardial blood flow in patients with transposition of the great arteries: – Risk factor for dysfunction of the morphologic systemic right ventricle late after atrial repair –

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 (MBF_rest ml · 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 (MBFstress ml · 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.

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.