Background

Coronary arteries obstruction is the main cause of mortality and morbidity in patients who underwent arterial switch for transposition of great arteries. Long-term outcome of coronary transfer and its consequences on myocardial perfusion is scarcely known.

Objective

To evaluate feasibility of cardiac MRI to describe coronary anatomy, myocardial perfusion and fibrosis after arterial switch operation.

Methods

110 patients (mean age 13.5 y) were included. Twenty-five/110 had had previously documented coronary artery obstruction. cMRI protocol included cine SSFP in short axis, two-chamber, three and four chamber view, and perfusion analysis before and after dipyridamole infusion. Anatomy was evaluated by 3D heart sequence in 78 patients. Finally, late enhancement was evaluated ten minutes after injection of contrast agent in 71 patients.

Results

Perfusion could be evaluated in all patients. One perfusion defect was identified. All patients with prior negative myocardial ischemia test had normal perfusion on MRI even those with mild to moderate coronary stenosis. Anatomical evaluation of proximal coronary arteries was possible in 71/78 patients. Finally, we found limited myocardial fibrosis in only two/78 patients who had left coronary artery obstruction that had been repaired.

Conclusion

cMRI is feasible and gives comprehensive information on coronary artery anatomy and physiology after the arterial switch operation. Use of cMRI as a screening tool for late coronary artery obstruction should be evaluated in larger series of patients to estimate its sensitivity and specificity.