Outcomes of coronary artery obstructions after the arterial switch operation for transposition of the great arteries.

OBJECTIVE: Coronary obstruction is a rare but common complication of the arterial switch operation for transposition of the great arteries (ASO-TGA). The majority of patients remain asymptomatic and no risk factors allow targeting for reinforced surveillance. We aim to review the natural history of patients diagnosed with coronary obstruction after ASO-TGA and occurrence of coronary related outcomes.

METHODS: We have retrospectively reviewed medical records of the 102 patients diagnosed with coronary obstruction after ASO-TGA in our institution from 1981 to 2022. Outcomes were antiischemic treatment introduction, revascularization (surgical or percutaneous angioplasty) and death; investigations which motivated revascularization were also reviewed.

RESULTS: 28/102 patients presented with myocardial ischemia in the immediate post-operative phase, 31 were diagnosed when symptomatic, and 43 were identified at the presymptomatic stage, according to our screening policy in preschool age children. Stenosis-related event occurrence was respectively 29/31 and 32/43 in the latter two subgroups. Coronary mortality reached 10% in patients diagnosed when symptomatic; no patients died in the presymptomatic subgroup. Of the 28 "low-risk" patients with no signs of ischemia at diagnosis, 10 developed obstruction warranting reintervention during follow-up. Revascularization was motivated by appearance of symptoms in patients with severe stenosis in normal coronary dispositions, and by clinical symptoms or documented silent ischemia in abnormal coronary patterns.

CONCLUSION: Occurrence of stenosis-related events remains significant in post-ASO patients, underlining the importance of early diagnosis for timely intervention. Initial anatomical evaluation identifies stenotic and at-risk patients, which will require periodical functional testing; follow-up modalities can be tailored to patient's individual anatomical characteristics.