Long-term results of the arterial switch operation for ventriculo-arterial discordance

The arterial switch operation (ASO) has become the standard surgical procedure for transposition of the great arteries (TGA) or variants with an excellent early outcome. However, there are concerns regarding neopulmonary stenosis, neoaortic regurgitation (neoAR) associated with neoaortic root dilatation and coronary artery disease.

A total of 220 early survivors of the ASO were included in this retrospective study between November 1987 and June 2011. The median age and weight at operation were 13 days (0-1768 days) and 3.52 kg (1.69-19 kg), respectively. The indications for the ASO included TGA with intact ventricular septum in 113 patients, TGA with ventricular septal defect in 90 and Taussig-Bing anomaly in 17 patients. The median follow-up period was 103.2 months (0.4-277.4 months). Statistical analyses with the Kaplan-Meier and Cox proportional hazards models were performed.

The actuarial late survival rate and freedom from reoperation at 23 years were 96.6 ± 1.3 and 81.9 ± 3.8%, respectively. Twenty-four (10.9%) patients underwent reoperations for right ventricular outflow tract obstruction in 10 patients, neoAR in four and coronary artery stenosis in three, etc. Freedom from neoAR of Grades IV, III and II at 23 years was 90.2 ± 6.6, 70.9 ± 9.6 and 20.3 ± 5.5%, respectively. The risk factors for neoAR were size discrepancy of the great arteries, aortic root dilatation after the ASO and follow-up duration after the ASO. NeoAR was significantly correlated with the size of aortic sinus and aortic sinotubular junction over time. Freedom from pulmonary stenosis (PS) of ≥ 36 and ≥ 20 mmHg at 23 years was 34.8 ± 18.0 and 17.7 ± 9.6%, respectively. The risk factors for PS were Taussig-Bing and arch anomalies. Coronary artery evaluation was performed in 95 (43.2%) patients with angiography, computed tomography or single-photon emission computed tomography, and five (5.3%) patients had abnormal coronary morphology or perfusion. Three patients underwent reoperation for coronary artery stenosis, and two had reversible perfusion defects in various regions, which were clinically not significant. Freedom from coronary events was 88.1 ± 6.4% at 22 years. A risk factor for coronary events was the single coronary artery.

The survival and functional outcomes of the ASO were excellent in the long-term. Strict serial surveillance is required to evaluate the long-term functional outcome of the ASO, particularly in a high-risk anatomy.