Early and long term outcome of the arterial switch operation for transposition of the great arteries: predictors and functional evaluation.

OBJECTIVES: The aims of this report were to study the early and late outcome in terms of mortality, freedom from reoperation, predictors for late pulmonary stenosis (PAS) and insufficiency of the neo-aortic valve (AVI) in patients with transposition of the great arteries (TGA) undergoing arterial switch operation (ASO).
MATERIALS AND METHODS: Between January 1990 and December 2001, 134 patients with TGA underwent ASO. The patients were divided in Group I (n=88)-TGA with intact ventricular septum and Group II (n=46)-TGA with ventricular septal defect (VSD). The pulmonary artery was reconstructed employing the direct anastomosis technique (PT-I) in 21 (15.7%) patients, the double-patch technique (PT-II) in 41 (30.6%), single pantaloon patch (partial circumference) (PT-III) in 46 (34%) and single pantaloon patch (total circumference) (PT-IV) in 35 (26%) patients. The mean follow-up was 3.4+/-1.3 years.
RESULTS: The hospital mortality was 17 (12.7%) patients. The mortality in Group I was significantly lower than Group II (P=0.002). The overall actuarial survival at 1, 3 and 5 years follow-up resulted to be 98, 93, and 91.5%, resulting to be significantly higher in Group I (P=0.032). The multivariate analysis revealed the complex TGA (P=0.007), VSD (P=0.032), coronary anomalies (P=0.004), aortic coarctation or hypoplastic aortic arch (P=0.021), left ventricular outflow tract obstruction (LVOTO) or moderate PAS (P=0.041) as strong predictors for poor free-reoperation cumulative survival. A strong inverse correlation was found between the mean trans-pulmonary gradient at follow-up and the age at the operation (r=-0.41, P<0.0001). The univariate analysis revealed the PT-I technique (P=0.002), prior moderate PAS (P=0.0001), and age <1 month (P=0.018) as strong predictors for moderate-to-severe PAS. The neo-AVI incidence was significantly higher in Group II (P=0.011). Predictors for neo-AVI were male sex (P=0.003), preoperative neo-AV Z-score >1 (P<0.001), prior or concomitant operation for aortic coarctation or hypoplastic aortic arch (P=0.001), LV retraining (P=0.003).
CONCLUSION: ASO remains the procedure of choice for the treatment of various forms of TGA with acceptable early and later outcome in terms of overall survival and free reoperation. Strong predictors for poor overall free-reoperation survival are complex TGA, VSD, coronary anomalies, aortic coarctation and LVOTO or moderate PAS. The pulmonary artery reconstruction using a single 'pantaloon patch' seems to offer less residual stenosis. Patients with a VSD and a significant mismatch between the neo-aortic root and distal aorta are at a higher risk for developing postoperative neo-AVI.