Risk factors for aortic insufficiency and aortic valve replacement after the arterial switch operation

Objective: Long-term results after the arterial switch operation have shown that patients may develop aortic insufficiency, and that some even require aortic valve replacement. Methods: A retrospective review of 479 hospital survivors after the arterial switch operation (ASO) was performed. Echocardiographic findings were reviewed and the incidence, as well as the progression, of aortic insufficiency (AI) was investigated. The combined end point of the study was defined as the first documented occurrence of moderate or more aortic insufficiency or the need for aortic valve replacement (AVR). Results: Upon discharge from the hospital 15% of the patients showed an AI of at least grade I, progressing to 20.7% after 1 year. At a mean follow-up time of 9.3 ± 6 years, 249 patients (53%) were free from AI, trivial AI was present 179 patients (38%), mild AI in 34 patients (7.2%) and moderate AI in 7 patients (1.5%). There is a progression of AI with time after ASO (r = 0.26, p < 0.001). A total of 18 patients reached the combined end point, out of which 11 underwent an AVR at a mean time of 11.2 years after ASO. Freedom from the end point was 99.7 ± 0.3%, 97.5 ± 1%, 91.9 ± 2%, 84.6 ± 6% at 5, 10, 15 and 20 years, respectively. The following risk factors were identified by univariate analysis: Taussig-Bing anomaly (p = 0.01), ventricular septal defect (VSD) (p = 0.006), prior pulmonary artery banding (p = 0.004), age over 12 months at time of ASO (p = 0.001) and a postoperative incidence of trivial AI (p < 0.0001). Independent risk factors by multivariate analysis were the presence of a left ventricular outflow tract obstruction (p < 0.0001) and at least a trivial AI at 1 year after the ASO (p < 0.0001). Conclusion: The incidence of trivial or mild AI after the ASO is considerable and a progression over time is evident. However, severe AI and the need for AVR are rare. Patients with VSD or Taussig-Bing anomaly, and those with left ventricular outflow tract obstruction exhibit a higher risk of developing significant aortic insufficiency. Particularly patients who have developed an AI at 1 year after the ASO need to be under close observation.