Morbidity of the arterial switch operation

The arterial switch operation (ASO) has become a safe, reproducible surgical procedure with low mortality in experienced centers. We examined morbidity, which remains significant, particularly for complex ASO.

From 2003 to 2011, 101 consecutive patients underwent ASO, arbitrarily classified as "simple" (n=52) or "complex" (n=49). Morbidity was measured in selected complications and postoperative hospitalization. Three outcomes were analyzed: ventilation time, postextubation hospital length of stay, and a composite morbidity index, defined as ventilation time+postextubation hospital length of stay+occurrence of selected major complications. Complexity was measured with the comprehensive Aristotle score.

The operative mortality was zero. Twenty-five major complications occurred in 23 patients: 6 of 25 (12%) in simple ASO and 19 of 49 (39%) in complex ASO (p=0.002). The most frequent complication was unplanned reoperation (15 vs 6, p=0.03). No patients required permanent pacing. The complex group had a significantly higher morbidity index and longer ventilation time and postextubation hospital length of stay. In multivariate analysis, factors independently predicting higher morbidity were the comprehensive Aristotle score, arch repair, bypass time, and malaligned commissures. Myocardial infarction caused one sudden late death at 3 months. Late coronary failure was 2%. Overall survival was 99% at a mean follow-up of 49±27 months.

In this consecutive series without operative mortality, morbidity was significantly higher in complex ASO. The only anatomic incremental risk factors for morbidity were aortic arch repair and malaligned commissures, but not primary diagnosis, weight less than 2.5 kg, or coronary patterns.