BACKGROUND: Today, percutaneous or surgical closure of atrial septal defects (ASD) in adults are considered effective and safe treatments. However, some cases of severe left ventricular dysfunction after ASD closure were observed. This study aims at identifying predictors for prolonged intensive care unit stay, and postoperative inotropic support after ASD closure. METHODS: Records of 281 adult patients who had undergone surgical closure of a secundum ASD between 1974 and 2000 at an age over 30 years (mean 43.8, maximum 76 years) were reviewed retrospectively. The endpoints were defined as prolonged intensive care unit stay (>2 days), and postoperative inotropic support (Dopamine, Dobutamine or Adrenalin). RESULTS: Thirty-day mortality rate was 0.7% (2 patients). Prolonged intensive care unit stay was observed in 70 patients (25%). Postoperative inotropic support was necessary in 84 patients (30%). Independent risk factors for prolonged intensive care unit stay in multivariate analysis were preoperative atrial fibrillation (p=0.011), and larger ASD (p=0.026). Older age at operation (p<0.001) and longer time on extracorporeal circulation (p<0.001) emerged as independent risk factor for postoperative use of inotropic support in multivariate analysis. CONCLUSIONS: Surgical ASD closure in adults is usually safe. However, a distinct subgroup of patients is at risk for prolonged intensive care treatment. Timely closure of the ASD must be advised since older age emerged as a predictor for postoperative use of inotropic support. Since atrial fibrillation is a strong independent risk factor for prolonged intensive care unit stay the preservation of sinus rhythm must be aimed at.