Some studies have shown an association between a prolonged intensive care unit (ICU) stay and risk factors such as mediastinal re-exploration, advanced age, low ejection fraction, lung disease and organ failure. The aim of this retrospective study was first to evaluate peri-operative risk factors (n = 2683) and secondly to evaluate long-term survival (n = 2563) in cardiac surgery patients with an ICU stay > 14 days. Long-term survival was assessed in an observational 3-year follow-up study. An ICU stay of > 14 days was associated independently with respiratory failure and dialysis-dependent acute renal failure, and with a significantly lower survival rate. Since an ICU stay is associated with a higher hospital and long-term mortality, measures should be taken throughout the entire hospital stay to identify and reduce the risk of organ failure.