Risk factors for poor outcome after ECMO treatment of low cardiac output after cardiac surgery

Aims: Approximately 1% of patients require ECMO support due to refractory cardiogenic shock following cardiac surgery. Such patients are at very high risk for subsequent morbidity and mortality.

Patients: From January 2002 to June 2006, 5093 patients underwent cardiac surgery in our institution. Eighty-five patients (1.67%) requiring ECMO treatment after cardiac surgery (CABG: n=44, valve-surgery: n=14, CABG and valve-surgery: n=7, heart-transplantation: n=6, other procedures: n=14). Mean age of these patients was 68.9 years, ranging from 24.07 to 85.27 years.

Results: Average duration of ECMO support was 1.4±1.01 days with a maximum of 7 days. Hospital mortality for all ECMO patients was 68.2%. Male gender (75% vs. 53%) and body mass index over 24 (74% vs. 55%) were associated with increased mortality rates. Survival was independent of patient's age, preoperative LV-function, number and age of myocardial infarctions. Mortality rates were higher in patients undergoing reoperation (77% vs. 63%). The number of preceding operations had no influence on outcome. Operations other than bypass surgery were associated with increased mortality rates (73% vs. 83%). Neither preoperative PTCA nor stent implantation influenced outcome. Preoperatively elevated values for Bilirubin, gGT or anemia had no influence, but impaired kidney function was associated with a poor outcome (75% vs. 69% mortality rates).

Conclusions: 31.8% patients are able to be discharged from hospital after ECMO-support. Male individuals undergoing a re-operation with impaired kidney function are at highest risk not surviving the procedure.