Cardiac surgery can be not infrequently complicated by cardiac low-output syndrome due to critical preoperative conditions such as cardiogenic shock, poor left ventricular function and severe myocardial ischemia. Suboptimal myocardial protection, technical errors at graft anastomoses or of prosthesis implantation, and hibernating myocardium may further contribute to cardiac low-output syndrome occurring immediately or shortly after cardiac surgery. In this setting, veno-arterial extracorporeal oxygenation (VA-ECMO) is the only means to provide cardiopulmonary support to recovery or as bridge to transplantation.

Data on the real benefit of VA-ECMO after cardiac surgery is limited and often derived from heterogeneous patient populations, which prevent conclusive results on the benefits of VA-ECMO in this setting. This issue will be investigated in the present retrospective European multicenter study.

In this setting, veno-arterial extracorporeal oxygenation (VA-ECMO) is the only means to provide cardiopulmonary support to recovery or as bridge to transplantation.

Data on the real benefit of VA-ECMO after cardiac surgery is limited and often derived from heterogeneous populations of patients who underwent different cardiac procedures. Patients with cardiac low-output after surgery for aortic dissection or valve surgery are expected to have different baseline characteristics (such as age and comorbidities) and underlying cardiac disease than patients undergoing isolated coronary surgery. Furthermore, available studies included patients operated two decades ago and this does not provide an exact measure of the benefits of this treatment strategy.

The possible benefits of using VA-ECMO after adult cardiac surgery will be investigated in this retrospective European multicenter study.

Cardiac surgery can be not infrequently complicated by cardiac low-output syndrome due to critical preoperative conditions such as cardiogenic shock, poor left ventricular function and severe myocardial ischemia. Prolonged aortic cross-clamping, ischemia-reperfusion injury, suboptimal myocardial protection, technical errors at graft anastomoses or of prosthesis implantation, and hibernating myocardium may further contribute to cardiac low-output syndrome occurring immediately or shortly after cardiac surgery. In this setting, veno-arterial extracorporeal oxygenation (VA-ECMO) is the only means to provide cardiopulmonary support to recovery or as bridge to transplantation.

Data on the real benefit of VA-ECMO after cardiac surgery is limited and often derived from heterogeneous and small size series of patients who underwent different cardiac surgery procedures. Patients with cardiac low-output after surgery for aortic dissection or valve surgery are expected to have different baseline characteristics (such as age and comorbidities) and underlying cardiac disease than patients undergoing isolated coronary surgery. Furthermore, available studies included patients operated two decades ago and, in view of the development of perfusion technology and perioperative care, this does not provide an exact measure of the current benefits of this treatment strategy. Importantly, the role of intra-aortic balloon pump, left ventricular venting, duration of VA-ECMO and hospital experience should be evaluated. The investigators sought to investigate these issues in a large multicenter study.

Patients and methods Patients who were treated with VA-ECMO for cardiac low-output after adult cardiac surgery (other than heart transplantation and/or implantation of a left ventricular assist device) in 21 centers of cardiac surgery from January 2010 to December 2017.

Eligibility criteria

• Patients aged > 18 years;
• Patients who required VA-ECMO after elective, urgent or emergency adult cardiac surgery such as coronary surgery, heart valve surgery and/or aortic root surgery because of postoperative low-cardiac output syndrome and/or acute respiratory failure.

Exclusion criteria

• Patients aged < 18 years;
• Any VA-ECMO implanted before index surgical procedure;
• Patients who underwent postoperatively veno-venous ECMO;
• Patients who required VA-ECMO after heart transplantation;
• Patients who required VA-ECMO after any left ventricular assist device.

Definition criteria Definition criteria and units of measurements are reported beside each baseline, operative and postoperative variables in the electronic datasheet.

Outcomes

1. Hospital death
2. Late death
3. Stroke
4. Tracheostomy
5. Gastrointestinal complications
6. Deep sternal wound infection
7. Vascular access site infection
8. Blood stream infection
9. Peripheral vascular injury
10. Major lower limb amputation
11. New onset dialysis
12. Peak postoperative serum creatinine level
13. Nadir postoperative pH during VA-ECMO
14. Peak postoperative arterial lactate level
15. Nadir postoperative hemoglobin level
16. Chest drainage output 24 h after surgery
17. Number of red blood cells units transfused intra- and postoperatively
18. Reoperation for intrathoracic bleeding
19. Reoperation for peripheral cannulation-related bleeding
20. Intensive care unit length of stay
21. Death on VA-ECMO

Analysis of clinical results

The aim of this registry is to perform a number of analysis evaluating:

1. Early and late survival of postcardiotomy VA-ECMO;
2. Predictors and causes of in-hospital death after successful weaning from postcardiotomy VA-ECMO;
3. Comparative analysis of peripheral versus central postcardiotomy VA-ECMO;
4. VA-ECMO plus intra-aortic baloon pump vs. isolated VA-ECMO;
5. Determinants of outcome after prolonged postcardiotomy VA-ECMO (>5 days).

Publication of results The results of these studies will be submitted for publication to international, peer-reviewed journals in the fields of critical care, cardiology or cardiac surgery.

Inclusion Criteria:

• Patients who required VA-ECMO after elective, urgent or emergency adult cardiac surgery such as coronary surgery, heart valve surgery and/or aortic root surgery.

Exclusion Criteria:

• Any VA-ECMO implanted before index surgical procedure;
• Patients who underwent postoperatively veno-venous ECMO;
• Patients who required VA-ECMO after heart transplantation;
• Patients who required VA-ECMO after any left ventricular assist device.

Patients who required VA-ECMO for acute heart failure occurring during the index hopsitalization for elective, urgent or emergency adult cardiac surgery such as coronary surgery, heart valve surgery and/or aortic root surgery.

Upon request, the investigators will ask the Ethical Committee of the participating centers for permission to share all individual participant data included in this registry with the exception of data through which the patients could be identified.