Background Revascularization of complex coronary artery disease, including multivessel coronary artery disease, left main stenosis, bifurcation stenosis and chronic total occlusions (CTO) can be performed by Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Graft (CABG), according to current guidelines.[1] In order to decide whether to revascularize by either CABG or PCI, patient characteristics, the presence of comorbidities, including diabetes, and coronary lesion complexity (e.g. SYNTAX) should be taken into consideration. Because of the ageing population with a higher incidence of comorbidities and higher surgical risk scores, high-risk PCI in complex coronary disease with high risk for periprocedural cardiogenic shock is increasingly performed.[2, 3] Mechanical Circulatory Support (MCS) devices for elective high-risk PCI can provide hemodynamic support, preventing hemodynamic failure during PCI. Several studies are performed using Intra-Aortic Balloon Pump (IABP) and co-axial left cardiac support device (Impella device (Abiomed, Danvers, USA)), showing no clear benefits in patients with high-risk PCI.[4-6] Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO) is a recent addition to mechanical support options, providing more extensive hemodynamic support in patients with potential or ongoing failure of circulation. This concept is already demonstrated in the setting of Extracorporeal Cardiopulmonary Resuscitation (ECPR).[7, 8] ECMO has the additional benefits of right ventricular unloading and blood oxygenation as opposed to IABP and Impella.[9] Our experience with fully percutaneous VA-ECMO in cardiogenic shock and for ECPR combined with the experience for Transcatheter Aortic Valve Replacement (TAVR) with local anaesthesia and mild sedation resulted in the selection of VA-ECMO as our preferred method in high risk PCI. Studies investigating the use of VA-ECMO support during high-risk PCI are however limited.[10-13]

Objective The aim of this study is to provide additional data concerning the short-term outcomes of elective high-risk PCI with VA-ECMO in a single PCI centre.

Methods Design We will perform a single-centre, retrospective registry, using data collected from medical records of included patients.

Inclusion criteria

• Patients older than 18 years, who underwent high-risk PCI with VA-ECMO support.
• The use of mechanical circulatory support (MCS) is indicated by HeartTeam based on patient and lesion characteristics described in the expert consensus on the use of MCS Devices for high-risk PCI. [14]

Exclusion criteria

• Non-elective PCI with VA-ECMO support, primarily applied for cardiogenic shock or ECPR.

Study Procedures All patients older than 18 years who underwent high-risk PCI with VA-ECMO support will be included in the registry. Baseline patient and angiographic characteristics, ECMO characteristics and short-term outcomes, described in the paragraph 'Study Endpoints and Definitions' will be collected from medical records.

The Dutch Act on Medical Research involving Human Subjects (WMO) does not apply to this study, because of the retrospective design of the study using only medical records and consequently patients are not subjected to additional procedures. Therefore, no written informed consent will be obtained from patients or legal representatives as well.

Data Collection All data will be collected in a cloud-based electronic case report form (eCRF, Castor Electronic Data Capture), which will be developed and managed by investigators in the Radboudumc. Only members of the study team will have access to the patient eCRFs and will be allowed to enter data in the system. The study team exists of the investigators mentioned earlier. The study team will collect the data from medical records and enter the data in Castor. All patient data will be encoded. Only the investigators involved will have access to the patient identification key.

Study Endpoints and Definitions Successful revascularization is defined as final residual stenosis <50% with a TIMI flow grade 3, achieved in at least one of the target vessels. Procedural success is defined as angiographic success without the occurrence of peri-procedural MACE, including death and myocardial infarction (MI). Additionally, MACE will be assessed during hospital stay and within 60-days follow-up after discharge and defined as a composite of death, MI, Target Vessel Revascularization (TVR) by PCI or CABG and clinical bleeding, assessed by the Bleeding Academic Research Consortium (BARC) scale. Bleeding complications of type 2 and higher are included.

Inclusion Criteria:

• Patients older than 18 years, who underwent high-risk PCI with VA-ECMO support.
• The use of mechanical circulatory support (MCS) is indicated by HeartTeam based on patient and lesion characteristics described in the expert consensus on the use of MCS Devices for high-risk PCI.

Exclusion Criteria:

- Non-elective PCI with VA-ECMO support, primarily applied for cardiogenic shock or ECPR.

All patients older than 18 years who are undergoing a high-risk PCI with VA-ECMO support, indicated by HeartTeam consensus based on patient and lesion characteristics, as described by the expert consensus. If a non-elective PCI with VA-ECMO support, primarily applied for cardiogenic shock or ECPR, is performed, patients are not eligible for inclusion.

Upon request, data supporting the findings and conclusion of this study will be made available by the PI.