Carbon Dioxide Surgical Field Flooding and Aortic No-touch Off-pump Coronary Artery Bypass Grafting to Reduce Neurological Injuries After Surgical Coronary Revascularization (CANON): a Randomised, Controlled, Investigator and Patient Blinded Single Center Superiority Trial With Three Parallel Arms.

Neurological injuries remain a major concern following coronary artery bypass grafting (CABG) that offset survival benefit of CABG over percutaneous coronary interventions. Among numerous efforts to combat this issue, is off-pump CABG (OPCABG) that obviates the need for extracorporeal circulation and is associated with improved outcomes. The objective of this study is to examine whether the neuroprotective effect of OPCABG can be further pronounced by the use of two state-of-the-art operating techniques.

In this randomised, controlled, investigator and patient blinded single center superiority trial with three parallel arms a total of 360 patients will be recruited. They will be allocated in a 1:1:1 ratio to two treatment and one control arms. Treatment arms undergoing either aortic no-touch OPCABG or OPCABG with a partial clamp applying carbon dioxide surgical field flooding will be compared against control arm undergoing OPCABG. The primary endpoint will be the appearance of new lesions on control brain magnetic resonance imaging 3 days after surgery. Secondary endpoints will include the prevalence of new focal neurological deficits in the first 7 days after surgery, the occurrence of postoperative cognitive dysfunction at either 1 week or 3 months after surgery and the incidence of delirium in the first 7 days after surgery. Data will be analysed on intention-to-treat principles and a per protocol basis.

Inclusion criteria

• elective and/or urgent coronary artery bypass

Exclusion criteria

• emergent and salvage setting
• score below age- and education-adjusted cut-off scores in mini mental state examination
• score above 8 on the subscales of hospital anxiety and depression scale
• neurologic deficit of any etiology
• previous psychiatric illness
• use of tranquilizers or antipsychotics
• alcohol or drug abuse
• history of cardiac surgery
• left ventricular ejection fraction less than 30%
• extracranial carotid artery stenosis of more than 70%
• body mass index of more than 35 kg/m2
• any contraindication for magnetic resonance imaging (e.g., magnetic resonance imaging - incompatible implantable device and claustrophobia)