The goal of PREACT-AF is to learn if posterior pericardiotomy works to prevent the incidence of postoperative atrial fibrillation (POAF) in patients undergoing cardiac surgery.

The main questions it aims to answer are:

Does posterior pericardiotomy prevent the incidence of POAF for participants after cardiac surgery? What medical problems do participants have when undergoing posterior pericardiotomy?

Approximately 30% of cardiac surgical patients develop post-operative atrial fibrillation (POAF). Its incidence varies depending on the type of cardiac operation. POAF is associated with short- and long-term adverse events, including mortality, stroke, and heart failure. POAF has also been significantly associated with unplanned hospitalization for heart failure.

During cardiac surgery, pericardial fluid tends to collect posterior to the left atrium. Even small amounts of fluid may trigger atrial arrhythmias. A posterior left pericardiotomy is a surgical procedure that involves cauterizing an opening between the left inferior pulmonary vein and the diaphragm. This procedure may allow for more prolonged drainage of the pericardial fluid into the left pleural space. Recent research evidence found that posterior pericardiotomy was associated with a significantly lower incidence of POAF.

The existing data on posterior pericardiotomy is promising for a reduction in POAF. However, no high-quality study has demonstrated that this reduction improves clinical outcomes in the years after cardiac surgery. The PRINCE trial's long-term follow-up of patients randomized to left posterior pericardiotomy could conclusively demonstrate whether the relationship of POAF to post-discharge clinical outcomes is causal and modifiable.

The PRINCE trial will evaluate the effectiveness and safety of posterior left pericardiotomy in preventing POAF and improving post-discharge clinical outcomes in a broad spectrum of cardiac surgery patients.

The intervention under investigation is left posterior pericardiotomy which is compared to no posterior pericardiotomy during cardiac surgery. The early co-primary outcome is in-hospital POAF, and the late co-primary outcome is the hierarchical composite of time to all-cause death, time to ischemic stroke, time to systemic arterial embolism, time to unplanned hospital visit/readmission for cardiac reasons, and time to atrial fibrillation after index hospital discharge.

The study will enrol 1400 patients from 30 centres, globally. Follow-up visits will be performed in person or by telephone 1 and 6 months post-randomization (+7 days), and then every 6 months (+30 days) until an average follow-up of 5 years for the study participants (estimated to be 4 years after completion of enrolment).

Inclusion Criteria:

• Patients greater than or equal to 18 years of age
• Requiring surgical intervention on the proximal aorta, cardiac valves, and/or coronary arteries
• Able to provide informed consent

Exclusion Criteria:

• History of atrial fibrillation or flutter
• Cardiac surgery procedures not included in the inclusion criteria (planned ventricular assistance device, aortic arch, transplantation surgery)
• Prior cardiac surgery requiring opening of the pericardium
• Previous surgical instrumentation of the left pleural cavity
• Patient undergoing minimally invasive cardiac surgery