This is a multi-centre, prospective cohort study to determine if asymptomatic PFO is a risk factor for developing perioperative overt and covert stroke in patients undergoing non-cardiac surgery.

There is emerging evidence regarding the increased risk of perioperative stroke in patients with PFO, leading to an important clinical practice question: whether PFO should be considered in the perioperative risk assessment in non-cardiac surgery patients. The evidence base, however, comes from retrospective studies with numerous limitations.

Patients referred for general, orthopedic, urological, gynecologic, spinal, or thoracic surgery will be screened and consented during the surgery pre-admission clinic visit, and then undergo PFO screening using transcranial Doppler (TCD) and transthoracic echocardiography (TTE). Patients screened PFO+ (n=102) and matched PFO- controls (n=102) will have DW-MRI between postoperative days 2 and 7. Study personnel will conduct phone surveys at 30-day and 1-year post-surgery to collect data on other clinical outcomes. Patients will also be administered cognitive and patient-reported outcome measures assessments before enrollment, and 30-day and 1-year follow-up.

Inclusion Criteria:

1. patients 18 years and above;
2. referred for an elective, non-cardiac, non-vascular and non-brain surgery;
3. with an estimated hospital length of stay ≥2 days. We will include patients referred for general, orthopedic, urological, gynecologic, spinal or thoracic surgery.

Exclusion Criteria:

1. patients in need for long-term, perioperative anticoagulants;
2. those with comorbidities that potentially increase the risk of perioperative stroke;
3. contraindications to MRI;
4. unable to complete or adhere to the study.

Adult patients referred for an elective, non-cardiac, non-vascular and non-brain surgery