Atrial fibrillation (AF) is a common and serious complication after lung resection. The incidence is likely underestimated, and risk may persist after leaving hospital. Recent development of simple wearable patch ECG devices may provide sensitive detection of AF in the extended postoperative period. Specific biomarkers may allow us to predict which patients are at risk of developing postoperative AF.

Postoperative atrial fibrillation (POAF) is a serious complication that can occur after thoracic surgery. A substantial proportion of AF is clinically silent, detectable only by ECG monitoring. Despite the lack of symptoms, it is still associated with increased risk of stroke, and may partly explain the risk of postoperative mortality after discharge from hospital.

No studies have been completed investigating the occurrence of AF in an extended period of monitoring following non-cardiac surgery, including thoracic surgery. In the limited literature on extended ECG monitoring following cardiac surgery, recurrent AF affected 24% of patients after discharge from hospital, and only 30% had symptoms. In total, 49% of patients in these studies had POAF up to two weeks after surgery.

Detection of POAF increases with more intensive monitoring. Therefore investigators believe that the incidence of POAF is underestimated, and extended monitoring using a patch ECG device will allow increased detection of clinically evident and silent POAF.

Investigators will place CardioSTAT (Icentia Inc, QC, Canada) patch ECG devices on patients immediately after thoracic surgery. They will be worn for two weeks continuously, following which they are returned by mail to the manufacturer. These devices are simple to apply and can be worn even in the shower and while exercising. Technologist interpretation is provided by the manufacturer, and will be corroborated by our study cardiologist.

Patients will also wear the patch ECG for 14 days prior to surgery. This will provide information on how many patients have silent AF at baseline, and will make it possible to determine whether AF after surgery is new or is an exacerbation of a pre-existing but unknown condition.

A total of 100 patients will allow a 95% confidence interval of 21-40% around an assumed true POAF incidence of 30%. The lower limit exceeds conventional estimates of POAF following thoracic surgery, and would provide strong support for our hypothesis.

Inclusion Criteria:

1. Adult patients, age ≥ 55 years at time of surgery, undergoing thoracic surgery with general anesthesia
2. Co-enrolment in the NT-proBNP biomarker monitoring study

Exclusion Criteria:

1. Patients with a prior history of documented AF
2. Patients with an implanted pacemaker or defibrillator
3. Patients currently taking anti-arrhythmic medication other than ß- blockers, calcium channel blockers or digoxin
4. Patients undergoing minor thoracic interventions/procedures (i.e., minor chest-wall surgeries, chest tube insertions, or needle pleural/lung biopsies)
5. Patients who are unable or unwilling to wear the CardioSTAT device as per manufacturer's guidelines, or who are unable/unwilling to return the device via mail to Icentia for procession and analysis
6. Patients with known allergy to adhesives

Adult patients who are undergoing elective thoracic surgery for non septic indications, both benign and malignant.