Changes to study staffing and lack of coordinator support.

The goal of this observational study is to use the WHOOP device to measure heart rate variability (HRV) in patients with coronary artery disease (CAD) before and after they have CABG (coronary artery bypass graft) surgery. The main questions it aims to answer are:

• Can changes in HRV, measured by the WHOOP device, help predict how well patients with CAD will recover after CABG surgery?
• Can HRV changes during the hospital stay give doctors useful information about the patient's recovery?

Participants will:

• Wear the WHOOP device before and after their CABG surgery to measure HRV.
• Share their health information to help researchers see how changes in HRV are connected to recovery.

This study will help find out if the WHOOP device can be used as a medical tool to track recovery in patients with CAD after CABG surgery.

Inclusion Criteria:

• 20 Years or older
• Coronary Artery Disease diagnosis
• Must be scheduled for isolated Coronary Artery Bypass Surgery

Exclusion Criteria: Participants will be excluded if they have the following;

• Acute heart failure
• Acute coronary syndrome (e.g. heart attack/myocardial infarction) in the last 3 months.
• Prior history of heart transplant
• Cardiac assist device (e.g., ventricular assist device, balloon pump)
• Current pacemaker
• Congenital heart disease
• Currently admitted and undergoing treatment for cardiac issues e.g., inotropes, etc,
• Atrial fibrillation
• Frequent premature ventricular complex
• Sinus node dysfunction
• Second and third-degree atrioventricular block
• Combined cardiac surgeries
• Unable to consent.

Participants for validation will come from the general population and will be allowed to come forward to the study team to express interest. Study team members will place flyers in public areas (e.g., waiting rooms) throughout the Tufts Medical Center campus. Flyers will contain contact information of the study team as well as a QR Code to a screening form for participants to fill out if they are interested in participating.

We plan to share all collected IPD, including demographic information, clinical measurements, and outcomes data (e.g., heart rate variability, recovery progress, and post-surgery health status). This data will be available for researchers who request it, in accordance with a data-sharing agreement.