The Pilot study for the COMFORT Trial is a single centre trial to determine the feasibility of the full COMFORT Trial.

The main COMFORT Trial will be a multi-centre trial to investigate the coronary artery bypass grafting outcomes when harvesting the Left Internal Mammary Artery (LIMA) using a skeletonized approach (artery is isolated without the surrounding veins, fascia and nerves) compared to harvesting the LIMA using a non-skeletonized approach (artery is isolated with the surrounding veins, fascia and nerves). Harvesting the LIMA with the non-skeletonized approach is the standard technique. Participants will complete a Coronary Artery Tomography scan at 1 year to determine if the LIMA graft remains open. Follow up of the participants will continue until 2 years post surgery.

Prior to expansion of the COMFORT Trial to multiple centres, a pilot phase will be conducted at UOHI to evaluate the feasibility of implementing the study protocol within the local clinical and research environment.

Conducting an initial pilot phase allows the study team to assess the practical aspects of trial implementation, including patient screening and recruitment, informed consent procedures, randomization workflow, intraoperative documentation of the harvesting technique, and completion of study data collection.

The pilot phase will also allow evaluation of study logistics related to follow-up procedures, including postoperative data collection and coordination of protocol-mandated computed tomography angiography (CTA). This process will help identify and address any operational challenges prior to broader trial implementation across participating centres.

Participants enrolled during the pilot phase will undergo the same randomized study procedures described in the main COMFORT Trial protocol. Data collected during this phase may contribute to the overall COMFORT Trial dataset, subject to confirmation that the pilot procedures align with the finalized trial protocol and statistical analysis plan.

Inclusion Criteria:

• Age 18 years or older
• Undergoing isolated CABG surgery with median sternotomy and a planned LIMA-LAD graft.
• Provision of written informed consent.

Exclusion Criteria:

• Non-sternotomy surgical approach (e.g., minimally invasive, thoracotomy)
• Emergency surgery (defined as surgery required within 24 hours or presentation
• History of prior ternotomy
• Currently receiving systemic antibiotics or with an active bacterial infection at the time of surgery
• History of chronic sternal pain prior to the index surgery.
• Known left subclavian artery stenosis (>50%)
• Previous radiation therapy to the chest
• Known allergy or contraindication to iodinated contrast media that cannot be managed with premedication.
• Estimated glomerular filtration rate (eGFR) <30 ml/min/1.73m2 at baseline (relative contraindications to CTA contrast). The eGFR will be determined by each participating institution according to their standard practice.

Data collectors, Research coordinators, CTA core laboratory readers, trial statisticians.

Only the operating surgeon and operating room staff will be unblinded to the treatment.