Comparative Outcomes of Mammary Artery Harvesting: Infection, Occlusion Rates and Thoracic Pain Assessment

The COMFORT trial is an international, multicentre, blinded, expertise-based randomized controlled trial evaluating two commonly used techniques for harvesting the left internal mammary artery (LIMA) during coronary artery bypass grafting (CABG): skeletonized and non-skeletonized (pedicled) harvesting.

Although skeletonized harvesting has been associated with reduced sternal wound complications and postoperative pain, concerns have emerged regarding its potential impact on graft patency and long-term cardiovascular outcomes. Existing evidence is largely derived from observational studies and post hoc analyses, and no adequately powered randomized trial has prospectively compared these techniques using systematic imaging-based graft assessment.

The COMFORT trial will enroll approximately 1,116 patients undergoing isolated CABG with a planned LIMA-to-LAD graft. Participants will be randomly assigned to undergo either skeletonized or non-skeletonized LIMA harvesting performed by surgeons experienced in both techniques. Participants and outcome assessors will remain blinded to treatment allocation.

Participants will undergo protocol-mandated coronary computed tomography angiography (CTA) at 1.5 years after surgery, with follow-up extending to 2 years. Independent blinded committees and a central CTA core laboratory will adjudicate imaging and clinical outcomes. In addition to graft assessment, the study will evaluate the effects of harvesting technique on cardiovascular outcomes, sternal wound complications, chronic postoperative pain, quality of life, and healthcare resource utilization.

The findings of COMFORT are expected to provide definitive evidence to guide surgical practice and inform future guidelines regarding the optimal method of internal mammary artery harvesting during CABG surgery.

• Skeletonized LIMA Harvesting (Procedure): Skeletonized (SK) harvesting of the left internal mammary artery (LIMA) to left anterior descending artery (LAD) graft: the LIMA is isolated without surrounding satellite veins, endothoracic fascia, and intercostal nerves
• Non-Skeletonized LIMA Harvesting (Procedure): Non-skeletonized (non-SK) harvesting of the LIMA-LAD graft: the LIMA is harvested with surrounding satellite veins, endothoracic fascia, and intercostal nerves (standard pedicled technique)

Primary outcomes

• Number of Participants with Graft Patency [1.5 years after surgery]: Binary assessment of LIMA-LAD graft patency versus graft failure

Secondary outcomes

• MACE [2 years after surgery]: The composite of cardiovascular mortality, myocardial infarction, or repeat revascularization
• Number of Participants with a Sternal Surgical Site Infection [90 days after surgery]: The composite of sternal surgical site infection
• Number of Participants with LIMA-LAD Driven Repeat Revascularization or Occlusion [2 years after surgery]: Any coronary revascularization procedure (PCI or CABG) targeting the LIMA-LAD graft territory, or occlusion of the LIMA-LAD graft revealed by clinically indicated coronary angiography or CTA

Sex: All, ages: 18 Years to any

Inclusion Criteria:

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

Exclusion Criteria:

1. Non-sternotomy surgical approach (e.g., minimally invasive, thoracotomy)
2. Emergency surgery (defined as surgery required within 24 hours of presentation)
3. History of prior sternotomy
4. Currently receiving systemic antibiotics or with an active bacterial infection at the time of surgery
5. History of chronic sternal pain prior to the index surgery
6. Known left subclavian artery stenosis (>50%)
7. Previous radiation therapy to the chest
8. Known allergy or contraindication to iodinated contrast media that cannot be managed with premedication
9. Estimated glomerular filtration rate (eGFR) <30 mL/min/1.73m² at baseline (relative contraindication to CTA contrast) as determined based on each centre's laboratory standard.
10. Known pregnancy or plans for pregnancy during the study period
11. Life expectancy less than 1.5 years due to non-cardiac conditions
12. Inability or unwillingness to comply with follow-up procedures including CTA at 1.5 years

• Andre Lamy, MD, Principal investigator, Population Health Research Institute