Left internal thoracic artery (LITA) has been acknowledged as the first graft of choice for coronary artery bypass grafting (CABG). However, it is still not conclusive which one is the best second graft of choice among right internal thoracic artery, radial artery, right gastroepiploic artery, saphenous vein, and etc., as well as its configuration for CABG.

In our institution, saphenous vein has been primarily used for the second graft and we have harvested it with 'No touch technique'. We have been demonstrated the excellent long-term patency of this 'No touch saphenous vein' in many studies. However, it is still unknown which configuration is the better strategy for the saphenous vein as a Y-composite graft based on the left internal thoracic artery versus an aortocoronary conduit. Thus, we aimed to evaluate morphologic change of saphenous vein graft by 1-year intravascular ultrasound (IVUS) study and angiographic patency results between Y-composite graft and aortocoronary conduit.

The enrolled patient underwent routine sternotomy, and left internal thoracic artery (LITA) and saphenous vein (SV) are harvested. After harvest, the patient is randomized to Y-composite group or aortocoronary group.

For Y-composite group, SV is anastomosed to LITA as Y-composite fashion. Then, LITA is anastomosed to left anterior descending artery. SV is anastomosed to the rest of the target vessels with sequential anastomosis technique (e.g. diagonal branch, obtuse marginal branch, posterolateral branch and posteriori descending artery).

For aortocoronary group, LITA is anastomosed to left anterior descending artery. Then, SV is anastomosed to ascending aorta using proximal anastomosis assist device without clamping the aorta. SV is anastomosed to the rest of the target vessels with sequential anastomosis technique (e.g. diagonal branch, obtuse marginal branch, posterolateral branch and posteriori descending artery).

After completion of anastomoses, residual portion of distal SV is collected for microscopic evaluation and measurement of intima-media thickness.

At the 1-year follow-up, IVUS study, in addition to coronary angiography, is performed to evaluate the morphologic changes and measure intima-media thickness of the saphenous vein graft.

Inclusion Criteria:

• A patient who is going to receive coronary artery bypass grafting
• Older than 19 years
• Coronary artery bypass grafting is going to be performed with left internal thoracic artery and saphenous vein graft

Exclusion Criteria:

• Other concomitant procedures (e.g. valve or aorta surgery) is planned
• Patients with severe comorbidities which limit the life expectancy of them below 1 year (e.g. terminal cancer)
• Patients whose left internal thoracic artery or saphenous vein is not available due to the low quality, severe injury, or absence of the graft

Individual participant data will not be shared because it is not allowed by our Institutional Review Board.