Arterial Grafts and Competitive Flow in CABG

Mechanism of Graft Failure

Arterial grafts, including LIMA, are more prone to closure from competitive flow because they are muscular conduits that respond to low-flow states with vasospasm and eventual atrophy, as noted by the American Heart Association 1, 2
The American College of Cardiology recommends that arterial grafts should not be used to bypass vessels with less than critical stenosis (<90% for right coronary artery) specifically because of competitive flow-related failure 1, 2

The American College of Cardiology and American Heart Association guidelines explicitly state that radial artery grafts should target vessels with "subocclusive stenoses" 4
Arterial grafting of the right coronary artery is only reasonable when critical (>90%) stenosis is present, with a Class IIb recommendation 1, 2
Using an arterial graft to bypass the right coronary artery with less than critical stenosis (<90%) is classified as Class III: HARM 1, 2

Never use arterial grafts (including LIMA) to bypass vessels without adequate stenosis severity, as competitive flow will promote graft failure, as advised by the American Heart Association 1, 2
Ensure target vessels have appropriate stenosis: LAD and left-sided vessels should have ≥70% stenosis; right coronary artery should have ≥90% stenosis for arterial grafting 1, 2, 4

Reassess target vessel stenosis severity before selecting arterial conduit, as recommended by the American College of Cardiology 1, 2, 4
If stenosis is <70% for left-sided vessels or <90% for right coronary artery, strongly consider SVG over arterial graft, according to the American Heart Association 1, 2
For patients with limited life expectancy where long-term patency is less critical, SVG is appropriate even for more severe stenoses, as noted by the American College of Cardiology 3