What is the patency rate of an artery to vein (arteriovenous) composite graft in coronary artery bypass grafting (CABG) for a typical adult patient with coronary artery disease?

Patency Rates of Artery-to-Vein Composite Grafts in CABG

Artery-to-vein composite grafts (where a saphenous vein is anastomosed to an arterial conduit rather than directly to the aorta) demonstrate superior patency rates compared to traditional aorta-to-vein grafts, with early postoperative patency of 100% and 1-year patency rates of 94.7-96.3%, approaching the performance of all-arterial composite grafts.

Understanding Composite Graft Configurations

Composite grafts refer to configurations where additional conduits are anastomosed to an arterial graft (typically the internal mammary artery) rather than directly to the aorta. This creates an "arteriovenous" or "artery-to-vein" composite when saphenous vein is used as the secondary conduit 1.

Key Patency Data for Composite Vein Grafts

• Early postoperative patency of saphenous vein composite grafts based on the left internal mammary artery is 100% in elderly patients undergoing off-pump CABG 1

• One-year patency of saphenous vein composite grafts is 94.7%, which is comparable to radial artery composite grafts at 97.4% 1

• Overall patency at 1 year across both arterial and venous composite configurations is 96.3% 1

Comparison with Traditional Aorta-to-Vein Grafts

The composite configuration offers substantial advantages over traditional saphenous vein grafts anastomosed directly to the aorta:

• Traditional aorta-to-vein saphenous grafts show 88% early patency, 81% at 1 year, 75% at 5 years, and only 50% at ≥15 years 2

• The occlusion rate for traditional vein grafts is 2.1% per year after the early postoperative period 2

• By comparison, 11.8% of traditional saphenous vein grafts fail within 7 days of surgery 3

Mechanisms Behind Superior Composite Graft Performance

The improved patency of composite vein grafts likely results from:

• Reduced exposure to high aortic pressure when the vein is anastomosed to an arterial conduit rather than directly to the aorta, potentially decreasing endothelial injury 4

• Elimination of aortic manipulation for proximal anastomosis, reducing risk of atheroembolism 3

• Better flow dynamics when the vein receives blood through an arterial conduit with more physiologic pressure characteristics 1

Clinical Evidence Supporting Composite Grafting

• A randomized trial in elderly patients (>70 years) demonstrated no difference in immediate postoperative morbidity and mortality between radial artery and saphenous vein composite grafts 1

• Total arterial revascularization with composite grafts (which can include vein composites) showed superior graft patency compared to conventional CABG with direct aortic anastomoses 5

• Recent evidence suggests that vein grafts used as composite grafts based on the internal mammary artery show similar mid-term patency rates to arterial grafts 4

Important Technical Considerations

For optimal composite vein graft performance:

• The composite configuration is particularly valuable when multiple grafts are needed beyond available arterial options 6

• Target vessels should have adequate stenosis severity (>70% for left-sided vessels) to prevent competitive flow that could compromise graft patency 7

• Perioperative aspirin and dipyridamole should be administered to improve early and 1-year patency 6

Critical Pitfall: Competitive Flow

• Competitive flow from other patent grafts can significantly reduce patency of arterial grafts to the LAD, with 10-year patency dropping from 100% to 81.4% when a concomitant saphenous vein graft is present in the left coronary system 8

• This competitive flow effect is particularly problematic when native coronary stenosis between anastomotic sites is <76%, where 5-year patency drops to 82.3% versus 98.6% with severe stenosis 8

• The same competitive flow principles likely apply to composite vein grafts, making appropriate target vessel selection critical 8

Comparison with All-Arterial Strategies

While composite vein grafts show excellent early-to-mid-term results:

• Bilateral internal mammary artery grafts demonstrate 95%, 91%, and 91% patency at 1,5, and 15 years respectively in patients operated on after age 12 3

• Radial artery grafts show 12.0% functional occlusion at 5 years versus 19.7% for saphenous vein grafts (P=0.03) 3

• However, the 1-year patency of 94.7% for composite vein grafts approaches that of radial artery composites at 97.4%, suggesting the composite configuration substantially improves vein graft performance 1