Radial Artery Versus Saphenous Vein Grafts in Coronary Artery Bypass Surgery

CSP #474 - Radial Artery vs. Saphenous Vein Grafts in Coronary Artery Bypass Surgery (Radial Artery)

VA patients with coronary artery disease and who have agreed to undergo coronary artery bypass graft surgery would be randomized to receive either radial artery or saphenous vein to the study vessel. The primary outcome variable is graft patency at one year.

Primary Hypothesis:

Radial artery grafts will have a higher graft patency rate at one year after coronary artery bypass graft surgery (CABG) compared to saphenous vein grafts.

Secondary Hypotheses:

Determine if there are any differences in clinical outcomes, cost and quality of life in patients receiving radial artery versus saphenous vein grafts.

Intervention: 1) Saphenous vein graft. This is the standard conduit for coronary artery bypass grafting to all areas of the heart except the left anterior descending (LAD) artery. 2) Radial artery. This is the experimental conduit. Preference should be given to harvesting from the non-dominant arm.

Primary Outcomes: 1-year post CABG surgery patency rates

Study Abstract:

Although the radial artery was introduced as a potential conduit for coronary artery bypass grafting in the 1970s, enthusiasm for its use was limited by the technical difficulty of harvesting the vessel and problems with perioperative vascular spasm. In spite of this, some surgeons persisted based on their belief that arterial conduits would be better than vein grafts, in terms of long-term patency. With the development of new harvesting techniques and the introduction of calcium channel blockers to prevent vasospasm, the use of the radial artery graft has increased in recent years. This use of the radial artery as a conduit is not based on any long-term prospective data regarding its patency. However, because the VA has been a leader in defining the long-term efficacy/patency of saphenous vein and internal mammary grafts, it is appropriate for the VA to investigate radial artery grafts. In fact, the VA under its Cooperative Studies Program, is probably the only health care delivery system that has the ability to undertake this study.

Study Design:

The study is a prospective, randomized, unblinded clinical trial. The population consists of VA patients with coronary artery disease documented by coronary arteriography and who have agreed to undergo coronary artery bypass surgery. Medical conditions which could affect blood flow through the patient's arm are the main exclusion criteria. These include Raynaud's symptoms, positive Allen test, neurologic or musculoskeletal disease affecting the arm and patients with one arm.

Patients who are eligible and agree to participate in the study will be randomly assigned to receive one radial artery graft or one saphenous vein graft to the following vessels: left anterior descending if internal mammary not used, circumflex, diagonal, and right coronary artery. The surgeon will determine the subject vessel preoperatively by selecting the vessel that is suitable for grafting.

The stratification factors will be the participating hospital and which vessel is to be bypassed, left anterior descending versus all other vessels.

History, physical examination, laboratory tests, and cardiac catheterization will be performed at baseline and at one year. Follow-up clinic visits will be at two weeks, three, six, and nine months post CABG. Coronary angiography will be performed one week and one year post surgery. Quality of life and hand/leg functional status will be assessed at baseline, three months, and one year. Cost measures will be captured.

Biostatistical Considerations:

For this trial, a sample size of 874 randomized patients will be required. This will provide 90% power to detect a difference in one-year patency rates of 92% for the radial artery versus 83% for the saphenous vein and an expected one-year catheter completion rate of 65%.

This is a five year study. There will be four years of patient accrual and one year of follow-up. Nine participating VA medical centers will be expected to randomize two patients per month.

Inclusion Criteria:

• Patients needing coronary artery bypass grafts.

Exclusion Criteria:

• Patients who require only a single vessel bypass and in whom the internal mammary artery will be used for that graft
• Patients with previous stripping and ligation of saphenous veins and in whom no venous conduit is available for bypass
• Patients with Raynaud's symptoms
• Patients who have a creatinine above 2.0 mg/dL or require hemodialysis
• Patients with a positive Allen test
• Patients with cardiogenic shock
• Patients who are unable to give consent
• Patients allergic to contrast material
• Patients undergoing repeat CABG or any form of robotic surgery
• Patients who do not have full use of both arms
• Patients who are pregnant
• Patients with neurologic or musculoskeletal disease affecting the arm
• Patients who refuse to participate
• Patient requires any concomitant valve operation in the mitral, aortic, or pulmonary position. Isolated tricuspid annuloplasty is acceptable, but tricuspid valve replacement excludes the patient from consideration.
• Patient requires concomitant Dor or Maze procedure
• Patient is in another research study
• No suitable radial target (there is no non-LAD vessel with a >70% stenosis)