Conduit choice for coronary artery bypass grafting after mediastinal radiation

Patients who have undergone prior mediastinal radiation might require coronary artery bypass grafting. However, there is some concern regarding potential radiation damage to the internal thoracic artery. Our objective was to assess the late patency of the internal thoracic artery and venous grafts in patients with prior mediastinal radiation.

Patients undergoing coronary artery bypass grafting at our clinic after prior mediastinal radiation were identified, and medical records, including operative reports, clinical notes, and coronary angiography, were reviewed.

Between 1985 and 2005, 138 patients had coronary artery bypass grafting after mediastinal radiation. Of these, 25 underwent clinically indicated postoperative angiography. The mean patient age was 56.1 +/- 13.8 years, and 24% were female. All patients received between 3000 and 6000 rads in fractionated doses. Seventy-two percent of patients had 3-vessel coronary artery disease. At late angiography (mean, 2.2 years), 6 (32%) of 19 internal thoracic arteries and 13 (27%) of 48 venous or radial arterial conduits showed stenosis of 70% or greater (P = .72). Assessing only grafts that were anastomosed to the left anterior descending coronary artery, 35% (6 of 17) of internal thoracic artery grafts and 60% (3 of 5) of non-internal thoracic artery grafts showed narrowing of 70% or greater (P = .61). Among patients who received a graft to the left anterior descending coronary artery (n = 113), however, age-adjusted survival at 5 years was superior among those receiving an internal thoracic artery graft to the left anterior descending coronary artery.

Internal thoracic artery graft patency among patients with prior radiation was less than expected and similar to that for venous grafts, although the effect of conduit disease versus distal target vessel runoff is unknown. Despite this, late survival was superior among those receiving an internal thoracic artery graft to the left anterior descending coronary artery. These data support use of an internal thoracic artery graft to the left anterior descending coronary artery when it appears grossly to be an acceptable conduit.