Thoracic radiation therapy and suitability of internal thoracic arteries for myocardial revascularization

Myocardial revascularization using internal thoracic arteries (ITAs) has been associated with superior clinical outcome. This study addresses the question of whether internal mammary arteries are unsuitable for grafting due to radiation-based damage in patients with history of thoracic radiation therapy. We review our experience in this subset of surgical candidates.

Forty-nine patients undergoing elective coronary artery bypass grafting with use of at least one ITA were enrolled and matched to 49 comparable nonirradiated individuals by propensity scoring system. Preoperative and postoperative data were collected and compared. A 18-month clinical follow-up was performed.

Intraoperative mammary artery flow was assessed by transthoracic Doppler echocardiography probe, and there was no significant difference between irradiated and nonirradiated individuals (36 +/- 8.3 mL/min vs 39 +/- 7.2 mL/min, p = 0.15). The two study groups were also comparable in terms of survival (overall mortality, 2%) and recurrence of angina and perfusion defect at control stress perfusion nuclear scan (p = 0.99 and p = 0.77, respectively). One arterial graft showed stenosis at postoperative angiography. The dose of radiation therapy administered did not correlate with graft flow values after anastomosis.

Our data suggest that the use of a monolateral or bilateral ITA is not associated with early graft failure in patients with history of chest/mediastinal irradiation. Skeletonization harvesting technique might be recommended because of the frequent presence of fibrous tissue around the in situ vessel. Arterial graft stenosis in thorax-irradiated patients should be attributed to the primary atherosclerotic disease rather than to irradiation itself.