Quality of internal thoracic artery grafts after mediastinal irradiation.

Background: With the increase of patients of advanced age requiring coronary artery bypass grafting (CABG), the number of those with previous mastectomy and irradiation of the chest increases proportionally. The question of whether mediastinal irradiation leads to relevant internal thoracic artery (ITA) graft damage remains unclear. The aim of the present study was to proof the quality of ITAs and to evaluate the early clinical outcome after using one or both ITAs in this specific population.
Methods: One hundred twenty-five patients (group A) with previous mastectomy or Hodgkin/non-Hodgkin disease and mediastinal irradiation operated on between January 1993 and September 2006 underwent CABG (n = 88) or CABG plus valve replacement (n = 37). Sixty-two patients received bilateral, 43 received unilateral ITAs, and 20 patients received veins. Postoperative complications and mortality were analyzed and compared with a propensity score pair-matched control group of 125 patients receiving CABG or CABG plus valve replacement within the same period (group B). A histomorphologic investigation was performed in 133 irradiated distal ITA segments and compared with a control group of 133 nonirradiated ITAs.
Results: Thirty-day mortality revealed 3.2% in group A versus 5.6% in group B. Sternal instabilities were more frequent in group A (3.2%) than in group B (0%). Mediastinitis occurred in 1.6% (group A) versus 1.6% (group B). Histomorphologic investigations did not identify any severe irradiation induced fibrosis or damage of ITA grafts.
Conclusions: From the histologic point of view, there is no need for restrictions in use of ITA conduits after mediastinal irradiation. Compared with a control group, cardiac surgery was associated with a slightly enhanced incidence of sternal instabilities.