Does the timing of reoperation influence the risk of graft infection?

Objective This study compared the incidence and characteristics of graft infection in patients who underwent early vs late revisional surgery of lower extremity arterial bypass grafts. Methods Between 1992 and July 2005, 500 revisional procedures were performed on 198 lower extremity bypass grafts. Patients whose revisions were performed 30 days after bypass were in the late revision (LR) group (n = 99). Infection was defined as cellulitis with graft exposure or purulence in continuity with a graft that required antibiotics and operation for infection control. Mean follow-up was 60 months (range, 2 to 60 months). Groups were compared using Student’s t test. Results The ER group included 66 autogenous and 33 prosthetic grafts. The LR group consisted of 53 autogenous and 46 prosthetic grafts. Of the 500 revisional procedures performed, 17 graft infections occurred (3.4%). Twelve (70.6%) were prosthetic grafts and five (29.4%) were autogenous grafts ( P = .004). Defining the infection rate per graft rather than per revisional procedure, the ER group had a significantly higher graft infection rate at 11% (11/99) compared with 6.1% in the LR group (6/99; P = .012). The risk of infection for prosthetic grafts was significantly higher within the ER group at 27.3% (9/33) compared with autogenous grafts at 3.1% (2/66; P = .0001). Infection developed in three vein grafts and three prosthetic grafts in the LR group ( P = NS). For prosthetic graft revisions only, infection risk was 27.3% (9/33) in the ER group and 6.5% (3/46) in the LR group ( P = .005). The most common cultured pathogen was methicillin resistant Staphylococcus aureus (ER, 6/11 vs LR, 3/6; P = NS. Within the ER group, the prevalence of Pseudomonas aeruginosa was significantly higher at 27.3% (3/11) compared with 0% (0/6) in the LR group ( P = .04). Conclusions Early revision of lower extremity arterial bypass grafts has a significantly higher risk of graft infection compared with revision >1 month after surgery. Infection will develop in approximately 25% (9/33) of prosthetic grafts that are reoperated on early. If feasible, reoperation should be delayed >1 month for prosthetic grafts needing revision. Endovascular or extra-anatomic interventions should be considered if early revision is mandated in this group.