Background: Pedicled bilateral internal thoracic artery grafting (BITA) has been discouraged in historical high-risk groups such as diabetes mellitus (DM), renal failure, old age, and obesity because of reported high incidence of mediastinitis. However, considering the fact that there are abundant short and long-term results including angiography study about the conventional pedicled grafts, it might be worthwhile reassessing the results of pedicled BITA grafting with modern techniques by a disciplined surgical team before abandoning the method.
Methods: Between September 1989 and September 1999, 1371 patients underwent isolated coronary artery bypass grafting (CABG) in Kumamoto central hospital. Of these patients, 558 patients who had bilateral ITA strategy (mean age 63.0+/-9.2 years, 13-79) were studied. The method of harvest of ITAs is consistently the use of conventional pedicled grafts. The use of bone wax and unnecessary electrocautery injury to the periostium or cartilage were avoided as much as possible. The only change in the surgical technique in the study period is the application of the pinpoint hemostasis for the presternal tissues from August 1997 (late period).
Results: In late period, there were significantly more patients with sternal sepsis risk factors such as diabetes mellitus (early: late; 19.3% vs. 34.8%, P<0.00003), and renal failure (0.3 vs. 9.7%, P<0.0001) as well as patients who had gastroepiploic artery grafting (16.9 vs 48.5%, P<0.0001) and those who required aortic non-touch technique (2.1 vs. 7.9%, P<0.001). The percentage of the patients receiving BITA grafting among the isolated CABG patients increased in the late period from 31.7% (331/1043) to 69.2% (227/328) (P<0.001), reflecting that a more aggressive approach towards bilateral ITA and arterial grafting has been taken in the late period. Overall operative mortality was 1.1% (n=6). Mediastinitis occurred in seven patients (1.3%). Of these, only one mediastinitis occurred in late period (0.4%). No mediastinitis occurred in 23 chronic renal dialysis patients. Among the 143 DM patients, there were three mediastinitis (2.1%). Of three, only one occurred in late period, yielding 1.3% mediastinitis rate. There was one mediastinitis (0.7%) among 134 elderly patients more than 70 years of age. Univariate analysis identified obesity as a risk factor for mediastinitis. And there was a trend of decreasing mediastinits in late period but did not reached a statistical significance (P<0.2). Multivariate analysis identified obesity and arteriosclerosis obliterates as independent risk factors. Neither diabetes mellitus, dialysis, female gender, nor old age were significant independent predictors of mediastinitis. Despite the significantly high percentage of high-risk patients in late group, there were no significant difference in mortality and morbidity between the two groups.
Conclusion: Pedicled BITA grafting is feasible with acceptable morbidity and shouldn't be abandoned even in high-risk patients such as DM, old age, and dialysis, especially combined with pinpoint-hemostasis, avoiding excessive use of bone wax, and strict aseptic technique. These point require a surgical team familiar with these techniques to maintain adequate skills in conduit procurement.