Mediastinitis after coronary artery bypass graft surgery. Risk factors and long-term survival.

BACKGROUND: Mediastinitis is a severe complication of coronary artery bypass graft surgery (CABG). The purpose of the present study was to determine preoperative and intraoperative variables that predict mediastinitis and to determine the impact of this complication on long-term survival.

METHODS AND RESULTS: Data on 20 preoperative and intraoperative variables were collected prospectively on 6459 consecutive patients who underwent CABG between January 1987 and January 1994. Eighty-three patients (1.3%) developed mediastinitis postoperatively, and a total of 24 patients (29%) died. Multivariate analysis identified 4 of the 20 variables as highly significant independent predictors for the development of mediastinitis: obesity (P = .0002), New York Heart Association congestive heart failure class (P = .002), previous heart surgery (P = .008), and duration of cardiopulmonary bypass (P = .05). A comprehensive review of the literature identified 13 other studies that evaluated 48 factors as predictors of mediastinitis; these data were critically analyzed and compared with the results from this series. In this series, postoperative interval mortality during the first 90 days after surgery for the patients with mediastinitis was 11.8% compared with 5.5% for the patients without mediastinitis. Interval mortality between 1 and 2 years after surgery remained high for the mediastinitis group (8.1%) relative to the nonmediastinitis group (2.3%). These differences were not eliminated by adjusting for important variables that influenced late survival in this population.

CONCLUSIONS: The present study and a review of the literature suggest that obesity and duration of surgery are the most important predictors of mediastinitis. Furthermore, although the early increase in mortality has been well described, the present study documents for the first time that mediastinitis has a significant negative influence on long-term survival independent of the patient's preoperative condition.