Evaluation of risk factors for hospital mortality and current treatment for poststernotomy mediastinitis

Purpose: Poststernotomy mediastinitis (PSM) following cardiovascular surgery remains an intractable complication associated with considerable mortality. It is therefore necessary to assess the risk factors associated with hospital mortality and evaluate the surgical treatment options for PSM. Methods: We identified 59 (2.2%) patients who developed PSM after cardiovascular surgery between January 1991 and January 2010. PSM was defined as deep sternal wound infection requiring surgical treatment. In all, 31 patients were infected with methicillin-resistant Staphylococcus aureus (MRSA); and 14 patients died in hospital from PSM. A total of 51 patients were treated by simple closure or tissue flap reconstruction after débridement (traditional treatment), and 8 underwent closure or reconstruction after negative-pressure wound therapy (NPWT). The risk factors for in-hospital mortality due to PSM were analyzed by comparing the characteristics of survivors and nonsurvivors. The available surgical treatments for mediastinitis were also assessed. Results: Univariate analysis identified age, sex, pulmonary disease, MRSA infection, prolonged mechanical ventilation and prolonged intensive care unit stay as risk factors for in-hospital mortality (P < 0.05). Multiple logistic regression analysis identified MRSA infection (odds ratio 20.263, 95% confidence interval 1.580-259.814; P = 0.0208) as an independent risk factor for hospital mortality. NPWT was associated with significantly less surgical failure than traditional treatment (P = 0.0204). There were no deaths as a result of PSM in patients who underwent NPWT irrespective of the presence of MRSA infection. Conclusion: MRSA infection was an independent risk factor for PSM-related in-hospital mortality. NPWT may improve the prognosis for patients with MRSA mediastinitis. © 2011 The Japanese Association for Thoracic Surgery.