Impact of deep sternal wound infection management with vacuum-assisted closure therapy followed by sternal osteosynthesis: a 15-year review of 23,499 sternotomies.

Objective: This study was undertaken to examine the outcome of patients with deep sternal wound infection (DSWI) now treated with vacuum-assisted closure (VAC) therapy as a bridge to sternal osteosynthesis with horizontal titanium plate fixation.

Methods: From 1992 to 2007, a consecutive cohort of 23,499 patients underwent open-heart surgery (OHS) in our institution. The period under study was divided in two according to the use of therapeutic modalities: conventional (1992-2001, N=118 DSWI): debridement/drainage with primary closure and irrigation (N=37), debridement/drainage, open packing followed by pectoralis myocutaneous flaps (PMFs) (N=81); contemporary (2002-2007, N=149 DSWI): conventional treatment (N=24) and VAC therapy (N=125/83.8%). VAC was followed by sternal osteosynthesis with horizontal titanium plates in 92 patients (61.7%).

Results: DSWI was diagnosed in 267 out of 23 499 (1.1%) patients of our entire series according to Center for Disease Control - Atlanta (CDC) criteria, 118 out of 13 180 (0.9%) in the first and 149 out of 10 319 (1.4%) in the second period (p=0.001). Hospital mortality (N=267/23,499) has been 10.25% for the entire cohort under study without any difference between groups (1992-2001: 11.4%; 2002-2007: 9.1%, p=0.67). More recently, VAC therapy (N=125) was associated with a lower mortality (4.8% vs 14.1%, p=0.01). Stepwise multivariable logistic regression analysis for both periods revealed that prolonged intubation in the intensive care unit (ICU), use of bilateral internal thoracic artery grafting (BIMA), diabetes, re-operation for bleeding and body mass index (BMI) >30 kgm(-2) are the most powerful predictors of DSWI. In the more recently treated patients using VAC therapy, combined procedures (valve and graft) also emerged as a significant predictor. For the entire study, Staphylococcus epidermidis (49.6%) has been the most frequently identified pathogen, followed by Staphylococcus aureus (38.8%). Methicillin-resistant S.aureus (MRSA) was observed in 4.9% of the cohort. Neither of these bacteria was associated with increased mortality. Survival analysis with Cox regression model and propensity score adjustment in patients with DSWI showed freedom from all-cause mortality at 1, 5 and 10 years to be, respectively, 91.8%, 80.4% and 61.3% compared with 94.0%, 85.5% and 70.2%, respectively, for patients submitted to OHS without DSWI (p=0.01). Early adjusted survival for patients with DSWI treated with VAC therapy was 92.8%, 89.8% and 88.0%, respectively, at 1, 2 and 3 years, compared with 83.0%, 76.4% and 61.3%, respectively, for patients with DSWI treated without VAC (p=0.02).

Conclusions: DSWI remains a major and challenging complication of OHS. VAC therapy with sternal preservation followed by delayed sternal osteosynthesis and PMF has been recently proposed as a new therapeutic strategy. Most patients treated with VAC therapy in our second group showed decreased perioperative mortality and increased short-term survival.