deep sternal wound infection ( dswi ) is a severe and life - threatening complication of median sternotomy after cardiac surgery , with an incidence ranging from 1% to 3%   and a mortality rate ranging from 19% to 29% . this complication is associated with prolonged hospital stay , augmented surgical load due to repeated wound revision , chest wall instability and consequent respiratory impairment , and elevated financial impact on hospital stay . although the predictive factors and risk profile of patients are well identified , the exact mechanism of dswi has not been clearly described . regarding the risk factors , there is a strong suggestion that impairment of vascular supply of the sternum may be one of the most important factors influencing the incidence of dswi , including obesity , diabetes mellitus , chronic obstructive pulmonary disease ( copd ) , connective tissue disease , steroid use , smoking , peripheral vascular disease ( pvd ) , and renal insufficiency . in addition , intraoperative factors ( e.g. , use of bilateral internal mammary arteries ) and postoperative variables ( e.g. , prolonged mechanical ventilation ; reoperation for bleeding ; postoperative transfusions ; and gastrointestinal , nephrologic , and respiratory complications ) have been shown to be associated with dswi [ 46 ] . although the risk factors and treatment modalities were well explored and described in recent reports , the long - term influence of dswi on postoperative life expectancy has seldom been addressed . in this report additionally , the natural history and evolution of history of patients with dswi after discharge from the hospital is described with a focus on major cardiovascular events . included in these analyses were a total of 4732 consecutive patients who underwent open heart surgery at university hospital lausanne , chuv , switzerland , from january 1995 to december 2005 . patients having assist device implantation , heart transplantation , recent steroid treatment , and age younger than 18 years were excluded . data from the institutional database were prospectively collected for variables such as age , sex , body mass index ( bmi ) , type of surgical intervention , urgency of operation , prior cardiac surgery , congestive cardiomyopathy , history of myocardial infarction , smoking , diabetes mellitus , hypertension , family history , preoperative ejection fraction , cancer , copd , and renal dysfunction . procedural data were also collected on the use of cardiopulmonary bypass and the number of distal anastomoses . postoperative parameters included emergency exploration due to hemodynamic instability , hospital mortality , length of stay , and major complications after surgery ( e.g. , transmural myocardial infarction , dswi sepsis , renal failure , and respiratory failure ) . follow - up ended on april 15 2011 and was performed by phone calls to the patients and referred physicians . deep sternal wound infection patients were compared in a ratio of 1 : 2 to the patients without infection ; the matching criteria were : age , sex , surgical intervention , renal impairment , copd , smoking , obesity , ejection fraction , and diabetes . matching was performed in the institutional database , in which patients are routinely registered according to preoperative co - morbidities , intervention type , and in - hospital events . deep sternal wound infection was defined according to the guidelines of the centers for disease control and diagnosis , which requires fulfillment of at least 1 of the following criteria : ( 1 ) an organism isolated from culture of mediastinal tissue or fluid ; ( 2 ) evidence of mediastinitis evident to the unaided eye ; or ( 3 ) presence of either chest pain , sternal instability , or fever ( 38c ) , and either purulent discharge from the mediastinum isolation of an organism isolated from blood culture or culture of drainage of the mediastinal area . statistical analyses were performed using spss software , version 17.0 ( spss , chicago , il , usa ) . data were tested for normality and equal distribution ( kolmogorov - smirnov test and assessment of skewness and kurtosis ) . risk factors of dswi were identified using a binary logistic regression model applied to the entire population , after stepwise selection of the variables to be entered into the model . adjusted odds ratios ( or ) and 95% confidence intervals ( ci95 ) were estimated . to control for risk factors of dswi , every patient with dswi was matched with 2 control patients without dswi , according to known risk factors of dswi , and to those identified here . balance between matched groups was checked using paired t tests for continuous variables , and mcnemar s test for categorical variables . in - hospital correlations between pre- , intra- , or postoperative variables and infection , or survival were evaluated by pearson or spearman correlation tests . differences in postoperative survival between patients with dswi and without dswi were assessed by kaplan - meier analysis , the log - rank test , and a cox regression model adjusted on parameters that were significantly correlated with survival or infection , as well as on the matching criteria mentioned above . unless otherwise specified , numerical data are presented as mean and standard deviation ( sd ) , and categorical data as group proportion ( % ) unless otherwise specified , and p < 0.05 was considered significant throughout . included in these analyses were a total of 4732 consecutive patients who underwent open heart surgery at university hospital lausanne , chuv , switzerland , from january 1995 to december 2005 . patients having assist device implantation , heart transplantation , recent steroid treatment , and age younger than 18 years were excluded . data from the institutional database were prospectively collected for variables such as age , sex , body mass index ( bmi ) , type of surgical intervention , urgency of operation , prior cardiac surgery , congestive cardiomyopathy , history of myocardial infarction , smoking , diabetes mellitus , hypertension , family history , preoperative ejection fraction , cancer , copd , and renal dysfunction . procedural data were also collected on the use of cardiopulmonary bypass and the number of distal anastomoses . postoperative parameters included emergency exploration due to hemodynamic instability , hospital mortality , length of stay , and major complications after surgery ( e.g. , transmural myocardial infarction , dswi sepsis , renal failure , and respiratory failure ) . follow - up ended on april 15 2011 and was performed by phone calls to the patients and referred physicians . deep sternal wound infection patients were compared in a ratio of 1 : 2 to the patients without infection ; the matching criteria were : age , sex , surgical intervention , renal impairment , copd , smoking , obesity , ejection fraction , and diabetes . matching was performed in the institutional database , in which patients are routinely registered according to preoperative co - morbidities , intervention type , and in - hospital events . deep sternal wound infection was defined according to the guidelines of the centers for disease control and diagnosis , which requires fulfillment of at least 1 of the following criteria : ( 1 ) an organism isolated from culture of mediastinal tissue or fluid ; ( 2 ) evidence of mediastinitis evident to the unaided eye ; or ( 3 ) presence of either chest pain , sternal instability , or fever ( 38c ) , and either purulent discharge from the mediastinum isolation of an organism isolated from blood culture or culture of drainage of the mediastinal area . statistical analyses were performed using spss software , version 17.0 ( spss , chicago , il , usa ) . data were tested for normality and equal distribution ( kolmogorov - smirnov test and assessment of skewness and kurtosis ) . risk factors of dswi were identified using a binary logistic regression model applied to the entire population , after stepwise selection of the variables to be entered into the model . adjusted odds ratios ( or ) and 95% confidence intervals ( ci95 ) were estimated . to control for risk factors of dswi , every patient with dswi was matched with 2 control patients without dswi , according to known risk factors of dswi , and to those identified here . balance between matched groups was checked using paired t tests for continuous variables , and mcnemar s test for categorical variables . in - hospital correlations between pre- , intra- , or postoperative variables and infection , or survival were evaluated by pearson or spearman correlation tests . differences in postoperative survival between patients with dswi and without dswi were assessed by kaplan - meier analysis , the log - rank test , and a cox regression model adjusted on parameters that were significantly correlated with survival or infection , as well as on the matching criteria mentioned above . unless otherwise specified , numerical data are presented as mean and standard deviation ( sd ) , and categorical data as group proportion ( % ) unless otherwise specified , and p < 0.05 was considered significant throughout . out of 4792 patients who received open heart surgery during the period between december 1995 and january 2005 , 74 patients ( 1.54% ) developed deep sternal infection ( dswi ) . matching of patients characteristics resulted in 2 groups : the dswi group ( n=74 ) compared to the control group ( n=148 ) without infection ( 1:2 match ) . significant independent predictors for the development of dswi were : active smoking ( or 2.19 , ci 1.353.53 , p=0.001 ) , obesity ( or 1.96 , ci 1.203.21 , p=0.007 ) , and insulin - dependent diabetes mellitus ( or 2.09 , ci 1.0510.06 , p=0.16 ) . the time to dswi diagnosis ranged between 3 and 36 days , with a median of 13 days . after diagnosis was established , the surgical revision was performed , including debridement of necrotic tissue and topical treatment with antiseptic solution . in the second part of the treatment , secondary closure of the open chest wound was performed in all patients : as direct closure in 54 cases ( 72.3% ) , as reconstruction with rotated rectus abdominis flap in 11 patents ( 14.8% ) , and as pectoral muscle flap in 9 cases ( 12.2% ) . lengths of interventions ( 26165 in dswi vs. 20855 min in controls ; p=0.09 ) , extracorporeal circulation time ( 11161 in dswi vs. 10569 min in controls ; p=0.74 ) , and aortic cross - clamping time ( 7642 min in dswi vs. 6735 min in controls ; p=0.17 ) were not different between the 2 groups . in - hospital mortality was significantly higher in the dswi group with 8% as compared to the control group with 2.7% ( p=0.03 ) . in the dswi group , the hospital stay was longer as compared to the control group , 35 vs. 11 days , p<0.001 ) . incidence of acute postoperative renal impairment was also higher ( 25% vs. 8% , p=0.009 ) . the frequencies of postoperative myocardial infarction , respiratory failure , and hemorrhage requiring re - intervention did not differ between patients with and without dswi ( table 2 ) . cardiac cause of death during follow - up was not significantly different between groups ( 15% in the dswi group vs. 11% in the control group , p=0.65 ) the median follow - up in the matched set was 125 months and the iqr ranged from 99 to 162 months . during follow - up , the mortality rate was 27.0% in the dswi group and 21.6% in controls ( log - rank test p value 0.57 , figure 1 ) . after adjustment on the parameters that were significantly correlated with survival or infection , as well as on the matching criteria mentioned above , the risk of death during follow - up was not related to the occurrence of dswi ( hr 1.5 , ci95 0.73.2 , p=0.33 ) . independent predictors for long - term mortality were preoperative cancer ( hr 12.1 , ci95 3.937.2 ; p<0.001 ) , surgery for heart valve in conjunction with aorto - coronary bypass ( hr 3.8 , ci95 1.69.1 ; p=0.003 ) , and preoperative chronic lung disease ( hr 2.6 , ci95 1.16.2 ; p=0.03 ) . deep sternal wound infection is one of the most serious postoperative complications after median sternotomy and it has a relatively high mortality . this has motivated numerous research groups to evaluate in detail the clinical profiles of patients with dswi as well as to explore the predictive factors that may presage this pathology . in this context , the influence of dswi on in - hospital and short - term mortality was one of the most intensively discussed subjects in the past [ 16 ] . . however , most risk factors for dswi are not amenable to modification . in order to reduce the incidence of dswi , different preventive measures were undertaken . for example , in patients with diabetes mellitus , tight control of blood sugar level reduced the incidence of dswi , and use of skeletonized mammary artery also significantly contributed to reduction of this complication . although the characteristics of dswi were well explored , long - term survival and mortality profile of the patients having dswi after hospital admission has not been sufficiently described and evaluated . to the best of our knowledge , few reports in the literature have discussed mid - term or long - term results following dswi [ 1012 ] . in the present study , a follow - up of more that 10 years was executed by phone calls to the patients and their personal physicians . incidence of dswi was 1.56% , with perioperative mortality of 8.1% ; both results are comparable to results published in the literature , in which the incidence of dswi is reported to be between 1.5% and 3% , with a perioperative mortality ranging from 15% to 30% [ 1012 ] . out of 74 patients , a cardiac cause of death was presented in 5 patients and sepsis was presented in 4 cases . in 1 case with cardiac cause of death , laceration of the right ventricle was the cause of death . in the 3 remaining cases , the total mortality was 27% in the dswi group and 21.6% in the controls ( p=0.57 ) , which actually corresponds to the long - term mortality after open heart surgery . mortality due to a cardiac event was not significantly different in the 2 groups investigated : 15% in dswi and 11% in controls . this result corresponds to the reports published in which the impact of dswi following cardiac surgery was evaluated over a period of 8 years . no further differences in 4-year and 8-year survival rate between the 2 groups were found ( 77.2% and 61.8% , respectively , in patients with dswi , as compared with 78.0% and 67.5% , respectively , in patients without dswi ) . however , we have to be aware that this statement is only true after the perioperative period passed . this can also be seen in the kaplan meier curve , where the survival between the 2 groups is parallel after the perioperative period . this means that the in - hospital period for patients is critical , with elevated mortality . if this phase is successfully survived , their life expectancy does not differ from that of patients without dswi . the in - hospital mortality was 7% , which is about 3 times higher than in the in - patient population without dswi . in the majority of cases , it was a consequence of septicemia and/or multi - organ failure . in addition to the septic events , repeated surgical revision with change of vac systems may contribute to elevated mortality . repeated surgical revisions are earmarked by repeated surgical trauma , which clearly increases perioperative stress . debridement and occasional sternal bone fractures due to infection , as well as debridement and repeated surgical manipulation with vac system , may contribute to laceration and perforation of the right ventricle . dswi is one of the most devastating complications in the postoperative period  patients suffer from a prolonged hospital stay coupled with repeated surgical interventions , which leads to increased hospital costs . the incidence has remained stable , and although different prevention measures have been proposed in the last decade , they have not lowered the prevalence of this complication . however , we believe that if prevention is impossible at this point of our knowledge , then treatment modalities may be changed to reduce the length of hospital stay , as well as reduce surgical trauma , mortality , and morbidity . however , to prove this hypothesis , further clinical trials should be conducted .