Overall cohort
A total of 64 patients with a deep sternal wound infection after a
previous cardiac procedure were identified during the study period.
Baseline and index operative, and operative characteristics of the DSWI
procedures are shown in Tables 1, 2, and 3 . In general, the
overall cohort was predominantly older men (mean 60 ± 12 years) who were
borderline obese (30.2 ± 7.1 kg/m2), hypertensive,
diabetic, and had coronary artery disease. Almost half were transferred
to our center from another institution for management of the DSWI after
a cardiac procedure elsewhere. The most common index cardiac procedure
was a coronary artery bypass grafting, followed by a valve repair or
replacement. DSWI after an aortic procedure or ventricular assist device
were less common in this cohort.
The median time to diagnosis of DSWI was 30 days (Interquartile Range
(IQR) 13.5 – 67 days). Positive wound cultures were documented in 54
(84%) with Gram-positive organisms being the most common. Twenty-one
(33%) patients had an attempt at medical management with antibiotics
alone, however, all eventually underwent surgical therapy as per study
design. A total of 135 operative procedures for treatment of the DSWI
were performed on these 64 patients. Surgical management was debridement
and wound therapy alone in 13 (20%), while 51 (80%) underwent flap
coverage as either a primary or secondary procedure.
Mean follow up was 34.1 ± 32.3 months. Overall survival was 93.9, 85.1,
and 80.8% at 1, 3, and 5 years respectively (Figure 1 ).
Univariate Cox proportional hazard modelling showed only a history of
hypertension was associated with overall mortality (hazard ratio (HR),
0.21, 95% confidence intervals, 0.05-0.96, p=0.44, see Supplemental
Table 1). A multivariable model of mortality with those variables with
univariate p valves <0.2 (infection diagnosed more than 30
days after index operation, male gender, history of hypertension, and
attempted medical management) showed infection diagnosed within 30 day
of index cardiac procedure and attempted initial medical management were
strongly associate with overall mortality (hazard ratios 25.0 and 9.9,
respectively), while the absence of hypertension was protective (hazard
ratio 0.10, Table 4) .