Risk factors for sternal wound infection and mid-term survival following coronary artery bypass surgery.

OBJECTIVE: To identify risk factors for sternal wound infection following coronary artery bypass surgery (CABG), and to compare early and mid-term survival outcome. METHODS: Data were prospectively collected for 4228 patients who underwent CABG surgery between April 1997 and March 2001. One hundred and nine (2.6%) patients developed sternal wound infection. We used logistic regression to identify independent risk factors associated with post-operative sternal wound infection. Patient records were linked to the National Strategic Tracing Service, which records all deaths in the UK, to establish current vital status. Deaths occurring over time were described using Kaplan-Meier techniques. To control for differences in patient characteristics, we used Cox proportional hazards analysis to calculate adjusted hazard ratios (HR) and 95% confidence intervals (CI). RESULTS: The results of the logistic regression analysis found that the independent predictors of sternal wound infection were obesity (odds ratio (OR) 2.0; P<0.001), New York Heart Association class >/=3 (OR 1.6; P=0.022), use of bilateral internal mammary arteries (OR 3.2; P<0.001), increasing number of grafts (OR 1.5; P<0.001), re-exploration for bleeding (OR 3.1; P=0.011), and increased duration of mechanical ventilation (for every 10 h (OR 1.12; P<0.001)). Three hundred and forty one (8.1%) deaths occurred during the study period with mean follow up of 3.2+/-1.3 years. The crude HR of mid-term mortality for sternal wound infection patients was 2.51 (95% CI 1.59-3.94, P<0.001). After adjustment for pre, intra and post-operative factors, the adjusted HR of mid-term mortality for sternal wound infection patients was 1.64 (95% CI 1.03-2.61, P=0.037). The adjusted freedom from death for sternal wound infections at 30 days, and 1, 2 and 4 years was 96.8, 93.7, 91.4 and 86.7%, respectively, compared with 98.1, 96.1, 94.7 and 91.7% for patients without sternal wound infections. CONCLUSIONS: In conclusion, we have identified risk factors for sternal wound infection, many of which are modifiable. We have also shown that there is a significant increase in mortality in patients with sternal wound infection during a 4-year follow-up period after CABG.

Do beating heart techniques applied to combined valve and graft operations reduce myocardial damage?

We examined the outcomes of combined beating heart CABG and valve surgery (hybrid) and compared these to conventional CABG and valve surgery (conventional). Between April 1997 and March 2006, 388 patients received combined CABG and valve surgery. Patient characteristics and cardiac enzyme release were collected prospectively. To account for differences in case-mix we used logistic regression to develop a propensity score for hybrid group membership and then performed a propensity-matched analysis. One hundred and forty patients underwent hybrid operation with a mean logistic EuroSCORE of 13.5%, compared to 248 who underwent conventional operation with a mean logistic EuroSCORE of 10.9% (P=0.006). Eighty-two patients from each group were successfully matched. The mean logistic EuroSCORE after matching was similar between the groups (11.3% vs. 12.9%; P=0.48). The median number of grafts per patient was also similar, three in each group (P=0.98). Post-op CK-MB levels were found to be significantly lower for hybrid patients (44 U/I vs. 29.5 U/I; P=0.037). In-hospital mortality was not statistically different (9.8% vs. 6.1%; P=0.39). Survival at 5 years was 74% for hybrid and 71% for conventional group (P=0.92). CK-MB levels in patients receiving hybrid CABG and valve surgery are reduced compared to conventional CABG and valve surgery.

On-pump versus off-pump surgical revascularization for left main stem stenosis: risk adjusted outcomes.

BACKGROUND: Recent publications have shown coronary surgery is safe and effective in patients with critical left main stem stenosis when using off-pump coronary surgery techniques. However, these studies were small and did not adjust for differences in case mix. METHODS: Between April 1997 and March 2003, 1,197 consecutive patients with critical left main stem stenosis (> 50%) underwent coronary surgery. Two hundred and fifty-nine (21.6%) of these patients had off-pump coronary surgery, while 938 (78.4%) received on-pump coronary surgery. Multivariate logistic regression and Cox proportional hazards analysis were used to assess the effect of off-pump coronary surgery on outcomes, while adjusting for patient characteristics (treatment selection bias). Treatment selection bias was controlled by constructing a propensity score from core patient characteristics. The propensity score was the probability of receiving off-pump coronary surgery and was included along with the comparison variable in the multivariable analyses of outcome. RESULTS: After adjusting for the propensity score, the requirement for inotropic support (22.4% versus 35.3%; p < 0.001) or a prolonged length of stay (5.3% versus 9.3%; p = 0.034) were significantly reduced after receiving off-pump coronary surgery. There was a trend to suggest that off-pump patients had a lower incidence of stroke and chest infection. The adjusted freedom from death in off-pump patients at 2 years was 94.6% compared with 93.6% for on-pump patients (p = 0.54). CONCLUSIONS: After risk adjustment, patients with critical left main stem stenosis can undergo off-pump coronary surgery safely, with results comparable with on-pump coronary surgery.