External validity of the Society of Thoracic Surgeons risk stratification tool for deep sternal wound infection after cardiac surgery in a UK population.

OBJECTIVES: Deep sternal wound infection (DSWI) is a devastating complication of cardiac surgery, with a historical incidence of 0.4-5%. Predicting which patients are at higher risk of infection may help instituting various preventive measures. Risk calculations for mortality have been used as surrogates to estimate the risk of deep sternal wound infection, with limited success. The Society of Thoracic Surgeons (STS) 2008 Risk Calculator modelled the risk of DSWI for cardiac surgical patients, but it has not been validated since its publication. We sought to assess the external validity of the STS-estimated risk of DSWI in a United Kingdom (UK) population. METHODS: Using our prospectively captured database, we retrospectively calculated the risk of DSWI for 14 036 patients undergoing valve, coronary artery bypass grafts or combined procedures between February 2001 and March 2010. DSWI was identified according to the Centre for Disease Control and Prevention definition. The receiver operator characteristic (ROC) curve was employed to test the performance of the model using the area under the ROC curve (AUROC). The calibration of the model was interrogated using the Hosmer-Lemeshow test for Goodness of Fit. RESULTS: A total of 135 (0.95%) patients developed DSWI. Although there was a statistically significant difference in the calculated risk of patients who contracted DSWI (0.44% ± 0.01) vs those who did not (0.28% ± 0.00, P < 0.0001), the AUROC of 0.699 (95% confidence interval: 0.6522-0.7414) denoted a modest discriminatory power, with the Hosmer-Lemeshow Goodness of Fit statistic (P < 0.001) suggesting poor calibration. A risk-adjusted modifier improved the calibration (P = 0.08). CONCLUSIONS: The STS risk calculator lacks adequate discriminatory power for estimating the isolated risk of developing deep sternal wound infection in a UK population. The discrimination is similar to the tool's validation c-statistic and may have a place in an integrated calculator.

Comparison of the EuroSCORE II and Society of Thoracic Surgeons 2008 risk tools.

OBJECTIVES: Risk stratification in cardiac surgery is uniquely detailed, led latterly by the EuroSCORE and the Society of Thoracic Surgeons (STS) risk calculators. The recently published EuroSCORE II (ES2) algorithms update estimated mortality in a broad spectrum of cardiac procedures. The 2008 STS tool, in comparison, predicts multiple outcomes for specific procedures. We sought to identify and compare the external validity of both contemporaneous tools in our population. METHODS: Data from our hospital database were collated for the period February 2001 to March 2010. Logistic regression coefficients from the risk calculations were applied to the data and the results presented as receiver-operating characteristic (ROC) curves. Statistical analyses were performed using the area under the ROC curve (AUROC) and the Hosmer-Lemeshow (H-L) goodness-of-fit test, with comparisons using the DeLong method. RESULTS: A total of 15 497 procedures were identified, of which 14 432 were appropriate for STS risk scoring (i.e. valve and/or graft procedures with no tricuspid valve operations etc.). For all procedures, ES2 and STS were equivalent (AUROC 0.818 vs 0.805, respectively, P = 0.343). For procedures appropriate for STS risk scoring, results were similar (AUROC ES2 vs STS, 0.816 vs 0.810, P = 0.714), whereas for procedures excluded by STS, the result was marginally worse (AUROC ES2 vs STS, 0.773 vs 0.784, P = 0.751). Goodness of fit in all cases was poor, primarily where risk was higher than 15% (H-L P < 0.0001). CONCLUSIONS: EuroSCORE II and STS both provide equivalent discrimination in predicting mortality in a British population, including those undergoing procedures for which the STS does not normally predict. Accounting for decile-grouped Hosmer-Lemeshow tests not being ideal for the assessment of calibration, both tools show good calibration for patients with low to moderate risk, with divergence from ~15% predicted risk.

Validation of EuroSCORE II in a modern cohort of patients undergoing cardiac surgery.

OBJECTIVE: We aimed to validate the new EuroSCORE II risk model in a contemporary cardiac surgery practice in the United Kingdom (UK). METHODS: The original logistic EuroSCORE was compared to EuroSCORE II with regard to accuracy of predicting in-hospital mortality. Analysis was performed on isolated coronary artery bypass grafts (CABG; n = 2913), aortic valve replacement (AVR; n = 814), mitral valve surgery (MVR; n = 340), combined AVR and CABG (n = 517), aortic (n = 350) and miscellaneous procedures (n = 642), and the above cases combined (n = 5576). RESULTS: In a single-institution experience, EuroSCORE II is a reasonable risk model for in-hospital mortality from isolated CABG (C-statistic 0.79, Hosmer-Lemeshow P = 0.052) and aortic procedures (C-statistic 0.81, Hosmer-Lemeshow P = 0.43), and excellent for mitral valve surgery (C-statistic 0.87, Hosmer-Lemeshow P = 0.6). EuroSCORE II is better than the original EuroSCORE, using contemporaneous data for combined AVR and CABG operations (C-statistic 0.74, Hosmer-Lemeshow P = 0.38). However, EuroSCORE II failed to improve on the original EuroSCORE model for isolated AVR (C-statistic 0.69, Hosmer-Lemeshow P = 0.07) and miscellaneous procedures (C-statistic 0.70, Hosmer-Lemeshow P = 0.99). EuroSCORE II has better calibration than the original EuroSCORE or the Society of Cardiothoracic Surgeons of Great Britain and Ireland (SCTS) modified EuroSCORE for cumulative sum survival (CUSUM) curves. CONCLUSIONS: EuroSCORE II improves on the original logistic EuroSCORE, though mainly for combined AVR and CABG cases. Concerns still exist, however, over its use for isolated AVR procedures, aortic surgery and miscellaneous procedures. There is still room for improvement in risk modelling.

Choice of conduit for coronary artery bypass grafting in poor ventricles.

BACKGROUND: advantages in the use of arterial grafts for coronary artery revascularizations have been reported previously. OBJECTIVES: we aimed to compare the outcome and survival rates of different conduits in patients with poor ventricular function (ejection fraction<30%). METHODS: in a 10-year period, 979 patients with an ejection fraction<30%, who underwent isolated first-time coronary artery bypass grafting, were divided into in 3 groups: (A) total arterial grafts (n=257), (B) total vein grafts (n=76), and (C) left internal mammary artery and vein grafts (n=610). Multivariate logistic regression was used to assess the effect of graft type on mortality, while adjusting for patient and disease characteristics. Hospital mortality and 5-year survival rates were compared among the groups. RESULTS: hospital mortality was 8.9% for group A, 11.8% for group B, and 5.7% for group C. Mortality at 5 years was 27.2% for group A, 42.3% for group B, and 28.7% for group C. After risk adjustment, hospital mortality and mid- and long-term mortality showed no significant differences among the groups. CONCLUSIONS: patients with poor ventricular function have a high mortality rate in both the short- and long-term with any type of conduit. Mortality rates with total arterial grafts and vein plus arterial grafts were comparable before and after risk adjustment.

Outcomes and predictors of prolonged ventilation in patients undergoing elective coronary surgery.

OBJECTIVES Despite the seriousness of prolonged mechanical ventilation (PMV) as a postoperative complication, previously proposed risk prediction models were met with limited success. The purpose of this study was to identify perioperative variables associated with PMV in elective primary coronary bypass surgery. PMV was defined as the need for intubation and mechanical ventilation for >72 h, after completion of the operation. METHODS Between April 1997 and September 2010, 10 ,977 consecutive patients were retrospectively reviewed. A series of two multivariate logistic regression analyses were carried out to identify preoperative predictors of prolonged ventilation and the impact of operative variables. RESULTS PMV occurred in 215 (1.96%) patients; 119 (55.3%) of these underwent tracheostomy. At multivariate analysis, predictors included NYHA higher than class II (odds ratio [OR], 1.77; 95% confidence intervals [CI], 1.34-2.34), renal dialysis (OR, 5.5; 95% CI, 2.08-14.65), age at operation (OR, 1.04; 95% CI, 1.02-1.06), reduced FEV(1) (OR, 0.99; 95% CI, 0.98-0.99), body mass index >35 kg/m(2) (OR, 1.73; 95% CI, 1.14-2.63). On serial logistic regression analyses, operative variables added little to the discriminatory power of the model. Kaplan-Meier survival curves showed reduced survival among PMV patients (P < 0.001) with an improved survival in the tracheostomy subgroup. CONCLUSIONS PMV after coronary bypass is associated with a reduction in early and mid-term survival. Risk modelling for PMV remains problematic even when examining a more homogenous lower risk group.

Sampling time error in EuroSCORE II.

Seasonal variation in mortality after cardiac surgery exists. EuroSCORE II accrued data over a 12-week period from May to July 2010. We investigated whether the accrual period for EuroSCORE II had a different mortality rate compared with the rest of the year. We found in a study population of 18,706 that the accrual period of EuroSCORE II may introduce bias into the predicted mortality, potentially reducing the accuracy of the new model.

Impact of chronic obstructive pulmonary disease severity on surgical outcomes in patients undergoing non-emergent coronary artery bypass grafting.

OBJECTIVES: Although the association between chronic obstructive pulmonary disease (COPD) and adverse surgical outcomes has been previously demonstrated, the impact of COPD severity on postoperative mortality and morbidity remains unclear. Our objective was to analyse the prognostic implication of COPD stages as defined by the Global Initiative for Chronic Obstructive Lung Disease. METHODS: Between September 1997 and April 2010, 13,638 patients undergoing first time isolated CABG were retrospectively reviewed, of whom 2421 patients were excluded due to lack of spirometry records or restrictive pattern on spirometry. The remaining 11,217 patients were divided into three groups: group 1 (including patients with normal spirometry and patients with mild COPD (FEV1/FVC ratio<70%, FEV1≥80% predicted), group 2 (moderate COPD: FEV1/FVC ratio<70%, 50%≤FEV1<80% predicted) and group 3 (severe COPD: FEV1/FVC ratio<70%, FEV1<50% predicted). Logistic regression was used to examine the effect of COPD severity on early mortality and morbidity, after adjusting for differences in patient characteristics. RESULTS: Early mortality in the three groups was 1.4, 2.9 and 5.7% respectively (P<0.001). Similarly, a consistent trend of increasing frequency of postoperative complications with advanced COPD stage was noted. On multivariate analysis, severe COPD was found to be significantly associated with early mortality [adjusted OR, 2.31 (95% CI) (1.23-4.36)], P=0.01. CONCLUSIONS: The severity of COPD as defined by spirometry can be a prognostic marker in patients undergoing CABG. Spirometric criteria may help refining currently used operative risk scores.

Does the outcome improve after radiofrequency ablation for atrial fibrillation in patients undergoing cardiac surgery? A propensity-matched comparison.

OBJECTIVES: Preoperative atrial fibrillation (AF) significantly reduces the survival rate post cardiac surgery. It has been shown that patients in persistent or paroxysmal AF have higher mid- and long-term mortality post cardiac surgery compared with those in sinus rhythm. In this study we aimed to assess whether radiofrequency (RF) ablation during cardiac surgery in these patients improves the survival. METHODS: For a period of 5 years (2005-10), we studied all the patients who underwent ablation for AF during cardiac surgery for persistent/paroxysmal AF in our institution. We used RF ablation on 113 patients who had AF for <5 years and where the atrial dimension measured <5.5 cm. A 1:2 propensity matching was performed to adjust for the preoperative and operative characteristics with a group in persistent/paroxysmal AF, who had cardiac surgery during the same period of time (2005-10) and did not undergo ablation. We compared the postoperative outcome and survival rates between the two groups. RESULTS: Before and after adjusting for the preoperative and operative characteristics, inotropic support, renal failure, stroke, intensive care unit and hospital stay, as well as in-hospital mortality were similar between the two groups. After 5 years the difference in the survival was significant between the groups; 91.1 and 83.2%, with and without ablation, respectively (P value = 0.038). CONCLUSIONS: Despite, the similar postoperative outcome with or without ablation in persistent/paroxysmal AF, 5-year survival was found to be significantly higher with the ablation during cardiac surgery. This improvement can be due to the fall in the incidence of cerebro-vascular events or bleeding with AF or warfarin. Ablation during cardiac surgery is a simple and quick procedure and should be considered if indicated.

Long-term survival after coronary artery bypass surgery stratified by EuroSCORE.

OBJECTIVES: Coronary artery bypass grafting (CABG) is performed for symptoms and for prognostic reasons. The EuroSCORE is widely utilized as a pre-operative risk prediction tool. We evaluated our long-term survival figures based on EuroSCORE. METHODS: A prospective database was retrospectively analysed and cross correlated with the UK strategic tracking service to evaluate survival after primary CABG. Patients were grouped based on their logistic EuroSCORE 0 to <5, 5 to <10, 10 to <15, 15 to <20, 20 to <25 and ≥25. RESULTS: We analysed 13,337 primary cardiac procedures. A total of 9961 procedures had a logistic EuroSCORE of 0 to <5, 2041 of 5 to <10, 636 of 10 to <15, 281 of 15 to <20, 137 of 20 to <25 and 281≥25. Long-term survival is significantly affected by logistic EuroSCORE, P < 0.001. Patients with a logistic EuroSCORE <5% had significantly better initial survival and a lower rate of death over a 10-year period, P<0.001. Patients with a logistic score over 25 had a significantly worse 5-year survival, P<0.001. Logistic EuroSCORE was poor at predicting survival when >5 and <25. Cox multivariate regression and neuronal network analysis confirmed that the additional factors, diabetes, body mass index (BMI), post-operative myocardial creatinine kinase myocardial isoenzyme (CKMB) and left internal mammary artery (LIMA) usage, which are not incorporated in EuroSCORE significantly predict long-term survival. CONCLUSIONS: Logistic EuroSCORE is a reasonable approximation for long-term survival after CABG, if the score is <5; however, its predictive capacity is limited due to the absence of LIMA usage, BMI, diabetes and CKMB in its calculation, all of which are significant factors affecting long-term survival.

A comparison of outcome in patients with preoperative atrial fibrillation and patients in sinus rhythm.

BACKGROUND: Approximately 10% to 15% of patients undergoing cardiac operations suffer from atrial fibrillation (AF) at the time of surgery. The current risk stratification methods do not include preoperative arrhythmias. The aim of this study was to assess the effect of preoperative AF on the immediate postoperative outcome of patients undergoing cardiac surgery as well as in the midterm and long-term outcomes. METHODS: We reviewed patient data for our institution for a 10-year period; a total of 14,320 patients undergoing any cardiac operation were included; 12,395 (86.5%) had sinus rhythm preoperatively and 1,925 (13.5%) were in persistent AF. After propensity matching and adjusting for the preoperative and operative characteristics, 1,800 patients remained in each group and were compared. RESULTS: Before and after adjusting for the preoperative and operative characteristics, inotropic support, ventilation time, renal failure, stroke, and surgical wound infection rates were all significantly higher for the patients with AF (p < 0.001). Intensive care unit stay and hospital stay as well as in-hospital mortality were also significantly higher among the patients with AF compared with the sinus rhythm group (p < 0.001). At 30 days, 5-year and 10-year mortality rates in the AF group were significantly higher compared with those in sinus rhythm group (p < 0.001). CONCLUSIONS: Atrial fibrillation preoperatively is associated with a higher incidence of postoperative complications. This arrhythmia is an important variable that appears to have been excluded from the current risk stratification systems. Our experience suggests that AF should be considered in the development/update of risk-stratifying methodologies to improve the predictive accuracy.

Comparing the outcome of on-pump versus off-pump coronary artery bypass grafting in patients with preoperative atrial fibrillation.

OBJECTIVES: Around 5-15% of patients undergoing coronary artery bypass grafting (CABG) suffer from preoperative/pre-existing atrial fibrillation (PAF). This is a benign arrhythmia but can affect the outcome of the surgery. The aim of this study was to assess the effect of PAF on the immediate postoperative course of patients undergoing on-pump (ONCAB) vs. off-pump (OPCAB) CABG. METHODS: Over a 10-year period, data were prospectively entered into the database of our institution. A total of 10,461 patients underwent CABG, of whom 477 (4.6%) were in PAF. We analyzed these patients in two separate groups: group A (n=310) who underwent ONCAB and group B (n=167) who underwent OPCAB. After 4:1 propensity matching and adjusting for the preoperative and operative characteristics of these two groups with patients in SR (sinus rhythm), early, mid- and long-term outcomes of PAF patients were analyzed. RESULTS: After adjusting for preoperative characteristics, postoperative complications were significantly higher in patients who had ONCAB when there was PAF compared to those in SR (P<0.001). In the OPCAB patients, on the other hand, there was no statistically significant difference in the postoperative complications between the patients with preoperative SR or PAF. In-hospital and short-term mortality were no different in the PAF group undergoing OPCAB compared to those in SR; however, the mid- and long-term survival rates in PAF patients who underwent OPCAB/ONCAB were worse compared than was seen in SR. CONCLUSIONS: PAF is associated with a higher incidence of postoperative complications. Our results have demonstrated that patients in PAF undergoing ONCAB are more susceptible to the postoperative complications compared to those in SR. However, there were no differences in mid- and long-term outcomes.

Do patients in congestive cardiac failure undergoing cardiac surgery demonstrate worse outcomes compared with those with a history of cardiac failure?

OBJECTIVES: Cardiac surgery in patients with symptoms of congestive cardiac failure (CCF) carries a significant risk of mortality and morbidity. Except for emergencies and in unstable cases, the recommendation has been to delay the operation until the patient is fully recovered. The objective of this study was to determine the consequences of cardiac surgery in patients with acute decompensated heart failure and to compare their outcomes with the results of the operation in patients with previous CCF. METHODS: We compared the outcomes of patients with CCF (n = 707) at the time of cardiac surgery (valve replacement or coronary artery bypass grafting [CABG]) with those with a history of CCF (n = 1583). The EuroSCORE was significantly higher in CCF patients (P < .001). Impaired renal function was also more commonly observed in patients with CCF (P < .001). After adjusting for preoperative characteristics, we compared the 2 groups with respect to postoperative complications, postoperative creatine kinase MB values, and in-hospital mortality. RESULTS: Before adjusting for preoperative characteristics, we found that in-hospital mortality (15.5%) and postoperative complications, such as arrhythmias (31%), renal failure (19%), stroke (4.7%), and myocardial infarction (MI) (3%), were significantly higher in the CCF group than in those with a previous history of CCF. When the patients were matched for preoperative characteristics, the rates of postoperative MI and arrhythmia were the main complications that were significantly higher in the CCF group, compared with the patients with previous CCF. The 2 groups were not significantly different with respect to in-hospital mortality. The results were not affected by the type of procedure (valve or CABG), and the main factor influencing mortality was the EuroSCORE. CONCLUSION: Despite the significant risk of mortality and morbidity in patients with current CCF, cardiac surgery to reverse the cause should not be delayed in these patients, because doing so may lead to further deterioration. Other risk factors, however, should be taken into consideration on an individual basis.

Atrial fibrillation postcardiac surgery: a common but a morbid complication.

OBJECTIVES: Despite all the advances in cardiac surgery, atrial fibrillation (AF) remains a common postoperative complication with unclear predisposing factors. Postoperative AF is often a short-lived and a self-limiting condition, but can result in debilitating and even lethal consequences. The aim of this study is to assess the effect of AF on patients postcardiac surgery. METHODS: In this retrospective study, we prospectively reviewed patient data for our institution for a 10-year period; a total of 17,379 patients with preoperative sinus rhythm (SR) who underwent cardiac surgery were included, of which 4984 (28.7%) had developed postoperative AF for any length of time. After propensity matching for the preoperative characteristics between the two groups; the group with AF and the group who remained in SR, postoperative complications, in-hospital mortality, mid-term survival rate (five years), and long-term survival rate (10 years) were compared. RESULTS: Before and after adjusting for the preoperative characteristics and type of the operation, postoperative complications, such as renal failure, surgical wound infection, stroke and myocardial infarction were significantly higher in the AF group compared to the SR group (P < 0.001). Inotropic support, use of intra-aortic balloon pump, and ventilation time were also considerably higher in the AF patients (P < 0.001). In-hospital mortality was also higher in the AF group. Likewise, 30-day, mid-term and long-term mortality rates were found to be considerably higher in the AF group. CONCLUSIONS: Despite all the modern anti-arrhythmic drugs, the incidence of AF remains unchanged. Patients who develop AF postcardiac surgery show a significantly worse outcome compared to those without AF. This study also highlights the importance of anticoagulation in AF to prevent the devastating consequences as a result of a cerebral stroke. We believe that not only immediate treatment of AF postoperatively should be implemented, but also measures should be taken to identify the risk factors of AF and to prevent AF postcardiac surgery.

The use of cell salvage in routine cardiac surgery is ineffective and not cost-effective and should be reserved for selected cases.

The reported benefits of intraoperative cell salvage are decreased requirement for blood transfusion and cost-effectiveness. This study was designed to challenge this hypothesis. We assessed intraoperative blood loss and the use of cell saver in our institution. In <7% of cases the volume of blood loss was sufficient enough to be washed and returned. We conclude that the routine use of cell savers in all cardiac operations affords no benefit and consumes additional revenue. We recommend that the system only be considered in selected high-risk cases or complex procedures.

Does avoidance of cardiopulmonary bypass confer any benefits in octogenarians undergoing coronary surgery?

OBJECTIVES: There remain concerns about hospital outcomes in octogenarians being referred for coronary artery bypass grafting (CABG). Avoiding the use of cardiopulmonary bypass (CPB) may be an attractive option to improve early outcomes in this group of patients. METHODS: Between April 1997 and March 2010, 343 consecutive patients aged 80-89 years received isolated first time CABG. We used logistic regression to develop a propensity score for off-pump group membership and then performed a propensity matched analysis comparing off-pump (n=107) to on-pump (n=107) groups for early mortality and morbidity. All analysis was performed retrospectively. RESULTS: Preoperative patient characteristics were comparable in both groups, with mean age 82.0 years (80.6-83.7 years) and logistic EuroSCORE 9.9 (6.1-19.5) in the on-pump group compared to 81.6 (80.7-83.2) and 8.5 (5.3-15.7) in the off-pump group (P=0.96, P=0.23, respectively). Postoperatively, in-hospital mortality was 6.5% in the on-pump group compared to 4.7% in the off-pump group (P=0.55). Postoperative complications showed no statistically significant difference between the two groups. However, off-pump was associated with a shorter mechanical ventilation and intensive care unit (ICU) stay and less use of inotropes. CONCLUSION: In our experience, avoiding CPB was not associated with a statistically significant reduction in early mortality, myocardial infarction or stroke rates. It was only associated with a shorter postoperative ventilation and ICU stay and less use of inotropes.

Does off-pump coronary artery revascularization improve the long-term survival in patients with ventricular dysfunction?

OBJECTIVES: Coronary artery revascularization with cardiopulmonary bypass (ONCAB) has been reported to carry several risks for patients with poor left ventricular (LV) function (ejection fraction <30%). Off-pump CABG (OPCAB) has been proposed to result in a better outcome, but mid- and long-term survival rates have never been compared. The aim of this study is to assess the effect of cardiopulmonary bypass on this group of patients. METHODS: In a 10-year period, a total of 934 patients with poor LV function undergoing isolated first-time coronary artery bypass graft were studied. They were divided into two groups, the ONCAB group, with 528 patients, and the OPCAB group with 406 patients. The EuroSCORE was significantly higher in the OPCAB group (P=0.049). After adjusting for the preoperative characteristics, postoperative complications, in-hospital mortality, mid-term survival rate (five years), and long-term survival rate (10 years) were compared. RESULTS: The average number of grafts was 3.7 in the ONCAB group and 3.1 in the OPCAB group (P<0.001). Postoperative complications of ONCAB and OPCAB groups such as; atrial fibrillation (29.6% vs. 28.6%), renal failure (9.3% vs. 9.6%), stroke (2.3% vs. 0.7%), and perioperative myocardial infarction (MI) (3.8% vs. 2.0%), were comparable between groups. Length of intensive care unit stay, hospital stay and ventilation time were considerably shorter in the OPCAB group (P<0.05). The incidence of wound infection was also lower in the OPCAB patients (P<0.05). After adjusting for the preoperative characteristics the incidence of most postoperative complications remained the same between the two groups, except for MI, which was lower in the OPCABs (P<0.04). Despite a lower number of proximal anastomoses in the OPCAB patients, the rate of stroke remained the same between the OPCAB and ONCAB patients (0.09% vs. 1.6%). In-hospital mortality was higher in ONCAB compared to OPCAB (7.8% vs. 5.7%), but this difference did not reach statistical significance (P=0.21). Likewise, mid-term and long-term survival rates were similar even with matched preoperative characteristics. However, re-intervention rate was found to be higher in the OPCABs (P<0.001). CONCLUSIONS: Despite the reported benefits of OPCAB, there was no significant influence on the in-hospital mortality, mid-term survival or long-term survival in patients with LV dysfunction. With adequate myocardial protection in ONCAB and complete revascularization in OPCAB, similar results are achievable.

Predictive accuracy of EuroSCORE: is end-diastolic dysfunction a missing variable?

OBJECTIVE: Left-ventricular function has been shown to be an important prognostic factor in estimating operative risk in cardiac surgery. As such, left-ventricular ejection fraction (LVEF) is included in the EuroSCORE. However, left-ventricular function is more comprehensively assessed by measures of both systolic and diastolic dysfunction. We hypothesised that end-diastolic dysfunction is an additional independent indicator for predicting outcome following coronary artery bypass grafting (CABG). METHODS: We retrospectively assessed all patients undergoing isolated off-pump CABG between October 2000 and September 2004 by two surgeons. Left-ventricular end-diastolic pressure (LVEDP), measured during cardiac catheterisation, was used as a measure of left-ventricular diastolic dysfunction. Logistic regression was used to assess the association between LVEDP (a continuous and dichotomous variable) and mortality, while adjusting for EuroSCORE. RESULTS: A total of 925 patients with complete LVEDP data were identified and stratified as follows: group 1 (LVEF >30% and LVEDP <20 mmHg), group 2 (LVEF <30% and LVEDP <20 mmHg), group 3 (LVEF >30% and LVEDP >20 mmHg) and group 4 (LVEF <30% and LVEDP >20 mmHg). Mortality increased progressively from group 2 (1.9%, odds ratio (OR) 1.22, RR 1.21, p 0.58) to group 3 (5.6%, OR 3.81, RR 3.66, p 0.07) and was highest in group 4 (7.4%, OR 5.18, RR 4.87, p 0.08). Receiver operating characteristic (ROC) curve c-characteristic improved from 0.7 to 0.78 when EuroSCORE was combined with LVEDP, identifying LVEDP as an independent predictor of mortality after adjusting for EuroSCORE. Logistic equation: odds of death = exp(-6.3283+[EuroSCORE x 0.1813]+[EDP x 0.0954]). CONCLUSIONS: LVEDP as a marker of diastolic dysfunction seems an important variable in predicting patient-specific risk and should be considered for incorporation in future risk models.

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.

A multi-centre additive and logistic risk model for in-hospital mortality following aortic valve replacement.

OBJECTIVE: To develop a multivariate prediction model for in-hospital mortality following aortic valve replacement. METHODS: Retrospective analysis of prospectively collected data on 4550 consecutive patients undergoing aortic valve replacement between 1 April 1997 and 31 March 2004 at four hospitals. A multivariate logistic regression analysis was undertaken, using the forward stepwise technique, to identify independent risk factors for in-hospital mortality. The area under the receiver operating characteristic (ROC) curve was calculated to assess the performance of the model. The statistical model was internally validated using the technique of bootstrap resampling, which involved creating 100 random samples, with replacement, of 70% of the entire dataset. The model was also validated on 816 consecutive patients undergoing aortic valve replacement between 1 April 2004 and 31 March 2005 from the same four hospitals. RESULTS: Two hundred and seven (4.6%) in-hospital deaths occurred. Independent variables identified with in-hospital mortality are shown with relevant co-efficient values and p-values as follows: (1) age 70-75 years: 0.7046, p<0.001; (2) age 75-85 years: 1.1714, p<0.001; (3) age>85 years: 2.0339, p<0.001; (4) renal dysfunction: 1.2307, p<0.001; (5) New York Heart Association class IV: 0.5782, p=0.003; (6) hypertension: 0.4203, p=0.006; (7) atrial fibrillation: 0.604, p=0.002; (8) ejection fraction<30%: 0.571, p=0.012; (9) previous cardiac surgery: 0.9193, p<0.001; (10) non-elective surgery: 0.5735, p<0.001; (11) cardiogenic shock: 1.1291, p=0.009; (12) concomitant CABG: 0.6436, p<0.001. Intercept: -4.8092. A simplified additive scoring system was also developed. The ROC curve was 0.78, indicating a good discrimination power. Bootstrapping demonstrated that estimates were stable with an average ROC curve of 0.76, with a standard deviation of 0.025. Validation on 2004-2005 data revealed a ROC curve of 0.78 and an expected mortality of 4.7% compared to the observed rate of 4.1%. CONCLUSIONS: We developed a contemporaneous multivariate prediction model for in-hospital mortality following aortic valve replacement. This tool can be used in day-to-day practice to calculate patient-specific risk by the logistic equation or a simple scoring system with an equivalent predicted risk.