Evidence-Based Determination of Cut-Off Points for Increased Cardiac-Surgery Mortality Risk With EuroSCORE II and STS: The Best-Performing Risk Scoring Models in a Single-Centre Australian Population.

OBJECTIVES: Risk scoring models (RSMs) are commonly used for estimation of postoperative-mortality risk in patients undergoing cardiac surgery, but their prediction accuracy may vary in different populations and clinical situations. The prognostic accuracies of some RSMs have not yet been fully evaluated in the Australian population. In this retrospective observational study, our aims were to assess the performance of four contemporary RSMs, to identify the best RSMs for prediction of postoperative-mortality in the single-centre cohort, and to determine a statistical threshold for classification of patients with increased or "higher" mortality risk. METHODS: The study population included patients who underwent cardiac surgery at Liverpool Hospital between January 2013 and December 2014. Demographic information was collected, and mortality risks were estimated with the ES2 (EuroSCORE II), STS (Society of Thoracic Surgeons Score), AS (AusSCORE total) and ASMR (AusSCORE multi-risk) RSMs. (Additive EuroSCORE) (AES) and LES (logistic EuroSCORE) were included for historical interest. Discrimination, the ability to stratify patients between mortality and no mortality outcomes, and calibration, the comparison of risk score estimated and observed outcome in the population, were evaluated for each RSM, to determine their predictive accuracy in the study population. Discrimination was assessed by the AUC (area under the receiver operating characteristic curve), and acceptable calibration by the p-value greater than 0.05 for the Hosmer-Lemeshow (H-L) test. The best AUCs in contempory models were compared using the DeLong test. For ES2 and STS risk scores, cut-off points, or thresholds, for patients at increased risk of mortality were derived using Youden's J-statistics, calculated from sensitivity and specificity of models in predicting mortality. RESULTS: From a total study population of 898 patients, 738 had scores for all six RSMs. The three EuroSCORE risk models and Youden's J-statistics analysis included the total population. Of the models in contemporary use, ES2 had higher discrimination (AUC=0.850) in this population than ASMR (AUC=0.767, p=0.024) and AS (AUC=0.739) and non-significantly higher discrimination than STS (AUC=0.806, p=0.19). All contemporary models had acceptable calibration but the older LES (H-L p=0.024) did not. Estimated mortality was closest to observed mortality with the ES2 model. Both AES and LES over predicted mortality. The RSM with the highest discrimination in isolated coronary artery bypass graft surgery (CAGs) (AUC=0.847), isolated valves (AUC=0.830), and females (AUC=0.784) was the ES2 model. STS discrimination was highest in CAGs plus valve procedures (AUC 0.891), and males (STS AUC=0.891). Cut-off points for risk scores to define increased risk populations were 3.0% for ES2 and 1.7% for STS. Similar proportions of patients in each RSM (ES2-26% to STS-32%) were defined as higher risk by the model threshold score depending on type of procedure. CONCLUSION: Among RSMs in contemporary use, ES2 and STS showed the best discrimination and acceptable calibration. Caution is recommended in specific subgroups. Increased mortality risk score cut-off points could be identified for these two RSMs in this single-centre cohort.

Independent Predictors of Postoperative Stroke With Cardiopulmonary Bypass.

OBJECTIVE: To assess predictive factors of postoperative stroke in cardiac surgery using cardiopulmonary bypass (CPB). DESIGN: This study was a retrospective observational study. SETTING: This study was conducted at a single institution (Liverpool Hospital, NSW, Australia). PARTICIPANTS: All patients with CPB treated surgically at Liverpool Hospital, NSW, between January 2016 and December 2018 INTERVENTIONS: Patients underwent cardiac surgery with CPB. MEASUREMENTS AND MAIN RESULTS: The primary outcome was cerebrovascular accident, or stroke. Univariate and multivariate analyses via Firth's logistic regression with regard to stroke were performed. The study comprised 1,092 patients over a three-year period. In this cohort, the stroke rate was 3.1%. Via univariate analysis of factors in relation to stroke post-CPB, recent or past stroke (odds ratio [OR] 5.43 v 2.32), diabetes mellitus (OR 1.92), dialysis dependence (OR 5.67), elective procedures (OR 0.34), aortic procedures (OR 4.02), bypass and cross-clamp times (OR 1.02 and 1.04), postoperative atrial fibrillation (OR 2.28), and hypoperfusion times all reached the significance level of p ≤ 0.1 to be included in the multivariate analysis. Multivariate analysis to find independent factors in relation to stroke yielded diabetes mellitus (OR 2.49; p = 0.025), dialysis dependence (OR 3.82; p = 0.03), aortic procedures (OR 3.93; p = 0.014), and elective procedures (OR 0.24; p = 0.026) as independently predictive or protective with regard to postoperative stroke. CONCLUSIONS: Independent predictors of stroke in this single center cohort included dialysis dependence, diabetes, and aortic procedures. Elective procedures were shown to be an independent protective factor.

Bleeding After Cardiac Surgery Is Associated With an Increase in the Total Cost of the Hospital Stay.

BACKGROUND: Cardiac surgery results in complications for some patients that lead to a longer hospital stay and higher costs. This study identified the presurgery characteristics of patients that were associated with the cost of their hospital stay and estimated how much of that cost could be attributed to a bleeding event, defined as requiring 3 units or more of packed red blood cells or returning to the operating room for bleeding. We also identified the presurgery characteristics that were associated with the bleeding event. METHODS: This prospective cohort of patients (n = 1459) underwent cardiac surgery at 3 tertiary referral hospitals in Australia during 2014 and 2015. Clinical data included the variables held by the Australian and New Zealand Society of Cardiac and Thoracic Surgeons registry. Cost data were collected as part of a state-level hospital data collection. RESULTS: Many of the baseline patient characteristics were associated with the total cost of cardiac surgery. After adjusting for these characteristics, the cost of cardiac surgery was 1.76 (confidence interval, 1.64-1.90) times higher for patients who had a bleeding event (P < .001), thus resulting in a median increase in costs (in Australian dollars) of $33,338 (confidence interval, $21,943-$38,415). Several baseline characteristics were strongly associated with a bleeding event. CONCLUSIONS: The impact of a bleeding event on the cost of cardiac surgery is substantial. This study identified a set of risk factors for bleeding that could be used to identify patients for discussion at the heart team level, where measures to minimize the risk of transfusion may be initiated.

Platelet Activity Measured by VerifyNow® Aspirin Sensitivity Test Identifies Coronary Artery Bypass Surgery Patients at Increased Risk for Postoperative Bleeding and Transfusion.

BACKGROUND: Identifying predictors of bleeding in patients before coronary artery bypass grafting surgery is important, given the complications of bleeding and finite supply of blood. Patient response to aspirin is heterogeneous and can be evaluated using point-of-care platelet function tests. We postulated that patients who hyper-respond to aspirin given preoperatively, as identified by VerifyNow® Aspirin assay (Accumetrics, Inc., San Diego, CA, USA), are at increased risk of bleeding and transfusion. METHODS: This prospective pilot study examined response to aspirin in patients undergoing coronary artery bypass grafting surgery (n = 61) from 2009 to 2013. Patients with aspirin reaction unit (ARU) values in the lower 50th percentile as identified by VerifyNow® assays were defined as aspirin hyper-responders. The proportion of patients transfused and the median adjusted indexed drop in haemoglobin were compared between aspirin hyper-responders and non-hyper-responders. Logistic regression was performed to determine factors associated with increased risk of transfusion. RESULTS: Seventy per cent (70%) of aspirin hyper-responders were transfused perioperatively compared with 39% of patients who did not hyper-respond, (OR 3.694, 95% CI 1.275-10.706, p = 0.014). VerifyNow® Aspirin hyper-responders had a greater median adjusted indexed drop in haemoglobin compared to non-hyper-responders (34.1 g/L versus 26.6 g/L respectively, p = 0.032). Multivariate analysis also showed VerifyNow® Aspirin hyper-response to be an independent predictor of transfusion (p = 0.016). Other variables such as age, gender, body mass index, renal insufficiency, and cross clamp and bypass times were not predictors of postoperative bleeding in this pilot cohort. CONCLUSIONS: VerifyNow® Aspirin is able to preoperatively identify aspirin hyper-responders at an increased risk of bleeding and subsequent transfusion in the context of coronary artery bypass graft surgery.

Late clinical outcomes of unselected patients with diabetic mellitus and multi-vessel coronary artery disease.

BACKGROUND: The Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multi-Vessel Disease (FREEDOM) clinical trial randomized only a proportion of screened patients with diabetes mellitus (DM) and multi-vessel disease (MVD). METHODS AND RESULTS: We determined late rates of death, non-fatal myocardial infarction (MI) and stroke in all 430 patients with DM who had MVD identified on angiographic screening for the FREEDOM Trial, which recruited from June 2006 -March 2010 at Liverpool Hospital, Sydney, Australia. Mortality at 6 years [median] was 23% among 192 FREEDOM-eligible patients and 26% among 238 FREEDOM-ineligible patients, of whom 139 [58%] had prior. CABG (mortality 31%). Overall, 196 (45%) had percutaneous coronary intervention (PCI), 127 (30%) underwent coronary artery bypass grafting (CABG) (who were 4 years younger; p = 0.003), and 107 (25%) had neither procedure of whom 80 were considered unsuitable for revascularization. Mortality was 26% post-PCI 16%, post-CABG and 33% among those who did not undergo revascularization (p = 0.01). On multivariable analyses, factors associated with late mortality were older age, hypertension and not undergoing CABG (all p < 0.05). Factors associated with late MI were presented with an acute coronary syndrome, whereas patients that underwent treatment with either PCI or CABG had less late MI (all p < 0.05). CONCLUSION: Among consecutive diabetic patients with MVD, at a median of 6-years CABG was associated with better survival and fewer non-fatal MI outcomes compared to PCI.

Does continuous infusion of local anaesthesia improve pain control and walking distance after coronary artery bypass graft surgery? A randomised controlled trial.

OBJECTIVES: To evaluate the effects of continuous infusion of ropivacaine compared to sham infusion or usual care on pain scores before and after physiotherapy treatment, distance walked and time to discharge from physiotherapy, after coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, randomised, double blind controlled trial. SETTING AND PARTICIPANTS: Seventy-five participants who underwent CABG surgery with left internal mammary artery grafts were allocated, to the ropivacaine group (n=26), the sham group (n=25), or usual care group (n=24). Participants in the ropivacaine group received 0.5% ropivacaine and participants in the sham group received normal saline, both as continuous infusions via two parasternally tunnelled catheters for 96hours continuously. The usual care group did not receive a device. All groups had patient-controlled analgesia and/or oral analgesia. RESULTS: Seventy-two participants completed the study. There was no significant between-group differences in pain scores, distance walked on any post operative day (POD) or number of participants discharged from physiotherapy by POD 4. For the group as a whole there was a significant linear decrease in pain score from mean (SD) 42 (24) mm on POD1 to 15 (16) mm on POD4 (p<0.001), (MD 27mm, 95% CI 22 to 32) and walking distance increased from 1 (5) m on POD1 to 183 (239) m on POD4 (p<0.001) MD 181m, 95% CI 126 to 236). CONCLUSION: Infusion of ropivacaine post CABG surgery was unable to reduce pain, increase distance walked or reduce time to physiotherapy discharge compared to sham or usual care. Trial registration number ACTRN12612001243808.

Does a combined procedure for cardiac surgery and thyroidectomy offer acceptable outcomes?

This best evidence topic on cardiothoracic surgery was written using a structured protocol. The question addressed was: 'in an adult patient requiring cardiac surgery, can a thyroidectomy for a large retrosternal goitre be performed with good outcomes as a combined procedure?' Of 150 papers identified through the literature search, 16 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, study type, patient group studied, relevant outcomes and results were tabulated. This paper includes 3 Level 4 papers and 13 case reports. All papers reported postoperative outcomes and five papers reported intraoperative outcomes. Of a total cohort of 32 patients, 25 were euthyroid prior to combined surgery. Twenty-nine of 32 thyroid surgeries were performed immediately prior to cardiac surgery in the combined procedure sequence. Post-procedural complications including transient recurrent laryngeal palsy and tracheomalacia were reported in 8 patients. There was one intraoperative death. Where reported, all patients were euthyroid on follow-up. All identified papers reported good outcomes with combined thyroidectomy and cardiac surgery.

Is home warfarin self-management effective? Results of the randomised Self-Management of Anticoagulation Research Trial.

AIMS: The Warfarin Self-Management Anticoagulation Research Trial (Warfarin SMART) was designed to determine whether patients self-managing warfarin (PSM) using the CoaguChek device and a dosing algorithm developed for the trial could keep the INR (International Normalised Ratio) test in target range at least as often as patients managed by usual care by the family doctor or hospital clinic. METHODS AND RESULTS: 310 patients were randomly assigned to PSM or usual care. The PSM group was trained to perform home INR testing and warfarin dosing using a validated ColourChart algorithm. The primary endpoint was the proportion of times over 12 months that a monthly, blinded "outcome INR test", measured in a central laboratory, was outside the patient's target therapeutic range. The rate of out-of-range outcome INRs was lower in PSM, and non-inferior to the usual care group (PSM: 36% vs. usual care: 41%, P<0.001 for non-inferiority; P=0.08 for superiority in closed-loop testing). The deviations from the patient's midpoint of target INR range (P=0.02) and number of extreme INRs (P=0.03) were significantly less in the PSM group than the usual-care group. There was no significant difference between groups in rates of bleeding or thrombotic adverse events. CONCLUSION: Patient self-management performed at least as well as usual care in maintaining the INR within the target range, without any safety concerns. This treatment modality for the long-term use of warfarin has the potential to change current local and international practice.

Risk factor modification in diabetic patients following angiographic identification of multi-vessel disease.

There is little information on whether identification of multi-vessel disease (MVD) in patients with diabetic mellitus (DM) affects risk factor management. From 1125 consecutively screened patients between June 2006 and March 2010, we examined 227 diabetic patients with MVD on coronary angiography. Diabetic control and cholesterol levels were assessed by glycated haemoglobin (HbA1c) and total cholesterol (TC) respectively which were evaluated at baseline and at 1-year follow-up. Patients were grouped by age into <55(n=33), 55-65(n=75), 66-75(n=75) and >75(n=44). Target levels were defined as HbA1c<7% and TC<4.0 mmol/L. Patients <55 years had the highest HbA1c at 9.1[7.6-11.2]% with the lowest proportion of patients (n=3; 11.1%) within target at baseline, while 66-75 years had the best HbA1c at 7.1[6.4-7.8]% with the highest proportion (n=28, 45.2%) reaching target (p<0.0001). At 1-year, the poorest HbA1c control was again observed in the age <55 with fewer patients achieving target compared to the 66-75 age group (HbA1c: 8.5% vs 6.9%; % of patients at target: 20.7% vs 54.5%; p<0.0001). Furthermore, the group <55 years demonstrated the worst TC control at 1-year with a significant increase compared to the baseline TC (p=0.01). Patients with a lower body mass index (BMI) were likely to have an improvement in HbA1c and reach target (p=0.01). Paradoxically, patients who were current smokers demonstrated a beneficial effect on optimal TC control (29.2% vs 15.4%, p=0.027). In younger diabetic patients, risk factor modification at 1-year was poor despite identification of MVD. Developing an effective education and monitoring programme to improve glycaemic control in this high risk group should be a priority.

Outcomes of coronary revascularization (percutaneous or bypass) in patients with diabetes mellitus and multivessel coronary disease.

Clinical outcomes in patients with diabetes mellitus and multivessel disease (MVD) undergoing coronary revascularization have not been extensively evaluated, we sought to examine outcomes in a diabetic cohort of 195 consecutive patients with MVD characterized by SYNTAX scores (SSs) undergoing nonrandomized revascularization, 102 (52%) by percutaneous intervention (PCI) and 93 (48%) by coronary artery bypass grafting (CABG) at Liverpool Hospital (Sydney, Australia) from June 2006 to March 2010. Clinical outcomes were assessed at a median term of 14 months. The overall median SS was 44, with significantly higher SSs in CABG- than PCI-treated patients (48 vs 39, p <0.0001). There was a similar incidence of all-cause death, nonfatal myocardial infarction and stroke in PCI- and CABG-treated patients (6.1% vs 8.3%, p = 0.383; 12% vs 4.9%, p = 0.152; 3.1% vs 3.5%, p = 0.680 respectively). However, the rates of target vessel revascularization and major adverse coronary and cerebral event were significantly higher in PCI-treated patients than in those undergoing CABG (20% vs 1.2%, p <0.0001; 29% vs 15%, p = 0.034). Despite a much higher SS, patients who underwent PCI achieved comparable outcomes at 1 year to those with diabetes mellitus and a SS ≥ 33 as reported in the SYNTAX trial. In conclusion, in this single-center nonrandomized observational study, coronary revascularization by PCI is associated with increased major adverse coronary and cerebral events at 1-year follow-up, predominantly driven by a high rate of target vessel revascularization. Thus, CABG should remain the revascularization procedure of choice for diabetic patients with MVD and high SSs.

Corynebacterium diphtheriae endocarditis--surgery for some but not all!

Corynebacterium diphtheriae endocarditis was thought to be a rare disease. We reviewed our experience in four cases of this disease treated over a period of 10 years. Seventy cases reported in literature were reviewed. The outcome is good if cases are carefully selected for medical or surgical treatment. We conclude that infective endocarditis due to C. diphtheriae, is perhaps more common than expected. It may be recognized more frequently and on occasion may be an aggressive disease. Those patients with an abnormal valve (including prosthetic valves) should be subjected to surgery at the earliest available opportunity, whereas patients with normal valves may be carefully watched during the course of medical treatment as long as immediate surgery can occur if needed.

Aortic valve allograft structural deterioration is associated with a subset of antibodies to human leukocyte antigens.

BACKGROUND AND AIM OF THE STUDY: The association between aortic valve allograft dysfunction in patients with long-term follow up and human leukocyte class 2 antigen donor/recipient mismatch suggests that elements of the anti-donor immune response penetrate and damage the aortic valve allograft. An aortic valve allograft recipient cohort was studied to determine whether presence of recipient antibodies to donor human leukocyte class 1 or 2 antigen was associated with shorter time to aortic valve allograft dysfunction. METHODS: Both donor and recipient human leukocyte antigen (HLA) type, HLA antibody information and echocardiography data were available for 148 recipients of cryopreserved aortic valve allografts between 1986 and 1998. Structural deterioration of the aortic valve allograft was defined as at least moderate aortic stenosis or regurgitation by echocardiography. Recipient sera were assayed for anti-HLA (class 1 and 2) antibodies using three assays: complement-dependent cytotoxicity (CDC) on T- and B-lymphocyte panels (CDC PRA); flow cytometry using HLA-coated beads (Flow PRA); and an ELISA using HLA-coated microwells. The donor specificity of anti-class 1 and 2 HLA antibodies was determined on T- and B-cell panels using CDC. Associations between the results of the three assays and donor-specific class 1 and 2 antibodies and time to structural deterioration were analyzed using Kaplan-Meier curves of freedom from structural deterioration. Cox proportional-hazards were used to determine independent predictors of time to structural deterioration. RESULTS: Patients highly positive for HLA class 2 antibodies using an ELISA had a significant association (p = 0.007) with shorter time to aortic valve allograft structural deterioration using both a log rank test and Cox proportional-hazards analysis. Patients (n = 15) with donor-specific antibodies to class 2 antigen (DR antigens) had significantly more structural deterioration (p = 0.035) than those without specific antibodies. CONCLUSION: The association between aortic valve allograft structural deterioration and high titer human leukocyte class 2 antigen antibodies, a subset detected by ELISA adds further information about the link between HLA class 2 mismatch and structural deterioration. Further studies are needed to confirm the importance of class 2 antibodies on outcome, and to determine by which method these antibodies should be detected. Potential recipients with pre-existing antibodies of these specific types might be expected to sustain accelerated allograft damage.

Migration and infection of a pace-sense lead from an abdominal defibrillator system.

A 47-year-old man had an ICD system with epicardial and endocardial components and an abdominal generator placed in 1990 following a cardiac arrest. Ten years later his BT10 lead was amputated due to an insulation defect, and he received a new pectoral generator with transvenous leads. A few months later he developed fevers, chills, and bacteremia. Evaluation demonstrated migration of the entire BT10 lead into the right atrium. Complete surgical explantation was required and the bacteremia resolved. This case illustrates the importance of solid anchoring of distal lead components following generator removal and the potential complication of intravascular lead migration.

Left ventricular assist device implantation via left thoracotomy: alternative to repeat sternotomy.

Repeat sternotomy for left ventricular assist device insertion may result in injury to the right heart or patent coronary grafts, complicating intraoperative and postoperative management. In 4 critically ill patients, left thoracotomy was used as an alternative to repeat sternotomy. Anastomosis of the outflow conduit to the descending thoracic aorta provided satisfactory hemodynamic support.