Stuart W. Grant

What is the impact of providing a transcatheter aortic valve implantation service on conventional aortic valve surgical activity: patient risk factors and outcomes in the first 2 years

Objectives To assess the impact of introducing a transcatheter aortic valve implantation (TAVI) service on aortic valve surgical activity and outcomes. Design A retrospective analysis of prospectively collected data. Setting University hospital of south Manchester. Patients 815 consecutive patients undergoing isolated aortic valve replacement (AVR) or coronary artery bypass grafting plus AVR from January 2006 to December 2009. Fifty consecutive patients who underwent TAVI from January 2008 to December 2009. Main outcome measures Aortic valve surgical activity in the 2u2005years before the introduction of a TAVI service and in the 2u2005years following. Outcomes following conventional aortic valve surgery and TAVI. Results In the 2u2005years following the introduction of TAVI at this centre, conventional AVR activity has increased by 37% compared with an 8% increase nationally (p<0.001). Compared with the 2u2005years before TAVI there was no change in the mean logistic EuroSCORE (7.4 vs 7.9 p=0.16) or crude mortality rate (2.9% vs 2.1% p=0.48). Fifty high-risk patients underwent TAVI with a 30-day mortality rate of 0%. The mean logistic EuroSCORE of the TAVI patients was 25.3. Conclusions TAVI is an emerging alternative to AVR in high-risk patients. Since the introduction of a TAVI service at this centre, conventional AVR activity has increased. Despite a trend of increasing mean logistic EuroSCORE indicating that more complex cases are being undertaken, there has been a non-significant reduction in the crude mortality rate. Offering a TAVI service has a positive impact on the volume of conventional AVR surgical activity.

Preoperative cardiopulmonary exercise testing and risk of early mortality following abdominal aortic aneurysm repair.

Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity. The aim of this study was to assess whether preoperative CPET identifies patients at risk of early death following elective open and endovascular abdominal aortic aneurysm (AAA) repair.

Cardiopulmonary exercise testing and survival after elective abdominal aortic aneurysm repair

BACKGROUNDnCardiopulmonary exercise testing (CPET) is increasingly used in the preoperative assessment of patients undergoing major surgery. The objective of this study was to investigate whether CPET can identify patients at risk of reduced survival after abdominal aortic aneurysm (AAA) repair.nnnMETHODSnProspectively collected data from consecutive patients who underwent CPET before elective open or endovascular AAA repair xa0(EVAR) at two tertiary vascular centres between January 2007 and October 2012 were analysed. A symptom-limited maximal CPET was performed on each patient. Multivariable Cox proportional hazards regression modelling was used to identify risk factors associated with reduced survival.nnnRESULTSnThe study included 506 patients with a mean age of 73.4 (range 44-90). The majority (82.6%) were men and most (64.6%) underwent EVAR. The in-hospital mortality was 2.6%. The median follow-up was 26 months. The 3-year survival for patients with zero or one sub-threshold CPET value ([Formula: see text] at AT<10.2 ml kg(-1) min(-1), peak [Formula: see text]<15 ml kg(-1) min(-1) or [Formula: see text] at AT>42) was 86.4% compared with 59.9% for patients with three sub-threshold CPET values. Risk factors independently associated with survival were female sex [hazard ratio (HR)=0.44, 95% confidence interval (CI) 0.22-0.85, P=0.015], diabetes (HR=1.95, 95% CI 1.04-3.69, P=0.039), preoperative statins (HR=0.58, 95% CI 0.38-0.90, P=0.016), haemoglobin g dl(-1) (HR=0.84, 95% CI 0.74-0.95, P=0.006), peak [Formula: see text]<15 ml kg(-1) min(-1) (HR=1.63, 95% CI 1.01-2.63, P=0.046), and [Formula: see text] at AT>42 (HR=1.68, 95% CI 1.00-2.80, P=0.049).nnnCONCLUSIONSnCPET variables are independent predictors of reduced survival after elective AAA repair and can identify a cohort of patients with reduced survival at 3 years post-procedure. CPET is a potentially useful adjunct for clinical decision-making in patients with AAA.

What is the impact of endoscopic vein harvesting on clinical outcomes following coronary artery bypass graft surgery

Objective Endoscopic vein harvesting (EVH) is increasingly used as an alternative to open vein harvesting (OVH) for coronary artery bypass graft (CABG) surgery. Concerns about the safety of EVH with regard to midterm clinical outcomes following CABG have been raised. The objective of this study was to assess the impact of EVH on short-term and midterm clinical outcomes following CABG. Design This was a retrospective analysis of prospectively collected multi-centre data. A propensity score was developed for EVH and used to match patients who underwent EVH to those who underwent OVH. Setting Blackpool Victoria Hospital, Plymouth Derriford Hospital and the University Hospital of South Manchester were the main study settings. Patients There were 4709 consecutive patients who underwent isolated CABG using EVH or OVH between January 2008 and July 2010. Main outcome measures The main outcome measure was a combined end point of death, repeat revascularisation or myocardial infarction. Secondary outcome measures included in-hospital morbidity, in-hospital mortality and midterm mortality. Results Compared to OVH, EVH was not associated with an increased risk of the main outcome measure at a median follow-up of 22u2005months (HR 1.15; 95% CI 0.76 to 1.74). EVH was also not associated with an increased risk of in-hospital morbidity, in-hospital mortality (0.9% vs 1.1%, p=0.71) or midterm mortality (HR 1.04; 95% CI 0.65 to 1.66). Conclusions This multi-centre study demonstrates that at a median follow-up of 22u2005months, EVH was not associated with adverse short-term or midterm clinical outcomes. However, before the safety of EVH can be clearly determined, further analyses of long-term clinical outcomes are required.

Performance of the EuroSCORE Models in Emergency Cardiac Surgery

Background—Accurate risk-adjustment models are useful for clinical decision making and are important for minimizing any tendency toward risk-averse clinical practice. In cardiac surgery, emergency patients are potentially at greatest risk of inappropriate risk-averse clinical decisions. UK cardiac surgery outcomes are currently risk-adjusted with EuroSCORE models. The objective of this study was to assess the performance of the EuroSCORE models in emergency cardiac surgery. Methods and Results—The National Institute for Cardiovascular Outcomes Research database was used to identify adult cardiac surgery procedures performed in the United Kingdom between April 2008 and March 2011. A subset of procedures (July 2010–March 2011) was used for EuroSCORE II validation. The outcome measure was in-hospital mortality. Model calibration (Hosmer–Lemeshow test, calibration plots, calculation of calibration intercept and slope) and discrimination (area under receiver-operating characteristic curve [area under the curve]) were assessed. In total, 109 988 cardiac procedures at 41 hospitals were included, of which 3342 were defined as emergency procedures. Compared with performance in all cardiac surgery and nonemergency cardiac surgery, the logistic EuroSCORE and EuroSCORE II models had poorer discrimination (area under the curve, 0.703 and 0.690, respectively) and poorer calibration for emergency surgery. The EuroSCORE risk factors of female sex, chronic pulmonary disease, neurological disease, active endocarditis, unstable angina, recent myocardial infarction, and pulmonary hypertension were not identified as important risk factors for emergency cardiac surgery. Conclusions—Both EuroSCORE models demonstrated poor calibration and comparatively poor discrimination for emergency cardiac surgery. This has important implications when these models are used for clinical decision making or to adjust governance analyses.

Does the choice of risk adjustment model influence the outcome of surgeon specific mortality analysis: a retrospective analysis of 14,637 patients under 31 surgeons

Objectives: To compare implications of using the logistic EuroSCORE and a locally derived model when analysing individual surgeon mortality outcomes. Design: Retrospective analysis of prospectively collected data. Setting: All NHS hospitals undertaking adult cardiac surgery in northwest England. Patients: 14u2009637 consecutive patients, April 2002 to March 2005. Main outcome measures: We have compared the predictive ability of the logistic EuroSCORE (uncalibrated), the logistic EuroSCORE calibrated for contemporary performance and a locally derived logistic regression model. We have used each to create risk-adjusted individual surgeon mortality funnel plots to demonstrate high mortality outcomes. Results: There were 458 (3.1%) deaths. The expected mortality and receiver operating characteristic (ROC) curve values were: uncalibrated EuroSCORE −5.8% and 0.80, calibrated EuroSCORE −3.1% and 0.80, locally derived model −3.1% and 0.82. The uncalibrated EuroSCORE plot showed one surgeon to have mortality above the northwest average, and no surgeon above the 95% control limit (CL). The calibrated EuroSCORE plot and the local model showed little change in surgeon ranking, but significant differences in identifying high mortality outcomes. Two of three surgeons above the 95% CL using the calibrated EuroSCORE revert to acceptable outcomes when the local model is applied but the finding is critically dependent on the calibration coefficient. Conclusions: The uncalibrated EuroSCORE significantly overpredicted mortality and is not recommended. Instead, the EuroSCORE should be calibrated for contemporary performance. The differences demonstrated in defining high mortality outcomes when using a model built for purpose suggests that the choice of risk model is important when analysing surgeon mortality outcomes.

Exercise during haemodialysis: West of Scotland pilot study.

Background: Exercise during dialysis (EDD) in End-Stage Renal Disease (ESRD) has been documented as an effective intervention to improving a patients aerobic capacity. Aims: This pilot study aimed to confirm physiological improvements, to establish its safety and practicality and to form guidelines for a long-term study, leading to the integration of EDD in ESRD therapy. Methods: A total of 17 patients on hospital haemodialysis were recruited: ten exercisers (age 42.4 ± 12.6) and six controls (age 41.0 ± 8.3). Both groups were initially tested for estimated VO2max, heart rate, blood pressure, leg extension peak torque, anxiety and depression levels, as well as biochemical and haematological values. The exercisers then underwent cycling ergometer exercise sessions during dialysis, twice weekly, for a total of 12 sessions. Both groups were re-tested after this period. Results: All test and exercise sessions were completed without complication. Compliance was high with only 1 exerciser failing to complete all 12 sessions. The exercisers showed a statistically significant increase (p < 0.05) in EDD workrates (44.3 to 52.1 watts) during the 12 sessions and a reduction in anxiety (p < 0.05). Statistical analysis showed no other significant changes in either group after the 6-week period. Conclusion: This pilot study has confirmed that aerobic EDD is feasible and well accepted by patients on hospital haemodialysis. EDD reduced anxiety scores and showed a trend for an improved level of aerobic fitness.

Dynamic prediction modeling approaches for cardiac surgery

Background— The calibration of several cardiac clinical prediction models has deteriorated over time. We compare different model fitting approaches for in-hospital mortality after cardiac surgery that adjust for cross-sectional case mix in a heterogeneous patient population. Methods and Results— Data from >300 000 consecutive cardiac surgery procedures performed at all National Health Service and some private hospitals in England and Wales between April 2001 and March 2011 were extracted from the National Institute for Cardiovascular Outcomes Research clinical registry. The study outcome was in-hospital mortality. Model approaches included not updating, periodic refitting, rolling window, and dynamic logistic regression. Covariate adjustment was made in each model using variables included in the logistic European System for Cardiac Operative Risk Evaluation model. The association between in-hospital mortality and some variables changed with time. Notably, the intercept coefficient has been steadily decreasing during the study period, consistent with decreasing observed mortality. Some risk factors, such as operative urgency and postinfarct ventricular septal defect, have been relatively stable over time, whereas other risk factors, such as left ventricular function and surgery on the thoracic aorta, have been associated with lower risk relative to the static model. Conclusions— Dynamic models or periodic model refitting is necessary to counteract calibration drift. A dynamic modeling framework that uses contemporary and available historic data can provide a continuously smooth update mechanism that also allows for inferences to be made on individual risk factors. Better models that withstand the effects of time give advantages for governance, quality improvement, and patient-level decision making.

Comparison of Three Contemporary Risk Scores for Mortality Following Elective Abdominal Aortic Aneurysm Repair

Objective/background A number of contemporary risk prediction models for mortality following elective abdominal aortic aneurysm (AAA) repair have been developed. Before a model is used either in clinical practice or to risk-adjust surgical outcome data it is important that its performance is assessed in external validation studies. Methods The British Aneurysm Repair (BAR) score, Medicare, and Vascular Governance North West (VGNW) models were validated using an independent prospectively collected sample of multicentre clinical audit data. Consecutive, data on 1,124 patients undergoing elective AAA repair at 17 hospitals in the north-west of England and Wales between April 2011 and March 2013 were analysed. The outcome measure was in-hospital mortality. Model calibration (observed to expected ratio with chi-square test, calibration plots, calibration intercept and slope) and discrimination (area under receiver operating characteristic curve [AUC]) were assessed in the overall cohort and procedural subgroups. Results The mean age of the population was 74.4 years (SD 7.7); 193 (17.2%) patients were women and the majority of patients (759, 67.5%) underwent endovascular aneurysm repair. All three models demonstrated good calibration in the overall cohort and procedural subgroups. Overall discrimination was excellent for the BAR score (AUC 0.83, 95% confidence interval [CI] 0.76–0.89), and acceptable for the Medicare and VGNW models, with AUCs of 0.78 (95% CI 0.70–0.86) and 0.75 (95% CI 0.65–0.84) respectively. Only the BAR score demonstrated good discrimination in procedural subgroups. Conclusion All three models demonstrated good calibration and discrimination for the prediction of in-hospital mortality following elective AAA repair and are potentially useful. The BAR score has a number of advantages, which include being developed on the most contemporaneous data, excellent overall discrimination, and good performance in procedural subgroups. Regular model validations and recalibration will be essential.

Conventional aortic valve replacement for high-risk aortic stenosis patients not suitable for trans-catheter aortic valve implantation: feasibility and outcome

OBJECTIVEnHigh-risk patients with aortic stenosis are increasingly referred to specialist multidisciplinary teams (MDTs) for consideration of trans-catheter aortic valve implantation (TAVI). A subgroup of these cases is unsuitable for TAVI, and high-risk conventional aortic valve replacement (AVR) is undertaken. We have studied our outcomes in this cohort.nnnMETHODSnData prospectively collected between March 2008 and November 2009 for patients (n = 28, nine male) undergoing high-risk AVR were analysed. The mean age was 78.4 ± 9.2 years. The mean additive EuroSCORE (European System for Cardiac Operative Risk Evaluation) was 10.0 ± 3.6 and mean logistic EuroSCORE was 19.9 ± 18.8. Three patients had undergone previous coronary artery bypass grafting (CABG).nnnRESULTSnThe mean ejection fraction was 51 ± 16%, mean valve area 0.56 ± 0.19 cm², and mean peak gradient 91 ± 27 mm Hg. Ascending aortic, right axillary artery and femoral artery cannulation was used in 64%, 29% and 7% of cases, respectively. Median cross-clamp and cardiopulmonary bypass times were 84 (68-143) min and 111 (94-223) min. The median (range) inserted valve size was 21 (19-25) mm. Median intensive care and overall hospital stay were 5 (2-37) and 11 (5-44) days, respectively. In-hospital mortality was 4% (one patient). Postoperative complications included re-operation for bleeding (7%), renal failure (21%), tracheostomy (14%), sternal wound infection (7%), atrial fibrillation (25%) and permanent pacemaker implantation (7%). Kaplan-Meier survival at median follow-up of 359 (148-744) days was 81% (one further death of non-cardiac aetiology). Quality-of-life assessment at follow-up also yielded satisfactory results.nnnCONCLUSIONSnMDT assessment of high-risk aortic stenosis in the era of TAVI has increased the number of referrals. Conventional open surgery remains a valid option for these patients, with acceptable in-hospital mortality and early/midterm outcomes but high in-hospital morbidity.