Jeffrey B. Rich

The Society of Thoracic Surgeons 2008 cardiac surgery risk models: part 1--coronary artery bypass grafting surgery.

BACKGROUND The first version of The Society of Thoracic Surgeons National Adult Cardiac Surgery Database (STS NCD) was developed nearly 2 decades ago. Since its inception, the number of participants has grown dramatically, patient acuity has increased, and overall outcomes have consistently improved. To adjust for these and other changes, all STS risk models have undergone periodic revisions. This report provides a detailed description of the 2008 STS risk model for coronary artery bypass grafting surgery (CABG). METHODS The study population consisted of 774,881 isolated CABG procedures performed on adult patients aged 20 to 100 years between January 1, 2002, and December 31, 2006, at 819 STS NCD participating centers. This cohort was randomly divided into a 60% training (development) sample and a 40% test (validation) sample. The development sample was used to identify predictor variables and estimate model coefficients. The validation sample was used to assess model calibration and discrimination. Model outcomes included operative mortality, renal failure, stroke, reoperation for any cause, prolonged ventilation, deep sternal wound infection, composite major morbidity or mortality, prolonged length of stay (> 14 days), and short length of stay (< 6 days and alive). Candidate predictor variables were selected based on their availability in versions 2.35, 2.41, and 2.52.1 of the STS NCD and their presence in (or ability to be mapped to) version 2.61. Potential predictor variables were screened for overall prevalence in the study population, missing data frequency, coding concerns, bivariate relationships with outcomes, and their presence in previous STS or other CABG risk models. Supervised backwards selection was then performed with input from an expert panel of cardiac surgeons and biostatisticians. After successfully validating the fit of the models, the development and validation samples were subsequently combined, and the final regression coefficients were estimated using the overall combined (development plus validation) sample. RESULTS The c-index for the mortality model was 0.812, and the c-indices for other endpoints ranged from 0.653 for reoperation to 0.793 for renal failure in the validation sample. Plots of observed versus predicted event rates revealed acceptable calibration in the overall population and in numerous subgroups. When patients were grouped into categories of predicted risk, the absolute difference between the observed and expected event rates was less than 1.5% for each endpoint. The final model intercept and coefficients are provided. CONCLUSIONS New STS risk models have been developed for CABG mortality and eight other endpoints. Detailed descriptions of model development and testing are provided, together with the final algorithm. Overall model performance is excellent.

The Society of Thoracic Surgeons 2008 cardiac surgery risk models: part 2--isolated valve surgery.

BACKGROUND Adjustment for case-mix is essential when using observational data to compare surgical techniques or providers. That is most often accomplished through the use of risk models that account for preoperative patient factors that may impact outcomes. The Society of Thoracic Surgeons (STS) uses such risk models to create risk-adjusted performance reports for participants in the STS National Adult Cardiac Surgery Database (NCD). Although risk models were initially developed for coronary artery bypass surgery, similar models have now been developed for use with heart valve surgery, particularly as the proportion of such procedures has increased. The last published STS model for isolated valve surgery was based on data from 1994 to 1997 and did not include patients undergoing mitral valve repair. STS has developed new valve surgery models using contemporary data that include both valve repair as well as replacement. Expanding upon existing valve models, the new STS models include several nonfatal complications in addition to mortality. METHODS Using STS data from 2002 to 2006, isolated valve surgery risk models were developed for operative mortality, permanent stroke, renal failure, prolonged ventilation (> 24 hours), deep sternal wound infection, reoperation for any reason, a major morbidity or mortality composite endpoint, prolonged postoperative length of stay, and short postoperative length of stay. The study population consisted of adult patients who underwent one of three types of valve surgery: isolated aortic valve replacement (n = 67,292), isolated mitral valve replacement (n = 21,229), or isolated mitral valve repair (n = 21,238). The population was divided into a 60% development sample and a 40% validation sample. After an initial empirical investigation, the three surgery groups were combined into a single logistic regression model with numerous interactions to allow the covariate effects to differ across these groups. Variables were selected based on a combination of automated stepwise selection and expert panel review. RESULTS Unadjusted operative mortality (in-hospital regardless of timing, and 30-day regardless of venue) for all isolated valve procedures was 3.4%, and unadjusted in-hospital morbidity rates ranged from 0.3% for deep sternal wound infection to 11.8% for prolonged ventilation. The number of predictors in each model ranged from 10 covariates in the sternal infection model to 24 covariates in the composite mortality plus morbidity model. Discrimination as measured by the c-index ranged from 0.639 for reoperation to 0.799 for mortality. When patients in the validation sample were grouped into 10 categories based on deciles of predicted risk, the average absolute difference between observed versus predicted events within these groups ranged from 0.06% for deep sternal wound infection to 1.06% for prolonged postoperative stay. CONCLUSIONS The new STS risk models for valve surgery include mitral valve repair as well as multiple endpoints other than mortality. Model coefficients are provided and an online risk calculator is publicly available from The Society of Thoracic Surgeons website.

Analyses of coronary graft patency after aprotinin use : results from the international multicenter aprotinin graft patency experience (IMAGE) trial

OBJECTIVE We examined the effects of aprotinin on graft patency, prevalence of myocardial infarction, and blood loss in patients undergoing primary coronary surgery with cardiopulmonary bypass. METHODS Patients from 13 international sites were randomized to receive intraoperative aprotinin (n = 436) or placebo (n = 434). Graft angiography was obtained a mean of 10.8 days after the operation. Electrocardiograms, cardiac enzymes, and blood loss and replacement were evaluated. RESULTS In 796 assessable patients, aprotinin reduced thoracic drainage volume by 43% (P < .0001) and requirement for red blood cell administration by 49% (P < .0001). Among 703 patients with assessable saphenous vein grafts, occlusions occurred in 15.4% of aprotinin-treated patients and 10.9% of patients receiving placebo (P = .03). After we had adjusted for risk factors associated with vein graft occlusion, the aprotinin versus placebo risk ratio decreased from 1.7 to 1.05 (90% confidence interval, 0.6 to 1.8). These factors included female gender, lack of prior aspirin therapy, small and poor distal vessel quality, and possibly use of aprotinin-treated blood as excised vein perfusate. At United States sites, patients had characteristics more favorable for graft patency, and occlusions occurred in 9.4% of the aprotinin group and 9.5% of the placebo group (P = .72). At Danish and Israeli sites, where patients had more adverse characteristics, occlusions occurred in 23.0% of aprotinin- and 12.4% of placebo-treated patients (P = .01). Aprotinin did not affect the occurrence of myocardial infarction (aprotinin: 2.9%; placebo: 3.8%) or mortality (aprotinin: 1.4%; placebo: 1.6%). CONCLUSIONS In this study, the probability of early vein graft occlusion was increased by aprotinin, but this outcome was promoted by multiple risk factors for graft occlusion.

Aprotinin for Primary Coronary Artery Bypass Grafting: A Multicenter Trial of Three Dose Regimens

BACKGROUND High-dose aprotinin reduces transfusion requirements in patients undergoing coronary artery bypass grafting, but the safety and effectiveness of smaller doses is unclear. Furthermore, patient selection criteria for optimal use of the drug are not well defined. METHODS Seven hundred and four first-time coronary artery bypass grafting patients were randomized to receive one of three doses of aprotinin (high, low, and pump-prime-only) or placebo. The patients were stratified as to risk of excessive bleeding. RESULTS All three aprotinin doses were highly effective in reducing bleeding and transfusion requirements. Consistent efficacy was not, however, demonstrated in the subgroup of patients at low risk for bleeding. There were no differences in mortality or the incidences of renal failure, strokes, or definite myocardial infarctions between the groups, although the pump-prime-only dose was associated with a small increase in definite, probable, or possible myocardial infarctions (p = 0.045). CONCLUSIONS Low-dose and pump-prime-only aprotinin regimens provide reductions in bleeding and transfusion requirements that are similar to those of high-dose regimens. Although safe, aprotinin is not routinely indicated for the first-time coronary artery bypass grafting patient who is at low risk for postoperative bleeding. The pump-prime-only dose is not currently recommended because of a possible association with more frequent myocardial infarctions.

The heart team of cardiovascular care.

The management of complex cardiovascular disease has changed markedly with the development of new strategies of care, an increasing amount of scientific evidence-based data and appropriate use criteria. Applying this plethora of information and synthesizing it for presentation and recommendations to the patient and family have assumed central importance. To facilitate this process of patient centric evidence-based care multidisciplinary Heart Teams have become identified as cornerstones. While specific strategies for implementation of these teams will vary, this broad approach will become the standard of cardiovascular care.

Postoperative Atrial Fibrillation Significantly Increases Mortality, Hospital Readmission, and Hospital Costs

BACKGROUND New-onset postoperative atrial fibrillation (POAF) is the most common complication following cardiac surgery. However, the magnitude of POAF on length of stay, resource utilization, and readmission rates remains an area of clinical interest. The purpose of this study was to examine the risk-adjusted impact of POAF on measures of mortality, hospital resources, and costs among multiple centers. METHODS A total of 49,264 patient records from a multi-institutional Society of Thoracic Surgeons (STS) certified database for cardiac operations (2001 to 2012) were extracted and stratified by the presence of POAF (19%) versus non-POAF (81%). The influence of POAF on outcomes was assessed by hierarchic regression modeling, adjusted for calculated STS predictive risk indices. RESULTS Mean age was 64±11 years, and median STS predicted risk of mortality for patients who developed POAF were incrementally higher (2% vs 1%, p<0.001) compared with non-POAF patients. The rate of POAF was highest among those undergoing aortic valve replacement+coronary artery bypass grafting, aortic valve, and mitral valve replacement operations. The POAF patients had a higher unadjusted incidence of mortality, morbidity, hospital readmission, longer intensive care unit (ICU) and postoperative length of stay, and higher hospital costs. After risk adjustment, POAF was associated with a twofold increase in the odds of mortality (adjusted odds ratio=2.04, p<0.001), greater hospital resource utilization, and increased costs; POAF was associated with 48 additional ICU hours (p<0.001), 3 additional hospital days (p<0.001), and

Performance of EuroSCORE II in a large US database: implications for transcatheter aortic valve implantation

3,000 (p<0.001) and

Costs for Surgical Aortic Valve Replacement According to Preoperative Risk Categories

9,000 (p<0.001) of increased ICU and total hospital-related costs, respectively. CONCLUSIONS New onset POAF is associated with increased risk-adjusted mortality, hospital costs, and readmission rates. Protocols to reduce the incidence of POAF have the potential to significantly impact patient outcomes and the delivery of high-quality, cost-effective patient care.

Regional collaboration as a model for fostering accountability and transforming health care.

OBJECTIVES Validation studies of European system for cardiac operative risk evaluation II (EuroSCORE II) have been limited to European datasets. Therefore, the aims of this study were to assess the performance of EuroSCORE II in a large multicentre US database, and compare it with the Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM). In addition, implications for patient selection for transcatheter aortic valve implantation (TAVI) were explored. METHODS EuroSCORE II and the STS-PROM were calculated for 50 588 patients from a multi-institutional statewide database of all cardiac surgeries performed since 2003. Model performance was assessed using the area under the receiver operator curve (AUC), observed vs expected (O:E) ratios and calibration plots. Analyses were performed for isolated coronary artery bypass grafting (CABG) (n = 40 871), aortic valve replacement (AVR) (n = 4107), AVR + CABG (n = 3480), mitral valve (MV) replacement (n = 1071) and MV repair (n = 1059). RESULTS The overall in-hospital mortality rate was 2.1%. EuroSCORE II was outperformed by the STS-PROM in the overall cohort with regard to discrimination (AUC = 0.77 vs 0.81, respectively; P < 0.001) and calibration (O:E = 0.68 vs 0.80, respectively). Discrimination for CABG was worse with EuroSCORE II (AUC = 0.77 vs STS-PROM: 0.81, P < 0.001). For other procedures discrimination was similar: AVR (AUC = 0.71 vs STS-PROM: 0.74, P = 0.40), AVR + CABG (AUC = 0.72 vs STS-PROM: 0.74, P = 0.47), MV repair (AUC = 0.82 vs STS-PROM: 0.86, P = 0.55) and MV replacement (AUC = 0.78 vs STS-PROM: 0.79, P = 0.69). Calibration of EuroSCORE II was worse for CABG (O:E = 0.68 vs STS-PROM: 0.80), similar in AVR + CABG (O:E = 0.76 vs STS-PROM: 0.70) and MV repair (O:E = 0.64 vs STS-PROM: 0.67), while EuroSCORE II may be more accurate in AVR (O:E = 0.96 vs STS-PROM: 0.76). Performance of both models improved when only recent cases (after 1 January 2008) were used. Ongoing TAVI trials aimed at patients with an estimated 4-10% risk of mortality are enrolling patients with mean estimated risks of 6.2% (EuroSCORE II) or 6.0% (STS-PROM), and an actual mortality rate of 4.6% (EuroSCORE II) or 4.8% (STS-PROM). CONCLUSIONS In a large US multicentre database, the STS-PROM performs better than EuroSCORE II for CABG. However, EuroSCORE II is a reasonable alternative in low-risk CABG patients and in those undergoing other cardiac surgical procedures. Clinical trials and physicians that use these scores recruit and treat patients who are at a lower risk than anticipated. This potentially leads to overtreatment with an investigational device. Decision-making should not solely be based on risk scores, but should comprise multidisciplinary heart team discussions.

Mitral valve repair rates correlate with surgeon and institutional experience

BACKGROUND The introduction of transcatheter aortic valve replacement (TAVR) led to more rigorous evaluation of surgical aortic valve replacement (SAVR) as a benchmark for TAVR. However, limited real-life cost data of SAVR are available. Therefore, the purpose of our study was to assess actual costs and resource utilization of SAVR in patients at different operating risk. METHODS Study data were drawn from a multi-institutional statewide database comprised of all cardiac surgical procedures in the Commonwealth of Virginia. The study included 2,530 elective, primary, isolated SAVRs performed from 2003 to 2012. Clinical data were matched with universal billing data. Patients were stratified into low-, intermediate- and high-risk categories according to the Society of Thoracic Surgeons- Predicted Risk of Mortality (STS-PROM) score: 0% to 4%, 4% to 8% , and greater than 8%, respectively. Clinical outcomes, resource use, and costs were compared between categories. RESULTS With increasing risk, there were higher rates of postoperative mortality (low 1.2% versus intermediate 2.7% versus high 6.2%, p < 0.001) and renal failure (2.7% vs 7.2% vs 10.6%; p < 0.001). The proportion of patients with any postoperative complication was higher with increasing risk (34% vs 48% vs 53%; p < 0.001). Length-of-stay increased from 6.8 days in the low-risk category to 10.2 and 11.3 days in the intermediate- and high-risk category, respectively (p < 0.001). There was an increase in mean total costs from the low- (n = 2,002) to intermediate- (n = 415) to high-risk (n = 113) category (