Sean M. O’Brien

Impact of renal dysfunction on outcomes of coronary artery bypass surgery : Results from the society of thoracic surgeons national adult cardiac database

Background— Although patients with end-stage renal disease are known to be at high risk for mortality after coronary artery bypass graft (CABG) surgery, the impact of lesser degrees of renal impairment has not been well studied. The purpose of this study was to compare outcomes in patients undergoing CABG with a range from normal renal function to dependence on dialysis. Methods and Results— We reviewed 483 914 patients receiving isolated CABG from July 2000 to December 2003, using the Society of Thoracic Surgeons National Adult Cardiac Database. Glomerular filtration rate (GFR) was estimated for patients with the use of the Modification of Diet in Renal Disease study formula. Multivariable logistic regression was used to determine the association of GFR with operative mortality and morbidities (stroke, reoperation, deep sternal infection, ventilation >48 hours, postoperative stay >2 weeks) after adjustment for 27 other known clinical risk factors. Preoperative renal dysfunction (RD) was common among CABG patients, with 51% having mild RD (GFR 60 to 90 mL/min per 1.73 m2, excludes dialysis), 24% moderate RD (GFR 30 to 59 mL/min per 1.73 m2, excludes dialysis), 2% severe RD (GFR <30 mL/min per 1.73 m2, excludes dialysis), and 1.5% requiring dialysis. Operative mortality rose inversely with declining renal function, from 1.3% for those with normal renal function to 9.3% for patients with severe RD not on dialysis and 9.0% for those who were dialysis dependent. After adjustment for other covariates, preoperative GFR was one of the most powerful predictors of operative mortality and morbidities. Conclusions— Preoperative RD is common in the CABG population and carries important prognostic importance. Assessment of preoperative renal function should be incorporated into clinical risk assessment and prediction models.

Outcomes Following Transcatheter Aortic Valve Replacement in the United States

IMPORTANCE Transcatheter aortic valve replacement (TAVR) was approved by the US Food and Drug Administration for the treatment of severe, symptomatic aortic stenosis and inoperable status (in 2011) and high-risk but operable status (starting in 2012). A national registry (the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy [STS/ACC TVT] Registry) was initiated to meet a condition for Medicare coverage and also facilitates outcome assessment and comparison with other trials and international registries. OBJECTIVE To report the initial US commercial experience with TAVR. DESIGN, SETTING, AND PARTICIPANTS We obtained results from all eligible US TAVR cases (n=7710) from 224 participating registry hospitals following the Edwards Sapien XT device commercialization (November 2011-May 2013). MAIN OUTCOMES AND MEASURES Primary outcomes included all-cause in-hospital mortality and stroke following TAVR. Secondary analyses included procedural complications and outcomes by clinical indication and access site. Device implantation success was defined as successful vascular access, deployment of a single device in the proper anatomic position, appropriate valve function without either moderate or severe AR, and successful retrieval of the delivery system. Thirty-day outcomes are presented for a representative 3133 cases (40.6%) at 114 centers with at least 80% complete follow-up reporting. RESULTS The 7710 patients who underwent TAVR included 1559 (20%) cases that were inoperable and 6151 (80%) cases that were high-risk but operable. The median age was 84 years (interquartile range [IQR], 78-88 years); 3783 patients (49%) were women and the median STS predicted risk of mortality was 7% (IQR, 5%-11%). At baseline, 2176 patients (75%) were either not at all satisfied (1297 patients [45%]) or mostly dissatisfied (879 patients [30%]) with their symptom status; 2198 (72%) had a 5-m walk time longer than 6 seconds (slow gait speed). The most common vascular access approach was transfemoral (4972 patients [64%]), followed by transapical (2197 patients [29%]) and other alternative approaches (536 patients [7%]); successful device implantation occurred in 7069 patients (92%; 95% CI, 91%-92%). The observed incidence of in-hospital mortality was 5.5% (95% CI, 5.0%-6.1%). Other major complications included stroke (2.0%; 95% CI, 1.7%-2.4%), dialysis-dependent renal failure (1.9%; 95% CI, 1.6%-2.2%), and major vascular injury (6.4%; 95% CI, 5.8%-6.9%). Median hospital stay was 6 days (IQR, 4-10 days), with 4613 (63%) discharged home. Among patients with available follow-up at 30 days (n=3133), the incidence of mortality was 7.6% (95% CI, 6.7%-8.6%) (noncardiovascular cause, 52%); a stroke had occurred in 2.8% (95% CI, 2.3%-3.5%), new dialysis in 2.5% (95% CI, 2.0%-3.1%), and reintervention in 0.5% (95% CI, 0.3%-0.8%). CONCLUSIONS AND RELEVANCE Among patients undergoing TAVR at US centers in the STS/ACC TVT Registry, device implantation success was achieved in 92% of cases, the overall in-hospital mortality rate was 5.5%, and the stroke rate was 2.0%. Although these postmarket US approval findings are comparable with prior published trial data and international experience, long-term follow-up is essential to assess continued efficacy and safety. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01737528.

Bedside Tool for Predicting the Risk of Postoperative Dialysis in Patients Undergoing Cardiac Surgery

Background— Estimation of an individual patient’s risk for postoperative dialysis can support informed clinical decision making and patient counseling. Methods and Results— To develop a simple bedside risk algorithm for estimating patients’ probability for dialysis after cardiac surgery, we evaluated data of 449 524 patients undergoing coronary artery bypass grafting (CABG) and/or valve surgery and enrolled in >600 hospitals participating in the Society of Thoracic Surgeons National Database (2002–2004). Logistic regression was used to identify major predictors of postoperative dialysis. Model coefficients were then converted into an additive risk score and internally validated. The model also was validated in a second sample of 86 009 patients undergoing cardiac surgery from January to June 2005. Postoperative dialysis was needed in 6451 patients after cardiac surgery (1.4%), ranging from 1.1% for isolated CABG procedures to 5.1% for CABG plus mitral valve surgery. Multivariable analysis identified preoperative serum creatinine, age, race, type of surgery (CABG plus valve or valve only versus CABG only), diabetes, shock, New York Heart Association class, lung disease, recent myocardial infarction, and prior cardiovascular surgery to be associated with need for postoperative dialysis (c statistic=0.83). The risk score accurately differentiated patients’ need for postoperative dialysis across a broad risk spectrum and performed well in patients undergoing isolated CABG, off-pump CABG, isolated aortic valve surgery, aortic valve surgery plus CABG, isolated mitral valve surgery, and mitral valve surgery plus CABG (c statistic=0.83, 0.85, 0.81, 0.75, 0.80, and 0.75, respectively). Conclusions— Our study identifies the major patient risk factors for postoperative dialysis after cardiac surgery. These risk factors have been converted into a simple, accurate bedside risk tool. This tool should facilitate improved clinician–patient discussions about risks of postoperative dialysis.

Trends in isolated coronary artery bypass grafting: An analysis of the Society of Thoracic Surgeons adult cardiac surgery database

OBJECTIVE Coronary artery bypass grafting (CABG) is the operation most commonly performed by cardiac surgeons. There are few contemporary data examining evolving patient characteristics and surgical outcomes of isolated CABG. We used the Society of Thoracic Surgeons adult cardiac surgery database to characterize trends in patient characteristics and outcomes after CABG over the past decade. METHODS From 2000 to 2009, 1,497,254 patients underwent isolated primary CABG at Society of Thoracic Surgeons participating institutions. Demographics, operative characteristics, and postoperative outcomes were assessed, and risk-adjusted outcomes were calculated. RESULTS Compared with the year 2000, patients undergoing isolated primary CABG in 2009 were more likely to have diabetes mellitus (33% vs 40%) and hypertension (71% vs 85%). There were clinically insignificant differences in age, gender, and body surface area. Between 2000 and 2009, there has been a 6.3% and 19.5% increase in the preoperative use of aspirin and beta-blockers, respectively. Between 2004 and 2009, there was a 7.8% increase in the use of angiotension-converting enzyme inhibitors preoperatively. Furthermore, between 2005 and 2009 there was a 3.8% increase in the use of statins preoperatively. The median number of distal anastomoses performed was unchanged between 2000 and 2009 (3; interquartile range, 2-4). There was a significant increase in the use of the internal thoracic artery (88% in 2000 vs 95% in 2009). The predicted mortality rates of 2.3% were consistent between 2000 and 2009. The observed mortality rate over this period declined from 2.4% in 2000 to 1.9% in 2009 representing a relative risk reduction of 24.4%. The incidence of postoperative stroke decreased significantly from 1.6% to 1.2%, representing a risk reduction of 26.4%. There was also a 9.2% relative reduction in the risk of reoperation for bleeding and a 32.9% relative risk reduction in the incidence of sternal wound infection. CONCLUSIONS Over the past decade, the risk profile of patients undergoing CABG has changed, with fewer smokers, more diabetic patients, and better medical therapy characterizing patients referred for surgical coronary revascularization. The left internal thoracic artery is nearly universally used and outcomes have improved substantially, with a significant decline in postoperative mortality and morbidity.

Clinical Predictors of Major Infections After Cardiac Surgery

Background—Major infections are infrequent but important complications of cardiac surgery. Predicting their occurrence is essential for future prevention. The objective of the current investigation was to create and validate a bedside scoring system to estimate patient risk for major infection (mediastinitis, thoracotomy or vein harvest site infection, or septicemia) after coronary artery bypass grafting. Methods and Results—Using the Society of Thoracic Surgeons National Cardiac Database, we analyzed 331 429 coronary artery bypass grafting cases from January 1, 2002, to December 31, 2003, to identify risk factors for major infection. Using logistic regression, 2 models were generated and validated using split-sample validation: (1) One limited to preoperative characteristics (preop model) and (2) one model including both preoperative and intraoperative characteristics (combined model). Major infection occurred in 11 636 patients (3.51%) (25.1% mediastinitis, 32.6% saphenous harvest site, 35.0% septicemia, 0.5% thoracotomy, 6.8% multiple sites). Patients with major infection had significantly higher mortality (17.3% versus 3.0%, P<0.0001) and postoperative length of stay >14 days (47.0% versus 5.9%, P<0.0001) than patients without major infection. Both the preop model (c-index 0.697) and combined model (c-index: 0.708) successfully discriminated between high- and low-risk patients. A simplified risk scoring system of 12 variables accurately predicted risk for major infection. Conclusions—We identified and validated a model that can identify patients undergoing cardiac surgery who are at high risk for major infection. These high-risk patients may be targeted for perioperative intervention strategies to reduce rates of major infection.

Influence of Hospital Procedural Volume on Care Process and Mortality for Patients Undergoing Elective Surgery for Mitral Regurgitation

Background— Few studies have examined the procedural volume–outcome relationship for heart valve surgery. None have examined process of care factors that may be mediators of this association. Methods and Results— This was a retrospective review of outcomes for 13 614 patients having elective surgery for mitral regurgitation between 2000 and 2003 in 575 North American centers participating in the Society of Thoracic Surgeons National Cardiac Database. Hospital annual mitral valve volume varied widely from 22 cases per year in the lowest-volume quartile to 394 in the highest. Unadjusted mortality rates decreased from 3.08% in the lowest-volume category to 1.11% in the highest-volume category. The risk-adjusted odds ratio for mortality in the highest-volume category compared with the lowest was 0.48 (95% confidence interval 0.28 to 0.82). The rates of mitral valve repair increased from 47.7% in the lowest-volume quartile to 77.4% in high-volume hospitals (P<0.0001). Similarly, the rates of bioprosthetic valve use for patients aged >65 years rose from 59% in the lowest-volume quartile to 75% in the highest-volume quartile (P=0.0002). The association between volume and mortality was still significant but attenuated when the risk adjustment was modified to adjust for mitral valve repair versus replacement. Conclusions— Hospital procedural volume was associated with higher frequency of valve repair, higher frequency of prosthetic valve usage in elderly patients, and lower adjusted operative mortality. Differences in care process may contribute to improved outcomes in higher-volume centers.

Clinical Outcomes at 1 Year Following Transcatheter Aortic Valve Replacement

IMPORTANCE Introducing new medical devices into routine practice raises concerns because patients and outcomes may differ from those in randomized trials. OBJECTIVE To update the previous report of 30-day outcomes and present 1-year outcomes following transcatheter aortic valve replacement (TAVR) in the United States. DESIGN, SETTING, AND PARTICIPANTS Data from the Society of Thoracic Surgeons/American College of Cardiology (STS/ACC) Transcatheter Valve Therapies Registry were linked with patient-specific Centers for Medicare & Medicaid Services (CMS) administrative claims data. At 299 US hospitals, 12 182 patients linked with CMS data underwent TAVR procedures performed from November 2011 through June 30, 2013, and the end of the follow-up period was June 30, 2014. EXPOSURE Transcatheter aortic valve replacement. MAIN OUTCOMES AND MEASURES One-year outcomes including mortality, stroke, and rehospitalization were evaluated using multivariate modeling. RESULTS The median age of patients was 84 years and 52% were women, with a median STS Predicted Risk of Operative Mortality (STS PROM) score of 7.1%. Following the TAVR procedure, 59.8% were discharged to home and the 30-day mortality was 7.0% (95% CI, 6.5%-7.4%) (n = 847 deaths). In the first year after TAVR, patients were alive and out of the hospital for a median of 353 days (interquartile range, 312-359 days); 24.4% (n = 2074) of survivors were rehospitalized once and 12.5% (n = 1525) were rehospitalized twice. By 1 year, the overall mortality rate was 23.7% (95% CI, 22.8%-24.5%) (n = 2450 deaths), the stroke rate was 4.1% (95% CI, 3.7%-4.5%) (n = 455 stroke events), and the rate of the composite outcome of mortality and stroke was 26.0% (25.1%-26.8%) (n = 2719 events). Characteristics significantly associated with 1-year mortality included advanced age (hazard ratio [HR] for ≥95 vs <75 years, 1.61 [95% CI, 1.24-2.09]; HR for 85-94 years vs <75 years, 1.35 [95% CI, 1.18-1.55]; and HR for 75-84 years vs <75 years, 1.23 [95% CI, 1.08-1.41]), male sex (HR, 1.21; 95% CI, 1.12-1.31), end-stage renal disease (HR, 1.66; 95% CI, 1.41-1.95), severe chronic obstructive pulmonary disease (HR, 1.39; 95% CI, 1.25-1.55), nontransfemoral access (HR, 1.37; 95% CI, 1.27-1.48), STS PROM score greater than 15% vs less than 8% (HR, 1.82; 95% CI, 1.60-2.06), and preoperative atrial fibrillation/flutter (HR, 1.37; 95% CI, 1.27-1.48). Compared with men, women had a higher risk of stroke (HR, 1.40; 95% CI, 1.15-1.71). CONCLUSIONS AND RELEVANCE Among patients undergoing TAVR in US clinical practice, at 1-year follow-up, overall mortality was 23.7%, the stroke rate was 4.1%, and the rate of the composite outcome of death and stroke was 26.0%. These findings should be helpful in discussions with patients undergoing TAVR.

Atrial Fibrillation Correction Surgery: Lessons From The Society of Thoracic Surgeons National Cardiac Database

BACKGROUND We used The Society of Thoracic Surgeons National Cardiac Database to document the utilization of surgical atrial fibrillation (AF) correction procedures in North America. We also examined the subset of patients having mitral valve surgery to determine whether concurrent surgical AF correction procedures were associated with an increased risk of morbidity or mortality. METHODS Retrospective review of outcomes for 67,389 patients with AF having cardiac surgery between January 2004 and December 2006 was conducted. Multivariable logistic regression was performed to assess whether concomitant AF correction procedures increased risk in the mitral valve surgery cohort. RESULTS Overall, 38% (25,718 of 67,389) of patients with AF undergoing cardiac surgery had an AF correction procedure, increasing from 28.1% in 2004 to 40.2% in 2006. Surgical AF correction was performed in 52% (6,415 of 12,235) of mitral valve surgery patients, 28% (2,965 of 10,590) of those having aortic valve surgery, and 24% (5,438 of 22,388) of those having isolated coronary artery bypass grafting. After adjusting for differences in preoperative characteristics, mitral valve surgery patients with a surgical AF correction procedure did not have a significantly higher risk of mortality (adjusted odds ratio, 1.00; 95% confidence interval, 0.83 to 1.20) or major morbidity. The risk for new permanent pacemaker implantation was higher (adjusted odds ratio, 1.26; 95% confidence interval, 1.07 to 1.49) in the AF correction with mitral valve surgery group. CONCLUSIONS Although a growing number of patients with AF are treated with concurrent AF correction procedures during cardiac surgery, nearly 60% of patients are left untreated. Among patients with AF and mitral valve disease, the addition of an AF correction procedure does not increase perioperative morbidity or mortality.

An empirically based tool for analyzing morbidity associated with operations for congenital heart disease

OBJECTIVE Congenital heart surgery outcomes analysis requires reliable methods of estimating the risk of adverse outcomes. Contemporary methods focus primarily on mortality or rely on expert opinion to estimate morbidity associated with different procedures. We created an objective, empirically based index that reflects statistically estimated risk of morbidity by procedure. METHODS Morbidity risk was estimated using data from 62,851 operations in the Society of Thoracic Surgeons Congenital Heart Surgery Database (2002-2008). Model-based estimates with 95% Bayesian credible intervals were calculated for each procedures average risk of major complications and average postoperative length of stay. These 2 measures were combined into a composite morbidity score. A total of 140 procedures were assigned scores ranging from 0.1 to 5.0 and sorted into 5 relatively homogeneous categories. RESULTS Model-estimated risk of major complications ranged from 1.0% for simple procedures to 38.2% for truncus arteriosus with interrupted aortic arch repair. Procedure-specific estimates of average postoperative length of stay ranged from 2.9 days for simple procedures to 42.6 days for a combined atrial switch and Rastelli operation. Spearman rank correlation between raw rates of major complication and average postoperative length of stay was 0.82 in procedures with n greater than 200. Rate of major complications ranged from 3.2% in category 1 to 30.0% in category 5. Aggregate average postoperative length of stay ranged from 6.3 days in category 1 to 34.0 days in category 5. CONCLUSIONS Complication rates and postoperative length of stay provide related but not redundant information about morbidity. The Morbidity Scores and Categories provide an objective assessment of risk associated with operations for congenital heart disease, which should facilitate comparison of outcomes across cohorts with differing case mixes.

Long-Term Safety and Effectiveness of Mechanical Versus Biologic Aortic Valve Prostheses in Older Patients Results From the Society of Thoracic Surgeons Adult Cardiac Surgery National Database

Background— There is a paucity of long-term data comparing biological versus mechanical aortic valve prostheses in older individuals. Methods and Results— We performed follow-up of patients aged 65 to 80 years undergoing aortic valve replacement with a biological (n=24 410) or mechanical (n=14 789) prosthesis from 1991 to 1999 at 605 centers within the Society of Thoracic Surgeons Adult Cardiac Surgery Database using Medicare inpatient claims (mean, 12.6 years; maximum, 17 years; minimum, 8 years), and outcomes were compared by propensity methods. Among Medicare-linked patients undergoing aortic valve replacement (mean age, 73 years), both reoperation (4.0%) and endocarditis (1.9%) were uncommon to 12 years; however, the risk for other adverse outcomes was high, including death (66.5%), stroke (14.1%), and bleeding (17.9%). Compared with those receiving a mechanical valve, patients given a bioprosthesis had a similar adjusted risk for death (hazard ratio, 1.04; 95% confidence interval, 1.01–1.07), higher risks for reoperation (hazard ratio, 2.55; 95% confidence interval, 2.14–3.03) and endocarditis (hazard ratio, 1.60; 95% confidence interval, 1.31–1.94), and lower risks for stroke (hazard ratio, 0.87; 95% confidence interval, 0.82–0.93) and bleeding (hazard ratio, 0.66; 95% confidence interval, 0.62–0.70). Although these results were generally consistent among patient subgroups, bioprosthesis patients aged 65 to 69 years had a substantially elevated 12-year absolute risk of reoperation (10.5%). Conclusions— Among patients undergoing aortic valve replacement, long-term mortality rates were similar for those who received bioprosthetic versus mechanical valves. Bioprostheses were associated with a higher long-term risk of reoperation and endocarditis but a lower risk of stroke and hemorrhage. These risks varied as a function of a patient’s age and comorbidities.