Systematic review and meta-analysis of mortality risk prediction models in adult cardiac surgery

OBJECTIVES

The most used mortality risk prediction models in cardiac surgery are the European System for Cardiac Operative Risk Evaluation (ES) and Society of Thoracic Surgeons (STS) score. There is no agreement on which score should be considered more accurate nor which score should be utilized in each population subgroup. We sought to provide a thorough quantitative assessment of these 2 models.

METHODS

We performed a systematic literature review and captured information on discrimination, as quantified by the area under the receiver operator curve (AUC), and calibration, as quantified by the ratio of observed-to-expected mortality (O:E). We performed random effects meta-analysis of the performance of the individual models as well as pairwise comparisons and subgroup analysis by procedure type, time and continent.

RESULTS

The ES2 {AUC 0.783 [95% confidence interval (CI) 0.765–0.800]; O:E 1.102 (95% CI 0.943–1.289)} and STS [AUC 0.757 (95% CI 0.727–0.785); O:E 1.111 (95% CI 0.853–1.447)] showed good overall discrimination and calibration. There was no significant difference in the discrimination of the 2 models (difference in AUC −0.016; 95% CI −0.034 to −0.002; P = 0.09). However, the calibration of ES2 showed significant geographical variations (P < 0.001) and a trend towards miscalibration with time (P=0.057). This was not seen with STS.

CONCLUSIONS

ES2 and STS are reliable predictors of short-term mortality following adult cardiac surgery in the populations from which they were derived. STS may have broader applications when comparing outcomes across continents as compared to ES2.

REGISTRATION

Prospero (https://www.crd.york.ac.uk/PROSPERO/) CRD42020220983.

Performance of EuroSCORE II and Society of Thoracic Surgeons risk scores in elderly patients undergoing aortic valve replacement surgery

BACKGROUND

In cardiac surgery, risk is estimated with models such as EuroSCORE II and the Society of Thoracic Surgeons (STS) score. Performance of these scores may vary across various patient age ranges.

AIM

To assess the effect of patient age on performance of the EuroSCORE II and STS scores, regarding postoperative mortality after surgical aortic valve replacement.

METHODS

In a prospective cohort of patients, we assessed risk stratification of EuroSCORE II and STS scores for discrimination of in-hospital mortality with the area under the receiver operating characteristic curve (AUROC) and calibration with the Hosmer-Lemeshow test. Two groups of patients were compared: elderly (aged>75years) and younger patients.

RESULTS

Of 1229 patients included, 635 (51.7%) were elderly. Mean EuroSCORE II score was 3.7±4.4% and mean STS score was 2.1±1.5%. Overall in-hospital mortality was 4.8% and was higher in the elderly compared with younger patients (6.6% vs. 2.8%; log-rank P=0.014). AUROC for the EuroSCORE II score was lower in elderly than in younger patients (0.731 vs. 0.784; P=0.025). Similarly, AUROC for the STS score was lower in elderly versus younger patients (0.738 vs. 0.768; P=0.017). In elderly patients, EuroSCORE II and STS scores were not adequately calibrated and significantly underestimated mortality. Age was independently associated with mortality, regardless of EuroSCORE II or STS score.

CONCLUSIONS

In this cohort, EuroSCORE II and STS scores did not perform as well in elderly patients as in younger patients. Elderly patients may be at increased postoperative risk, regardless of risk score.

MAGGIC, STS, and EuroSCORE II Risk Score Comparison After Aortic and Mitral Valve Surgery

OBJECTIVES

To compare the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) risk score with the established Society of Thoracic Surgeons (STS) and EuroSCORE II risk prediction models regarding mortality discrimination after aortic and mitral valve surgery.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary academic medical center.

PARTICIPANTS

A total of 259 patients who underwent open aortic valve replacement or open mitral valve repair/replacement from 2009-2014.

INTERVENTIONS

Retrospective chart review.

MEASUREMENTS AND MAIN RESULTS

MAGGIC, STS, and EuroSCORE II risk scores for each patient were studied using binary logistic regression and receiver operating characteristic analysis for the primary endpoint of one-year mortality and secondary endpoint of 30-day mortality. One-year mortality C-statistics were similar across risk scores (STS 0.709, 95% confidence interval [CI] 0.578-0.841; MAGGIC 0.673, 95% CI 0.547-0.799; EuroSCORE II 0.642, 95% CI 0.521-0.762; p = 0.56 between STS and MAGGIC; p = 0.20 between STS and EuroSCORE II; and p = 0.69 between MAGGIC and EuroSCORE II). Thirty-day mortality C-statistics also were similar between STS (0.797, 95% CI 0.655-0.939; p < 0.0001 v null hypothesis), MAGGIC (0.721, 95% CI 0.581-0.860; p = 0.33 v STS), and EuroSCORE II (0.688, 95% CI 0.557-0.818; p = 0.06 v STS; p = 0.68 v MAGGIC).

CONCLUSIONS

The MAGGIC risk score performs similarly to STS and EuroSCORE II risk models in mortality discrimination after aortic and mitral valve surgery, albeit in a small sample size. This finding has important implications in establishing MAGGIC as a viable prognostic model in this population subset, with fewer variables and ease of use representing key advantages over STS and EuroSCORE II.

Quantifying the impact from stroke during support with continuous flow ventricular assist devices: An STS INTERMACS analysis

INTRODUCTION

Adverse events, especially strokes, during the implantation of continuous flow durable left ventricular assist devices (LVADs) remain the major barriers to greater application among patients with ambulatory advanced heart failure.

METHODS

Between June 2014 and June 2017, a total of 9,489 patients in the Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support database received 10,285 continuous flow LVADs, with follow-up through June 2018.

RESULTS

During the follow-up period, 1,515 (16%) patients suffered 1 or more strokes, with a nearly equal frequency of ischemic and hemorrhagic etiology. The risk of stroke was about 4% in the first month, 9% during the first 6 months, and 14% in the first year. By multivariable hazard function analysis, the major risk factors identified in the early phase were LVAD centrifugal flow device and concomitant cardiac surgery, whereas in the constant phase (longer term), a history of repeated non-compliance was most associated with a stroke event. Using a modulated renewal model, the occurrence of an ischemic and especially a hemorrhagic stroke dominated as risk factors for subsequent mortality. Six-month survival after an ischemic stroke was 70%, and after a hemorrhagic stroke, it was <50%. Disabling stroke as judged by Modified Rankin Score was associated with significantly worse survival at 1 and 2 years compared with strokes with mild or no early disability.

CONCLUSIONS

This study confirms the 20% incidence of stroke over the first 2 years with axial flow and hybrid (magnetic and hydrodynamic) levitated centrifugal flow pumps. This study suggests a major increase in 1- and 2-year mortality among those with an initial disabling vs non-disabling stroke. To better understand the impact of strokes after implantation and the effect of prevention and intervention strategies, we need more complete Modified Rankin Scores and quality of life data during the stroke recovery period.

Myocardial revascularization: the evolution of the STS database and quality measurement for improvement

The Society of Thoracic Surgeons (STS) is a not-for-profit organization dedicated to helping clinicians and researchers provide optimal outcomes for patients undergoing heart, lung, and esophageal surgery. The organization was founded in 1964 and has grown to now include over 7300 members in over 90 countries. The STS created a national database that collects detailed clinical information on patients undergoing adult cardiac, pediatric and congenital cardiac, and general thoracic operations. The data collected are used to produce risk-adjusted, nationally benchmarked performance assessments and feedback; facilitate voluntary public reporting; support quality initiatives; develop evidence-based guidelines; monitor long-term clinical outcomes; track device performance; and promote high-quality research collaboratives.

Characterizing cardiac arrest in children undergoing cardiac surgery: A single-center study

OBJECTIVES

To characterize cardiac arrest in children undergoing cardiac surgery using single-center data from the Society of Thoracic Surgeons and Pediatric Advanced Life Support Utstein-Style Guidelines.

METHODS

Patients aged 18 years or less having a cardiac arrest for 1 minute or more during the same hospital stay as heart operation qualified for inclusion (2002-2014). Patients having a cardiac arrest both before or after heart operation were included. Heart operations were classified on the basis of the first cardiovascular operation of each hospital admission (the index operation). The primary outcome was survival to hospital discharge.

RESULTS

A total of 3437 children undergoing at least 1 heart operation were included. Overall rate of cardiac arrest among these patients was 4.5% (n = 154) with survival to hospital discharge of 84 patients (66.6%). Presurgery cardiac arrest was noted among 28 patients, with survival of 21 patients (75%). Among the 126 patients with postsurgery cardiac arrest, survival was noted among 84 patients (66.6%). Regardless of surgical case complexity, the median days between heart operation and cardiac arrest, duration of cardiac arrest, and survival after cardiac arrest were similar. The independent risk factors associated with improved chances of survival included shorter duration of cardiac arrest (odds ratio, 1.12; 95% confidence interval, 1.05-1.20; P = .01) and use of defibrillator (odds ratio, 4.51; 95% confidence interval, 1.08-18.87; P = .03).

CONCLUSIONS

This single-center study demonstrates that characterizing cardiac arrest in children undergoing cardiac surgery using definitions from 2 societies helps to increase data granularity and understand the relationship between cardiac arrest and heart operation in a better way.

New frontiers in aortic therapy: focus on current trials and devices in transcatheter aortic valve replacement

The first decade of clinical experience with transcatheter aortic valve replacement since 2002 saw the development of 2 main valve systems, namely the Edwards Sapien balloon-expandable valve series and the Medtronic self-expanding CoreValve. These 2 valve platforms now have achieved commercial approval and application worldwide in patients with severe aortic stenosis whose perioperative risk for surgical intervention is high or extreme. In the second decade of transcatheter aortic valve replacement, clinical experience and refinements in valve design have resulted in clinical drift towards lower patient risk cohorts. There are currently 2 major trials, PARTNER II and SURTAVI, that are both evaluating the role of transcatheter aortic valve replacement in intermediate-risk patient cohorts. The results from these landmark trials may usher in a new clinical paradigm for transcatheter aortic valve replacement in its second decade.

Heart valve surgery: EuroSCORE vs. EuroSCORE II vs. Society of Thoracic Surgeons score

BACKGROUND

This is a validation study comparing the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II with the previous additive (AES) and logistic EuroSCORE (LES) and the Society of Thoracic Surgeons' (STS) risk prediction algorithm, for patients undergoing valve replacement with or without bypass in Pakistan.

PATIENTS AND METHODS

Clinical data of 576 patients undergoing valve replacement surgery between 2006 and 2013 were retrospectively collected and individual expected risks of death were calculated by all four risk prediction algorithms. Performance of these risk algorithms was evaluated in terms of discrimination and calibration.

RESULTS

There were 28 deaths (4.8%) among 576 patients, which was lower than the predicted mortality of 5.16%, 6.96% and 4.94% by AES, LES and EuroSCORE II but was higher than 2.13% predicted by STS scoring system. For single and double valve replacement procedures, EuroSCORE II was the best predictor of mortality with highest Hosmer and Lemmeshow test (H-L) p value (0.346 to 0.689) and area under the receiver operating characteristic (ROC) curve (0.637 to 0.898). For valve plus concomitant coronary artery bypass grafting (CABG) patients actual mortality was 1.88%. STS calculator came out to be the best predictor of mortality for this subgroup with H-L p value (0.480 to 0.884) and ROC (0.657 to 0.775).

CONCLUSIONS

For Pakistani population EuroSCORE II is an accurate predictor for individual operative risk in patients undergoing isolated valve surgery, whereas STS performs better in the valve plus CABG group.

Chronic obstructive pulmonary disease in patients undergoing transcatheter aortic valve implantation: insights on clinical outcomes, prognostic markers, and functional status changes

OBJECTIVES

This study sought to determine the effects of chronic obstructive pulmonary disease (COPD) on clinical outcomes in patients undergoing transcatheter aortic valve implantation (TAVI) and to determine the factors associated with worse outcomes in COPD patients.

BACKGROUND

No data exist on the factors determining poorer outcomes in COPD patients undergoing TAVI.

METHODS

A total of 319 consecutive patients (29.5% with COPD) who underwent TAVI were studied. Functional status was evaluated by New York Heart Association (NYHA) functional class, Duke Activity Status Index, and the 6-min walk test (6MWT) at baseline and at 6 to 12 months. The TAVI treatment was considered futile if the patient either died or did not improve in NYHA functional class at 6-month follow-up.

RESULTS

Survival rates at 1 year were 70.6% in COPD patients and 84.5% in patients without COPD (p = 0.008). COPD was an independent predictor of cumulative mortality after TAVI (hazard ratio: 1.84; 95% confidence interval: 1.08 to 3.13; p = 0.026). Improvement in functional status was observed after TAVI (p < 0.001 for NYHA functional class, Duke Activity Status Index, and 6MWT), but COPD patients exhibited less (p = 0.036) improvement in NYHA functional class. Among COPD patients, a shorter 6MWT distance predicted cumulative mortality (p = 0.013), whereas poorer baseline spirometry results (FEV1 [forced expiratory volume in the first second of expiration]) determined a higher rate of periprocedural pulmonary complications (p = 0.040). The TAVI treatment was futile in 40 COPD patients (42.5%) and a baseline 6MWT distance <170 m best determined the lack of benefit after TAVI (p = 0.002).

CONCLUSIONS

COPD was associated with a higher rate of mortality at mid-term follow-up. Among COPD patients, a higher degree of airway obstruction and a lower exercise capacity determined a higher risk of pulmonary complications and mortality, respectively. TAVI was futile in more than one-third of the COPD patients, and a shorter distance walked at the 6MWT predicted the lack of benefit after TAVI. These results may help to improve the clinical decision-making process in this challenging group of patients.

Perioperative mechanical circulatory support in children: an analysis of the Society of Thoracic Surgeons Congenital Heart Surgery Database

OBJECTIVES

Analyses of mechanical circulatory support (MCS) in pediatric heart surgery have primarily focused on single-center outcomes or narrow applications. We describe the patterns of use, patient characteristics, and MCS-associated outcomes across a large multicenter cohort.

METHODS

Patients (aged <18 years) in the Society of Thoracic Surgeons (STS) Congenital Heart Surgery Database (2000-2010) were included. The characteristics and outcomes of those receiving postoperative MCS were described, and bayesian hierarchical models were used to examine variations in the adjusted MCS rates across institutions.

RESULTS

Of 96,596 operations (80 centers), MCS was used in 2.4%. The MCS patients were younger (13 vs 195 days, P < .0001) and more often had STS-defined preoperative risk factors (57.2% vs 32.7%, P < .0001). The operations with the greatest MCS rates included the Norwood procedure (17%) and complex biventricular repairs (arterial switch, ventricular septal defect, and arch repair [14%]). More than one half of the MCS patients did not survive to hospital discharge (53.2% vs 2.9% of non-MCS patients; P < .0001). MCS-associated mortality was greatest for truncus arteriosus and Ross-Konno operations (both 71%). The hospital-level MCS rates adjusted for patient characteristics and case mix varied by 15-fold across institutions, with both high- and low-volume hospitals having substantial variation in MCS rates.

CONCLUSIONS

Perioperative MCS use varied widely across centers. The MCS rates were greatest overall for the Norwood procedure and complex biventricular repairs. Although MCS can be a life-saving therapy, more than one half of MCS patients will not survive to hospital discharge, with mortality >70% for some operations. Future studies aimed at better understanding the appropriate indications, optimal timing, and management of MCS could help to reduce the variation in MCS use across hospitals and improve outcomes.

Simple bedside clinical evaluation versus established scores in the estimation of operative risk in valve replacement for severe aortic stenosis

BACKGROUND

The operative risk of cardiac surgery is ascertained preoperatively on the basis of scores validated in multinational studies. However, the value they add to a simple bedside clinical evaluation (CE) remains controversial.

AIMS

To compare operative mortality (defined as death from all causes before the 31st postoperative day) predicted by CE with that predicted by additive and logistic EuroSCOREs, EuroSCORE II and Society of Thoracic Surgeons (STS), Ambler and age-creatinine-ejection fraction (ACEF) scores in patients undergoing aortic valve replacement (AVR) for severe aortic stenosis.

METHODS

Overall, 314 consecutive patients were included who underwent AVR between October 2009 and November 2011 (22% with coronary artery bypass graft); mean age 73.4 ± 9.7 years (29% aged>80 years). Based on CE, patients were divided into four predefined groups of increasing estimated mortality risk: I ≤ 3.9%; II 4-6.9%; III 7-9.9%; IV ≥ 10%. The positive and negative predictive values of the six scores and CE were compared.

RESULTS

The observed overall operative mortality was 5.7%. The distribution of the four predicted mortality groups by each score was highly variable. The positive predictive value, calculated for the 64 patients classified at highest risk by CE (groups III or IV) or each score, was 17.2% for EuroSCORE II, 14.1% for CE and STS scores, 10.9% for additive and logistic EuroSCOREs, 10.6% for ACEF and 10.2% for Ambler. The positive predictive value of each score in the low-risk groups (I and II) ranged from 2.8% to 4.4%.

CONCLUSION

A simple bedside CE appears as reliable as the various established scores for predicting operative risk in patients undergoing surgical aortic valve replacement. The development and validation of more comprehensive risk stratification tools, including risk factors thus far neglected, seems warranted.

Incremental risk of the Cox-maze IV procedure for patients with atrial fibrillation undergoing mitral valve surgery

OBJECTIVE

More than 50% of atrial fibrillation surgery occurs in the setting of mitral valve surgery. Despite this, no risk models have been validated for concomitant arrhythmia surgery. The purpose of the present study was to quantify the additional risk of performing the Cox-maze IV procedure for patients undergoing mitral valve surgery.

METHODS

From January 2002 to June 2011, 213 patients with mitral valve disease and preoperative atrial fibrillation underwent mitral valve surgery only (n = 109) or in conjunction with a Cox-maze IV procedure (n = 104). The operative mortality for the mitral valve procedure alone was predicted for each group using the Society of Thoracic Surgeons perioperative risk calculator. The risk attributed to the added Cox-maze IV procedure was calculated by comparing the predicted mortality rate of an isolated mitral valve procedure and the actual mortality rate of mitral valve surgery with a concomitant Cox-maze IV procedure.

RESULTS

For patients not undergoing a Cox-maze IV procedure, the predicted and actual postoperative mortality rate was 5.5% and 4.6% (5 of 109), respectively. For patients receiving mitral valve surgery and a concomitant Cox-maze IV, the predicted and actual postoperative mortality of the mitral valve procedure was 2.5% and 2.9% (3 of 104), respectively, and not significantly different. Patients not offered a Cox-maze IV procedure had significantly more serious comorbidities.

CONCLUSIONS

For patients with atrial fibrillation and mitral valve disease undergoing mitral valve surgery, the decision to offer a concomitant Cox-maze IV procedure will be influenced by the underlying comorbid conditions. Nonetheless, in selected lower risk patients, the addition of a Cox-maze IV procedure did not significantly affect the procedural mortality.

Preoperative atrial fibrillation and long-term survival after open heart surgery in a rural tertiary heart institute

BACKGROUND

Preoperative atrial fibrillation (AF) is associated with increased morbidity and mortality after open heart surgery. However, the impact of preoperative AF on long-term survival after open heart surgery has not been widely examined in rural populations. Patients from rural regions are less likely to receive treatment for cardiac conditions and to have adequate medical insurance coverage.

OBJECTIVE

To examine the influence of preoperative AF on long-term survival following open heart surgery in rural eastern North Carolina.

METHODS

Long-term survival was compared in patients with and without preoperative AF after coronary artery bypass grafting (CABG) and CABG plus valve (CABG + V) surgery between 2002 and 2011. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using a Cox regression model.

RESULTS

The study population consisted of 5438 patients. A total of 263 (5%) patients had preoperative AF. Preoperative AF was an independent predictor of long-term survival (open heart surgery: adjusted HR = 1.6, 95% CI = 1.3-2.0; CABG: adjusted HR = 1.6, 95% CI = 1.3-2.1; CABG + V: adjusted HR = 1.6, 95% CI = 1.1-2.3).

CONCLUSION

Preoperative AF is an important predictor of long-term survival after open heart surgery in this rural population.

Evaluation of the reliability of clinical staging of T2 N0 esophageal cancer: a review of the Society of Thoracic Surgeons database

BACKGROUND

Clinical staging of esophageal cancer has improved with positron-emission tomography/computed tomography and endoscopic ultrasound imaging. Despite such progress, small single-center studies have questioned the reliability of clinical staging of T2 N0 esophageal cancer. This study broadly examines the adequacy of clinical staging of T2 N0 disease using The Society of Thoracic Surgeons database.

METHODS

We retrospectively studied 810 clinical stage T2 N0 patients from 2002 to 2011, with 58 excluded because of incomplete pathologic staging data. Clinical stage, pathologic stage, and preoperative characteristics were recorded. Logistic regression analysis was used to identify factors associated with upstaging at the time of surgical intervention.

RESULTS

Among 752 clinical stage T2 N0 patients, 270 (35.9%) received induction therapy before the operation. Of 482 patients who went directly to surgical intervention, 132 (27.4%) were confirmed as pathologic T2 N0, 125 (25.9%) were downstaged (ie, T0-1 N0), and 225 (46.7%) were upstaged at the operation (T3-4 N0 or Tany N1-3). Exclusive tumor upstaging (ie, pathologic T3-4 N0) accounted for 41 patients (18.2%), whereas exclusive nodal upstaging (ie, pathological T1-2 N1-3) accounted for 100 (44.5%). Combined tumor and nodal upstaging (ie, pathological T3-4 N1-3) accounted for 84 patients (37.3%). Among patients who received induction therapy, 103 (38.1%) were upstaged vs 225 (46.7%) without induction therapy (p = 0.026). Comparing the induction therapy group and the primary surgical group, postoperative 30-day mortality (3.7% vs 3.7%, p > 0.99) and morbidity (46.3% vs 45%, p = 0.76) were similar.

CONCLUSIONS

Despite advances in staging techniques, clinical staging of T2 N0 esophageal cancer remains unreliable. Recognizing T2 N0 as a threshold for induction therapy in esophageal cancer, many surgeons have opted to treat T2 N0 disease with induction therapy, even though one-quarter of these patients will be pathologic T1 N0. Although this study demonstrated similar perioperative morbidity and mortality with and without induction therapy, further study is needed to examine the effect of upstaging on long-term survival.

Trends in aortic clamp use during coronary artery bypass surgery: effect of aortic clamping strategies on neurologic outcomes

OBJECTIVE

The purpose of the present study was to determine the effect of different clamping strategies during coronary artery bypass grafting on the incidence of postoperative stroke.

METHODS

In the present case-control study, all patients at Emory hospitals from 2002 to 2009 with postoperative stroke after isolated coronary artery bypass grafting (n = 141) were matched 1:4 to a contemporaneous cohort of patients without postoperative stroke (n = 565). The patients were matched according to the Society of Thoracic Surgeons' predicted risk of postoperative stroke score, which is based on 26 variables. The patients who received on-pump and off-pump coronary artery bypass grafting were matched separately. Multiple logistic regression analysis with adjusted odds ratios was performed to identify the operative variables associated with postoperative stroke.

RESULTS

Among the on-pump cohort, the single crossclamp technique was associated with a decreased risk of stroke compared with the double clamp (crossclamp plus partial clamp) technique (odds ratio, 0.385; P = .044). Within the on-pump cohort, no significant difference was seen in the incidence of stroke according to clamp use. Epiaortic ultrasound of the ascending aorta increased from 45.3% in 2002 to 89.4% in 2009. From 2002 to 2009, clamp use decreased from 97.7% of cases to 72.7%.

CONCLUSIONS

During on-pump coronary artery bypass grafting, the use of a single crossclamp compared with the double clamp technique decreased the risk of postoperative stroke. The use of any aortic clamp decreased and epiaortic ultrasound use increased from 2002 to 2009, indicating a change in the operative technique and surgeon awareness of the potential complications associated with manipulation of the aorta.