Decreased Left Atrial Cardiomyocyte FGF13 Expression Increases Vulnerability to Postoperative Atrial Fibrillation in Humans

Postoperative atrial fibrillation (POAF) is the most common complication after cardiac surgery and a significant cause of increased morbidity and mortality. The development of novel POAF therapeutics has been limited by an insufficient understanding of molecular mechanisms promoting atrial fibrillation. In this observational cohort study, we enrolled 28 patients without a history of atrial fibrillation that underwent mitral valve surgery for degenerative mitral regurgitation and obtained left atrial tissue samples along the standard atriotomy incision in proximity to the right pulmonary veins. We isolated cardiomyocytes and performed transcriptome analyses demonstrating 13 differentially expressed genes associated with new-onset POAF. Notably, decreased expression of fibroblast growth factor 13 (FGF13), a fibroblast growth factor homologous factor known to modulate voltage-gated sodium channel Na V 1.5 inactivation, had the most significant association with POAF. To assess the functional significance of decreased FGF13 expression in atrial myocytes, we performed patch clamp experiments on neonatal rat atrial myocytes after siRNA-mediated FGF13 knockdown, demonstrating action potential prolongation. These critical findings indicate that decreased FGF13 expression promotes vulnerability to POAF.

Impact of Pulmonary Complications on Outcomes and Resource Use After Elective Cardiac Surgery

OBJECTIVE

To characterize the impact of pulmonary complications (PCs) on mortality, costs, and readmissions after elective cardiac operations in a national cohort and to test for hospital-level variation in PC.

BACKGROUND

PC after cardiac surgery are targets for quality improvement efforts. Contemporary studies evaluating the impact of PC on outcomes are lacking, as is data regarding hospital-level variation in the incidence of PC.

METHODS

Adults undergoing elective coronary artery bypass grafting and/or valve operations were identified in the 2016-2019 Nationwide Readmissions Database. PC was defined as a composite of reintubation, prolonged (>24 hours) ventilation, tracheostomy, or pneumonia. Generalized linear models were fit to evaluate associations between PC and outcomes. Institutional variation in PC was studied using observed-to-expected ratios.

RESULTS

Of 588,480 patients meeting study criteria, 6.7% developed PC. After risk adjustment, PC was associated with increased odds of mortality (14.6, 95% CI, 12.6-14.8), as well as a 7.9-day (95% CI, 7.6-8.2) increase in length of stay and $41,300 (95% CI, 39,600-42,900) in attributable costs. PC was associated with 1.3-fold greater hazard of readmission and greater incident mortality at readmission (6.7% vs 1.9%, P <0.001). Significant hospital-level variation in PC was present, with observed-to-expected ratios ranging from 0.1 to 7.7.

CONCLUSIONS

Pulmonary complications remain common after cardiac surgery and are associated with substantially increased mortality and expenditures. Significant hospital-level variation in PC exists in the United States, suggesting the need for systematic quality improvement efforts to reduce PC and their impact on outcomes.

Volume-outcome relationship in septal myectomy for hypertrophic obstructive cardiomyopathy

BACKGROUND

Septal myectomy is the gold standard treatment for refractory hypertrophic obstructive cardiomyopathy. The present study characterized the association of septal myectomy volume and cardiac surgery volume with outcomes after septal myectomy.

METHODS

Adults undergoing septal myectomy for hypertrophic obstructive cardiomyopathy were identified in the 2016 to 2019 Nationwide Readmissions Database. Centers were grouped into low-, medium-, and high-volume hospitals by tertiles based on institutional septal myectomy caseload. Overall cardiac surgery volume was similarly assessed. Generalized linear models were used to test the association between hospital septal myectomy or cardiac surgery volume and in-hospital mortality, mitral valve repair, and 90-day non-elective readmission.

RESULTS

Of 3,337 patients, 30.8% underwent septal myectomy at high-volume hospitals, whereas 39.1% were managed at low-volume hospitals. Patients at high-volume hospitals had a similar burden of comorbidities at low-volume hospitals, although congestive heart failure was more prevalent at high-volume hospitals. Despite comparable rates of mitral regurgitation, patients more commonly avoided mitral valve intervention at high-volume hospitals compared with low-volume hospitals (72.9% vs 68.3%; P = .007). After risk adjustment, high-volume hospital status was associated with reduced odds of mortality (0.24; 95% CI, 0.08-0.77) and readmission (0.59; 95% CI, 0.3-0.97). Among cases requiring mitral intervention, high-volume hospital status was associated with greater odds of valve repair (5.33; 95% CI, 2.54-11.13) relative to low-volume hospitals. Overall cardiac surgery volume was not associated with any studied outcome.

CONCLUSION

Greater septal myectomy volume, but not overall cardiac surgery volume, was associated with reduced mortality and greater mitral valve repair relative to replacement after septal myectomy. These findings suggest that septal myectomy for hypertrophic obstructive cardiomyopathy should be performed at centers with expertise in this operation.

Transcatheter and Surgical Aortic Valve Replacement in Patients With Bicuspid Aortic Valve Stenosis

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is not widely used in patients with bicuspid aortic valve (BAV) disease and has not yet been studied in randomized clinical trials. We characterized the rate of use and outcomes of TAVR and surgical aortic valve replacement (SAVR) in patients with BAV.

METHODS

Adults with BAV stenosis receiving SAVR or TAVR procedures were abstracted from the 2012 to 2019 Nationwide Readmissions Database (NRD). Risk-adjusted analyses were performed with NRD-provided weights and inverse probability of treatment weights (IPTW) to examine the association of treatment strategy on inpatient mortality, complications, and hospitalization resource utilization. Nonelective readmissions within 90 days of discharge and reintervention at the first readmission were also examined.

RESULTS

Of an estimated 56 331 patients with BAV requiring aortic valve replacement, 6.8% underwent TAVR. Unadjusted analysis demonstrated higher index hospitalization mortality for TAVR compared with SAVR. Upon risk adjustment using NRD-provided weights, the odds of pacemaker implantation remained significantly higher for TAVR patients compared with SAVR, with no significant difference in mortality. When NRD-provided survey weights were applied, TAVR had higher rates of 90-day readmission. Adjustment with inverse probability of treatment weights resolved these differences between the 2 groups. Regardless of the risk-adjustment method, the odds of reintervention were consistently higher among BAV TAVR patients compared with SAVR.

CONCLUSIONS

The present analysis demonstrates comparable in-hospital mortality and morbidity for TAVR and SAVR patients in the moderate-risk era. With increasing TAVR use in BAV, surgeons must further refine selection criteria with consideration of concomitant aortopathy and implications of reintervention.

Regional Variation in the Use and Outcomes of Transcatheter Aortic Valve Replacement in California

BACKGROUND

Transcatheter aortic valve replacement (TAVR) has been widely adopted for management of aortic stenosis. The purpose of this study was to examine regional access to and outcomes following TAVR in California.

METHODS

Patients undergoing TAVR or isolated surgical aortic valve replacement (SAVR) from 2008 to 2019 in California were identified in the Office of Statewide Health Planning and Development database. California was divided into seven regions: Northern California, San Francisco Bay Area, Central California, Los Angeles, Inland Empire, Orange, and San Diego. Regional TAVR volumes were normalized to Medicare beneficiaries or isolated SAVR volume. Outcomes included risk-adjusted 30-day mortality and major adverse cardiovascular and cerebral events (MACCE). Trends were studied using non-parametric tests, and regional outcomes using logistic regression.

RESULTS

TAVR volume increased annually since 2011, with 7148 cases performed in California in 2019. After normalization, variation in utilization of TAVR was evident, with the least performed in Central California. TAVR to SAVR ratios in 2019 were greatest in Northern California, Los Angeles, and San Diego, and least in the Inland Empire. After risk adjustment, there were no significant regional differences in 30-day mortality, but lower 30-day MACCE in the San Francisco Bay Area.

CONCLUSIONS

Regional differences in TAVR utilization exist, with limited access in Central California and the Inland Empire, but risk-adjusted outcomes are similar. Efforts to reach underserved areas through existing program expansion or regional referrals may distribute transcatheter technology more equitably across California.

Transcatheter Aortic Valve Replacement for Severe Aortic Valve Stenosis: Do Patients Experience Better Quality of Life Regardless of Gradient?

BACKGROUND

Aortic valve replacement improves survival for patients with low-gradient aortic valve stenosis, but there is a paucity of data on postoperative quality of life for this population.

METHODS

In a single-center retrospective analysis of 304 patients with severe aortic valve stenosis who underwent transcatheter aortic valve replacement, patients were divided into 4 groups based on mean pressure gradient, left ventricular ejection fraction, and stroke volume index. Using the Kansas City Cardiomyopathy Questionnaire-12, quality of life was assessed immediately before and 1 month after transcatheter aortic valve replacement.

RESULTS

Most patients in the low-flow, low-gradient group were men; this group had higher relative rates of cardiovascular disease and type 2 diabetes than the paradoxical low-flow, low-gradient group; the normal-flow, low-gradient group; and the high-gradient group. All-cause mortality did not differ significantly among the groups at 1 month after surgery, and all groups experienced a significant improvement in quality-of-life scores after surgery. The mean improvement was 27 points in the low-flow, low-gradient group, 25 points in the paradoxical low-flow, low-gradient group, 30 points in the normal-flow, low-gradient group, and 30 points in the high-gradient group (all P < .001).

CONCLUSION

Quality of life improves significantly across all subgroups of aortic valve stenosis after trans-catheter aortic valve replacement, regardless of flow characteristics or aortic valve gradients.

The Impact of COVID-19 on Racial and Ethnic Disparities in Cardiac Procedural Care

OBJECTIVE

The primary objective of this study was to evaluate whether the COVID-19 pandemic altered the racial and ethnic composition of patients receiving cardiac procedural care.

DESIGN

This was a retrospective observational study.

SETTING

This study was conducted at a single tertiary-care university hospital.

PARTICIPANTS

A total of 1,704 adult patients undergoing transcatheter aortic valve replacement (TAVR) (n = 413), coronary artery bypass grafting (CABG) (n = 506), or atrial fibrillation (AF) ablation (n = 785) from March 2019 through March 2022 were included in this study.

INTERVENTIONS

No interventions were performed as this was a retrospective observational study.

MEASUREMENTS AND MAIN RESULTS

Patients were grouped based on the date of their procedure: pre-COVID (March 2019 to February 2020), COVID Year 1 (March 2020 to February 2021), and COVID Year 2 (March 2021 to March 2022). Population-adjusted procedural incidence rates during each period were examined and stratified based on race and ethnicity. The procedural incidence rate was higher for White patients versus Black, and non-Hispanic patients versus Hispanic patients for every procedure and every period. For TAVR, the difference in procedural rates between White patients versus Black patients decreased between the pre-COVID and COVID Year 1 (12.05-6.34 per 1,000,000 persons). For CABG, the difference in procedural rates between White patients versus Black, and non-Hispanic patients versus Hispanic patients did not change significantly. For AF ablations, the difference in procedural rates between White patients versus Black patients increased over time (13.06 to 21.55 to 29.64 per 1,000,000 persons in the pre-COVID, COVID Year 1, and COVID Year 2, respectively).

CONCLUSION

Racial and ethnic disparities in access to cardiac procedural care were present throughout all study time periods at the authors' institution. Their findings reinforce the continuing need for initiatives to reduce racial and ethnic disparities in healthcare. Further studies are needed to fully elucidate the effects of the COVID-19 pandemic on healthcare access and delivery.

Outcomes of heart transplant recipients bridged with percutaneous versus durable left ventricular assist devices

BACKGROUND

The new United Network for Organ Sharing (UNOS) heart allocation policy prioritizes temporary percutaneous over durable left ventricular assist devices (LVAD) as bridge to transplant. We sought to examine 1-year outcomes of heart transplant recipients bridged with Impella versus durable LVADs.

METHODS

All primary adult orthotopic heart transplant recipients registered in UNOS between January 2016 and June 2021 were analyzed. Recipients were identified as being bridged with isolated durable or percutaneous LVAD at the time of transplant. Baseline characteristics were compared and 1-year survival was examined using the Kaplan Meier method and multivariable Cox proportional hazards regression.

RESULTS

During our study period, heart transplant recipients bridged with LVADs were divided between 5422(94%) durable and 324(6%) percutaneous options. Impella-bridged recipients were more likely to be status 1A under the old allocation system (98% vs. 70%, p < .01) and status 2 or higher under the new allocation system (99% vs. 24%, p < .01). Impella-bridged recipients were less likely to be obese (27% vs. 42%, p < .01), have ischemic cardiomyopathy (27% vs. 34%, p < .01), and were more likely to be on inotropic agents at the time of transplant (68% vs. 6%, p < .01). One-year post-transplant survival was not significantly different between the two groups on univariable (HR .87, 95% CI .56-1.37) or multivariable analysis (aHR .63, 95% CI .37-1.07).

CONCLUSIONS

Following the UNOS allocation policy change, Impella utilization has increased with no significant difference in 1-year survival compared to bridge with durable LVADs. Impella may be a reasonable alternative to durable LVADs in select patients.

Longitudinal profiling in patients undergoing cardiac surgery reveals postoperative changes in DNA methylation

BACKGROUND

Cardiac surgery and cardiopulmonary bypass induce a substantial immune and inflammatory response, the overactivation of which is associated with significant pulmonary, cardiovascular, and neurologic complications. Commensurate with the immune and inflammatory response are changes in the heart and vasculature itself, which together drive postoperative complications through mechanisms that are poorly understood. Longitudinal DNA methylation profiling has the potential to identify changes in gene regulatory mechanisms that are secondary to surgery and to identify molecular processes that predict and/or cause postoperative complications. In this study, we measure DNA methylation in preoperative and postoperative whole blood samples from 96 patients undergoing cardiac surgery on cardiopulmonary bypass.

RESULTS

While the vast majority of DNA methylation is unchanged by surgery after accounting for changes in cell-type composition, we identify several loci with statistically significant postoperative changes in methylation. Additionally, two of these loci are associated with new-onset postoperative atrial fibrillation, a significant complication after cardiac surgery. Paired statistical analysis, use of FACS data to support sufficient control of cell-type heterogeneity, and measurement of IL6 levels in a subset of patients add rigor to this analysis, allowing us to distinguish cell-type variability from actual changes in methylation.

CONCLUSIONS

This study identifies significant changes in DNA methylation that occur immediately after cardiac surgery and demonstrates that these acute alterations in DNA methylation have the granularity to identify processes associated with major postoperative complications. This research also establishes methods for controlling for cell-type variability in a large human cohort that may be useful to deploy in other longitudinal studies of epigenetic marks in the setting of acute and chronic disease.

Left Atrial Appendage Closure During Cardiac Surgery: Safe but Underutilized in California

Objective

Left atrial appendage (LAA) closure is associated with reduced rates of stroke in patients with atrial fibrillation (AF). We evaluated trends in LAA closure, the association of LAA closure with stroke/systemic embolism, and its safety profile in patients with AF who underwent cardiac surgery in California. We further tested for hospital-level variation in concomitant LAA closure.

Methods

Adults who underwent coronary artery bypass grafting and/or valve surgery with preoperative AF were identified in the 2016 to 2019 Office of Statewide Health Planning and Development databases. Propensity score matching was performed to study risk-adjusted associations of LAA closure with ischemic stroke/systemic embolism. Hospital-level variation was studied using intraclass correlation coefficients.

Results

Among 18,434 patients with AF who underwent coronary artery bypass grafting/valve surgery, 47.7% received LAA closure. Rates of LAA closure increased from 44.4% to 51.4% from 2016 to 2019 (P < .001). In 4652 propensity score-matched patients, LAA closure was associated with reduced incidence of stroke/systemic embolism at discharge (1.6% vs 3.1%; P < .001) and readmission with stroke/systemic embolism at 1 year (2.9% vs 4.5%; P = .004). LAA closure was not associated with acute kidney injury, pulmonary complications, blood transfusion, reoperation, or in-hospital mortality. Approximately 18% of the risk-adjusted variation in LAA use was attributed to the hospital, with median center-level rate of 44.9% (interquartile range, 29.6%-57.4%).

Conclusions

LAA closure was associated with minimal surgical morbidity, and reduced short- and midterm incidence of stroke/systemic embolism. Although the use of LAA closure has increased, substantial variation exists among programs in California, suggesting the need for further standardization of care.

An Unusual Case of Left Ventricular Outflow Tract Pseudoaneurysm

Left ventricular outflow tract (LVOT) pseudoaneurysm is a rare condition with a wide range of causes and various clinical outcomes. The causes range from infections, trauma to the chest wall, and iatrogenic origins. We present a unique case of idiopathic LVOT pseudoaneurysm in a patient with no obvious clinical risk factors. (Level of Difficulty: Advanced.).

Morbidity and Mortality associated with Blood Transfusions in Elective Adult Cardiac Surgery

OBJECTIVES

Perioperative transfusion thresholds have garnered increasing scrutiny as restrictive strategies have been shown to be noninferior. The study authors used data from a statewide academic collaborative to test the association between transfusion and 30-day mortality.

DESIGN

All adult patients undergoing coronary artery bypass grafting (CABG) and/or valve surgeries between 2013 and 2019 in the authors' Academic Cardiac Surgery Consortium were examined. The relationship between the number of overall packed red blood cell (pRBC) and coagulation product (CP) (fresh frozen plasma, cryoprecipitate, platelets) transfusions on 30-day mortality was evaluated. Multivariate regression was used to evaluate predictors of transfusion and study endpoints. Machine learning (ML) models also were developed to predict 30-day mortality and rank transfusion-related features by relative importance.

SETTING

At an Academic Cardiac Surgery Consortium of 5 institutions.

PARTICIPANTS

Patients ≥18 years old undergoing CABG and/or valve surgeries.

MEASUREMENTS AND MAIN RESULTS

Of the 7,762 patients (median hematocrit [HCT] 39%, IQR 35%-43%) who were included in the final study cohort, >40% were transfused at least 1 unit of pRBC or CP. In adjusted analyses, higher preoperative HCT was associated with reduced odds of mortality (adjusted odds ratio [aOR] 0.95, 95% CI 0.92-0.98), renal failure (aOR 0.95, 95% CI 0.92-0.98), and prolonged mechanical ventilation (aOR 0.97, 95% CI 0.95-0.99). In contrast, perioperative transfusions were associated with increased 30-day mortality after adjustment for preoperative HCT and other baseline features. The ML models were able to predict 30-day mortality with an area under the curve of 0.814-to-0.850, with perioperative transfusions displaying the highest feature importance.

CONCLUSIONS

The present analysis found increasing HCT to be associated with a lower incidence of mortality. The study authors also found a direct dose-response association between transfusions and all study endpoints examined.

Parsimonious machine learning models to predict resource use in cardiac surgery across a statewide collaborative

Objective

Methods

Results

Conclusions

Influence of center surgical aortic valve volume on outcomes of transcatheter aortic valve replacement

Objective

Methods

Results

Conclusions

Ventricular Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy (Analysis Spanning 60 Years Of Practice): AJC Expert Panel

Surgical myectomy remains the time-honored primary treatment for hypertrophic cardiomyopathy patients with drug refractory limiting symptoms due to LV outflow obstruction. Based on >50 years experience, surgery reliably reverses disabling heart failure by permanently abolishing mechanical outflow impedance and mitral regurgitation, with normalization of LV pressures and preserved systolic function. A consortium of 10 international currently active myectomy centers report about 11,000 operations, increasing significantly in number over the most recent 15 years. Performed in experienced multidisciplinary institutions, perioperative mortality for myectomy has declined to 0.6%, becoming one of the safest currently performed open-heart procedures. Extended myectomy relieves symptoms in >90% of patients by ≥ 1 NYHA functional class, returning most to normal daily activity, and also with a long-term survival benefit; concomitant Cox-Maze procedure can reduce the number of atrial fibrillation episodes. Surgery, preferably performed in high volume clinical environments, continues to flourish as a guideline-based and preferred high benefit: low treatment risk option for adults and children with drug refractory disabling symptoms from obstruction, despite prior challenges: higher operative mortality/skepticism in 1960s/1970s; dual-chamber pacing in 1990s, alcohol ablation in 2000s, and now introduction of strong negative inotropic drugs potentially useful for symptom management.

Defining value in cardiac surgery: A contemporary analysis of cost variation across the United States

Objective

Isolated coronary artery bypass grafting and aortic valve replacement are common cardiac operations performed in the United States and serve as platforms for benchmarking. The present national study characterized hospital-level variation in costs and value for coronary artery bypass grafting and aortic valve replacement.

Methods

Adults undergoing elective, isolated coronary artery bypass grafting or aortic valve replacement were identified in the 2016-2018 Nationwide Readmissions Database. Center quality was defined by the proportion of patients without an adverse outcome (death, stroke, respiratory failure, pneumonia, sepsis, acute kidney injury, and reoperation). High-value hospitals were defined as those with observed-to-expected ratios less than 1 for costs and greater than 1 for quality, whereas the converse defined low-value centers.

Results

Of 318,194 patients meeting study criteria, 71.9% underwent isolated coronary artery bypass grafting and 28.1% underwent aortic valve replacement. Variation in hospital-level costs was evident, with median center-level cost of $36,400 (interquartile range, 29,500-46,700) for isolated coronary artery bypass grafting and $38,400 (interquartile range, 32,300-47,700) for aortic valve replacement. Observed-to-expected ratios for quality ranged from 0.2 to 10.9 for isolated coronary artery bypass grafting and 0.1 to 11.7 for isolated aortic valve replacement. Hospital factors, including volume and quality, contributed to approximately 9.9% and 11.2% of initial cost variation for isolated coronary artery bypass grafting and aortic valve replacement. High-value centers had greater cardiac surgery operative volume and were more commonly teaching hospitals compared to low-value centers, but had similar patient risk profiles.

Conclusions

Significant variation in hospital costs, quality, and value exists for 2 common cardiac operations. Center volume was associated with value and partly accounts for variation in costs. Our findings suggest the need for value-based care paradigms to reduce expenditures and optimize outcomes.

DNA Methylation-Based Prediction of Post-operative Atrial Fibrillation

Background

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and post-operative atrial fibrillation (POAF) is a major healthcare burden, contributing to an increased risk of stroke, kidney failure, heart attack and death. Genetic studies have identified associations with AF, but no molecular diagnostic exists to predict POAF based on pre-operative measurements. Such a tool would be of great value for perioperative planning to improve patient care and reduce healthcare costs. In this pilot study of epigenetic precision medicine in the perioperative period, we carried out bisulfite sequencing to measure DNA methylation status in blood collected from patients prior to cardiac surgery to identify biosignatures of POAF.

Methods

We enrolled 221 patients undergoing cardiac surgery in this prospective observational study. DNA methylation measurements were obtained from blood samples drawn from awake patients prior to surgery. After controlling for clinical and methylation covariates, we analyzed DNA methylation loci in the discovery cohort of 110 patients for association with POAF. We also constructed predictive models for POAF using clinical and DNA methylation data. We subsequently performed targeted analyses of a separate cohort of 101 cardiac surgical patients to measure the methylation status solely of significant methylation loci in the discovery cohort.

Results

A total of 47 patients in the discovery cohort (42.7%) and 43 patients in the validation cohort (42.6%) developed POAF. We identified 12 CpGs that were statistically significant in the discovery cohort after correcting for multiple hypothesis testing. Of these sites, 6 were amenable to targeted bisulfite sequencing and chr16:24640902 was statistically significant in the validation cohort. In addition, the methylation POAF prediction model had an AUC of 0.79 in the validation cohort.

Conclusions

We have identified DNA methylation biomarkers that can predict future occurrence of POAF associated with cardiac surgery. This research demonstrates the use of precision medicine to develop models combining epigenomic and clinical data to predict disease.

Implementation and Outcomes of an Urban Mobile Adult Extracorporeal Life Support Program

Objective

Methods

Results

Conclusions

Factors Associated With High Resource Use in Elective Adult Cardiac Surgery From 2005 to 2016

BACKGROUND

Lack of consensus remains about factors that may be associated with high resource use (HRU) in adult cardiac surgical patients. This study aimed to identify patient-related, hospital, and perioperative characteristics associated with HRU admissions involving elective cardiac operations.

METHODS

Data from the National Inpatient Sample was used to identify patients who underwent coronary artery bypass graft, valve replacement, and valve repair operations between 2005 and 2016. Admissions with HRU were defined as those in the highest decile for total hospital costs. Multivariable regressions were used to identify factors associated with HRU.

RESULTS

An estimated 1,750,253 hospitalizations coded for elective cardiac operations. The median hospitalization cost was $34,700 (interquartile range, $26,800- to $47,100), with the HRU (N = 175,025) cutoff at $66,029. Although HRU patients comprised 10% of admissions, they accounted for 25% of cumulative costs. On multivariable regression, patient-related characteristics predictive of HRU included female sex, older age, higher comorbidity burden, non-White race, and highest income quartile. Hospital factors associated with HRU were low-volume hospitals for both coronary artery bypass graft and valvular operations. Among postoperative outcomes, mortality, infectious complications, extracorporeal membrane oxygenation use, and hospitalization for more than 8 days were associated with greater odds of HRU.

CONCLUSIONS

In this nationwide study of elective cardiac surgical patients, several important patient-related and hospital factors, including patients' race, comorbidities, postoperative infectious complications, and low hospital operative volume were identified as predictors of HRU. These highly predictive factors may be used for benchmarking purposes and improvement in surgical planning.

Timing of Coronary Artery Bypass Grafting in Acute Coronary Syndrome: A National Analysis

BACKGROUND

Timing of surgical revascularization for acute coronary syndrome (ACS) remains debated. We assessed the impact of timing to CABG on mortality and resource utilization in a national cohort.

METHODS

Adults admitted for ACS in the 2009-2018 National Inpatient Sample were grouped by time from coronary angiography to CABG (Δt): 0, 1-3, 4-7, and >7 days. Generalized linear models were fit to evaluate associations between Δt and in-hospital mortality and hospitalization costs. Timing and mortality of CABG for ACS was compared between high-performing hospitals (below the median risk adjusted mortality for all CABG and valve operations) and others.

RESULTS

Of 444,065 patients, time to CABG was Δt=0 in 12.3%, Δt=1-3 in 57.3%, Δt=4-7 in 26.3%, and Δt>7 in 4.2%. Risk-adjusted mortality was greatest at Δt=0 (4.5%, 95% confidence interval, CI, 4.1-4.9) and Δt>7 (4.0%, 95% CI 3.4-4.7), but similar for operations performed at Δt=1-3 (1.8%, 95% CI 1.7-1.9) and Δt=4-7 (2.1%, 95% CI 1.9-2.3). Compared to Δt=1-3, hospitalization costs were greater by $6,400 (95% CI 5,900-6,900) for Δt=4-7 and $21,200 (95% CI 19,800-22,600) for Δt>7. High-performing hospitals had similar time to CABG as others (2 vs 2 days, p=0.17), but lower mortality (0.9% vs 3.3%, p<0.001).

CONCLUSIONS

Revascularization on day 1-3 and 4-7 led to comparable in-hospital mortality, with greater rates on day 0 and after day 7. Costs were greater for revascularization at day 4-7 compared to day 1-3. These findings support the reduction of time to revascularization to 1-3 days when deemed clinically appropriate and feasible.

Validity of echocardiography for detection of left ventricular thrombus with surgical validation in patients awaiting durable left ventricular assist device

OBJECTIVE

Unrecognized left ventricular thrombi (LVT) can have devastating clinical implications and precludes patients with end-stage heart failure from undergoing left ventricular assist device (LVAD) implantation without cardiopulmonary bypass assistance. We assessed the reliability of an echocardiogram to diagnose LVT in patients with end-stage heart disease who underwent LVAD implantation.

METHODS

A single-center retrospective study evaluated 232 consecutive adult patients requiring implantation of durable LVADs between 2005 and 2019. The validity of preoperative transthoracic echocardiogram (TTE) and intraoperative transesophageal echocardiogram (TEE) for diagnosing LVT was compared to direct inspection at the time of LVAD implantation.

RESULTS

There were 232 patients that underwent LVAD implantation, with 226 patients (97%) receiving a preoperative TTE. Of those 226 patients, 32 patients (14%) received ultrasound enhancing agents (UEA). Intraoperative TEE images were available in 195 patients (84%). The sensitivity of TTE without UEA was 22% and specificity was 90% for detecting LVT, compared to 50% and 86%, respectively, for TTE with UEA. For intraoperative TEE, the sensitivity and specificity were 46% and 96%, respectively. The false omission rate ranged from 4% to 8% for all modalities of echocardiography.

CONCLUSION

Among patients undergoing LVAD implantation, preoperative TTE and intraoperative TEE had poor sensitivity for LVT detection. Up to 8% of echocardiograms were incorrectly concluded to be negative for LVT on surgical validation. The low sensitivity and positive predictive value for diagnosing LVT suggest that echocardiography has limited reliability in this cohort of patients who are at high risk of LVT formation and its subsequent complications.

Impact of Postoperative Infections on Readmission and Resource Use in Elective Cardiac Surgery

BACKGROUND

Efforts to reduce postoperative infections have garnered national attention, leading to practice guidelines for cardiac surgical perioperative care. The present study characterized the impact of healthcare-acquired infection (HAI) on index hospitalization costs and post-discharge healthcare utilization.

METHODS

Adults undergoing elective coronary artery bypass grafting (CABG) and/or valve operations were identified in the 2016-2018 Nationwide Readmissions Database. Infections were categorized into bloodstream, gastrointestinal, pulmonary, surgical site, or urinary tract infections. Generalized linear or flexible hazard models were used to assess associations between infections and outcomes. Observed-to-expected (O/E) ratios were generated to examine inter-hospital variation in HAI.

RESULTS

Of an estimated 444,165 patients, 8.0% developed HAI. Patients with HAI were older, had a greater burden of chronic diseases, and more commonly underwent CABG/valve or multi-valve operations (all p<0.001). HAI was independently associated with mortality (odds ratio 4.02, 95% CI 3.67-4.40), non-home discharge (3.48, 95% CI 3.21-3.78), and a cost increase of $23,000 (95% CI 20,900-25,200). At 90 days, HAI was associated with greater hazard of readmission (1.29, 95% CI 1.24-1.35). Pulmonary infections had the greatest incremental impact on patient-level ($24,500, 95% CI 23,100-26,00) and annual cohort costs ($121.8 million, 95% CI 102.2-142.9 million). Significant hospital level variation in HAI was evident, with O/E ranging from 0.17 to 4.3 for cases performed in 2018.

CONCLUSIONS

Infections following cardiac surgery remain common and are associated with inferior outcomes and increased resource use. The presence of inter-hospital variation in this contemporary cohort emphasizes the ongoing need for systematic approaches in their prevention and management.

Nontechnical skills training in cardiothoracic surgery: A pilot study

OBJECTIVE

The importance of nontechnical skills in surgery is widely recognized. We demonstrate the feasibility of administering and assessing the results of a formal Non-Technical Skills in Surgery (NOTSS) curriculum to cardiothoracic surgery residents.

METHODS

Eight cardiothoracic surgery residents participated in the NOTSS curriculum. They were assessed on their cognitive (situation awareness, decision-making) and social (communication and teamwork, leadership) skills based on simulated vignettes. The residents underwent pretraining NOTSS assessments followed by self-administered confidence ratings regarding the 4 skills. Subsequently, a formal NOTSS lecture was delivered and additional readings from the NOTSS textbook was assigned. A month later, the residents returned for post-training NOTSS assessments and self-administered confidence ratings. Changes across days (or within-day before vs after curriculum) were assessed using Wilcoxon signed rank test.

RESULTS

There was a significant improvement in the overall NOTSS assessment score (P = .01) as well as in the individual categories (situation awareness, P = .02; decision-making, P = .02; communication and teamwork, P = .01; leadership, P = .02). There was also an increase in resident self-perception of improvement on the post-training day (P = .01).

CONCLUSIONS

We have developed a simulation-based NOTSS curriculum in cardiothoracic surgery that can be formally integrated into the current residency education. This pilot study indicates the feasibility of reproducible assessments by course educators and self-assessments by participating residents in nontechnical skills competencies.

Correction to: Combating an invisible enemy: the American military response to global pandemics

An amendment to this paper has been published and can be accessed via the original article.

Combating an invisible enemy: the American military response to global pandemics

The present moment is not the first time that America has found itself at war with a pathogen during a time of international conflict. Between crowded barracks at home and trenches abroad, wartime conditions helped enable the spread of influenza in the fall of 1918 during World War I such that an estimated 20-40% of U.S. military members were infected. While the coronavirus disease 2019 (COVID-19) pandemic is unparalleled for most of today's population, it is essential to not view it as unprecedented lest the lessons of past pandemics and their effect on the American military be forgotten. This article provides a historical perspective on the effect of the most notable antecedent pandemic, the Spanish Influenza epidemic, on American forces with the goal of understanding the interrelationship of global pandemics and the military, highlighting the unique challenges of the current pandemic, and examining how the American military has fought back against pandemics both at home and abroad, both 100 years ago and today.

Predictors and In-Hospital Outcomes Among Patients Using a Single Versus Bilateral Mammary Arteries in Coronary Artery Bypass Grafting

The benefit of bilateral mammary artery (BIMA) use during coronary artery bypass grafting (CABG) continues to be debated. This study examined nationwide trends in BIMA use and factors influencing its utilization. Using the National Inpatient Sample, adults undergoing isolated multivessel CABG between 2005 and 2015 were identified and stratified based on the use of a single mammary artery or BIMA. Regression models were fit to identify patient and hospital level predictors of BIMA use and characterize the association of BIMA on outcomes including sternal infection, mortality, and resource utilization. An estimated 4.5% (n = 60,698) of patients underwent CABG with BIMA, with a steady increase from 3.8% to 5.0% over time (p<0.001). Younger age, male gender, and elective admission, were significant predictors of BIMA use. Moreover, private insurance was associated with higher odds of BIMA use (adjusted odds ratio 1.24) compared with Medicare. BIMA use was not a predictor of postoperative sternal infection, in-hospital mortality, or hospitalization costs. Overall, BIMA use remains uncommon in the United States despite no significant differences in acute postoperative outcomes. Several patient, hospital, and socioeconomic factors appear to be associated with BIMA utilization.

Left atrial thrombus mimicking myxoma in a patient with hereditary hemorrhagic telangiectasia: Diagnostic and therapeutic dilemmas

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by the development of arteriovenous malformations. The arteriovenous shunts may result in high output heart failure, which predisposes to atrial dilatation and atrial fibrillation. Due to recurrent bleeding from epistaxis or the gastrointestinal tract, patients with HHT and atrial fibrillation are at high risk of bleeding if anticoagulated for stroke prevention. In this report, we present a case of a 74-year-old woman with a history of HHT and atrial fibrillation who developed a large left atrial thrombus that initially was thought to represent an atrial myxoma. The diagnosis was confirmed with cardiac magnetic resonance imaging, and the patient underwent surgical resection of the thrombus. This case demonstrates the role of different imaging modalities in the assessment of left atrial masses and presents an opportunity to review the data on safety of anticoagulation in patients with HHT.

Acute Care Surgery in Heart Transplant Recipients

Orthotopic heart transplantation (OHT) is the optimal treatment for end-stage heart failure. We reviewed our institutional experience between 2008 and 2012 with acute care surgery (ACS) consultations and procedures within 1 year of OHT in recipients bridged to transplantation with medical therapy (MT, n = 169), including intravenous inotropes, and ventricular assist devices (VADs, n = 74). In total, 28 consultations were required in 21 patients (9%) and 16 procedures were performed in 11 patients (5%). The interval from transplantation to consultation was shorter for the MT group (50 vs 82 days; P = 0.015), whereas the interval from consultation to operation was longer (5 vs 1 day; P = 0.03). Patients undergoing MT were more likely to require consultation for abdominal problems (88 vs 27%; P = 0.004). All but one of the seven ischemic/inflammatory abdominal problems occurred in the MT group. Complications occurred after five ACS procedures (31%) in two patients undergoing MT and three patients undergoing VAD. Mortality was 24 per cent with five deaths occurring within 30 days of ACS consultation and/or operation. In summary, this is one of the largest series of ACS problems in patients undergoing OHT bridged to transplant with MT or VAD. With similar incidence in MT and VAD groups, ACS consultations and operations are infrequent with high mortality and morbidity.

Incidence, Predictors, and Impact of Clostridium difficile Infection on Cardiac Surgery Outcomes

BACKGROUND

Clostridium difficile infection (CDI) has been associated with morbidity and mortality after cardiac operations. The present study examined incidence, predictors, and impact of CDI on inpatient mortality and resource utilization.

METHODS

An analysis of adult patients undergoing elective coronary artery bypass grafting or valvular operations from 2005 to 2016 was performed using the National Inpatient Sample. Trends in CDI were assessed using a modified Cochran-Armitage analysis. Multivariable multilevel regressions were used to identify predictors of CDI, and propensity-matched pairs were generated using Mahalanobis 1-to-1 matching to compare mortality, length of stay, and costs of CDI patients with the non-CDI cohort.

RESULTS

The overall rate of CDI for an estimated 2,026,267 patients who underwent elective major cardiac surgery was 0.5% with no change in incidence (P for trend = .99). Predictors of CDI included advanced age (≥65 y; adjusted odds ratio [AOR], 1.88; 95% confidence interval [CI], 1.58-2.24), female gender (AOR, 1.29; 95% CI, 1.15-1.44), heart failure (AOR, 1.57; 95% CI, 1.40-1.76), and combined coronary artery bypass grafting/valve operations (AOR, 1.60; 95% CI, 1.24-2.08). Neither region nor bed size was associated with CDI. In contrast CDI mortality was lower at teaching hospitals compared with rural hospitals. Among matched pairs CDI was independently associated with higher mortality, length of stay, and Gross Domestic Product-adjusted costs.

CONCLUSIONS

CDI occurs in less than 1% of all elective, major cardiac operations. Patient predictors included advanced age, female gender, and several chronic comorbidities. Teaching institutions had the highest odds of CDI but lowest odds of case fatality. Further investigation of factors contributing to CDI is warranted to disseminate institutional best practices.

Trends in utilization, mortality, and resource use after implantation of left ventricular assist devices in the United States

OBJECTIVES

Adoption of implantable left ventricular assist devices has dramatically improved survival and quality of life in suitable patients with end-stage heart failure. In the era of value-based healthcare delivery, assessment of clinical outcomes and resource use associated with left ventricular assist devices is warranted.

METHODS

Adult patients undergoing left ventricular assist device implantation from 2008 to 2016 were identified using the National Inpatient Sample. Hospitals were designated as low-volume, medium-volume, or high-volume institutions based on annual institutional left ventricular assist device case volume. Multivariable logistic regression was used to evaluate adjusted odds of mortality across left ventricular assist device volume tertiles.

RESULTS

Over the study period, an estimated 23,972 patients underwent left ventricular assist device implantation with an approximately 3-fold increase in the number of annual left ventricular assist device implantations performed (P for trend <.001). In-hospital mortality in patients with left ventricular assist devices decreased from 19.6% in 2008 to 8.1% in 2016 (P for trend <.001) and was higher at low-volume institutions compared with high-volume institutions (12.0% vs 9.2%, P < .001). Although the overall adjusted mortality was higher at low-volume compared with high-volume institutions (adjusted odds ratio, 1.66; 95% confidence interval, 1.28-2.15), this discrepancy was only significant for 2008 and 2009 (low-volume 2008 adjusted odds ratio, 5.5; 95% confidence interval, 1.9-15.8; low-volume 2009 adjusted odds ratio, 2.3; 95% confidence interval, 1.4-3.8).

CONCLUSIONS

Left ventricular assist device use has rapidly increased in the United States with a concomitant reduction in mortality and morbidity. With maturation of left ventricular assist device technology and increasing experience, volume-related variation in mortality and resource use has diminished. Whether the apparent uniformity in outcomes is related to patient selection or hospital quality deserves further investigation.

Deep Venous Thrombosis and Pulmonary Embolism in Cardiac Surgical Patients

BACKGROUND

Deep venous thrombosis and pulmonary embolism are life-threatening complications after surgery, warranting prophylaxis. However prophylaxis is not uniformly practiced among cardiac surgical patients. This study aimed to characterize the national incidence, mortality, and costs associated with thromboembolism after cardiac surgery.

METHODS

The 2005 to 2015 National Inpatient Sample was used to identify all adult patients undergoing coronary artery bypass grafting or valve surgery. International Classification of Disease codes were used to identify patients with deep venous thrombosis and pulmonary embolism.

RESULTS

Of approximately 3 million patients undergoing cardiac surgery, 1.62% developed deep venous thrombosis and 0.38% pulmonary embolism. Those with deep venous thrombosis and pulmonary embolism were more commonly women (33.2% and 36.2 vs 31.2%, P < .001), older (68.1 and 66.0% vs 65.7 years, P < .001), and had a higher Elixhauser comorbidity index (4.0 and 4.7 vs 3.7, P < .001). Deep venous thrombosis and pulmonary embolism were associated with increased mortality (4.95% and 14.8% vs 2.67%, P < .001). After adjustment for baseline differences, deep venous thrombosis was associated with an incremental increase in cost of $12,308, whereas pulmonary embolism was associated with $13,879 cost increase after cardiac surgery. Pulmonary embolism was an independent predictor of mortality (adjusted odds ratio, 3.39; 95% confidence interval, 2.74-4.18).

CONCLUSIONS

The mortality and financial burden related to thromboembolism in cardiac surgery are significant. Prophylaxis may be indicated in cardiac surgery patients to improve quality of care and reduce healthcare costs. Future controlled randomized trials investigating the benefit of thromboembolism prophylaxis in cardiac surgery are warranted.

American Board of Thoracic Surgery 10-Year Maintenance of Certification Exam Improves and Validates Knowledge Acquisition

BACKGROUND

Previous "high-stakes" examinations by the American Board of Thoracic Surgery (ABTS) required remote testing, were noneducational, and were not tailored to individual practices. Given the ABTS mission of public safety and diplomate education, the ABTS Maintenance of Certification (MOC) examination was revised in 2015 to improve the educational experience and validate knowledge acquired.

METHODS

The ABTS-MOC Committee developed a web-based, secure examination tailored to the specialty-specific practice profile (cardiac, general thoracic, cardiothoracic, congenital) of the individual surgeon. After an initial answer to each question, an educational critique was reviewed before returning to the initial question and logging a second (final) response. Intraexam learning was assessed by comparing scores before and after reading the critique. Diplomate feedback was obtained.

RESULTS

A total of 988 diplomates completed the 10-year MOC examination between 2015 and 2017. Substantive learning was demonstrated with an 18%, 17%, 20%, and 9% improvement in cardiac, general thoracic, cardiothoracic, and congenital final scores, respectively. This improvement was most notable among diplomates with the lowest initial scores. Fewer diplomates failed the new exam (<1% vs 2.3%). Diplomate postexam survey highlighted marked improvements in clinical relevance (35% vs 78%), convenience (37% vs 78%), and learning (15% vs 45%). Over 80% acknowledged educational value, and 97% preferred the new format.

CONCLUSIONS

The new MOC process demonstrates increased knowledge acquisition through a convenient, secure, web-based practice-focused examination. This approach provides feedback, identifies baseline knowledge gaps for individual diplomates, and validates new knowledge attained.

Trends in Readmission and Costs After Transcatheter Implantation Versus Surgical Aortic Valve Replacement in Patients With Renal Dysfunction

Patients with renal dysfunction are at increased risk for developing aortic valve pathology. In the present era of value-based healthcare delivery, a comparison of transcatheter and surgical aortic valve replacement (SAVR) readmission performance in this population is warranted. All adult patients who underwent transcatheter or SAVR from 2011 to 2014 were identified using the Nationwide Readmissions Database, containing data for nearly 50% of US hospitalizations. Patients were further stratified as chronic kidney disease stage 1 to 5 as well as end-stage renal disease requiring dialysis. Kaplan-Meier, Cox Hazard, and multivariable regression models were generated to identify predictors of readmission and costs. Of the 350,609 isolated aortic valve replacements, 4.7% of patients suffered from chronic kidney disease stages 1 to 5 or end-stage renal disease. Transcatheter aortic valve patients with chronic kidney disease stages 1 to 5/or end-stage renal disease were older (81.9 vs 72.9 years, p <0.0001) with a higher prevalence of heart failure (15.2 vs 4.3%, p = 0.04), and peripheral vascular disease (31.1 vs 22.8%, p <0.0001) compared to their SAVR counterparts. Transcatheter aortic valve replacement in chronic kidney disease stage 1 to 3 patients had a higher rate of readmission due to heart failure and pacemaker placement than SAVR. Transcatheter aortic valve replacement was associated with increased costs compared with SAVR for all renal failure patients. In conclusion, in this national cohort of chronic and end-stage renal disease patients, transcatheter aortic valve implantation was associated with increased mortality, readmissions for chronic kidney disease stages1 to 3, and index hospitalization costs.

Comparison of Frequency of Late Gastrointestinal Bleeding With Transcatheter Versus Surgical Aortic Valve Replacement

Improvements in technology and operator experience have led to exponential growth of transcatheter aortic valve implantation (TAVI) programs. Late bleeding complications were recently highlighted after TAVI with a high impact on morbidity. The purpose of the present study was to assess the incidence and financial impact of late Gastrointestinal (GI) bleeding after TAVI, and compare with the surgical cohort. Retrospective analysis of the National Readmissions Database was performed from January 2011 to December 2014, and patients who underwent TAVI or surgical aortic valve replacement (SAVR) were identified. Incidence of readmission with a diagnosis of GI bleeding was utilized as the primary end point. Overall, 43,357 patients were identified who underwent TAVI, whereas 310,013 patients underwent SAVR. Compared with SAVR, TAVI patients were older (81 vs 68y, p < 0.001), more women (48% vs 36%, p < 0.001), and had higher Elixhauser Comorbidity Index (6 vs 5, p < 0.001). Hospital stay was shorter with TAVI (5 vs 8 days, p < 0.001), but raw in-hospital mortality rates were similar (4.2% vs 3.8%, p = 0.022). In the TAVI cohort, 3.3% of patients were rehospitalized for GI bleeding compared with 1.5% of the SAVR cohort (p < 0.001). Average time to bleeding readmission was similar between cohorts (92 vs 84 days, p = 0.049). After multivariable adjustment, TAVI remained significantly associated with readmissions for GI bleeding compared with SAVR Adjusted Odds Ratio (AOR 1.54 [1.38 to 1.71], p < 0.001). In this national cohort study, TAVI was associated with more frequent readmissions for late GI bleeding compared with SAVR. In conclusion, strategies to reduce late GI bleeding may serve as important targets for improvement in overall quality of care.

Clinical phenomapping and outcomes after heart transplantation

BACKGROUND

Survival after heart transplantation (HTx) is limited by complications related to alloreactivity, immune suppression, and adverse effects of pharmacologic therapies. We hypothesize that time-dependent phenomapping of clinical and molecular data sets is a valuable approach to clinical assessments and guiding medical management to improve outcomes.

METHODS

We analyzed clinical, therapeutic, biomarker, and outcome data from 94 adult HTx patients and 1,557 clinical encounters performed between January 2010 and April 2013. Multivariate analyses were used to evaluate the association between immunosuppression therapy, biomarkers, and the combined clinical end point of death, allograft loss, retransplantation, and rejection. Data were analyzed by K-means clustering (K = 2) to identify patterns of similar combined immunosuppression management, and percentile slopes were computed to examine the changes in dosages over time. Findings were correlated with clinical parameters, human leucocyte antigen antibody titers, and peripheral blood mononuclear cell gene expression of the AlloMap (CareDx, Inc., Brisbane, CA) test genes. An intragraft, heart tissue gene coexpression network analysis was performed.

RESULTS

Unsupervised cluster analysis of immunosuppressive therapies identified 2 groups, 1 characterized by a steeper immunosuppression minimization, associated with a higher likelihood for the combined end point, and the other by a less pronounced change. A time-dependent phenomap suggested that patients in the group with higher event rates had increased human leukocyte antigen class I and II antibody titers, higher expression of the FLT3 AlloMap gene, and lower expression of the MARCH8 and WDR40A AlloMap genes. Intramyocardial biomarker-related coexpression network analysis of the FLT3 gene showed an immune system-related network underlying this biomarker.

CONCLUSIONS

Time-dependent precision phenotyping is a mechanistically insightful, data-driven approach to characterize patterns of clinical care and identify ways to improve clinical management and outcomes.