A model for delivery of extracorporeal life support in a stand-alone veterans affairs medical center.

INTRODUCTION: For the Veterans Health Administration (VHA) to continue to perform complex cardiothoracic surgery, there must be an established pathway for providing urgent/emergent extracorporeal life support (ECLS). Partnership with a nearby tertiary care center with such expertise may be the most resource-efficient way to provide ECLS services to patients in post-cardiotomy cardiogenic shock or respiratory failure. The goal of this project was to assess the efficiency, safety, and outcomes of surgical patients who required transfer for perioperative ECLS from a single stand-alone Veterans Affairs Medical Center (VAMC) to a separate ECLS center. METHODS: Cohort consisted of all cardiothoracic surgery patients who experienced cardiogenic shock or refractory respiratory failure at the local VAMC requiring urgent or emergent institution of ECLS between 2019 and 2022. The primary outcomes are the safety and timeliness of transport. RESULTS: Mean time from the initial shock call to arrival at the ECLS center was 2.8 h. There were no complications during transfer. Six patients (86%) survived to decannulation. CONCLUSION: These results suggest that complex cardiothoracic surgery can be performed within the VHA system and when there is an indication for ECLS, those services can be safely and effectively provided at an affiliated, properly equipped center.

The impact of a statewide payment reform on transcatheter aortic valve replacement (TAVR) utilization and readmissions.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) is an increasingly used but relatively expensive procedure with substantial associated readmission rates. It is unknown how cost-constrictive payment reform measures, such as Maryland's All Payer Model, impact TAVR utilization given its relative expense. This study investigated the impact of Maryland's All Payer Model on TAVR utilization and readmissions among Maryland Medicare beneficiaries. METHODS: This was a quasi-experimental investigation of Maryland Medicare patients undergoing TAVR between 2012 and 2018. New Jersey data were used for comparison. Longitudinal interrupted time series analyses were used to study TAVR utilization and difference-in-differences analyses were used to investigate post-TAVR readmissions. RESULTS: During the first year of payment reform (2014), TAVR utilization among Maryland Medicare beneficiaries dropped by 8% (95% confidence interval [CI]: -9.2% to -7.1%; p < 0.001), with no concomitant change in TAVR utilization in New Jersey (0.2%, 95% CI: 0%-1%, p = 0.09). Longitudinally, however, the All Payer Model did not impact TAVR utilization in Maryland compared to New Jersey. Difference-in-differences analyses demonstrated that implementation of the All Payer Model was not associated with significantly greater declines in 30-day post-TAVR readmissions in Maryland versus New Jersey (-2.1%; 95% CI: -5.2% to 0.9%; p =0.1). CONCLUSIONS: Maryland's All Payer Model resulted in an immediate decline in TAVR utilization, likely a result of hospitals adjusting to global budgeting. However, beyond this transition period, this cost-constrictive reform measure did not limit Maryland TAVR utilization. In addition, the All Payer Model did not reduce post-TAVR 30-day readmissions. These findings may help inform expansion of globally budgeted healthcare payment structures.

Temporary Mechanical Circulatory Support for Transcatheter Aortic Valve Replacement.

INTRODUCTION: This study aimed to characterize the use of temporary mechanical circulatory support (tMCS) among patients undergoing transcatheter aortic valve replacement (TAVR) using a nationally representative database. MATERIALS AND METHODS: The 2012-2018 National Inpatient Sample was queried for adult patients who underwent isolated TAVR. The tMCS group was comprised of those who required extracorporeal membrane oxygenation, percutaneous ventricular assist device, or intra-aortic balloon pump during index hospitalization. We evaluated temporal trends in the utilization of tMCS using Cuzick's test. Furthermore, a multivariable logistic regression was used to identify factors associated with tMCS use and its impact on in-hospital mortality, selected complications, and nonhome discharge. RESULTS: Of an estimated 215,925 patients who underwent TAVR, 3085 (1.4%) required tMCS during their hospital course. The most common modality of tMCS was intra-aortic balloon pump (49%), followed by extracorporeal membrane oxygenation (27%) then percutaneous ventricular assist device (18%). Seven percent of tMCS patients were supported by > 1 device. The annual incidence of tMCS usage decreased over the study period, from 3% in 2012 to 1% in 2018 (P-trend < 0.01). Nonelective admission, congestive heart failure, coagulopathy, and liver disease were strong independent predictors of requiring tMCS. Patients requiring tMCS had a 31.8% in-hospital mortality rate (adjusted odds ratio = 23, 95% confidence interval 18.5-28.5), longer length of stay (9 d versus 3, P < 0.001), and higher costs ($84,600 versus $48,100, P < 0.001) than those who did not. CONCLUSIONS: The use of tMCS during TAVR has decreased over time but remains associated with a 23-fold increased mortality rate and significant clinical and resource utilization burden.

Late Outcomes After Aortic Root Enlargement During Aortic Valve Replacement: Meta-Analysis With Reconstructed Time-To-Event Data.

OBJECTIVES: The present authors aimed to assess the late outcomes of patients undergoing aortic root enlargement (ARE) at the time of surgical aortic valve replacement (SAVR). DESIGN: Study-level meta-analysis with reconstructed time-to-event data. SETTING: Follow-up of patients after surgical procedure. PARTICIPANTS: Adult patients with aortic valve disease requiring surgery. INTERVENTIONS: SAVR with ARE versus SAVR without ARE. MEASUREMENTS AND MAIN RESULTS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline. The following databases were searched for studies meeting the authors' inclusion criteria and published by November 30, 2021: PubMed/MEDLINE, Embase, SciELO, LILACS, CCTR/CENTRAL, and Google Scholar. Nine nonrandomized studies met the authors' eligibility criteria. All studies were nonrandomized. A total of 213,134 patients (SAVR with ARE: 7,556 patients; SAVR without ARE: 205,578 patients) were included from studies published from 1997 to 2021. The total rate of AAE was 3.7%, varying in the studies from 2.9% to 28.1%. The studies consisted of patients whose mean age varied from 63 to 79 years. Patients in the SAVR with ARE group had a significantly better overall survival (hazard ratio [HR] 0.94, 95% confidence interval [CI] 0.90-0.99, p = 0.016) in the unmatched populations, but the matched analysis revealed no difference between SAVR with/without ARE in terms of overall survival (HR, 1.06; 95% CI, 0.90-1.25; p = 0.474). CONCLUSIONS: In the context of patients undergoing SAVR with or without ARE, patients who undergo ARE do not experience worse late outcomes. Further randomized controlled trials are needed to confirm or refute the authors' current findings.

Preoperative Liver Stiffness is Associated With Hospital Length of Stay After Cardiac Surgery.

OBJECTIVES: Risk assessment models for cardiac surgery do not account for the degrees of liver dysfunction. Ultrasound shear-wave elastography measures liver stiffness (LSM), a quantitative measurement related to fibrosis, congestion, and inflammation. The authors hypothesized that preoperative liver stiffness would be associated with hospital length of stay after cardiac surgery. DESIGN: Prospective observational study. SETTING: University hospital, single center. PARTICIPANTS: One hundred five adult patients undergoing nonemergent cardiac surgery. INTERVENTIONS: Preoperative liver stiffness measured by ultrasound elastography. MEASUREMENTS AND MAIN RESULTS: The associations were analyzed using linear mixed models, with adjustments for preoperative variables, duration of cardiopulmonary bypass, and type of surgery. Median liver stiffness was 6.4 kPa (range, 4.1-18.6 kPa). The median length of hospital stay was 6 days (range, 3-18 d). Each unit increase in liver stiffness, treated as a continuous variable, was associated with an increase of 0.32 ± 0.10 days in the hospital (p = 0.002). When treated as a categorical variable (<6 kPa, 6-9.4 kPa, and ≥9.5 kPa), LSM ≥9.5 kPa v LSM <6 kPa was associated strongly with an increase in hospital length of stay of 3.25 ± 0.87 days (p = 0.0003). CONCLUSIONS: A preoperative LSM ≥9.5 kPa was associated with a significantly longer postoperative hospital length of stay. This association appeared independent of preoperative comorbidities commonly associated with coronary disease. Preoperative liver stiffness is a novel risk metric that is associated with the postoperative hospital length of stay after cardiac surgery.

Cerebral autoregulation in the operating room and intensive care unit after cardiac surgery.

BACKGROUND: Cerebral autoregulation monitoring is a proposed method to monitor perfusion during cardiac surgery. However, limited data exist from the ICU as prior studies have focused on intraoperative measurements. Our objective was to characterise cerebral autoregulation during surgery and early ICU care, and as a secondary analysis to explore associations with delirium. METHODS: In patients undergoing cardiac surgery (n=134), cerebral oximetry values and arterial BP were monitored and recorded until the morning after surgery. A moving Pearson's correlation coefficient between mean arterial proessure (MAP) and near-infrared spectroscopy signals generated the cerebral oximetry index (COx). Three metrics were derived: (1) globally impaired autoregulation, (2) MAP time and duration outside limits of autoregulation (MAP dose), and (3) average COx. Delirium was assessed using the 3-Minute Diagnostic Interview for CAM-defined Delirium (3D-CAM) and the Confusion Assessment Method for the ICU (CAM-ICU). Autoregulation metrics were compared using χ2 and rank-sum tests, and associations with delirium were estimated using regression models, adjusted for age, bypass time, and logEuroSCORE. RESULTS: The prevalence of globally impaired autoregulation was higher in the operating room vs ICU (40% vs 13%, P<0.001). The MAP dose outside limits of autoregulation was similar in the operating room and ICU (median 16.9 mm Hg×h; inter-quartile range [IQR] 10.1-38.8 vs 16.9 mm Hg×h; IQR 5.4-35.1, P=0.20). In exploratory adjusted analyses, globally impaired autoregulation in the ICU, but not the operating room, was associated with delirium. The MAP dose outside limits of autoregulation in the operating room and ICU was also associated with delirium. CONCLUSIONS: Metrics of cerebral autoregulation are altered in the ICU, and may be clinically relevant with respect to delirium. Further studies are needed to investigate these findings and determine possible benefits of autoregulation-based MAP targeting in the ICU.

Aortitis masquerading as intramural hematoma: When to observe, when to operate? A case report.

Radiologic evidence of aortic disease is not always consistent with the diagnosis. With a lack of accompanying symptoms or with an atypical presentation, diagnosis, and management of aortic pathology rely greatly on imaging techniques. We report the case of a 58-year-old female who presented with incidental radiographic findings consistent with a type A aortic intramural hematoma and a vague left-sided chest discomfort. After follow-up, imaging was consistent with disease progression and hematoma expansion; the affected segment was resected and pathology reported lymphoplasmacytic aortitis as the underlying etiology of the imaging findings rather than an intramural hematoma. The patient lacked symptoms or serology consistent with the rheumatologic disease, and the postoperative course was uneventful. The management of a suspected ascending intramural hematoma is controversial, especially when the patient presents with atypical signs and symptoms. Features of disease progression may warrant urgent surgical intervention.

Ochronotic heart disease leading to severe aortic valve and coronary artery stenosis.

Cardiac ochronosis is a rare disease, estimated to affect 1 in 250,000 persons. While there is extensive evidence of the musculoskeletal alterations of the disease, cardiac involvement has not been widely studied and most information we currently have derives from case reports and case series. We report the case of a 64-year old patient with a known history of alkaptonuria who presented with dyspnea and weight loss. On evaluation, he was found to have severe aortic stenosis, coronary artery disease, and interventricular septal hypertrophy. Surgery revealed extensive ochronotic pigment deposition affecting the cardiac septum, both internal thoracic arteries, the native coronary arteries, and the aortic valve. Ochronotic heart disease is an often disregarded presentation of alkaptonuria. More information is needed on the course of the disease, as well as long-term outcomes after valve replacement surgery and/or coronary artery bypass grafting in patients with alkaptonuria.

Functional Outcomes of Frail Patients After Cardiac Surgery: An Observational Study.

BACKGROUND: Although frailty has been associated with major morbidity/mortality and increased length of stay after cardiac surgery, few studies have examined functional outcomes. We hypothesized that frailty would be independently associated with decreased functional status, increased discharge to a nonhome location, and longer duration of hospitalization after cardiac surgery, and that delirium would modify these associations. METHODS: This was an observational study nested in 2 trials, each of which was conducted by the same research team with identical measurement of exposures and outcomes. The Fried frailty scale was measured at baseline. The primary outcome (defined before data collection) was functional decline, defined as ≥2-point decline from baseline in Instrumental Activities of Daily Living (IADL) score at 1 month after surgery. Secondary outcomes were absolute decline in IADL score, discharge to a new nonhome location, and duration of hospitalization. Associations were analyzed using linear, logistic, and Poisson regression models with adjustments for variables considered before analysis (age, gender, race, and logistic European Score for Cardiac Operative Risk Evaluation [EuroSCORE]) and in a propensity score analysis. RESULTS: Data were available from 133 patients (83 from first trial and 50 from the second trial). The prevalence of frailty was 33% (44 of 133). In adjusted models, frail patients had increased odds of functional decline (primary outcome; odds ratio [OR], 2.41 [95% confidence interval {CI}, 1.03-5.63]; P = .04) and greater decline at 1 month in the secondary outcome of absolute IADL score (-1.48 [95% CI, -2.77 to -0.30]; P = .019), compared to nonfrail patients. Delirium significantly modified the association of frailty and change in absolute IADL score at 1 month. In adjusted hypothesis-generating models using secondary outcomes, frail patients had increased discharge to a new nonhome location (OR, 3.25 [95% CI, 1.37-7.69]; P = .007) and increased duration of hospitalization (1.35 days [95% CI, 1.19-1.52]; P < .0001) compared to nonfrail patients. The increased duration of hospitalization, but no change in functional status or discharge location, was partially mediated by increased complications in frail patients. CONCLUSIONS: Frailty may identify patients at risk of functional decline at 1 month after cardiac surgery. Perioperative strategies to optimize frail cardiac surgery patients are needed.

Changes in aorta hemodynamics in Left-Right Type 1 bicuspid aortic valve patients after replacement with bioprosthetic valves: An in-silico study.

Bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality with a high rate of concomitant aortic valve and ascending aorta (AAo) pathologic changes throughout the patient's lifetime. The etiology of BAV-related aortopathy was historically believed to be genetic. However, recent studies theorize that adverse hemodynamics secondary to BAVs also contribute to aortopathy, but their precise role, specifically, that of wall shear stress (WSS) magnitude and directionality remains controversial. Moreover, the primary therapeutic option for BAV patients is aortic valve replacement (AVR), but the role of improved post-AVR hemodynamics on aortopathy progression is also not well-understood. To address these issues, this study employs a computational fluid dynamics model to simulate personalized AAo hemodynamics before and after TAVR for a small cohort of 6 Left-Right fused BAV patients. Regional distributions of five hemodynamic metrics, namely, time-averaged wall shear stress (TAWSS) and oscillating shear index (OSI), divergence of wall shear (DWSS), helicity flux integral & endothelial cell activation potential (ECAP), which are hypothesized to be associated with potential aortic injury are computed in the root, proximal and distal ascending aorta. BAVs are characterized by strong, eccentric jets, with peak velocities exceeding 4 m/s and axially circulating flow away from the jets. Such conditions result in focused WSS loading along jet attachment regions on the lumen boundary and weaker, oscillating WSS on other regions. The jet attachment regions also show alternating streaks of positive and negative DWSS, which may increase risk for local tissue stretching. Large WSS magnitudes, strong helical flows and circumferential WSS have been previously implicated in the progression of BAV aortopathy. Post-intervention hemodynamics exhibit weaker, less eccentric jets. Significant reductions are observed in flow helicity, TAWSS and DWSS in localized regions of the proximal AAo. On the other hand, OSI increases post-intervention and ECAP is observed to be low in both pre- and post-intervention scenarios, although significant increases are also observed in this ECAP. These results indicate a significant alleviation of pathological hemodynamics post AVR.

Robotic-enhanced hybrid ablation for persistent and long-standing atrial fibrillation: Early assessment of feasibility, safety, and efficacy.

Objectives: To assess feasibility, safety, and early efficacy of robotic-enhanced epicardial ablation (RE-EA) as first stage of a hybrid approach to patients with persistent (PsAF) and long-standing atrial fibrillation (LSAF). Methods: Single-center, retrospective analysis of patients with documented PsAF and LSAF who underwent RE-EA followed by catheter-guided endocardial ablation. Postoperatively, patients were monitored for major adverse events and underwent rhythm follow-up at 3 and 12 months. Results: Between January 2021 and June 2023, we performed RE-EA in 64 patients (73.5% male, CHA2DS2-VASc 2.7 ± 1.6, BMI 34.1 ± 6.3 kg/m2). Mean AF preoperative duration and left atrial volume index were, respectively, 85 months and 47.5 mL/m2. Through the robotic approach, the intended lesion set was completed in all patients without cardiopulmonary bypass support, conversion to thoracotomy/sternotomy, blood transfusions, or perioperative mortality. The average LOS was 1.7 days, with only 1 patient requiring intensive care unit admission and >65% of patients discharged within 24 hours. At follow-up, 2 (3.1%) patients experienced new left pleural effusion or hemidiaphragm paralysis requiring treatment. There were no readmissions related to AF, stroke, thromboembolic events, or deaths. The mean interval between the epicardial and endocardial stages of the procedure was 5.9 months. Rhythm follow-up showed AF resolution in 73.4% and 71.9% of patients at 3 and 12 months, respectively. Conclusions: RE-EA is a feasible and safe, first-stage approach for the treatment of patients with PsAF and LSAF. It improves exposure of the intended targets, favors short hospital stay, and facilitates return to activity with satisfactory AF treatment in the short term.

Towards Longitudinal Monitoring of Leaflet Mobility in Prosthetic Aortic Valves via In-Situ Pressure Sensors: In-Silico Modeling and Analysis.

BACKGROUND: Transcatheter aortic valves (TAVs) are susceptible to leaflet thrombosis which may lead to thromboembolic events, and early detection and intervention are believed to be the key to avoiding such adverse outcomes. An embedded sensor system installed on the valve stent, coupled with an appropriate machine learning-based continuous monitoring algorithm can facilitate early detection to predict severity of reduced leaflet motion (RLM) and avoid adverse outcomes. METHODS: We present a data-driven, in silico, proof-of-concept analysis of a pressure microsensor based system for quantifying RLM in TAVs. We generate a dataset of 21 high-fidelity transvalvular flow simulations with healthy and mildly stenotic TAVs to train a logistic regression model to correlate individual leaflet mobility in each simulation with principal components of corresponding hemodynamic pressure recorded at strategic locations of the TAV stent. A separate test dataset of 7 simulations is also generated for prospective assessment of model performance. RESULTS: An array of 6 sensors embedded on the TAV stent, with two sensors tracking individual leaflet, successfully correlates leaflet mobility with recorded pressure. The sensors are placed along leaflet centerlines, one in the sinus, and the other at the sino-tubular junction. The regression model is tuned using cross-validation to achieve high accuracy on both training (R2 = 0.93) and test (R2 = 0.77) sets. CONCLUSION: Discrete blood pressure recordings on TAV stents can be successfully correlated with individual leaflet mobility. Further development of this technology can enable longitudinal monitoring of TAVs and early detection of valve failure.

Balancing carcinoid crisis and right ventricular dysfunction during tricuspid and pulmonic valve replacement for carcinoid heart disease: A case report.

INTRODUCTION AND IMPORTANCE: Carcinoid tumors are rare malignancies of neuroendocrine origin that can manifest with a constellation of systemic symptoms including right-sided cardiac involvement. Many patients with carcinoid heart disease require valve replacement, but intraoperative management of carcinoid syndrome varies within the literature. CASE PRESENTATION: A 72-year-old man with carcinoid syndrome underwent tricuspid and pulmonic valve replacement with multiple episodes of carcinoid crisis intraoperatively as well as right ventricular dysfunction after cardiopulmonary bypass. CLINICAL DISCUSSION: Octreotide is the mainstay in prevention and treatment of intraoperative carcinoid crisis, but reported dosages and timing varies significantly. The use of exogenous catecholamines is also controversial as they are thought to paradoxically worsen carcinoid symptoms. Our patient was managed successfully with both an octreotide infusion and intermittent boluses, as well as exogenous catecholamines for right ventricular support during and after cardiopulmonary bypass. CONCLUSION: The management of carcinoid syndrome in patients undergoing valve surgery for carcinoid heart disease is dependent on timely prevention and treatment of carcinoid crisis and effective mitigation of right ventricular dysfunction.

Causal determinants of postoperative length of stay in cardiac surgery using causal graphical learning.

OBJECTIVE: We aimed to learn the causal determinants of postoperative length of stay in cardiac surgery patients undergoing isolated coronary artery bypass grafting or aortic valve replacement surgery. METHODS: For patients undergoing isolated coronary artery bypass grafting or isolated aortic valve replacement surgeries between 2011 and 2016, we used causal graphical modeling on electronic health record data. The Fast Causal Inference (FCI) algorithm from the Tetrad software was used on data to estimate a Partial Ancestral Graph (PAG) depicting direct and indirect causes of postoperative length of stay, given background clinical knowledge. Then, we used the latent variable intervention-calculus when the directed acyclic graph is absent (LV-IDA) algorithm to estimate strengths of causal effects of interest. Finally, we ran a linear regression for postoperative length of stay to contrast statistical associations with what was learned by our causal analysis. RESULTS: In our cohort of 2610 patients, the mean postoperative length of stay was 219 hours compared with the Society of Thoracic Surgeons 2016 national mean postoperative length of stay of approximately 168 hours. Most variables that clinicians believe to be predictors of postoperative length of stay were found to be causes, but some were direct (eg, age, diabetes, hematocrit, total operating time, and postoperative complications), and others were indirect (including gender, race, and operating surgeon). The strongest average causal effects on postoperative length of stay were exhibited by preoperative dialysis (209 hours); neuro-, pulmonary-, and infection-related postoperative complications (315 hours, 89 hours, and 131 hours, respectively); reintubation (61 hours); extubation in operating room (-47 hours); and total operating room duration (48 hours). Linear regression coefficients diverged from causal effects in magnitude (eg, dialysis) and direction (eg, crossclamp time). CONCLUSIONS: By using retrospective electronic health record data and background clinical knowledge, causal graphical modeling retrieved direct and indirect causes of postoperative length of stay and their relative strengths. These insights will be useful in designing clinical protocols and targeting improvements in patient management.

Impact of intraoperative blood products, fluid administration, and persistent hypothermia on bleeding leading to reexploration after cardiac surgery.

OBJECTIVE: Risk factors for severe postoperative bleeding after cardiac surgery remain multiple and incompletely elucidated. We evaluated the impact of intraoperative blood product transfusions, intravenous fluid administration, and persistently low core body temperature (CBT) at intensive care unit arrival on risk of perioperative bleeding leading to reexploration. METHODS: We retrospectively queried our tertiary care center's Society of Thoracic Surgeons Institutional Database for all index, on-pump, adult cardiac surgery patients between July 2016 and September 2022. Intraoperative fluid (crystalloid and colloid) and blood product administrations, as well as perioperative CBT data, were harvested from electronic medical records. Linear and nonlinear mixed models, treating surgeon as a random effect to account for inter-surgeon practice differences, were used to assess the association between above factors and reexploration for bleeding. RESULTS: Of 4037 patients, 151 (3.7%) underwent reexploration for bleeding. Reexplored patients experienced remarkably greater postoperative morbidity (23% vs 6%, P < .001) and 30-day mortality (14% vs 2%, P < .001). In linear models, progressively increasing IV crystalloid administration (adjusted odds ratio, 1.11, 95% confidence interval, 1.03-1.19) and decreasing CBT on intensive care unit arrival (adjusted odds ratio, 1.20; 95% confidence interval, 1.05-1.37) were associated with greater risk of bleeding leading to reexploration. Nonlinear analysis revealed increasing risk after ∼6 L of crystalloid administration and a U-shaped relationship between CBT and reexploration risk. Intraoperative blood product transfusion of any kind was not associated with reexploration. CONCLUSIONS: We found evidence of both dilution- and hypothermia-related effects associated with perioperative bleeding leading to reexploration in cardiac surgery. Interventions targeting modification of such risk factors may decrease the rate this complication.

Prediction of operative mortality for patients undergoing cardiac surgical procedures without established risk scores.

OBJECTIVE: Current cardiac surgery risk models do not address a substantial fraction of procedures. We sought to create models to predict the risk of operative mortality for an expanded set of cases. METHODS: Four supervised machine learning models were trained using preoperative variables present in the Society of Thoracic Surgeons (STS) data set of the Massachusetts General Hospital to predict and classify operative mortality in procedures without STS risk scores. A total of 424 (5.5%) mortality events occurred out of 7745 cases. Models included logistic regression with elastic net regularization (LogReg), support vector machine, random forest (RF), and extreme gradient boosted trees (XGBoost). Model discrimination was assessed via area under the receiver operating characteristic curve (AUC), and calibration was assessed via calibration slope and expected-to-observed event ratio. External validation was performed using STS data sets from Brigham and Women's Hospital (BWH) and the Johns Hopkins Hospital (JHH). RESULTS: Models performed comparably with the highest mean AUC of 0.83 (RF) and expected-to-observed event ratio of 1.00. On external validation, the AUC was 0.81 in BWH (RF) and 0.79 in JHH (LogReg/RF). Models trained and applied on the same institution's data achieved AUCs of 0.81 (BWH: LogReg/RF/XGBoost) and 0.82 (JHH: LogReg/RF/XGBoost). CONCLUSIONS: Machine learning models trained on preoperative patient data can predict operative mortality at a high level of accuracy for cardiac surgical procedures without established risk scores. Such procedures comprise 23% of all cardiac surgical procedures nationwide. This work also highlights the value of using local institutional data to train new prediction models that account for institution-specific practices.

Hospital variability in modifiable factors driving coronary artery bypass charges.

OBJECTIVE: Coronary artery bypass grafting is associated with significant interhospital variability in charges. Drivers of hospital charge variability remain elusive. We identified modifiable factors associated with statewide interhospital variability in hospital charges for coronary artery bypass grafting. METHODS: Charge data were used as a surrogate for cost. Society of Thoracic Surgeons data from Maryland institutions and charge data from the Maryland Health Care Commission were linked to characterize interhospital charge variability for coronary artery bypass grafting. Multivariable linear regression was used to identify perioperative factors independently related to coronary artery bypass grafting charges. Of the factors independently associated with charges, we analyzed which factors varied between hospitals. RESULTS: A total of 10,337 patients underwent isolated coronary artery bypass grafting at 9 Maryland hospitals from 2012 to 2016, of whom 7532 patients were available for analyses. Mean normalized charges for isolated coronary artery bypass grafting varied significantly among hospitals, ranging from $30,000 to $57,000 (P < .001). Longer preoperative length of stay, operating room time, and major postoperative morbidity including stroke, renal failure, prolonged ventilation, reoperation, and deep sternal wound infection were associated with greater hospital charges. Incidence of major postoperative events, except stroke and deep sternal wound infection, was variable between hospitals. In a univariate linear regression model, patient risk profile only accounted for approximately 10% of statistical variance in charges. CONCLUSIONS: There is significant charge variability for coronary artery bypass grafting among hospitals within the same state. By targeting variation in preoperative length of stay, operating room time, postoperative renal failure, prolonged ventilation, and reoperation, cardiac surgery programs can realize cost savings while improving quality of care for this resource-intense patient population.

Early Reexploration for Bleeding Is Associated With Improved Outcome in Cardiac Surgery.

BACKGROUND: Reexploration after cardiac surgery, most frequently for bleeding, is a quality metric used to assess surgical performance. This may cause surgeons to delay return to the operating room in favor of attempting nonoperative management. This study investigated the impact of the timing of reexploration on morbidity and mortality. METHODS: This study was a single-institution retrospective review of all adult cardiac surgery patients from July 2010 to June 2020. Time to reexploration was assessed, and outcomes were compared across increasing time intervals. Reported bleeding sites were classified into 5 groups, and bleeding rate (chest tube output) was compared across bleeding sites. Univariable analysis was performed using the Fisher exact and Kruskal-Wallis tests. Multivariable logistic regression models were used for risk-adjusted analyses. RESULTS: Of 10 070 eligible patients, 251 (2.5%) required reexploration for postoperative bleeding. The most common site of bleeding was "any suture line" (n = 70; 28%). Interestingly, in 30% of cases (n = 75) "no active bleeding" site was reported. The highest rate of bleeding (mL/h) was observed in the "any mediastinal structure" group (median, 450; interquartile range [IQR], 185, 8878), and the lowest rate was noted in the "no active bleeding" group (median, 151.2; IQR, 102, 270). Both morbidity rates (0-4 hours, 12.3% vs 25-48 hours, 37.5%; P = .001) and mortality rates (0-4 hours, 3.1% vs 25-48 hours, 43.8%; P = .001) escalated significantly with increasing time to reexploration. CONCLUSIONS: Delayed reexploration for bleeding after cardiac surgery is associated with increased risk for morbidity and mortality. Early surgical intervention, particularly within 4 hours, may improve outcomes. Implications from using reoperation as a performance metric may lead to unnecessary delay and patient harm.