MALDI Imaging Mass Spectrometry as a Lipidomic Approach to Heart Valve Research

BACKGROUND

Valvular disease is characterized in part by lipid deposition, but systematic analysis of the patterns of global lipid expression in healthy and diseased valve tissues are unknown. This is due in part to tissue limitations for lipidomic preparations and technologies for evaluating lipid distribution in tissues. The study aim was to examine the application of matrixassisted laser desorption ionization imaging mass spectrometry (MALDI IMS) to the aortic valve during development and disease, as an approach to detect and map lipids and ultimately better understand valve structure and function.

METHODS

Established MALDI IMS strategies were applied to thin tissue sections of heart valves to map lipids to corresponding morphological features. Healthy prenatal and adult ovine aortic valve tissues were evaluated using the developed techniques. Lipid expression levels were compared between prenatal and adult valves using Wilcoxon rank sum testing and area under the receiver operating curves. A classification algorithm was used to determine distinct lipid signatures in adult extracellular matrix (ECM) substructures, including fibrosa and spongiosa layers. Lipid patterns were examined in heart valve tissue from pediatric patients with congenital aortic valve stenosis (CAVS).

RESULTS

Lipid levels were decreased in adult ovine aortic valves when compared with prenatal valves. Classification algorithms applied to lipid signatures reported distinct lipid signatures mapping to ECM substructures in the adult aortic valve, but could not distinguish amorphous structures at pre-natal day 5. In CAVS, the in-situ lipid aggregation of distinct lipid species showed unique patterning both concurrent and divergent with ECM disarray. Fatty acid content varied between normal and diseased human aortic valves.

CONCLUSIONS

MALDI IMS provides a new and useful approach to evaluate lipid biology in heart valve tissue. These findings define a role for lipid regulation in aortic valve development and demonstrate patterns of lipid deregulation in congenital disease.

The Society of Thoracic Surgeons Congenital Heart Surgery Database Mortality Risk Model: Part 2-Clinical Application

BACKGROUND

The empirically derived 2014 Society of Thoracic Surgeons Congenital Heart Surgery Database Mortality Risk Model incorporates adjustment for procedure type and patient-specific factors. The purpose of this report is to describe this model and its application in the assessment of variation in outcomes across centers.

METHODS

All index cardiac operations in The Society of Thoracic Surgeons Congenital Heart Surgery Database (January 1, 2010, to December 31, 2013) were eligible for inclusion. Isolated patent ductus arteriosus closures in patients weighing less than or equal to 2.5 kg were excluded, as were centers with more than 10% missing data and patients with missing data for key variables. The model includes the following covariates: primary procedure, age, any prior cardiovascular operation, any noncardiac abnormality, any chromosomal abnormality or syndrome, important preoperative factors (mechanical circulatory support, shock persisting at time of operation, mechanical ventilation, renal failure requiring dialysis or renal dysfunction (or both), and neurological deficit), any other preoperative factor, prematurity (neonates and infants), and weight (neonates and infants). Variation across centers was assessed. Centers for which the 95% confidence interval for the observed-to-expected mortality ratio does not include unity are identified as lower-performing or higher-performing programs with respect to operative mortality.

RESULTS

Included were 52,224 operations from 86 centers. Overall discharge mortality was 3.7% (1,931 of 52,224). Discharge mortality by age category was neonates, 10.1% (1,129 of 11,144); infants, 3.0% (564 of 18,554), children, 0.9% (167 of 18,407), and adults, 1.7% (71 of 4,119). For all patients, 12 of 86 centers (14%) were lower-performing programs, 67 (78%) were not outliers, and 7 (8%) were higher-performing programs.

CONCLUSIONS

The 2014 Society of Thoracic Surgeons Congenital Heart Surgery Database Mortality Risk Model facilitates description of outcomes (mortality) adjusted for procedural and for patient-level factors. Identification of low-performing and high-performing programs may be useful in facilitating quality improvement efforts.

Impact of Patient Characteristics on Hospital-Level Outcomes Assessment in Congenital Heart Surgery

BACKGROUND

Accurate hospital outcome measures in congenital heart surgery are important to multiple initiatives. While methods have been developed to account for differences in procedural case-mix, characteristics patients bring into the operation that may also vary across hospitals and influence outcome have received less attention. We evaluated the impact of these characteristics in a large cohort.

METHODS

Patients undergoing congenital heart surgery at centers participating in The Society of Thoracic Surgeons Congenital Heart Surgery Database (2010 to 2013) with adequate data quality were included. Variation across hospitals in important patient characteristics was examined, and hospital operative mortality rates were compared with and without adjustment for patient characteristics.

RESULTS

Overall, 86 centers (52,224 patients) were included. There was greater than twofold variation across hospitals for nearly all patient characteristics examined. For example, the proportion of a center's surgical population comprised of neonates ranged from 12.8% to 26.6% across hospitals; the proportion with a non-cardiac anomaly ranged from 0.7% to 5.0%. When hospital mortality rankings were evaluated based on "standard" (adjustment for differences in procedural case-mix alone) versus "full" models (adjustment for both differences in procedural case-mix and patient characteristics), 14.0% changed their ranking for mortality by 20 or greater positions, 34.9% of centers changed which mortality quartile they were classified in, and 14.0% changed their statistical classification (statistically higher, lower, or same-as-expected mortality).

CONCLUSIONS

Characteristics of patients undergoing congenital heart surgery vary across centers and impact hospital outcomes assessment. Methods to assess outcomes and relative performance should account for these characteristics.

Valvular interstitial cells suppress calcification of valvular endothelial cells

BACKGROUND

Calcific aortic valve disease (CAVD) is the most common heart valve disease in the Western world. We previously proposed that valvular endothelial cells (VECs) replenish injured adult valve leaflets via endothelial-to-mesenchymal transformation (EndMT); however, whether EndMT contributes to valvular calcification is unknown. We hypothesized that aortic VECs undergo osteogenic differentiation via an EndMT process that can be inhibited by valvular interstitial cells (VICs).

APPROACH AND RESULTS

VEC clones underwent TGF-β1-mediated EndMT, shown by significantly increased mRNA expression of the EndMT markers α-SMA (5.3 ± 1.2), MMP-2 (13.5 ± 0.6) and Slug (12 ± 2.1) (p < 0.05), (compared to unstimulated controls). To study the effects of VIC on VEC EndMT, clonal populations of VICs were derived from the same valve leaflets, placed in co-culture with VECs, and grown in control/TGF-β1 supplemented media. In the presence of VICs, EndMT was inhibited, shown by decreased mRNA expression of α-SMA (0.1 ± 0.5), MMP-2 (0.1 ± 0.1), and Slug (0.2 ± 0.2) (p < 0.05). When cultured in osteogenic media, VECs demonstrated osteogenic changes confirmed by increase in mRNA expression of osteocalcin (8.6 ± 1.3), osteopontin (3.7 ± 0.3), and Runx2 (5.5 ± 1.5). The VIC presence inhibited VEC osteogenesis, demonstrated by decreased expression of osteocalcin (0.4 ± 0.1) and osteopontin (0.2 ± 0.1) (p < 0.05). Time course analysis suggested that EndMT precedes osteogenesis, shown by an initial increase of α-SMA and MMP-2 (day 7), followed by an increase of osteopontin and osteocalcin (day 14).

CONCLUSIONS

The data indicate that EndMT may precede VEC osteogenesis. This study shows that VICs inhibit VEC EndMT and osteogenesis, indicating the importance of VEC-VIC interactions in valve homeostasis.

Quality-Cost Relationship in Congenital Heart Surgery

BACKGROUND

There is an increasing focus on optimizing health care quality and reducing costs. The care of children undergoing heart surgery requires significant investment of resources, and it remains unclear how costs of care relate to quality. We evaluated this relationship across a multicenter cohort.

METHODS

Clinical data from The Society of Thoracic Surgeons Database were merged with cost data from the Pediatric Health Information Systems Database for children undergoing heart surgery (2006 to 2010). Hospital-level costs were modeled using Bayesian hierarchical methods adjusting for case-mix, and hospitals were categorized into cost tertiles. The primary quality metric evaluated was in-hospital mortality.

RESULTS

Overall, 27 hospitals (30,670 patients) were included. Median adjusted cost per case was $82,360 and varied fivefold across hospitals, while median adjusted mortality was 3.4% and ranged from 2.4% to 5.0% across hospitals. Overall, hospitals in the lowest cost tertile had significantly lower adjusted mortality rates compared with the middle and high cost tertiles (2.5% vs 3.8% and 3.5%, respectively, both p < 0.001). When assessed at the individual hospital level, most (75%) but not all hospitals in the lowest cost tertile were also in the lowest mortality tertile. Similar relationships were seen across the spectrum of surgical complexity. Lower cost hospitals also had shorter length of stay and trends toward fewer major complications.

CONCLUSIONS

Lowest cost hospitals generally deliver the highest quality care for children undergoing heart surgery, although there is some variation in this relationship. This information is important in the design of initiatives aiming to optimize health care value in this population.

Outcomes of surgery for young children with multivessel pulmonary vein stenosis

OBJECTIVE

We pursued a multimodality approach to the treatment of patients with pulmonary vein stenosis, incorporating sutureless surgical repair, catheter interventions, and adjunctive chemotherapy. We report our outcomes after surgery.

METHODS

Between January 2007 and August 2013, 49 patients with multivessel pulmonary vein stenosis underwent operations at our institution. We retrospectively reviewed data from a pulmonary vein stenosis registry and the medical records.

RESULTS

At the time of the index operation, the median patient age was 6 months (range, 32 days-48 months) and weight was 4.9 kg (range, 2.1-13.4 kg). Fourteen patients (28%) died during the follow-up period (median follow-up was 0.5 years [range, 0.04-4.9 years]). There were 2 deaths (4%) within 30 days. Age at repair <6 months, weight at repair <3 kg, and a preoperative right ventricular systolic pressure < ¾ systemic were found to be associated with mortality. One patient required repeat operation for recurrent stenosis. Thirty-nine patients (80%) underwent postoperative catheterizations. The median number of catheterizations per patient was 2 (range, 0-14). Twenty-nine patients (59%) underwent catheterizations with pulmonary vein intervention. The median number of catheterizations with intervention per patient was 1 (range, 0-14). There were no identifiable associations with need for or number of catheterizations with intervention. Ten patients were listed for lung transplantation: 4 patients were de-listed, 3 patients died waiting, and 3 patients underwent transplant.

CONCLUSIONS

Using a multimodality approach, we observed acceptable early survival after operation in patients with pulmonary vein stenosis, despite the need for catheter reinterventions. Lung transplantation remains a viable option.

Cost-effectiveness of revascularization strategies: the ASCERT study

BACKGROUND

ASCERT (American College of Cardiology Foundation and the Society of Thoracic Surgeons Collaboration on the Comparative Effectiveness of Revascularization Strategies) was a large observational study designed to compare the long-term effectiveness of coronary artery bypass graft (CABG) and percutaneous coronary intervention (PCI) to treat coronary artery disease (CAD) over 4 to 5 years.

OBJECTIVES

This study examined the cost-effectiveness of CABG versus PCI for stable ischemic heart disease.

METHODS

The Society of Thoracic Surgeons and American College of Cardiology Foundation databases were linked to the Centers for Medicare and Medicaid Services claims data. Costs for the index and observation period (2004 to 2008) hospitalizations were assessed by diagnosis-related group Medicare reimbursement rates; costs beyond the observation period were estimated from average Medicare participant per capita expenditure. Effectiveness was measured via mortality and life-expectancy data. Cost and effectiveness comparisons were adjusted using propensity score matching with the incremental cost-effectiveness ratio expressed as cost per quality-adjusted life-year gained.

RESULTS

CABG patients (n = 86,244) and PCI patients (n = 103,549) were at least 65 years old with 2- or 3-vessel coronary artery disease. Adjusted costs were higher for CABG for the index hospitalization, study period, and lifetime by $10,670, $8,145, and $11,575, respectively. Patients undergoing CABG gained an adjusted average of 0.2525 and 0.3801 life-years relative to PCI over the observation period and lifetime, respectively. The life-time incremental cost-effectiveness ratio of CABG compared to PCI was $30,454/QALY gained.

CONCLUSIONS

Over a period of 4 years or longer, patients undergoing CABG had better outcomes but at higher costs than those undergoing PCI.

Reciprocal interactions between mitral valve endothelial and interstitial cells reduce endothelial-to-mesenchymal transition and myofibroblastic activation

Thickening of mitral leaflets, endothelial-to-mesenchymal transition (EndMT), and activated myofibroblast-like interstitial cells have been observed in ischemic mitral valve regurgitation. We set out to determine if interactions between mitral valve endothelial cells (VEC) and interstitial cells (VIC) might affect these alterations. We used in vitro co-culture in Transwell™ inserts to test the hypothesis that VIC secrete factors that inhibit EndMT and conversely, that VEC secrete factors that mitigate the activation of VIC to a myofibroblast-like, activated phenotype. Primary cultures and clonal populations of ovine mitral VIC and VEC were used. Western blot, quantitative reverse transcriptase PCR (qPCR) and functional assays were used to assess changes in cell phenotype and behavior. VIC or conditioned media from VIC inhibited transforming growth factorβ (TGFβ)-induced EndMT in VEC, as indicated by reduced expression of EndMT markers α-smooth muscle actin (α-SMA), Slug, Snai1 and MMP-2 and maintained ability of VEC to mediate leukocyte adhesion, an important endothelial function. VEC or conditioned media from VEC reversed the spontaneous cell culture-induced change in VIC to an activated phenotype, as indicated by reduced expression of α-SMA and type I collagen, increased expression chondromodulin-1 (Chm1), and reduced contractile activity. These results demonstrate that mitral VEC and VIC secrete soluble factors that can reduce VIC activation and inhibit TGFβ-driven EndMT, respectively. These findings suggest that the endothelium of the mitral valve is critical for the maintenance of a quiescent VIC phenotype and that, in turn, VIC prevent EndMT. We speculate that disturbance of the ongoing reciprocal interactions between VEC and VICs in vivo may contribute to the thickened and fibrotic leaflets observed in ischemic mitral regurgitation, and in other types of valve disease.

Measuring hospital performance in congenital heart surgery: administrative versus clinical registry data

BACKGROUND

In congenital heart surgery, hospital performance has historically been assessed using widely available administrative data sets. Recent studies have demonstrated inaccuracies in case ascertainment (coding and inclusion of eligible cases) in administrative versus clinical registry data; however, it is unclear whether this impacts assessment of performance on a hospital level.

METHODS

Merged data from The Society of Thoracic Surgeons (STS) database (clinical registry) and the Pediatric Health Information Systems (PHIS) database (administrative data set) for 46,056 children undergoing cardiac operations (2006-2010) were used to evaluate in-hospital mortality for 33 hospitals based on their administrative versus registry data. Standard methods to identify/classify cases were used: Risk Adjustment in Congenital Heart Surgery, version 1 (RACHS-1) in the administrative data and STS-European Association for Cardiothoracic Surgery (STAT) methodology in the registry.

RESULTS

Median hospital surgical volume based on the registry data was 269 cases per year; mortality was 2.9%. Hospital volumes and mortality rates based on the administrative data were on average 10.7% and 4.7% lower, respectively, although this varied widely across hospitals. Hospital rankings for mortality based on the administrative versus registry data differed by 5 or more rank positions for 24% of hospitals, with a change in mortality tertile classification (high, middle, or low mortality) for 18% and a change in statistical outlier classification for 12%. Higher volume/complexity hospitals were most impacted. Agency for Healthcare Quality and Research (AHRQ) methods in the administrative data yielded similar results.

CONCLUSIONS

Inaccuracies in case ascertainment in administrative versus clinical registry data can lead to important differences in assessment of hospital mortality rates for congenital heart surgery.

A method to account for variation in congenital heart surgery charges

BACKGROUND

In response to societal pressure to reduce expenditures and increase quality, we sought to develop a methodology to predict hospital charges related to congenital heart surgery.

METHODS

Patients undergoing congenital heart surgery at Boston Children's Hospital in fiscal years 2007 to 2009 comprised the derivation cohort. Clinical data, including Current Procedural Terminology coding of the primary surgical intervention, were collected prospectively and linked to total hospital charges for an episode of care. Surgical charge categories were developed to group surgical procedure types using empiric data and expert consensus. A multivariable model was built using surgical charge categories and additional patient and procedural characteristics to predict the outcome, total hospital charges. A contemporary cohort for fiscal years 2010 to 2012 was used to validate surgical charge categories and the multivariable model.

RESULTS

In the derivation cohort, 2,105 cases met inclusion criteria. One hundred three surgical procedure types were categorized into seven surgical charge categories, yielding a grouper variable with an R(2) explanatory value of 47.3%. Explanatory value increased with consideration of patient age, admission status, and preoperative ventilator dependence (R(2) = 59.4%), as well as weight category, noncardiac abnormality, and genetic syndrome other than trisomy 21 (R(2) = 61.5%). Additional variability in charge was explained when extracorporeal membrane oxygenation utilization and greater than one operating room visit during the episode of care were added (R(2) = 74.3%). The contemporary cohort yielded an R(2) explanatory value of 67.7%.

CONCLUSIONS

The combination of clinical data with resource utilization information resulted in a statistically valid predictive model for total hospital charges in congenital heart surgery.

Linking the congenital heart surgery databases of the Society of Thoracic Surgeons and the Congenital Heart Surgeons' Society: part 2--lessons learned and implications

PURPOSE

A link has been created between the Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) and the Congenital Heart Surgeons' Society Database (CHSS-D). Five matrices have been created that facilitate the automated identification of patients who are potentially eligible for the five active CHSS studies using the STS-CHSD. These matrices are now used to (1) estimate the denominator of patients eligible for CHSS studies and (2) compare "eligible and enrolled patients" to "potentially eligible and not enrolled patients" to assess the generalizability of CHSS studies.

METHODS

The matrices were applied to 40 consenting institutions that participate in both the STS-CHSD and the CHSS to (1) estimate the denominator of patients that are potentially eligible for CHSS studies, (2) estimate the completeness of enrollment of patients eligible for CHSS studies among all CHSS sites, (3) estimate the completeness of enrollment of patients eligible for CHSS studies among those CHSS institutions participating in each CHSS cohort study, and (4) compare "eligible and enrolled patients" to "potentially eligible and not enrolled patients" to assess the generalizability of CHSS studies. The matrices were applied to all participants in the STS-CHSD to identify patients who underwent frequently performed operations and compare "eligible and enrolled patients" to "potentially eligible and not enrolled patients" in following five domains: (1) age at surgery, (2) gender, (3) race, (4) discharge mortality, and (5) postoperative length of stay. Completeness of enrollment was defined as the number of actually enrolled patients divided by the number of patients identified as being potentially eligible for enrollment.

RESULTS

For the CHSS Critical Left Ventricular Outflow Tract Study (LVOTO) study, for the Norwood procedure, completeness of enrollment at centers actively participating in the LVOTO study was 34%. For the Norwood operation, discharge mortality was 15% among 227 enrolled patients and 16% among 1768 nonenrolled potentially eligible patients from the 40 consenting institutions. Median postoperative length of stay was 31 days and 26 days for these enrolled and nonenrolled patients. For the CHSS anomalous aortic origin of a coronary artery (AAOCA) study, for AAOCA repair, completeness of enrollment at centers actively participating in the AAOCA study was 40%.

CONCLUSION

Determination of the denominator of patients eligible for CHSS studies and comparison of "eligible and enrolled patients" to "potentially eligible and not enrolled patients" provides an estimate of the extent to which patients in CHSS studies are representative of the overall population of eligible patients; however, opportunities exist to improve enrollment.

Development of a charge adjustment model for cardiac catheterization

A methodology that would allow for comparison of charges across institutions has not been developed for catheterization in congenital heart disease. A single institution catheterization database with prospectively collected case characteristics was linked to hospital charges related and limited to an episode of care in the catheterization laboratory for fiscal years 2008-2010. Catheterization charge categories (CCC) were developed to group types of catheterization procedures using a combination of empiric data and expert consensus. A multivariable model with outcome charges was created using CCC and additional patient and procedural characteristics. In 3 fiscal years, 3,839 cases were available for analysis. Forty catheterization procedure types were categorized into 7 CCC yielding a grouper variable with an R (2) explanatory value of 72.6%. In the final CCC, the largest proportion of cases was in CCC 2 (34%), which included diagnostic cases without intervention. Biopsy cases were isolated in CCC 1 (12%), and percutaneous pulmonary valve placement alone made up CCC 7 (2%). The final model included CCC, number of interventions, and cardiac diagnosis (R (2) = 74.2%). Additionally, current financial metrics such as APR-DRG severity of illness and case mix index demonstrated a lack of correlation with CCC. We have developed a catheterization procedure type financial grouper that accounts for the diverse case population encountered in catheterization for congenital heart disease. CCC and our multivariable model could be used to understand financial characteristics of a population at a single point in time, longitudinally, and to compare populations.

Technical performance score as predictor for post-discharge reintervention in valve-sparing tetralogy of Fallot repair

Recognition of late problems following repair of tetralogy of Fallot (TOF) with a transannular patch has stimulated modifications to preserve pulmonary valve (PV) function. This study assesses the ability of technical performance score (TPS) to determine the need for post-discharge reinterventions (RIs) in valve-sparing TOF repair. We retrospectively reviewed 157 patients following valve-sparing repair of TOF from 2007-2012. We assigned TPS as Class 1 (optimal), Class 2 (adequate), or Class 3 (inadequate) based on discharge echo and clinical criteria. Preoperative, discharge, and follow-up PV Z scores and post-discharge RIs were documented. Reasons for Class 2 or 3 designation were right ventricular outflow tract (RVOT) gradient in 52, pulmonary regurgitation in 13, residual ventricular septal defects in 7, both RVOT gradient and ventricular septal defects in 13, and both RVOT gradient and pulmonary regurgitation in 37 patients. Median follow-up was 19.6 (range: 0.1-86.1) months. Class 3 patients had a significantly longer median intensive care unit and hospital stay compared with Class 1 (3 vs 2 days [P = 0.015] and 7 vs 5 days [P < 0.001], respectively). Post-discharge RIs were significantly lower in Class 1 vs Class 2 and Class 3 (P = 0.003). Class 1 patients had significantly larger PV Z scores compared with Class 2 or Class 3 patients (P < 0.001). TPS is associated with post-discharge RI rate after valve-sparing TOF repair. Preoperative PV Z score is highly correlated with Class I TPS. Patient selection based on preoperative PV Z scores may help determine if valve-sparing approach is appropriate, thus minimizing the need for RIs.

The importance of patient-specific preoperative factors: an analysis of the society of thoracic surgeons congenital heart surgery database

BACKGROUND

The most common forms of risk adjustment for pediatric and congenital heart surgery used today are based mainly on the estimated risk of mortality of the primary procedure of the operation. The goals of this analysis were to assess the association of patient-specific preoperative factors with mortality and to determine which of these preoperative factors to include in future pediatric and congenital cardiac surgical risk models.

METHODS

All index cardiac operations in The Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) during 2010 through 2012 were eligible for inclusion. Patients weighing less than 2.5 kg undergoing patent ductus arteriosus closure were excluded. Centers with more than 10% missing data and patients with missing data for discharge mortality or other key variables were excluded. Rates of discharge mortality for patients with or without specific preoperative factors were assessed across age groups and were compared using Fisher's exact test.

RESULTS

In all, 25,476 operations were included (overall discharge mortality 3.7%, n=943). The prevalence of common preoperative factors and their associations with discharge mortality were determined. Associations of the following preoperative factors with discharge mortality were all highly significant (p<0.0001) for neonates, infants, and children: mechanical circulatory support, renal dysfunction, shock, and mechanical ventilation.

CONCLUSIONS

Current STS-CHSD risk adjustment is based on estimated risk of mortality of the primary procedure of the operation as well as age, weight, and prematurity. The inclusion of additional patient-specific preoperative factors in risk models for pediatric and congenital cardiac surgery could lead to increased precision in predicting risk of operative mortality and comparison of observed to expected outcomes.

Excess costs associated with complications and prolonged length of stay after congenital heart surgery

BACKGROUND

While there is an increasing emphasis on both optimizing quality of care and reducing health care costs, there are limited data regarding how to best achieve these goals for common and resource-intense conditions such as congenital heart disease. We evaluated excess costs associated with complications and prolonged length of stay (LOS) after congenital heart surgery in a large multicenter cohort.

METHODS

Clinical data from The Society of Thoracic Surgeons Database were linked to estimated costs from the Pediatric Health Information Systems Database (2006 to 2010). Excess cost per case associated with complications and prolonged LOS was modeled for 9 operations of varying complexity adjusting for patient baseline characteristics.

RESULTS

Of 12,718 included operations (27 centers), average excess cost per case in those with any complication (versus none) was $56,584 (+$132,483 for major complications). The 5 highest cost complications were tracheostomy, mechanical circulatory support, respiratory complications, renal failure, and unplanned reoperation or reintervention (ranging from $57,137 to $179,350). Patients with an additional day of LOS above the median had an average excess cost per case of $19,273 (+$40,688 for LOS 4 to 7 days above median). Potential cost savings in the study cohort achievable through reducing major complications (by 10%) and LOS (by 1 to 3 days) were greatest for the Norwood operation ($7,944,128 and $3,929,351, respectively) and several other commonly performed operations of more moderate complexity.

CONCLUSIONS

Complications and prolonged LOS after congenital heart surgery are associated with significant costs. Initiatives able to achieve even modest reductions in these morbidities may lead to both improved outcomes and cost savings across both moderate and high complexity operations.

Outcomes differ in patients who undergo immediate intraoperative revision versus patients with delayed postoperative revision of residual lesions in congenital heart operations

OBJECTIVES

In a previous study of infants less than 6 month old, we found that delayed revision of residual lesions resulted in worse patient outcomes compared with intraoperative revision. We explored a larger cohort to determine if this finding persisted.

METHODS

A prospective cohort followed from index surgery to discharge from January 2011 to September 2013 were divided into 4 groups: (1) intraoperative revisions (IO) of residual lesions, (2) delayed postoperative revision (PO) of residual lesions during the same hospital stay, (3) both intraoperative and delayed (BOTH) revision of residual lesions, (4) no intraoperative or postoperative revision (NO). Linear and logistic regression analyses were used to compare outcomes of postoperative hospital length of stay, postoperative adverse events (AE), hospital costs, and mortality, after adjusting for age, prematurity, presence of extracardiac anomalies, and RACHS-1 (Risk Adjustment for Congenital Heart Surgery-1) risk category known to affect outcomes.

RESULTS

Of the 2427 patients discharged after a congenital cardiac operation, 1886 were eligible for this study after exclusion of adults, procedures performed off cardiopulmonary bypass, and transplants and assist devices. On multivariable modeling adjusting for other significant patient factors, the NO group fared better than the other 3 groups. The IO group had significantly lower postoperative length of stay, AE rate, and hospital costs compared with the PO and BOTH groups, but showed no significant differences in mortality.

CONCLUSIONS

Intraoperative correction of residual lesions results in shorter length of stay, and lower postoperative AE and costs compared with delayed postoperative revision of residual lesions.

Impact of Empiric Nesiritide or Milrinone Infusion on Early Postoperative Recovery After Fontan Surgery

Background—

We sought to determine whether empirical nesiritide or milrinone would improve the early postoperative course after Fontan surgery. We hypothesized that compared with milrinone or placebo, patients assigned to receive nesiritide would have improved early postoperative outcomes.

Methods and Results—

In a single-center, randomized, double-blinded, placebo-controlled, multi-arm parallel-group clinical trial, patients undergoing primary Fontan surgery were assigned to receive nesiritide, milrinone, or placebo. A loading dose of study drug was administered on cardiopulmonary bypass followed by a continuous infusion for ≥12 hours and ≤5 days after cardiac intensive care unit admission. The primary outcome was days alive and out of the hospital within 30 days of surgery. Secondary outcomes included measures of cardiovascular function, renal function, resource use, and adverse events. Among 106 enrolled subjects, 35, 36, and 35 were randomized to the nesiritide, milrinone, and placebo groups, respectively, and all were analyzed based on intention to treat. Demographics, patient characteristics, and operative factors were similar among treatment groups. No significant treatment group differences were found for median days alive and out of the hospital within 30 days of surgery (nesiritide, 20 [minimum to maximum, 0–24]; milrinone, 18 [0–23]; placebo, 20 [0–23]; P =0.38). Treatment groups did not significantly differ in cardiac index, arrhythmias, peak lactate, inotropic scores, urine output, duration of mechanical ventilation, intensive care or chest tube drainage, or adverse events.

Conclusions—

Compared with placebo, empirical perioperative nesiritide or milrinone infusions are not associated with improved early clinical outcomes after Fontan surgery.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00543309.

Tri-layered elastomeric scaffolds for engineering heart valve leaflets

Tissue engineered heart valves (TEHVs) that can grow and remodel have the potential to serve as permanent replacements of the current non-viable prosthetic valves particularly for pediatric patients. A major challenge in designing functional TEHVs is to mimic both structural and anisotropic mechanical characteristics of the native valve leaflets. To establish a more biomimetic model of TEHV, we fabricated tri-layered scaffolds by combining electrospinning and microfabrication techniques. These constructs were fabricated by assembling microfabricated poly(glycerol sebacate) (PGS) and fibrous PGS/poly(caprolactone) (PCL) electrospun sheets to develop elastic scaffolds with tunable anisotropic mechanical properties similar to the mechanical characteristics of the native heart valves. The engineered scaffolds supported the growth of valvular interstitial cells (VICs) and mesenchymal stem cells (MSCs) within the 3D structure and promoted the deposition of heart valve extracellular matrix (ECM). MSCs were also organized and aligned along the anisotropic axes of the engineered tri-layered scaffolds. In addition, the fabricated constructs opened and closed properly in an ex vivo model of porcine heart valve leaflet tissue replacement. The engineered tri-layered scaffolds have the potential for successful translation towards TEHV replacements.

Electrospun PGS:PCL microfibers align human valvular interstitial cells and provide tunable scaffold anisotropy

Tissue engineered heart valves (TEHV) can be useful in the repair of congenital or acquired valvular diseases due to their potential for growth and remodeling. The development of biomimetic scaffolds is a major challenge in heart valve tissue engineering. One of the most important structural characteristics of mature heart valve leaflets is their intrinsic anisotropy, which is derived from the microstructure of aligned collagen fibers in the extracellular matrix (ECM). In the present study, a directional electrospinning technique is used to fabricate fibrous poly(glycerol sebacate):poly(caprolactone) (PGS:PCL) scaffolds containing aligned fibers, which resemble native heart valve leaflet ECM networks. In addition, the anisotropic mechanical characteristics of fabricated scaffolds are tuned by changing the ratio of PGS:PCL to mimic the native heart valve's mechanical properties. Primary human valvular interstitial cells (VICs) attach and align along the anisotropic axes of all PGS:PCL scaffolds with various mechanical properties. The cells are also biochemically active in producing heart-valve-associated collagen, vimentin, and smooth muscle actin as determined by gene expression. The fibrous PGS:PCL scaffolds seeded with human VICs mimick the structure and mechanical properties of native valve leaflet tissues and would potentially be suitable for the replacement of heart valves in diverse patient populations.

Composite outcomes in coronary bypass surgery versus percutaneous intervention

BACKGROUND

Recent observational studies show that patients with multivessel coronary disease have a long-term survival advantage with coronary artery bypass grafting (CABG) compared with percutaneous coronary intervention (PCI). Important nonfatal outcomes may also affect optimal treatment recommendation.

METHODS

CABG was compared with percutaneous catheter intervention by using a composite of death, myocardial infarction (MI), or stroke. Medicare patients undergoing revascularization for stable multivessel coronary disease from 2004 through 2008 were identified in national registries. Short-term clinical information from the registries was linked to Medicare data to obtain long-term follow-up out to 4 years from the time of the procedure. Propensity scoring with inverse probability weighting was used to adjust for baseline risk factors.

RESULTS

There were 86,244 CABG and 103,549 PCI patients. The mean age was 74 years, with a median 2.67 years of follow-up. At 4 years, the propensity-adjusted adjusted cumulative incidence of MI was 3.2% in CABG compared with 6.6% in PCI (risk ratio, 0.49; 95% confidence interval, 0.45 to 0.53). At 4 years, the cumulative incidence of stroke was 4.5% in CABG compared with 3.1% in PCI patients (risk ratio, 1.43; 95% confidence interval, 1.31 to 1.54). This difference was primarily due to the higher 30-day stroke rate for CABG (1.55% vs 0.37%). For the composite of death, MI, or stroke, the 4-year adjusted cumulative incidence was 21.6% for CABG and 26.7% for PCI (risk ratio, 0.81; 95% confidence interval, 0.78 to 0.83).

CONCLUSIONS

The 4-year composite event rate of death, MI, and stroke favored CABG, whereas the risk of stroke alone favored PCI.

Linking the congenital heart surgery databases of the Society of Thoracic Surgeons and the Congenital Heart Surgeons' Society: part 1--rationale and methodology

PURPOSE

The Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) is the largest Registry in the world of patients who have undergone congenital and pediatric cardiac surgical operations. The Congenital Heart Surgeons' Society Database (CHSS-D) is an Academic Database designed for specialized detailed analyses of specific congenital cardiac malformations and related treatment strategies. The goal of this project was to create a link between the STS-CHSD and the CHSS-D in order to facilitate studies not possible using either individual database alone and to help identify patients who are potentially eligible for enrollment in CHSS studies.

METHODS

Centers were classified on the basis of participation in the STS-CHSD, the CHSS-D, or both. Five matrices, based on CHSS inclusionary criteria and STS-CHSD codes, were created to facilitate the automated identification of patients in the STS-CHSD who meet eligibility criteria for the five active CHSS studies. The matrices were evaluated with a manual adjudication process and were iteratively refined. The sensitivity and specificity of the original matrices and the refined matrices were assessed.

RESULTS

In January 2012, a total of 100 centers participated in the STS-CHSD and 74 centers participated in the CHSS. A total of 70 centers participate in both and 40 of these 70 agreed to participate in this linkage project. The manual adjudication process and the refinement of the matrices resulted in an increase in the sensitivity of the matrices from 93% to 100% and an increase in the specificity of the matrices from 94% to 98%.

CONCLUSION

Matrices were created to facilitate the automated identification of patients potentially eligible for the five active CHSS studies using the STS-CHSD. These matrices have a sensitivity of 100% and a specificity of 98%. In addition to facilitating identification of patients potentially eligible for enrollment in CHSS studies, these matrices will allow (1) estimation of the denominator of patients potentially eligible for CHSS studies and (2) comparison of eligible and enrolled patients to potentially eligible and not enrolled patients to assess the generalizability of CHSS studies.