Seventh Annual Society of Thoracic Surgeons Pedimacs Report.

BACKGROUND: The Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs), supported by The Society of Thoracic Surgeons, provides detailed information on pediatric patients supported with ventricular assist devices (VADs). METHODS: From September 19, 2012, to December 31, 2022, 1463 devices in 1219 patients aged <19 years were reported to the registry from 40 North American hospitals. RESULTS: Cardiomyopathy remains the most common underlying etiology (59%), followed by congenital heart disease (26%) and myocarditis (8%). Implantable continuous devices were most common (39%) type, followed by paracorporeal pulsatile (28%) and paracorporeal continuous (27%) devices. At 6 months after VAD implantation, a favorable outcome (transplant, recovery, or alive on device) was achieved in 85% of patients, which was greatest among those on implantable continuous VADs (92%) and least for paracorporeal continuous VADs (68%), although the patient population supported on these devices is different. CONCLUSIONS: This Seventh Pedimacs Report demonstrates the continued importance of VADs in the treatment of children. With the complexity of cardiac physiologies and sizes of patients, multiple types of devices are used, including paracorporeal continuous, paracorporeal pulsatile, and implantable continuous devices. The preoperative risk factors and differences in patient populations may account for some of the differences in survival observed among these devices. This report, along with other collaborative work, continues to advance the care of this challenging and vulnerable population.

Contemporary outcomes of pediatric cardiac transplantation with a positive retrospective crossmatch.

BACKGROUND: A positive crossmatch (+ XM) has traditionally been associated with adverse outcomes following pediatric heart transplantation. However, more recent studies suggest that favorable intermediate-term outcomes may be achieved despite a + XM. This study's hypothesis is that children with a + XM have similar long-term survival, but higher rate of complications such as rejection, coronary allograft vasculopathy (CAV), and infection, compared to patients with a negative (-) XM. METHODS: The Pediatric Heart Transplant Society Registry (PHTS) database was queried from 2010-2021 for all patients <18 years of age with a known XM. Baseline demographics were compared between + XM and - XM groups using appropriate parametric and non-parametric group comparisons. Cox Proportional Hazards Modeling was used to identify risk factors for post-transplant graft loss, rejection, and CAV. RESULTS: Of 4599 pediatric heart transplants during the study period, XM results were available for 3914 (85%), of which 373 (9.5%) had a + XM. Univariate analysis showed lower 10-year survival for patients with + XM (HR = 1.3, p = .04). Multivariate analyses revealed no significant difference in 10-year survival in the 2 groups; however, time to first rejection (p = .0001) remained significantly shorter in the + XM group. CONCLUSIONS: Pediatric patients transplanted across a + XM experience earlier rejection; however, after multivariate adjustment, + XM is not independently associated with intermediate-term graft loss. The risk of heart transplantation against a + XM must be balanced with the ongoing risk of waitlist mortality.

Expanding use of the HeartMate 3 ventricular assist device in pediatric and adult patients within the Advanced Cardiac Therapies Improving Outcomes Network (ACTION).

BACKGROUND: We report current outcomes in patients supported with the HeartMate 3 (HM3) ventricular assist device in a multicenter learning network. METHODS: The Advanced Cardiac Therapies Improving Outcomes Network database was queried for HM3 implants between 12/2017 and 5/2022. Clinical characteristics, postimplant course, and adverse events were collected. Patients were stratified according to body surface area (BSA) (<1.4 m2, 1.4-1.8 m2, and >1.8 m2) at device implantation. RESULTS: During the study period, 170 patients were implanted with the HM3 at participating network centers, with median age 15.3years; 27.1% were female. Median BSA was 1.68 m2; the smallest patient was 0.73 m2 (17.7 kg). Most (71.8%) had a diagnosis of dilated cardiomyopathy. With a median support time of 102.5days, 61.2% underwent transplantation, 22.9% remained supported on device, 7.6% died, and 2.4% underwent device explantation for recovery; the remainder had transferred to another institution or transitioned to a different device type. The most common adverse events included major bleeding (20.8%) and driveline infection (12.9%); ischemic and hemorrhagic stroke were encountered in 6.5% and 1.2% of patients, respectively. Patients with BSA <1.4 m2 had a higher incidence of infection, renal dysfunction, and ischemic stroke. CONCLUSIONS: In this updated cohort of predominantly pediatric patients supported with the HM3 ventricular assist device, outcomes are excellent with <8% mortality on device. Device-related adverse events including stroke, infection, and renal dysfunction were more commonly seen in smaller patients, highlighting opportunities for improvements in care.

Patient and Device Selection in Pediatric MCS: A Review of Current Consensus and Unsettled Questions.

The field of pediatric ventricular assist device (VAD) support has expanded significantly over the past 20 years, with one third of pediatric heart transplant recipients currently being bridged to transplant with a VAD. Despite increased pediatric VAD utilization, however, there remains little formalized guidance for patient or device selection. The population of children with advanced heart failure is quite heterogeneous, and the available data suggest that VAD outcomes vary significantly based upon patient size, anatomy, level of illness, and type of device implanted. In an effort to better understand current practice patterns and identify populations for whom there does not appear to be a consensus approach to achieving optimal VAD outcomes, the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) has surveyed clinical decision-making among member sites and conducted a review of the available literature regarding patient population-specific VAD outcomes and center-specific practices related to patient and device selection. Rather than aiming to provide clinical guidelines, this document offers an overview of contemporary approaches to patient and device selection, highlighting specific populations for whom there is not a consensus approach to achieving reliably good VAD outcomes, as these populations may benefit most from future research and quality improvement efforts directed toward identifying best practice.

Current Practices in Treating Cardiomyopathy and Heart Failure in Duchenne Muscular Dystrophy (DMD): Understanding Care Practices in Order to Optimize DMD Heart Failure Through ACTION.

Cardiac disease has emerged as a leading cause of mortality in Duchenne muscular dystrophy in the current era. This survey sought to identify the diagnostic and therapeutic approach to DMD among pediatric cardiologists in Advanced Cardiac Therapies Improving Outcomes Network. Pediatric cardiology providers within ACTION (a multi-center pediatric heart failure learning network) were surveyed regarding their approaches to cardiac care in DMD. Thirty-one providers from 23 centers responded. Cardiac MRI and Holter monitoring are routinely obtained, but the frequency of use and indications for ordering these tests varied widely. Angiotensin converting enzyme inhibitor and aldosterone antagonist are generally initiated prior to onset of systolic dysfunction, while the indications for initiating beta-blocker therapy vary more widely. Seventeen (55%) providers report their center has placed an implantable cardioverter defibrillator in at least 1 DMD patient, while 11 providers (35%) would not place an ICD for primary prevention in a DMD patient. Twenty-three providers (74%) would consider placement of a ventricular assist device (VAD) as destination therapy (n = 23, 74%) and three providers (10%) would consider a VAD only as bridge to transplant. Five providers (16%) would not consider VAD at their institution. Cardiac diagnostic and therapeutic approaches vary among ACTION centers, with notable variation present regarding the use of advanced therapies (ICD and VAD). The network is currently working to harmonize medical practices and optimize clinical care in an era of rapidly evolving outcomes and cardiac/skeletal muscle therapies.

Learning networks in pediatric heart failure and transplantation.

BACKGROUND: Learning networks have emerged in medicine as a novel organizational structure that contains elements of quality improvement, education, and research with the goal of effecting rapid improvements in clinical care. In this article, the concept of a learning network is defined and highlighted in the field of pediatric heart failure and transplantation. METHODS: Learning networks are defined, with particular attention paid to the recent creation of the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) for children with heart failure and those being supported with ventricular assist devices (VAD). RESULTS: The mission, goals, and organizational structure of ACTION are described, and recent initiatives promoted by ACTION are highlighted, such as stroke reduction initiatives, practice harmonization protocols, and use of ACTION data to support the recent US Food and Drug Administration approval of newer VAD for pediatric patients. CONCLUSIONS: The learning network, exemplified by ACTION, is distinguished from traditional clinical research collaboratives by contributions in research, quality improvement, patient-reported outcomes, and education, and serves as an effective vehicle to drive clinical improvement in the care of children with advanced heart failure.

Expanding the donor pool for congenital heart disease transplant candidates by implementing 3D imaging-derived total cardiac volumes.

BACKGROUND: Heart transplant waitlist mortality remains high in infants <1 year of age and among those with CHD. Currently, the median accepted donor-to-recipient weight percentage is approximately 130% of the recipient's weight. We hypothesized that patients with CHD may accept a larger organ using novel 3D-derived imaging data to estimate donor and recipient TCV. METHODS: A single-center, retrospective study was performed using CT data for 13 patients with CHD and 94 control patients. 3D visualization software was used to create digital 3D heart models that provide an estimate of TCV. In addition, echocardiograms obtained prior to cross-sectional imaging were reviewed for presence of ventricular chamber dilation. RESULTS: Sixty-two percent (8/13) of patients with CHD had 3D-derived TCV resulting in a weight that was >130% larger than their actual weight. This was seen in single-ventricle patients following Blalock-Taussig shunt and Fontan palliation, and patients with biventricular repair. Of those, 75% (6/8) had reported moderate-to-severe ventricular chamber dilation by echocardiogram or cardiac magnetic resonance imaging. CONCLUSIONS: In a large portion of patients with CHD, 3D-derived TCV place the recipient at a higher listing weight than their actual weight. We propose obtaining cross-sectional imaging to better assess TCV in a recipient, which may increase the donor range for CHD recipients and improve organ utilization in pediatrics.

Mechanical circulatory support in children: past, present and future.

Rapid advances in the field of mechanical circulatory support (MCS) have dramatically changed the management of pediatric patients with heart failure. There is now emphasis on timely implantation of ventricular assist devices (VADs) to preserve or recover end-organ function, and increased focus on post-implant management to improve the stroke rate. Transplant waitlist mortality has significantly decreased in the era of VAD use. Devices approved for adults are being used off-label in children with excellent outcomes, allowing chronic therapy and discharge home to become part of pediatric VAD therapy.

Heart transplantation in survivors of childhood cancer.

There are approximately 450,000 survivors of childhood cancer due, in large part, to successes of therapeutic regimens. With this success comes an increase in the number of patients developing cardiotoxicity as a result of cancer therapies. In certain cases, this includes heart failure recalcitrant to medical therapy, and consideration for heart transplantation may be necessary. However, this group of patients has unique comorbidities that may affect outcomes. Despite this, available data show that complications and overall survival are similar for patients transplanted for anthracycline-induced cardiomyopathy compared to those with other cardiomyopathies, demonstrating that this is a viable treatment option for this population. As other cancer therapies become more common, new cardiovascular toxicities are recognized. Whether heart transplantation will be appropriate for all patients with cancer-therapy related cardiotoxicity (CTRC) will require demonstration of similarly good outcomes to ensure proper allocation of organs.

Post-operative Assessment of the Arterial Switch Operation: A Comparison of Magnetic Resonance Imaging and Echocardiography.

After an arterial switch operation (ASO), serial imaging is necessary to monitor for maladaptive changes. We compared cardiac magnetic resonance imaging (CMR) to 2-D transthoracic echocardiography (TTE) in assessing post-operative ASO patients. We performed a retrospective review of patients at a single tertiary care center who underwent an ASO and subsequently had a CMR performed from 7/2010 to 7/2016. Those with single ventricle anatomy, congenitally corrected transposition of the great arteries, or previous atrial switch operation were excluded. TTE obtained within 6 months of the CMR was used for comparison. Parameters compared included ventricular size and systolic function, semilunar valve regurgitation, neo-aortic root dimension, and the presence of branch pulmonary artery (PA) stenosis (on CMR by the Nakata index or right/left flow differential; on TTE by peak velocity > 2 m/s or PA diameter Z score < - 2). Forty-seven patients with 90 CMR and 86 TTE studies met inclusion criteria. CMR and TTE assessment of right ventricular (RV) and left ventricular function did not statistically differ. RV dilation was overdetected by TTE (p = 0.046). Right pulmonary artery and left pulmonary artery (LPA) visualization by TTE was worse than CMR (p < 0.01). There was no statistically significant difference between CMR and TTE assessment of branch PA stenosis; however, there was poor agreement between the use of Z score and velocity when determining branch PA stenosis by TTE (κ < 0). Assessment of neo-pulmonary regurgitation (PR) and neo-aortic regurgitation (AR) was significantly different between CMR and TTE (p < 0.05). Assessment for delayed enhancement was performed in 18% of CMR studies (n = 16), with perfusion defects appreciated in three patients. Substantial differences between CMR and TTE exist when examining the post-operative ASO patient. CMR was superior for evaluation of the branch PAs, which commonly require re-intervention. TTE failed to recognize altered ventricular function in several cases. Differences between TTE and CMR could alter management is some cases. Incorporation of CMR into the routine surveillance of patients who received an ASO is warranted.

Myocardial Fibrosis and Left Ventricular Dysfunction in Duchenne Muscular Dystrophy Carriers Using Cardiac Magnetic Resonance Imaging.

The goal of our study was to characterize the degree of myocardial fibrosis and left ventricular dysfunction in our cohort of Duchenne muscular dystrophy (DMD) carriers using cardiac magnetic resonance imaging (CMR). Seventy percent of males with DMD have mothers who are carriers of the Xp21 mutation. Carrier phenotypic characteristics range from asymptomatic to left ventricular (LV) dysfunction and cardiomyopathy. The true prevalence of cardiac involvement in DMD carriers is unknown. We performed a retrospective observational study. All female DMD carriers who underwent clinical CMR studies at Cincinnati Children's Hospital Medical Center from December 6, 2006, to August 28, 2013, were evaluated. Patients underwent standard CMR assessment with LV function assessment and late gadolinium enhancement (LGE). In addition, offline feature tracking strain analysis was performed on the basal, mid, and apical short axis. Twenty-two patients were studied, of which 20 underwent adequate testing for myocardial LGE. Four of 22 patients (18 %) were found to have LV dysfunction (ejection fraction <55 %). Seven of 20 DMD carriers (35 %) were found to have LGE. The patients with evidence of LGE had an overall trend to lower absolute deformation parameters; however, this did not meet statistical significance when correcting for multiple comparisons. Our study demonstrates a high rate of LGE as well as LV dysfunction in DMD carriers. Cardiovascular and musculoskeletal symptoms were not statistically different between those with and without cardiac involvement. This study demonstrates the importance of surveillance CMR evaluation of DMD carriers.