Physician-researchers from the Cardiac Center at Children’s Hospital of Philadelphia (CHOP) recently presented new research at the American Heart Association’s Scientific Sessions 2019 in Philadelphia. From chest tube reduction to the underlying genetics of cardiomyopathy, CHOP’s team covered a variety of topics and themes aimed at improving care for pediatric cardiac patients undergoing a variety of procedures.
Successful Reduction of Postoperative Chest Tube Duration and Length Of Stay After Congenital Heart Surgery
One “model” congenital heart center demonstrated shorter chest tube (CT) duration and length of stay (LOS) compared with other centers. Susan K. Schachtner, MD, medical director of the Cardiac Care Unit at CHOP, co-authored a multicenter study (led by Dr. Katherine Bates from the University of Michigan) that tested whether that “model” center’s approach of removing CTs earlier with higher volumes of output could be applied to other centers to reduce variation in CT management and improve outcomes, with the ultimate goal of reducing CT duration by 20 percent.
The team studied 1767 patients from nine centers. The study showed that median CT duration decreased from 88.8 hours to 68.9 hours and median postoperative LOS decreased from eight days to seven days. Rates of CT replacement and readmission for effusion did not change when the new methods were applied. The authors were able to successfully lower postoperative CT duration and LOS and plan to spread the method to other centers.
Genetic Variant Burden and Outcomes in Pediatric Cardiomyopathy
With advances in next generation sequencing technology, an increasing number of genetic variants have emerged as potential causes for pediatric cardiomyopathy. However, previous research has not firmly established a correlation between those variants and clinical outcomes for those affected with the condition. Researchers believe that variants of unknown significance (VUS) may serve as important genetic modifiers that influence outcomes by creating a greater genetic variant burden on the patient.
Danielle S. Burstein, MD, an attending cardiologist in the Division of Cardiology at CHOP, and her colleagues, studied 420 patients with either dilated cardiomyopathy (DCM, 38 percent), hypertrophic cardiomyopathy (HCM, 41 percent), or another form of cardiomyopathy (21 percent). The study found that across all types of cardiomyopathy, known pathogenic variants alone were not associated with a major adverse cardiac event (MACE). However, the presence of VUS without any pathogenetic variants was associated with MACE in patients with DCM and HCM, and the presence of VUS with pathogenetic variants was associated with MACE across all cardiomyopathy subtypes.
The authors showed that increased VUS burden is associated with worse outcomes and that universal genetic testing may improve genetic risk stratification models for prognosis and potential therapy.
Impaired Maternal-Fetal Environment is Associated with Increased Mortality after Stage 1 Norwood Procedure for Single Ventricle Heart Disease
The environment shared between a mother and her unborn child can have important ramifications when it comes to the outcomes of cardiac surgery. Jill J. Savla, MD, an attending cardiologist with the Division of Cardiology, and her colleagues hypothesized that an impaired maternal-fetal environment (MFE) would be associated with an increased risk of death after a child had undergone a stage 1 Norwood procedure for single ventricle heart disease.
This retrospective cohort study included 273 neonates born between June 2008 and June 2018. Of those, 72 had been exposed to an impaired MFE, and as a result had more preterm births than those who did not have an impaired environment (18 percent compared with 7 percent) and lower birth weights. Impaired MFE was associated with significantly higher risk of death after the researchers adjusted for age of surgery, ethnicity, cardiac diagnosis, genetic syndrome, birth era and surgeon. Further, this association was not fully explained by prematurity and low birth weight, suggesting that there are other important ways in which an impaired MFE affects post-operative outcomes. The authors said prenatal exposures and methods of improving the MFE need to be considered when treating this vulnerable population.
Placental Villous Infarcts Are a Marker of Impaired Fetal Growth and Poor Post-surgical Outcome in Infants with Critical Congenital Heart Defects
Another important aspect of the maternal-fetal environment is the placenta. In another study, researchers investigated the role of placental insufficiency and its relationship to gene damaging variants involved in angiogenesis, or the creation of blood vessels, as well as intermediate survival.
The study team led by Rebecca L. Linn, MD, a attending pathologist in the Division of Anatomic Pathology at CHOP, analyzed 79 placentas of infants who required surgical repair in the first 6 months of life for congenital heart disease. Of those patients, 21 had a placental villous infarction, and 8 patients had more than one infarct. These infarcts were significantly associated with reduced weight and length and was associated with lower survival. The presence of damaging positive regulation of angiogenesis (PRA) gene variants was not associated with placental infarct. However, multiple infarcts were associated with at least one damaging PRA gene variant in the mother.
Linn and her colleagues concluded that placental infarction is associated with impaired fetal growth and poor survival after cardiac surgery in pregnancies involving a fetus with congenital heart disease. There may also be an underlying genetic predisposition to these infarctions that warrants further investigation.
Comparison of Management Strategies for the Neonate with Symptomatic Tetralogy of Fallot: A Study from the Congenital Catheterization Research Collaborative
Currently, cardiologists choose one of two methods of early intervention for managing neonates with tetralogy of Fallot and symptomatic cyanosis (sTOF): initial palliation followed by later complete repair, or primary repair. Andrew C. Glatz, MD MSCE, an interventional cardiologist in the Cardiac Center at CHOP, was the senior author for the first multicenter study that sought to compare the two strategies. This study was performed using the 9 center Congenital Catheterization Research Collaborative.
A cohort of 327 neonates who went through the initial palliation method was compared with a cohort of 223 neonates who went through the primary repair method. Preprocedural ventilation, prematurity and DiGeorge syndrome were more common among the patients who received initial palliation. The observed risk of death or transplantation did not differ significantly between the groups. After applying a propensity score adjustment, the primary risk of death or transplantation remained similar but favored initial palliation during early follow-up (three months or less) and primary repair during late follow-up (more than three months).
Early mortality, risk exposure and procedural complications were lower in neonates that had undergone the initial palliation strategy, but cumulative exposures and reinterventions favored the primary repair method. The authors believe that each strategy has potential benefits.
Teens with Heart Disease Improve Exercise Capacity in Large Clinical Trial
The largest-ever clinical trial of a medication for pediatric cardiology patients found that an oral drug significantly improved exercise capacity in adolescent patients with severe, congenital single ventricle heart defects. David J. Goldberg, MD, pediatric cardiologist in the Cardiac Center at CHOP and co-principal investigator of the multicenter Fontan Udenafil Exercise Longitudinal Assessment Trial (FUEL), says the physiologic benefits represent a milestone in the care of those who have undergone the Fontan procedure, a palliative operation for single-ventricle disease.
Read more about the trial results here.