Impact of pharmacotherapy on interstage mortality and weight gain in children with single ventricle

Association of Digoxin Use With Transplant-Free Interstage Survival in Infants Palliated With a Stage 1 Hybrid Procedure

Background Digoxin prescription in patients with single-ventricle physiology after stage 1 palliation is associated with reduced interstage death. Prior literature has primarily included patients having undergone the Norwood procedure. We sought to determine if digoxin prescription at discharge in infants following hybrid stage 1 palliation was associated with improved transplant-free interstage survival. Methods and Results A retrospective multicenter cohort analysis was conducted using data from the National Pediatric Cardiology Quality Improvement Collaborative registry data from 2008 to 2021. Infants with functional single ventricles and aortic arch obstruction discharged home after the hybrid stage 1 palliation hospitalization were included. Patients were excluded if they had supraventricular tachycardia or conversion to Norwood operation. The primary outcome was transplant-free survival. Multivariable logistic regression analysis including a propensity score for digoxin use identified associations between digoxin use and interstage death or transplant. Of 259 included infants from 45 sites, 158 (61%) had hypoplastic left heart syndrome. Forty-nine percent had a gestational age ≤38 weeks, 18% had a birth weight <2.5 kg, and 58% had a preoperative risk factor. Of the 259 subjects, 129 (50%) were discharged on digoxin. Interstage death or transplant occurred in 30 (23%) patients in the no-digoxin group compared with 18 (14%) in the digoxin group (P=0.06). With multivariate analysis, discharge digoxin prescription was associated with a lower risk of interstage death or transplant (adjusted odds ratio, 0.48 [95% CI, 0.24-0.93]; P=0.03). Conclusions In infants with single-ventricle physiology who underwent hybrid stage 1 palliation, digoxin prescription at hospital discharge was associated with improved interstage transplant-free survival.

Attributable mortality benefit of digoxin treatment in hypoplastic left heart syndrome after the Norwood operation: An instrumental variable-based analysis using data from the Pediatric Health Information Systems Database

BACKGROUND

Observational studies have demonstrated an association between the use of digoxin and reduced interstage mortality after Norwood operation for hypoplastic left heart syndrome (HLHS). Digoxin use has increased significantly but remains variable between different hospitals, independent of case-mix. Instrumental variable analyses have the potential to overcome unmeasured confounding, the major limitation of previous observational studies and to generate an estimate of the attributable benefit of treatment with digoxin.

METHODS

A cohort of neonates with HLHS born from January 1, 2007 to December 31, 2021 who underwent Norwood operation at Pediatric Health Information Systems Database hospitals and survived >14 days after operation were studied. Using hospital-specific, 6-month likelihood of administering digoxin as an instrumental variable, analyses adjusting for both unmeasured confounding (using the instrumental variable) and measured confounders with multivariable logistic regression were performed.

RESULTS

The study population included 5,148 subjects treated at 47 hospitals of which 63% were male and 46% non-Hispanic white. Of these, 44% (n = 2,184) were prescribed digoxin. Treatment with digoxin was associated with superior 1-year transplant-free survival in unadjusted analyses (85% vs 82%, P = .02). This survival benefit persisted in an instrumental-variable analysis (OR: 0.71, 95% CI: 0.54-0.94, P = .01), which can be converted to an absolute risk reduction of 5% (number needed to treat of 20).

CONCLUSIONS

In this observational study of patients with HLHS after Norwood using instrumental variable techniques, a significant benefit in 1-year transplant-free survival attributable to digoxin was demonstrated. In the absence of clinical trial data, this should encourage the use of digoxin in this vulnerable population.

Gabapentin Can Improve Irritability and Feeding Tolerance in Single Ventricle Interstage Patients: A Case Series

Visceral hyperalgesia is common among children with complex medical conditions. Infants with complex congenital heart disease, specifically single ventricle interstage patients, are often found to have feeding intolerance and irritability. Gabapentin treatment has shown promise for symptomatic improvement for visceral hyperalgesia in some patients. We present a case series of five patients in which four of the five patients showed improvement within 48 h of starting gabapentin. The use of gabapentin in single ventricle interstage patients to treat visceral hyperalgesia shows promise based on our case series, but future multi-center prospective studies would be beneficial.

Current evidence for pharmacologic therapy following stage 1 palliation for single ventricle congenital heart disease

INTRODUCTION

Infants with single ventricle congenital heart disease are vulnerable to complications between stage 1 and stage 2 of palliation. Pharmaceutical treatment during this period is varied and often dependent on institutional practices as there is little evidence supporting a particular treatment path.

AREAS COVERED

This review focuses on medical management of patients following stage I palliation. We performed a scoping review of the current literature regarding angiotensin converting enzyme inhibitors and digoxin treatment in the interstage period. In addition, we discuss other medication classes frequently used in these patients.

EXPERT OPINION

Due to significant heterogeneity of anatomy, rarity of disease, and other confounding factors, there is limited evidence to support most commonly used medications within the interstage period. Digoxin is associated with improved mortality within the interstage period and should be considered; however, no large randomized controlled trial exists supporting its use. Prevention of thrombotic complication with aspirin is also associated with improved outcomes and should be considered unless a contraindication exists. The addition of other prescriptions in this patient population should be considered only after an evaluation of the risks and benefits of each medication, recognizing the burden and risk of polypharmacy in this fragile patient population.

Digoxin Associated With Greater Transplant-Free Survival in High- vs Low-Risk Interstage Patients

BACKGROUND

Digoxin has been associated with reduced interstage mortality for patients with functional single ventricles with aortic hypoplasia or ductal-dependent systemic circulation. The NEONATE (type of stage 1 palliation operation, postoperative extracorporeal membrane oxygenation, discharge with opiates, no digoxin at discharge, postoperative arch obstruction, moderate to severe tricuspid regurgitation without an oxygen requirement, and extra oxygen required at discharge in patients with moderate to severe tricuspid regurgitation) score can stratify patients by risk of death or transplantation (DTx) on the basis of clinical factors. The study investigators suspected a variable transplant-free survival benefit of digoxin in high-risk vs low-risk patients.

METHODS

National Pediatric Cardiology Quality Improvement Collaborative patients discharged after stage 1 palliation with complete data were categorized as high- or low-risk on the basis of a modified NEONATE score. The primary outcome of DTx was evaluated. A mixed-effect regression evaluated associations between digoxin prescription and risk factors.

RESULTS

A total of 1199 patients were included; 399 (33%) were high risk. Baseline demographics were similar between the cohorts. Blalock-Taussig shunt or a hybrid operation, postoperative extracorporeal membrane oxygenation, opiate prescription, and significant tricuspid regurgitation or arch obstruction were more common in high-risk patients. The odds of DTx were 65% lower in high-risk patients prescribed digoxin compared with patients who were not (P = .001). Digoxin prescription was associated with 60.8% lower DTx in the high-risk cohort (7.8% vs 19.9%; P = .001). There was no significant difference in the DTx rate according to digoxin prescription in the low-risk cohort (4.7% vs 5.7%; P = .46). Blalock-Taussig shunt, aortic arch obstruction, and significant tricuspid regurgitation were most strongly associated with deriving a benefit from digoxin.

CONCLUSIONS

Digoxin use is associated with significant improvement in transplant-free survival in high-risk but not in low-risk interstage patients. A tailored approach to the use of digoxin in interstage patients may be warranted.

Trends in Discharge Prescription of Digoxin After Norwood Operation: An Analysis of Data from the Pediatric Health Information System (PHIS) Database

Quality improvement efforts have focused on reducing interstage mortality for infants with hypoplastic left heart syndrome (HLHS). In 1/2016, two publications reported that use of digoxin was associated with reduced interstage mortality. The degree to which these findings have affected real world practice has not been evaluated. The discharge medications of neonates with HLHS undergoing Norwood operation between 1/2007 and 12/2018 at Pediatric Health Information Systems Database hospitals were studied. Mixed effects models were calculated to evaluate the hypothesis that the likelihood of digoxin prescription increased after 1/2016, adjusting for measurable confounders with furosemide and aspirin prescription measured as falsification tests. Interhospital practice variation was measured using the median odds ratio. Over the study period, 6091 subjects from 45 hospitals were included. After adjusting for measurable covariates, discharge after 1/2016 was associated with increased odds of receiving digoxin (OR 3.9, p < 0.001). No association was seen between date of discharge and furosemide (p = 0.26) or aspirin (p = 0.12). Prior to 1/2016, the likelihood of receiving digoxin was decreasing (OR 0.9 per year, p < 0.001), while after 1/2016 the rate has increased (OR 1.4 per year, p < 0.001). However, there remains significant interhospital variation in the likelihood of receiving digoxin even after adjusting for known confounders (median odds ratio = 3.5, p < 0.0001). Following publication of studies describing an association between digoxin and improved interstage survival, the likelihood of receiving digoxin at discharge increased without similar changes for furosemide or aspirin. Despite concerted efforts to standardize interstage care, interhospital variation in pharmacotherapy in this vulnerable population persists.

Digoxin Use in Infants with Single Ventricle Physiology: Secondary Analysis of the Pediatric Heart Network Infant Single Ventricle Trial Public Use Dataset

Digoxin has been associated with reduced interstage mortality after Norwood procedure. We sought to determine its association with survival and change in weight-for-age Z-score (WAZ) before the superior cavopulmonary connection (SCPC) surgery and at 14 months in a heterogeneous group of single ventricle infants. We performed a post-hoc analysis of the Pediatric Heart Network Infant Single Ventricle public use dataset to determine associations between digoxin and survival, transplant-free survival, and change in WAZ pre-SCPC and at 14 months. Sub-analyses of survival and transplant-free survival were performed for subjects who underwent Damus-Kaye-Stansel (DKS)/Norwood. Propensity score weighting was used in Cox hazard-proportion models. Of 229 subjects, 82 (36%) received digoxin and 147 (64%) received no digoxin. Pre-SCPC and 14-month survival and transplant-free survival were not significantly different between the digoxin and no digoxin groups for the main cohort and DKS/Norwood sub-group. However, in DKS/Norwood subjects there was a trend towards improved interstage transplant-free survival in the digoxin group (95.7 vs. 89.6%, p = 0.08). Digoxin was associated with a greater decrease in WAZ from birth to pre-SCPC (- 1.96 ± 0.19 vs. - 1.31 ± 0.18, p < 0.001) and birth to 14 months (- 0.64 ± 0.15 vs. - 0.19 ± 0.15, p = 0.03). Digoxin was not associated with improved survival during the interstage or at 14 months in a mixed single ventricle cohort, but there was a trend towards improved interstage transplant-free survival in post-Norwood infants. As digoxin was associated with poorer weight gain, further research is needed to identify the risks/benefits for anatomic subtypes of infants with single ventricles.

Increased Fracture Risk with Furosemide Use in Children with Congenital Heart Disease

OBJECTIVES

To determine the association of furosemide therapy with the incidence of bone fractures in children with congenital heart disease.

STUDY DESIGN

We conducted a retrospective cohort study with data extracted from the 2008-2014 Texas Medicaid databases. Pediatric patients aged <12 years diagnosed with congenital heart disease, cardiomyopathy, or heart failure were included. Patients taking furosemide were categorized into a furosemide-adherent group (medication possession ratio of ≥70%), and a furosemide-nonadherent group (medication possession ratio of <70%). A third group of patients was matched to the furosemide user groups by using propensity score matching. A multivariate logistic regression and Cox proportional hazard model with a Kaplan-Meier plot (time-to-fracture) were used to compare the 3 groups, controlling for baseline demographics and clinical characteristics.

RESULTS

After matching, 3912 patients (furosemide adherent, n = 254; furosemide nonadherent, n = 724; no furosemide, n = 2934) were identified. The incidence of fractures was highest for the furosemide-adherent group (9.1%; 23 of 254), followed by the furosemide-nonadherent group (7.2%; 52 of 724), which were both higher than for patients who did not receive furosemide (5.0%; 148 of 2934) (P < .001). Using logistic regression, both furosemide groups were more likely to have fractures than the no furosemide group: furosemide-adherent OR of 1.9 (95% CI, 1.17-2.98; P = .009); furosemide nonadherent OR of 1.5 (95% CI, 1.10-2.14; P = .01). In the Cox proportional hazard model, the risk of fractures for the furosemide-adherent group was significantly higher compared with the no furosemide group (HR, 1.6; 95% CI, 1.00-2.42; P = .04).

CONCLUSIONS

Furosemide therapy, even with nonconsistent dosing, was associated with an increased risk of bone fractures in children with congenital heart disease.

Angiotensin converting enzyme inhibitors and interstage failure in infants with hypoplastic left heart syndrome

INTRODUCTION

Angiotensin converting enzyme inhibitors are commonly prescribed medications after the Norwood procedure. There are little data that can be used to determine if angiotensin converting enzyme inhibitors improve interstage outcomes in children with single ventricle defects. The objective of this study was to investigate the relationship between angiotensin converting enzyme inhibitors and interstage failure among infants born with hypoplastic left heart syndrome.

METHODS

We conducted a retrospective cohort study using data from the National Pediatric Cardiology Quality Improvement Collaborative database (collected between 2008 and 2015). We used logistic regression models to assess the exposure-outcome associations and propensity score matching to account for differences in baseline patient characteristics associated with use of angiotensin converting enzyme inhibitors.

RESULTS

A total of 1 487 neonates participated in the study. Thirty-nine percent of patients were prescribed angiotensin converting enzyme inhibitors after the Norwood procedure; 11% experienced interstage failure (death, heart transplantation, and not being a candidate for the second-stage surgery). Before propensity score matching, patients receiving angiotensin converting enzyme inhibitors were significantly more likely to experience interstage failure, compared to patients not on angiotensin converting enzyme inhibitors (OR = 1.44; 95% CI: 1.04, 1.99; P = 0.03). Although there was an increased odds of interstage failure among patients receiving angiotensin converting enzyme inhibitors compared to patients not receiving angiotensin converting enzyme inhibitors in the propensity score-matched cohort, this association was not significantly different (adjusted OR = 1.29; 95% CI: 0.88, 1.95; P = 0.18).

CONCLUSION

Angiotensin converting enzyme inhibitor therapy did not demonstrate a beneficial effect on interstage failure among infants with hypoplastic left heart syndrome, even when patient characteristics associated with the use of angiotensin converting enzyme inhibitors were considered.

Interstage Home Monitoring After Newborn First-Stage Palliation for Hypoplastic Left Heart Syndrome: Family Education Strategies

Children born with hypoplastic left heart syndrome are at high risk for serious morbidity, growth failure, and mortality during the interstage period, which is the time from discharge home after first-stage hypoplastic left heart syndrome palliation until the second-stage surgical intervention. The single-ventricle circulatory physiology is complex, fragile, and potentially unstable. Multicenter initiatives have been successfully implemented to improve outcomes and optimize growth and survival during the interstage period. A crucial focus of care is the comprehensive family training in the use of home surveillance monitoring of oxygen saturation, enteral intake, weight, and the early recognition of "red flag" symptoms indicating potential cardiopulmonary or nutritional decompensation. Beginning with admission to the intensive care unit of the newborn with hypoplastic left heart syndrome, nurses provide critical care and education to prepare the family for interstage home care. This article presents detailed nursing guidelines for educating families on the home care of their medically fragile infant with single-ventricle circulation.

Use of ACE inhibitors in Fontan: Rational or irrational?

BACKGROUND

Despite a lack of evidence supporting the use of angiotensin-converting enzyme (ACE) inhibitors in patients with a Fontan circulation, their use is frequent. We decided to identify the rationale for ACE inhibitor therapy in patients within the Australia and New Zealand Fontan Registry.

METHODS

All patients in the Registry taking an ACE inhibitor at last follow up were identified, and a review of medical records was undertaken to determine the rationale for treatment initiation and reasons for treatment continuation or dose increase.

RESULTS

In 2015, 36% of the surviving patients in the Registry (462/1268) were taking an ACE inhibitor. Indications for initiation of therapy were ventricular systolic or diastolic dysfunction (29%), atrioventricular valve regurgitation (19%), preservation of normal ventricular function (7%), prolonged effusions at Fontan (6%), hypertension (6%), other (6%) and unknown (2%). No indication was stated in the remaining patients (25%). Those with hypoplastic left heart syndrome were more likely to be on an ACE inhibitor than those with an alternative primary morphology (70% vs 32%; p<0.001). Only 36% of the patients treated with an ACE inhibitor at last follow up (166/462) had an indication that would generally justify treatment in a two-ventricle circulation.

CONCLUSION

It is likely that the use of ACE inhibitors in patients with a Fontan circulation is excessive within our region. The coordination of prospective, multicentre studies and initiatives such as the Australia and New Zealand Fontan Registry will facilitate further investigations to guide treatment decisions in the growing Fontan population.

Association of Digoxin With Interstage Mortality: Results From the Pediatric Heart Network Single Ventricle Reconstruction Trial Public Use Dataset

BACKGROUND

Mortality for infants with single ventricle congenital heart disease remains as high as 8% to 12% during the interstage period, the time between discharge after the Norwood procedure and before the stage II palliation. The objective of our study was to determine the association between digoxin use and interstage mortality in these infants.

METHODS AND RESULTS

We conducted a retrospective cohort study using the Pediatric Heart Network Single Ventricle Reconstruction Trial public use dataset, which includes data on infants with single right ventricle congenital heart disease randomized to receive either a Blalock-Taussig shunt or right ventricle-to-pulmonary artery shunt during the Norwood procedure at 15 institutions in North America from 2005 to 2008. Parametric survival models were used to compare the risk of interstage mortality between those discharged to home on digoxin versus those discharged to home not on digoxin, adjusting for center volume, ascending aorta diameter, shunt type, and socioeconomic status. Of the 330 infants eligible for this study, 102 (31%) were discharged home on digoxin. Interstage mortality for those not on digoxin was 12.3%, compared to 2.9% among those on digoxin, with an adjusted hazard ratio of 3.5 (95% CI, 1.1-11.7; P=0.04). The number needed to treat to prevent 1 death was 11 patients. There were no differences in complications between the 2 groups during the interstage period.

CONCLUSIONS

Digoxin use in infants with single ventricle congenital heart disease is associated with significantly reduced interstage mortality.

Survey of how pediatric cardiologists noninvasively evaluate patients with hypoplastic left heart syndrome

BACKGROUND

The evaluation of right ventricular (RV) function is important in patients with hypoplastic left heart syndrome (HLHS). Echocardiographic qualitative grading has been the prevalent method used in the past, but newer technologies allowing for quantitative assessment of RV function may have changed this fact. The goal of this study was to determine the current routine noninvasive evaluation of patients with HLHS and what, if any, methods are used to assess systolic and diastolic function in this population.

METHODS

Web-based survey was conducted using various listservs. Timing of echocardiograms between surgical stages was assessed. Methods of assessing systolic and diastolic function were evaluated.

RESULTS

Two hundred seventy-seven physicians who averaged 12.8 ± 9.6 years removed from training responded. Largest percentage of respondents was echocardiographers (44.2%) in a university-based practice (73.3%) from North America (91.7%). There were 54.3% of respondents who performed echocardiograms monthly between stages I and II, 48.8% who performed echocardiograms every 6 months between stages II and III, and 67.0% who performed echocardiograms annually after stage III procedure. The main method for systolic grading was qualitative grading (95.5%) and for diastolic grading were tricuspid blood inflow velocities (56.8%). Qualitative grading was considered the method of choice for systolic grading for 38.8% of respondents and tissue Doppler velocities was the method of choice for diastolic grading for 35.3% of respondents. There were 4.0% of respondents who routinely perform a cardiac magnetic resonance imaging (cMRI) between stages I and II, 8.0% between stages II and III, and 24.2% after stage III procedure.

CONCLUSION

Variability in the noninvasive assessment of the RV in patients with HLHS continues to exist. Qualitative RV systolic assessment was still the predominant method used to assess function despite newer imaging techniques to allow for quantification. Future studies are needed to determine which values are most useful in reviewing function in this complex patient population.

Hypoplastic left heart syndrome - unresolved issues

Hypoplastic left heart syndrome (HLHS) is one of the most challenging congenital heart defects. At present, it is expected that - at best - 70% of newborns with HLHS will reach adulthood. This review addresses the problems of right ventricular (RV) failure and insufficient growth of pulmonary vasculature in these patients. In order to further improve long-term prognosis translational research to control RV function, growth of pulmonary arteries and progress in chronic circulatory support are clearly needed to provide a further improvement for adults with HLHS.