Rivaroxaban, a direct Factor Xa inhibitor, versus acetylsalicylic acid as thromboprophylaxis in children post-Fontan procedure: Rationale and design of a prospective, randomized trial (the UNIVERSE study)

Evaluation, analysis, and reporting of medication adherence for clinical trials of anticoagulants in children: guidance from the ISTH SSC Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis

In response to growing recognition that nonadherence prevents children, adolescents, and young adults from achieving the therapeutic benefits of anticoagulant medication, the International Society on Thrombosis and Haemostasis Scientific and Standardization Committee Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis convened a working party on medication adherence. The primary aim of this article was to synthesize recommendations from the larger adherence science literature to provide guidance regarding the classification, collection, and interpretation of anticoagulation adherence data. The secondary aim of this article was to evaluate the degree to which trials published from 2013 to 2023 adhered to these guidance recommendations. As less than half of all trials reported on adherence and none included all recommended elements, the proposed International Society on Thrombosis and Haemostasis Scientific and Standardization Committee guidance has the potential to enhance the rigor and reproducibility of pediatric anticoagulant research.

Detection of occult thrombosis in individuals with Fontan circulation by cardiac MRI

OBJECTIVE

Identifying thrombus formation in Fontan circulation has been highly variable, with reports between 17 and 33%. Initially, thrombus detection was mainly done through echocardiograms. Delayed-enhancement cardiac MRI is emerging as a more effective imaging technique for thrombus identification. This study aims to determine the prevalence of occult cardiac thrombosis in patients undergoing clinically indicated cardiac MRI.

METHODS

A retrospective chart review of children and adults in the Duke University Hospital Fontan registry who underwent delayed-enhancement cardiac MRI. Individuals were excluded if they never received a delayed-enhancement cardiac MRI or had insufficient data. Demographic characteristics, native heart anatomy, cardiac MRI measurements, and thromboembolic events were collected for all patients.

RESULTS

In total, 119 unique individuals met inclusion criteria with a total of 171 scans. The median age at Fontan procedure was 3 (interquartile range 1, 4) years. The majority of patients had dominant systemic right ventricle. Cardiac function was relatively unchanged from the first cardiac MRI to the third cardiac MRI. While 36.4% had a thrombotic event by history, only 0.5% (1 patient) had an intracardiac thrombus detected by delayed-enhancement cardiac MRI.

CONCLUSIONS

Despite previous echocardiographic reports of high prevalence of occult thrombosis in patients with Fontan circulation, we found very low prevalence using delayed-enhancement cardiac MRI. As more individuals are reaching adulthood after requiring early Fontan procedures in childhood, further work is needed to develop thrombus-screening protocols as a part of anticoagulation management.

How I treat pediatric venous thromboembolism in the DOAC era

ABSTRACT

The direct oral anticoagulants (DOACs) rivaroxaban and dabigatran are newly licensed for the treatment and prevention of venous thromboembolism (VTE) in children and mark a renaissance in pediatric anticoagulation management. They provide a convenient option over standard-of-care anticoagulants (heparins, fondaparinux, and vitamin K antagonists) because of their oral route of administration, child-friendly formulations, and significant reduction in monitoring. However, limitations related to therapeutic monitoring when needed and the lack of approved reversal agents for DOACs in children raise some safety concerns. There is accumulating experience of safety and efficacy of DOACs in adults for a broad scope of indications; however, the cumulative experience of using DOACs in pediatrics, specifically for those with coexisting chronic illnesses, is sparse. Consequently, clinicians must often rely on their experience for treating VTE and extrapolate from data in adults while using DOACs in children. In this article, the authors share their experience of managing 4 scenarios that hematologists are likely to encounter in their day-to-day practice. Topics addressed include (1) appropriateness of indication; (2) use for special populations of children; (3) considerations for laboratory monitoring; (4) transition between anticoagulants; (5) major drug interactions; (6) perioperative management; and (7) anticoagulation reversal.

Updated guidance for efficacy and safety outcomes for clinical trials in venous thromboembolism in children: communication from the ISTH SSC Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis

Despite the growing number of pediatric antithrombotic clinical trials, standardized safety and efficacy outcome definitions for pediatric venous thromboembolism (VTE) clinical trials have not been updated since 2011. Many recent trials have adapted the recommended definitions, leading to heterogeneity in outcomes and limiting our ability to compare studies. The International Society on Thrombosis and Haemostasis Scientific and Standardization Subcommittee (SSC) on Pediatric and Neonatal Thrombosis and Hemostasis organized a Task Force to update the efficacy and safety outcome definitions for pediatric VTE clinical trials. The outcome definitions used in the recent pediatric antithrombotic trials, definitions recommended for adult studies, and regulatory guidelines were summarized and reviewed by the Task Force as the basis for this updated guidance. Major updates to the efficacy outcomes include the removal of VTE-related mortality as a part of a composite primary outcome and explicit inclusion of all deep venous anatomic sites. Safety outcomes were updated to include a new bleeding severity category: patient important bleeding, no intervention, which encompasses bleeding for which a patient seeks care but there is no change in management. Menstrual bleeding can now be included in any bleeding category when the criteria are met. We hope that these updated outcome definitions will allow the investigators to focus on clinically relevant and patient-important outcomes and provide standardization to facilitate continued high-quality evidence for the use of antithrombotic therapies in children.

Just DOAC: Use of direct-acting oral anticoagulants in pediatrics

PURPOSE

The aim of this article is to provide an overview of the current literature for direct-acting oral anticoagulant (DOAC) use in pediatric patients and summarize ongoing trials.

SUMMARY

In treatment of venous thromboembolism (VTE) in pediatric patients, evidence supports use of both dabigatran and rivaroxaban. Dabigatran has been shown to be noninferior to standard of care (SOC) in terms of efficacy, with similar bleeding rates. Similarly, treatment with rivaroxaban in children with acute VTE resulted in a low recurrence risk and reduced thrombotic burden, without increased risk of bleeding, compared to SOC. Treatment of pediatric cerebral venous thrombosis as well as central venous catheter-related VTE with rivaroxaban appeared to be both safe and efficacious and similar to that with SOC. Dabigatran also has a favorable safety profile for prevention of VTE, and rivaroxaban has a favorable safety profile for VTE prevention in children with congenital heart disease. Many studies with several different DOACs are ongoing to evaluate both safety and efficacy in unique patient populations, as well as VTE prevention.

CONCLUSION

The literature regarding pediatric VTE treatment and prophylaxis is growing, but the need for evidence-based pediatric guidelines remains. Additional long-term, postauthorization studies are warranted to further elucidate safety and efficacy in clinical scenarios excluded in clinical trials. Additional data on safety, efficacy, and dosing strategies for reversal agents are also necessary, especially as the use of DOACs becomes more common in the pediatric population.

Utility of the Total Thrombus-Formation Analysis System as a Tool for Evaluating Thrombogenicity and Monitoring Antithrombotic Therapy in Pediatric Fontan Patients

BACKGROUND

There is no consensus regarding thromboprophylaxis after Fontan procedure, and novel tools to assess thrombogenicity are needed to establish optimal thromboprophylaxis. The Total Thrombus-formation Analysis System (T-TAS) was developed for the quantitative analysis of thrombus formation using microchips with thrombogenic surfaces. This prospective study evaluated the utility of T-TAS in the assessment of thrombogenicity in pediatric Fontan patients.

METHODS AND RESULTS

The participants included 20 consecutive Fontan patients who underwent cardiac catheterization and 30 healthy controls. Blood samples collected without and with antithrombotic therapy (aspirin or aspirin and warfarin) were used for T-TAS to compute the area under the curve (AUC) in the atheroma (AR₁₀-AUC₃₀) and platelet (PL₁₈-AUC₁₀) chips. A higher AUC indicates higher thrombogenicity. T-TAS values showed that patients in the Fontan group without antithrombotic therapy had lower thrombogenicity than those in the control group [PL₁₈-AUC₁₀, median (interquartile range) 356 (313-394) vs. 408 (392-424); AR₁₀-AUC₃₀, median (interquartile range) 1270 (1178-1351) vs. 1382 (1338-1421)]. Aspirin and warfarin therapies significantly decreased PL₁₈-AUC₁₀ and AR₁₀-AUC₃₀, respectively, compared with those of patients without antithrombotic therapy (P < 0.001 for each comparison). Subgroup analysis divided by low (< 9 mmHg) or high (≥ 9 mmHg) central venous pressure (CVP) showed that CVP affects the reduction in AR₁₀-AUC₃₀ with antithrombotic therapy.

CONCLUSIONS

T-TAS may be a useful tool for monitoring thrombogenicity and antithrombotic therapy in Fontan patients.

Application of a clinical decision rule and laboratory assays in pediatrics: Adult heparin-induced thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is rare among pediatric patients. The diagnosis of HIT depends upon clinical decision tools to assess its pretest probability, supported by laboratory evidence of anti-platelet factor 4 (anti-PF4)/heparin antibodies.

AIMS

To compare the use of the 4Ts score clinical decision tool, clinical characteristics, and laboratory findings between pediatric and adult patients with suspected HIT.

METHODS

We compiled all pediatric patients in our center for whom HIT testing was performed during the years 2015-2021. These were compared with a cohort of consecutive adult patients. Laboratory diagnosis of HIT was performed with particle gel immunoassay (PaGIA) as screening test and confirmed by an automated latex-enhanced immunoturbidimetric assay (LIA) and/or by functional flow cytometry assay (FCA).

RESULTS

The cohort included 34 children (under 18 years) and 105 adults. Adults mostly received heparins for thromboembolism prophylaxis and treatment (72.4%, n = 76), and were more frequently treated with low-molecular-weight heparin (LMWH). Children were mostly exposed during cardiopulmonary bypass and extracorporeal membrane oxygenation (ECMO, 61.8%, n = 21), and were more frequently treated with unfractionated heparin (UFH). Compared with adults, children had significantly higher 4Ts scores. Nevertheless, adults had a slightly higher rate of a positive diagnosis of HIT. Six out of 16 adults with confirmed HIT presented with thrombosis (37.5%), whereas all three pediatric patients with HIT presented with thrombosis (p = .087).

CONCLUSIONS

4Ts scores are higher in children compared with adult patients for whom laboratory tests for HIT were obtained. A potentially higher incidence of thrombosis in children with HIT may be attributable to the severity of underlying illness.

Direct Oral Anticoagulant Reversal in the Pediatric Emergency Department

ABSTRACT

Direct oral anticoagulants have been used in the adult population for years and are being used more frequently in pediatrics. Direct oral anticoagulants are chosen preferentially because they do not require close outpatient monitoring, have an equal or better safety profile, and are easy for patients to take. Warfarin is the previous, more commonly used oral anticoagulant and acts as a vitamin K antagonist. Direct oral anticoagulants mechanism of action is different in that they directly inhibit part of the coagulation cascade accomplishing the same end goal. Given their differing mechanisms, they require alternate medications for proper reversal when concerned about overdose of life-threatening bleeds. This review will outline the most commonly used direct oral anticoagulants in pediatric populations and the supporting (mainly adult) data available for proper reversal of these medications in times of need.

Model‐informed bridging of rivaroxaban doses for thromboprophylaxis in pediatric patients aged 9 years and older with congenital heart disease

Rivaroxaban is approved in various regions for the treatment of acute venous thromboembolism (VTE) in children aged between 0 and 18 years and was recently investigated for thromboprophylaxis in children aged between 2 and 8 years (with body weights <30 kg) with congenital heart disease who had undergone the Fontan procedure. In the absence of clinical data, rivaroxaban doses for thromboprophylaxis in post‐Fontan children aged 9 years and older or ≥30 kg were derived by a bridging approach that used physiologically‐based pharmacokinetic (PBPK) and population pharmacokinetic (popPK) models based on pharmacokinetic (PK) data from 588 pediatric patients and from adult patients who received 10 mg once daily for thromboprophylaxis after major orthopedic surgeries as a reference. Both models showed a tendency toward underestimating rivaroxaban exposure in post‐Fontan patients aged between 2 and 5 years but accurately described rivaroxaban PK in post‐Fontan patients aged between 5 and 8 years. Under the assumption that hepatic function is not impaired in post‐Fontan patients, PBPK and popPK simulations indicated that half of the rivaroxaban doses for the same body weight given to pediatric patients treated for acute VTE would yield in pediatric post‐Fontan patients exposures similar to the exposure observed in adult patients receiving 10 mg rivaroxaban once daily for thromboprophylaxis. Simulation‐derived doses (7.5 mg rivaroxaban once daily for body weights 30–<50 kg and 10 mg once daily for body weights ≥50 kg) were therefore included in the recent US label of rivaroxaban for thromboprophylaxis in children aged 2 years and older with congenital heart disease who have undergone the Fontan procedure.

Anticoagulation in Pediatric Patients

Special aspects of anticoagulation in children include the different epidemiology of thrombosis, developmental changes in the coagulation system, age-dependent pharmacokinetics of anticoagulants, risk of bleeding, and practical hurdles to anticoagulation. The classical anticoagulants so far used in children have several limitations, resulting in the need for regular monitoring. The pharmacological properties of direct oral anticoagulants (DOACs) and the special challenges of anticoagulation in children make the DOACs particularly attractive for children. All DOACs have pediatric development programs, targeting various indications for prevention and treatment of thrombosis. Child-appropriate formulations have been developed, age-specific dosing information generated, and safety and efficacy evaluated in ongoing phase 3 trials. Rivaroxaban and dabigatran have already been authorized for children for treatment of acute venous thrombosis and for extended secondary prevention. Their safety and efficacy have been demonstrated comparable to that of standard-of-care anticoagulants, without need for monitoring. Further studies are ongoing, which are expected to lead to pediatric authorizations of DOACs for primary venous thromboembolic event prevention in some high-risk settings. More real-life data will be necessary from postmarketing studies and registries to complement the evidence base for DOAC use in children, particularly in the youngest age groups and special disease populations.

Increased Risk for Thromboembolism After Fontan Surgery: Considerations for Thromboprophylaxis

The Fontan circulation introduces an increased risk of thromboembolism which is associated with substantial mortality and morbidity. Adverse outcomes of thromboembolic complications post-Fontan surgery vary in both nature and severity, ranging from local tissue infarction and pulmonary embolism to Fontan failure and ischemic stroke. Furthermore, recent studies have identified that subclinical stroke is common yet underdiagnosed in Fontan patients. Fontan patients are commonly treated with antiplatelet agents and/or anticoagulants as primary thromboprophylaxis. Optimal thromboprophylaxis management in the Fontan population is still unclear, and clinical consensus remains elusive despite the growing literature on the subject. This perspective will describe the nature of thromboembolism post-Fontan surgery and provide evidence for the use of both current and emerging thromboprophylaxis options for children and adults living with Fontan circulation.

A systematic review of the evidence supporting post-operative antithrombotic use following cardiopulmonary bypass in children with CHD

OBJECTIVES

To determine the optimal antithrombotic agent choice, timing of initiation, dosing and duration of therapy for paediatric patients undergoing cardiac surgery with cardiopulmonary bypass.

METHODS

We used PubMed and EMBASE to systematically review the existing literature of clinical trials involving antithrombotics following cardiac surgery from 2000 to 2020 in children 0-18 years. Studies were assessed by two reviewers to ensure they met eligibility criteria.

RESULTS

We identified 10 studies in 1929 children across three medications classes: vitamin K antagonists, cyclooxygenase inhibitors and indirect thrombin inhibitors. Four studies were retrospective, five were prospective observational cohorts (one of which used historical controls) and one was a prospective, randomised, placebo-controlled, double-blind trial. All included were single-centre studies. Eight studies used surrogate biomarkers and two used clinical endpoints as the primary endpoint. There was substantive variability in response to antithrombotics in the immediate post-operative period. Studies of warfarin and aspirin showed that laboratory monitoring levels were frequently out of therapeutic range (variably defined), and findings were mixed on the association of these derangements with bleeding or thrombotic events. Heparin was found to be safe at low doses, but breakthrough thromboembolic events were common.

CONCLUSION

There are few paediatric prospective randomised clinical trials evaluating antithrombotic therapeutics post-cardiac surgery; most studies have been observational and seldom employed clinical endpoints. Standardised, validated endpoints and pragmatic trial designs may allow investigators to determine the optimal drug, timing of initiation, dosing and duration to improve outcomes by limiting post-operative morbidity and mortality related to bleeding or thrombotic events.

Real-World Anticoagulant Use and Incidence of Venous Thromboembolism and Major Bleeding in Children

PURPOSE

Children generally have a lower risk of venous thromboembolism (VTE) than adults, but those with acute and chronic conditions requiring hospitalization and surgical procedures are at increased risk. Anticoagulant use in children has not been systematically studied, and limited data exist. This study aimed to provide data on the conditions associated with use of anticoagulants, the type of anticoagulant used in children, and the incidence of thromboembolism and major bleeding events reported in this population.

METHODS

To increase understanding of the use of anticoagulant therapies in children with at-risk conditions, 3 health claims databases in the United States were analyzed to describe the characteristics of use of heparins, warfarin, and direct oral anticoagulants (DOACs). Cumulative drug exposure was determined for continuous exposure, defined as >30 days. Unadjusted event rates of VTE and major bleeding after exposure to these therapies were reported. The data were presented descriptively and are not intended for comparison or to imply any causation.

FINDINGS

Anticoagulants were infrequently used in the pediatric population, including at any time point after Fontan surgery for congenital heart disease. Heparins were used most frequently in the population overall and especially for patients aged <12 years. DOACs were used least often and primarily for patients ages 12 to <18 years. Among pediatric patients exposed to anticoagulants, unadjusted incidence rates of VTE per 1000 person-years of exposure ranged from 30.8 to 34.0 for all DOACs, 21.6 to 46.2 for warfarin, and 6.0 to 7.3 for heparins. Rates per 1000 person-years for major bleeding ranged from 0 to 4.9 for all DOACs, 4.3 to 6.7 for warfarin, and 3.7 to 4.6 for heparins.

IMPLICATIONS

With results from clinical trials evaluating DOACs in the pediatric population expected in the next 2 years, these descriptive real-world data may provide a baseline understanding of current prescribing patterns and outcomes associated with the use of DOACs and other anticoagulants in routine pediatric clinical practice. This information represents the use of real-world evidence and may function as the benchmark for evaluating changes in prescription practices and potential outcomes in the future.

Thromboprophylaxis for Children Post-Fontan Procedure: Insights From the UNIVERSE Study

Background Patients with single-ventricle physiology who undergo the Fontan procedure are at risk for thrombotic events associated with significant morbidity and mortality. The UNIVERSE Study evaluated the efficacy and safety of a novel liquid rivaroxaban formulation, using a body weight-adjusted dosing regimen, versus acetylsalicylic acid (ASA) in children post-Fontan. Methods and Results The UNIVERSE Study was a randomized, multicenter, 2-part, open-label study of rivaroxaban, in children who had undergone a Fontan procedure, to evaluate its dosing regimen, safety, and efficacy. Part A was the single-arm part of the study that determined the pharmacokinetics/pharmacodynamics and safety of rivaroxaban in 12 participants before proceeding to part B, whereby 100 participants were randomized 2:1 to open-label rivaroxaban versus ASA. The study period was 12 months. A total of 112 participants were enrolled across 35 sites in 10 countries. In part B, for safety outcomes, major bleeding occurred in one participant on rivaroxaban (epistaxis that required transfusion). Clinically relevant nonmajor bleeding occurred in 6% of participants on rivaroxaban versus 9% on ASA. Trivial bleeding occurred in 33% of participants on rivaroxaban versus 35% on ASA. For efficacy outcomes, 1 participant on rivaroxaban in part B had a pulmonary embolism (2% overall event rate); and for ASA, 1 participant had ischemic stroke and 2 had venous thrombosis (9% overall event rate). Conclusions In this study, participants who received rivaroxaban for thromboprophylaxis had a similar safety profile and fewer thrombotic events, albeit not statistically significant, compared with those in the ASA group. Registration URL: https://www.clinicaltrials.gov. Identifier: NCT02846532.

Dosing Regimen Prediction and Confirmation with Rivaroxaban for Thromboprophylaxis in Children after the Fontan Procedure: Insights from the Phase III UNIVERSE Study

Thrombosis remains an important complication for children with single ventricle physiology post-Fontan procedure and effective thromboprophylaxis is an important unmet medical need. To obviate conventional dose-finding studies and expedite clinical development, a rivaroxaban dose regimen for this indication was determined utilizing a model-informed drug development approach. A physiologically based pharmacokinetic (PBPK) rivaroxaban model was used to predict a pediatric dosing regimen that would produce drug exposures similar to that of 10 mg once daily in adults. This regimen was used in an open-label, multicenter Phase 3 study, which investigated the use of rivaroxaban for thromboprophylaxis in post-Fontan patients 2 to 8 years of age. The pharmacokinetics (PK) of rivaroxaban was assessed in Part A (n = 12) and in Part B (n = 64) of UNIVERSE. The safety and efficacy in the rivaroxaban group were compared to those in the acetylsalicylic acid group for 12 months. Pharmacodynamic endpoints were assessed in both parts of the study. Rivaroxaban exposures achieved in Part A and B were similar to the adult reference exposures. Prothrombin time also showed similarity to the adult reference. Exposure-response analysis did not identify a quantitative relationship between rivaroxaban exposures and efficacy/safety outcomes within the observed exposure ranges. A body-weight based dose regimen selected by PBPK modeling was shown in the UNIVERSE study to be appropriate for thromboprophylaxis in the post-Fontan pediatric population. Model-based dose selection can support pediatric drug development and bridge adult dose data to pediatrics, thereby obviating the need for dose-finding studies in pediatric programs. This article is protected by copyright. All rights reserved.

Population pharmacokinetic analysis of rivaroxaban in children and comparison to prospective physiologically-based pharmacokinetic predictions

Rivaroxaban has been investigated in the EINSTEIN‐Jr program for the treatment of acute venous thromboembolism (VTE) in children aged 0 to 18 years and in the UNIVERSE program for thromboprophylaxis in children aged 2 to 8 years with congenital heart disease after Fontan‐procedure. Physiologically‐based pharmacokinetic (PBPK) and population pharmacokinetic (PopPK) modeling were used throughout the pediatric development of rivaroxaban according to the learn‐and‐confirm paradigm. The development strategy was to match pediatric drug exposures to adult exposure proven to be safe and efficacious. In this analysis, a refined pediatric PopPK model for rivaroxaban based on integrated EINSTEIN‐Jr data and interim PK data from part A of the UNIVERSE phase III study was developed and the influence of potential covariates and intrinsic factors on rivaroxaban exposure was assessed. The model adequately described the observed pediatric PK data. PK parameters and exposure metrics estimated by the PopPK model were compared to the predictions from a previously published pediatric PBPK model for rivaroxaban. Ninety‐one percent of the individual post hoc clearance estimates were found within the 5th to 95th percentile of the PBPK model predictions. In patients below 2 years of age, however, clearance was underpredicted by the PBPK model. The iterative and integrative use of PBPK and PopPK modeling and simulation played a major role in the establishment of the bodyweight‐adjusted rivaroxaban dosing regimen that was ultimately confirmed to be a safe and efficacious dosing regimen for children aged 0 to 18 years with acute VTE in the EINSTEIN‐Jr phase III study.

Unique Challenges of Randomised Controlled Trials in Pediatric Cardiology

Pediatric cardiology has evolved over time with reductions in childhood mortality due to congenital heart disease. Surgical innovation drove early changes in care. Increasingly, the need for more robust evidence provided by randomised controlled trials (RCTs) has been recognised. Although the number of RCTs has increased, there remains a relative paucity of truly impactful trials in the field. However, those trials that have changed practice have demonstrated the potential and importance of this work. Examples include the PRIMACORP trial, which established the safety and efficacy of milrinone after cardiac surgery, and the Single Ventricle Reconstruction trial, which was the first multicentre pediatric cardiac surgical RCT. The successful conduct and important findings emanating from these trials serve as beacons as clinicians strive to improve the evidence base in this field. The establishment of national and international networks such as the Pediatric Heart Network and the Canadian Pediatric Cardiology Research Network provide a strong foundation for future collaborative work. Despite this progress, there remain important challenges to designing and executing RCTs in pediatric cardiology. These include issues of greater disease and patient heterogeneity and increased costs. The use of innovative study designs and analytic methods and the establishment of core outcome measures have the potential to overcome some of the issues related to the smaller patient numbers compared with adult disciplines. As pediatric cardiologists look to the future, it is imperative that we work together to derive the maximum benefit from the considerable efforts directed toward conducting impactful clinical trials in pediatric cardiology.

Could DOAC Be a Better Choice Than Warfarin in Low Compliance Patients with Fontan Procedure?

Background and Objectives: After the Fontan procedure, thromboembolic events need to be prevented. We present a young patient with a history of Fontan procedure and poor adherence to warfarin who developed systemic thromboembolism. He was changed to maintenance dabigatran, which is one of the available direct oral anticoagulants (DOACs). Case presentation: A 20-year-old man was diagnosed with cerebral infarct, pulmonary thromboembolism (PTE), and renal infarcts. He was prescribed warfarin to prevent thromboembolic events after the Fontan procedure. Based on his poor adherence to warfarin, we decided to change the anticoagulant therapy from warfarin to dabigatran 150 mg bid. One month later, his pulmonary thromboembolism regressed. Conclusion: Our case report showed a young adult with low compliance to warfarin who developed cerebral, pulmonary, and renal thromboembolic events. Thus, in our opinion, the change from warfarin to a DOAC was necessary for further prevention and treatment of PTE. A change from warfarin to a DOAC should be considered in patients with poor compliance who are at high risk of thromboembolic events, for example, after the Fontan procedure.

Evaluating the Longevity of the Fontan Pathway

Children born with single ventricle physiology who undergo Fontan palliation face a diverse set of long-term complications. However, patient follow-up has in large part been limited to single institutional experiences without uniform application of diagnostic modalities to screen for relevant outcomes. Additionally, the use of different graft materials and variable surgical technique as part of the Fontan procedure has further complicated the evaluation of single ventricle patients. The purpose of this review is to define the changes in the Fontan pathway specific to the graft material used and its relationship to patient outcomes. As a means of introduction, we briefly review the historical evolution of the Fontan procedure with a focus on the intent behind design changes and incorporation of different biomaterials. We further delineate changes to the Fontan pathway which include the development of stenosis, differential growth, thrombosis, and calcification. Ultimately, the recognition of the changes noted within the Fontan pathway need to be assessed relative to their impact on patient hemodynamics, functional capacity, and Fontan-associated comorbidities.

Rationale and design of a prospective, observational, multicentre study on the safety and efficacy of apixaban for the prevention of thromboembolism in adults with congenital heart disease and atrial arrhythmias: the PROTECT-AR study

INTRODUCTION

The risk for stroke in adults with congenital heart disease (ACHD) is increased, especially in the setting of commonly ensuing atrial arrhythmias (AA), namely atrial fibrillation, atrial flutter or intra-atrial re-entrant tachycardia. Data are limited regarding treatment with non-vitamin K oral anticoagulants in long-term studies involving patients with ACHD and AA.

METHODS AND ANALYSIS

PReventiOn of ThromboEmbolism in Adults with Congenital HearΤ disease and Atrial aRrhythmias is a prospective, multicenter, single-arm, non-interventional cohort study designed to investigate the safety and efficacy of apixaban for the prevention of thromboembolism in ACHD with AA in a 'real-world' setting. Eligible patients will be evaluated by the means of available registries and clinical counter. The study aims to accumulate approximately 500 patient-years of exposure to apixaban as part of routine care. Enrolment will take place at four ACHD centres in Greece. The first patient was enrolled in July 2019. The primary efficacy endpoint is a composite of stroke, systemic or pulmonary embolism and intracardiac thrombosis. The primary safety endpoint is major bleeding, according to the International Society on Thrombosis and Haemostasis bleeding criteria.

ETHICS AND DISSEMINATION

The study protocol has been approved by the institutional review board/independent ethics committee at each site prior to study commencement. All patients will provide written informed consent. Results will be disseminated at scientific meetings and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03854149; Pre-results.