Thromboprophylaxis in Patients With Fontan Circulation

Comparative effectiveness among thromboprophylaxis strategies after the Fontan operation: A systematic review and network meta-analysis

INTRODUCTION

A variety of thromboprophylaxis regimens have been administered in patients following the Fontan procedure. However, consensus guidelines regarding the optimal thromboprophylaxis strategy have not yet been developed.

METHOD

A network meta-analysis was conducted to evaluate the comparative effectiveness among available thromboprophylaxis regimens and major bleeding events associated with these regimens.

RESULTS

A total of 28 comparative studies with 4430 Fontan patients were included. The incidence of thromboembolic events (TE) was significantly lower in individuals who underwent thromboprophylaxis compared to those who did not. Compared to a no-treatment strategy, nonvitamin K oral anticoagulants (NOACs) showed the largest treatment effect for preventing TE (OR = 0.08, 95 % CI 0.03 to 0.21), followed by warfarin (OR = 0.16, 95 % CI 0.10 to 0.27), and aspirin (OR = 0.23, 95 % CI 0.14 to 0.38). Indeed, NOACs were significantly more effective than aspirin in preventing TE (OR = 0.35, 95 % CI 0.14 to 0.84). Aspirin was associated with the lowest occurrence of major bleeding events, followed by NOACs, no medication, and warfarin. NOACs were shown to possess a highly favorable overall profile.

CONCLUSION

Prescribing thromboprophylaxis drugs, either antiplatelets or anticoagulants, may be more effective in preventing TE after the Fontan operation than not doing so. Among the included regimens, NOACs demonstrated significantly greater efficacy than aspirin; however, they did not show statistically significant superiority over warfarin. Aspirin exhibited lower rates of major bleeding compared to both NOACs and warfarin. Overall, NOACs tended to offer the most advantageous balance of efficacy and safety. However, the findings should be interpreted considering the certainty and limitations of the evidence, including potential residual confounding in observational studies.

Morbidity and mortality in adults with a Fontan circulation beyond the fourth decade of life

AIMS

To evaluate the late outcomes of adults (above 35 years) with a Fontan-type circulation, for whom current data on morbidity and mortality are lacking.

METHODS AND RESULTS

Data were collected retrospectively on consecutive patients with Fontan circulation above the age of 35 years followed in three European specialist centres. Overall, 115 Fontan patients were included [median age 35 (range 35-48) years, 47.8% female]. The most common underlying congenital heart disease diagnosis was tricuspid atresia (n = 58, 50.4%), and the age at first Fontan completion was 9.1 (interquartile range 5.0-15.8) years. Almost two-thirds (61.7%) of patients had undergone an atriopulmonary Fontan, and 23.5% had received a total cavopulmonary connection. One-third required repeat surgery or intervention. Most patients (55.9%) were in New York Heart Association functional class II or class I (30.6%), 76 (66.1%) patients had experienced at least one arrhythmia, and eight (7.0%) protein-losing enteropathy. At a median follow-up of 5.0 (2.4-10.3) years, 15 (13.0%) patients were referred for transplantation assessment and 19 (16.5%) patients died, mainly from heart failure (84.2%). Univariable predictors of death or transplantation included lower serum albumin level [hazard ratio (HR) 1.09 per g/L decrease, 95% confidence interval (CI): 1.04-1.15, P = 0.0009], prior heart failure admission (HR 4.28, 95% CI:1.75-10.44, P = 0.001), prior atrial tachycardia or flutter (HR 3.02, 95% CI: 1.23-7.38, P = 0.02), and baseline pulmonary vasodilator therapy (HR 8.59, 95% CI:1.05-70.13, P = 0.04). Lower serum albumin and prior atrial tachycardia or flutter remained significant on bivariable analysis.

CONCLUSION

Our study highlights the significant morbidity and mortality in older adults with a Fontan-type circulation, emphasizing the need for lifelong specialist surveillance with frequent risk stratification, close monitoring, and early consideration for transplantation assessment.

Percutaneous pulmonary aspiration thrombectomy in an adolescent fontan patient using a large-bore system

We describe the safe and effective percutaneous pulmonary thrombectomy in an 18-year-old female with a Fontan circulation using the FlowTriever® device (Inari Medical®, Irvine, US). Aspiration thrombectomy of both pulmonary arteries was performed using 24 and 16 F FlowTriever® catheters retrieving large amounts of thrombus material resulting in near total angiographic recanalization.

Incidence and Risk Factors for Stroke After Combined Heart-Kidney and Heart-Liver Transplantation

OBJECTIVE

While stroke is a well-recognized complication of isolated heart transplantation, stroke in patients undergoing simultaneous heart-liver (HLT) and heart-kidney transplantation (HKT) has not been explored. This study assessed postoperative stroke incidence, risk factors, and outcomes in HLT and HKT compared with isolated heart transplant.

METHODS

The United Network for Organ Sharing database was queried for adult patients undergoing HLT, HKT, and isolated heart transplants between 1994 and 2022. Patients were stratified by presence of in-hospital stroke after transplant. Post-transplant survival at 1-year was assessed using Kaplan-Meier analysis and log-rank tests. Separate multivariable logistic regression models were constructed to identify risk factors for stroke after HKT and HLT.

RESULTS

Of 2326 HKT recipients, 85 experienced stroke, and of 442 HLT recipients, 19 experienced stroke. Stroke was more common after HKT and HLT than after an isolated heart transplant (3.7% vs. 4.3% vs. 2.9%, p = 0.01). One-year post-transplant survival was lower in those with stroke among both HKT recipients (64.5% vs. 88.7%, p(log-rank) < 0.001) and HLT recipients (43.8% vs. 87.4%, p(log-rank) < 0.001. Pre-transplant pVAD, prior stroke, postoperative dialysis, diabetes, prior cardiac surgery, and heart cold ischemic time were independent risk factors for stroke after HKT, after adjusting for age, sex, and need for blood transfusion on the waitlist. For HLT, postoperative dialysis was a significant risk factor.

CONCLUSIONS

Stroke is more common after HKT and HLT than after isolated heart transplant, and results in poor survival. Independent risk factors for stroke include pre-transplant percutaneous VAD (HKT) and postoperative dialysis (HKT and HLT).

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.

Complex Congenital Heart Disease in the Adult

Congenital heart disease (CHD), a heterogeneous group of structural abnormalities of the cardiovascular system, is the most frequent cause of severe birth defects. Related to improved pediatric outcomes, there are now more adults living with CHD, including complex lesions, than children. Adults with CHD are at high risk for complications related to their underlying anatomy and past surgical palliative interventions. Adults with CHD require close monitoring and proactive management strategies to improve outcomes.

Systematic Review of Randomized Clinical Trials on Direct Oral Anticoagulants in Pediatric Heart Diseases

BACKGROUND

Direct oral anticoagulants (DOACs) have been widely applied in adults for thrombosis prophylaxis. However, the effect of DOACs in pediatric patients with congenital or acquired heart diseases who need anticoagulation therapy remains unclear.

METHODS

We systematically searched the databases of PubMed, Embase, and the Cochrane Library, as well as the ClinicalTrials.gov registry and the World Health Organization's International Clinical Trials Registry Platform until June 2024 to identify relevant randomized clinical trials (RCTs). If the number of included studies was less than 5, we performed a narrative review to assess the effect of DOACs in pediatric patients.

RESULTS

Four studies were included. In the UNIVERSE study, thrombotic events occurred in 2% of the rivaroxaban group and 9% of the aspirin group, with bleeding events in 36% and 41%, respectively. The ENNOBLE-ATE study showed no thromboembolic events in the edoxaban group and 1.7% in the SOC group (rate difference: -0.07%, 95% CI: -0.22 to 0.07%). Major bleeding rates were similar (rate difference: -0.03%, 95% CI: -0.18 to 0.12%). The SAXOPHONE trial showed no thromboembolic events in either group and similar major bleeding rates (-0.8%, 95% CI: -8.1 to 3.3%). In the DIVERSITY trial, 81% of dabigatran patients achieved the primary outcome versus 59.3% in the SOC group (Odds ratio: 0.342, 95% CI: 0.081-1.229). No major bleeding occurred in either group.

CONCLUSION

Existing studies suggest that the use of DOACs hold promise as an effective and safe alternative for preventing and treating thromboembolism in pediatric patients with heart conditions.

Apixaban for Prevention of Thromboembolism in Pediatric Heart Disease

BACKGROUND

Children with heart disease frequently require anticoagulation for thromboprophylaxis. Current standard of care (SOC), vitamin K antagonists or low-molecular-weight heparin, has significant disadvantages.

OBJECTIVES

The authors sought to describe safety, pharmacokinetics (PK), pharmacodynamics, and efficacy of apixaban, an oral, direct factor Xa inhibitor, for prevention of thromboembolism in children with congenital or acquired heart disease.

METHODS

Phase 2, open-label trial in children (ages, 28 days to <18 years) with heart disease requiring thromboprophylaxis. Randomization 2:1 apixaban or SOC for 1 year with intention-to-treat analysis.

PRIMARY ENDPOINT

a composite of adjudicated major or clinically relevant nonmajor bleeding. Secondary endpoints: PK, pharmacodynamics, quality of life, and exploration of efficacy.

RESULTS

From 2017 to 2021, 192 participants were randomized, 129 apixaban and 63 SOC. Diagnoses included single ventricle (74%), Kawasaki disease (14%), and other heart disease (12%). One apixaban participant (0.8%) and 3 with SOC (4.8%) had major or clinically relevant nonmajor bleeding (% difference -4.0 [95% CI: -12.8 to 0.8]). Apixaban incidence rate for all bleeding events was nearly twice the rate of SOC (100.0 vs 58.2 per 100 person-years), driven by 12 participants with ≥4 minor bleeding events. No thromboembolic events or deaths occurred in either arm. Apixaban pediatric PK steady-state exposures were consistent with adult levels.

CONCLUSIONS

In this pediatric multinational, randomized trial, bleeding and thromboembolism were infrequent on apixaban and SOC. Apixaban PK data correlated well with adult trials that demonstrated efficacy. These results support the use of apixaban as an alternative to SOC for thromboprophylaxis in pediatric heart disease. (A Study of the Safety and Pharmacokinetics of Apixaban Versus Vitamin K Antagonist [VKA] or Low Molecular Weight Heparin [LMWH] in Pediatric Subjects With Congenital or Acquired Heart Disease Requiring Anticoagulation; NCT02981472).

Risk Factors for Thromboembolic and Bleeding Events in Patients After the Fontan Operation (Insights from the National Database of Health Insurance Claims of Japan)

Risk stratification of thromboembolic events (TEs) and bleeding events is important for the appropriate selection of thromboprophylaxis in patients after the Fontan operation. Therefore, we clarified the risk factors for TEs and bleeding events in patients after the Fontan operation using the National Database of Health Insurance Claims and Specific Health Checkups of Japan. We conducted a retrospective cohort study including 2,515 patients who underwent the Fontan operation between June 2011 and September 2019. The end points were TEs and bleeding events within 1 year of the Fontan operation analysis. We analyzed the risk factors for these end points using a multivariate analysis. In total, 1,903 patients were included in the analysis. The median age at the time of the Fontan operation was 3 (1 to 22) years, and 1,067 patients (56%) were male. The incidence rates of TEs and bleeding events were 12% and 11%, respectively. Age (odds ratio [OR] 1.1 per 1 year older, p <0.05) was an independent risk factor for TEs. Thromboprophylaxis with aspirin after the Fontan operation significantly reduced TEs (OR 0.3, p <0.05). A history of postoperative hemorrhage (OR 1.5, p <0.05) and the use of a potassium channel blocker (OR 2.1, p <0.05) were independent risk factors for bleeding events. In conclusion, aspirin was found to reduce the risk of TEs within 1 year of the Fontan operation. The results of this study will be useful in selecting effective and safe thromboprophylaxis in patients after the Fontan operation.

Five decades of Fontan palliation: What have we learned? What should we expect?

The Fontan procedure is the final palliative surgery in a series of staged surgeries to reroute the systemic venous blood flow directly to the lungs, with the ventricle(s) pumping oxygenated blood to the body. Advances in medical and surgical techniques have improved patients' overall survival after the Fontan procedure. However, Fontan-associated chronic comorbidities are common. In addition to chronic cardiac dysfunction and arrhythmias, complications involving other organs such as the liver, lungs, intestine, lymphatic system, brain, and blood frequently occur. This narrative review focuses on the immediate and late consequences in children, pregnant women, and other adults with Fontan circulation. In addition, we describe the technical advancements that might change the way single-ventricle patients are managed in future.

Transcatheter thrombectomy of acute pulmonary embolism in an adult Fontan patient: a case report

Background

The Fontan operation is a well-described palliative procedure for functional single-ventricle patients. This population has an increased risk of thrombo-embolic events. Adequate imaging, and therefore diagnosis, requires an understanding of the unique anatomy and physiology of a Fontan. Optimal strategies for the prevention and treatment of thrombo-embolic complications in the Fontan population are poorly defined.

Case summary

A 28-year-old female with a history of Ebstein anomaly of the tricuspid valve status post-Fontan presented with chest pain and acute hypoxia. Computed tomographic angiography (CTA) reported a submassive pulmonary embolism (PE). She was initiated on a heparin drip. Catheterization demonstrated elevated Fontan pressures and a large thrombus in the right lower pulmonary artery that was removed with an aspiration device. The patient was transitioned to a direct oral anticoagulant (DOAC) following the procedure.

Discussion

Thrombotic complications are common in the adult Fontan population. Given the morbidity and mortality associated with this complication, the use of proper imaging techniques is imperative. Traditional CTA imaging for PE in Fontan patients often has contrast filling defects related to their anatomy and physiology. Utilization of adequate imaging techniques helps decrease cost and additional radiation exposure. In addition, it avoids inappropriate hospitalization, need for anticoagulation, and potential need for catheterization toconfirm or exclude the presence of PE. For Fontan patients with a thrombus, prior event, and no contraindications, current guidelines recommend oral anticoagulation with a vitamin K antagonist; however, there are increasing data on the use of DOACs in this population.

Challenges in diagnosing pulmonary embolism in an adult with Fontan physiology: a case report

BACKGROUND

With the increasing longevity of congenital heart disease patients and limited number of adult congenital heart disease specialists, it is becoming increasingly imperative for general cardiologists to understand not only the unique physiology of Fontan patients but also imaging protocol considerations when treating this group of patients.

CASE SUMMARY

Here, we present a patient with a history of congenital tricuspid atresia status after the Fontan procedure who presented for gut translocation-related bacteraemia. Importantly, the patient was falsely diagnosed with pulmonary embolism resulting from inaccurate acquisition of computed tomography imaging.

DISCUSSION

This case illustrates the complex intricacies that clinicians should consider when facing the challenge of treating Fontan patients.

Cardiac Drugs in ACHD Cardiovascular Medicine

Adult congenital heart disease (ACHD) is a growing population that requires life-long care due to advances in pediatric care and surgical or catheter procedures. Despite this, drug therapy in ACHD remains largely empiric due to the lack of clinical data, and formalized guidelines on drug therapy are currently lacking. The aging ACHD population has led to an increase in late cardiovascular complications such as heart failure, arrhythmias, and pulmonary hypertension. Pharmacotherapy, with few exceptions, in ACHD is largely supportive, whereas significant structural abnormalities usually require interventional, surgical, or percutaneous treatment. Recent advances in ACHD have prolonged survival for these patients, but further research is needed to determine the most effective treatment options for these patients. A better understanding of the use of cardiac drugs in ACHD patients could lead to improved treatment outcomes and a better quality of life for these patients. This review aims to provide an overview of the current status of cardiac drugs in ACHD cardiovascular medicine, including the rationale, limited current evidence, and knowledge gaps in this growing area.