Strategies for thromboprophylaxis in Fontan circulation: a meta-analysis

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.

Machine Learning Analysis of Predictors for Inhaled Nitric Oxide Therapy Administration Time Post Congenital Heart Disease Surgery: A Single-Center Observational Study

Background Congenital heart disease (CHD) is a structural deformity of the heart present at birth. Pulmonary hypertension (PH) may arise from increased blood flow to the lungs, persistent pulmonary arterial pressure elevation, or the use of cardiopulmonary bypass (CPB) during surgical repair. Inhaled nitric oxide (iNO) selectively reduces high blood pressure in the pulmonary vessels without lowering systemic blood pressure, making it useful for treating children with postoperative PH due to heart disease. However, reducing or stopping iNO can exacerbate postoperative PH and hypoxemia, necessitating long-term administration and careful tapering. This study aimed to evaluate, using machine learning (ML), factors that predict the need for long-term iNO administration after open heart surgery in CHD patients in the postoperative ICU, primarily for PH management. Methods We used an ML approach to establish an algorithm to predict 'patients with long-term use of iNO' and validate its accuracy in 34 pediatric postoperative open heart surgery patients who survived and were discharged from the ICU at Kagoshima University Hospital between April 2016 and March 2019. All patients were started on iNO therapy upon ICU admission. Overall, 16 features reflecting patient and surgical characteristics were utilized to predict the patients who needed iNO for over 168 hours using ML analysis with AutoGluon. The dataset was randomly classified into training and test cohorts, comprising 80% and 20% of the data, respectively. In the training cohort, the ML model was constructed using the important features selected by the decrease in Gini impurity and a synthetic oversampling technique. In the testing cohort, the prediction performance of the ML model was evaluated by calculating the area under the receiver operating characteristics curve (AUC) and accuracy. Results Among 28 patients in the training cohort, five needed iNO for over 168 hours; among six patients in the testing cohort, one needed iNO for over 168 hours. CPB, aortic clamp time, in-out balance, and lactate were the four most important features for predicting the need for iNO for over 168 hours. In the training cohorts, the ML model achieved perfect classification with an AUC of 1.00. In the testing cohort, the ML model also achieved perfect classification with an AUC of 1.00 and an accuracy of 1.00. Conclusion The ML approach identified that four factors (CPB, in-out balance, aortic cross-clamp time, and lactate) are strongly associated with the need for long-term iNO administration after open heart surgery in CHD patients. By understanding the outcomes of this study, we can more effectively manage iNO administration in postoperative open heart surgery in CHD patients with PH, potentially preventing the recurrence of postoperative PH and hypoxemia, thereby contributing to safer patient management.

The Lifesaving Impact of Transcatheter Interventions in the Early Post-Fontan Palliation Period

Despite advancements in postoperative outcomes after Fontan surgery, there remains a risk of suboptimal outcomes and significant morbidity in the early postoperative period. Anatomical obstructions in the Fontan pathway can lead to prolonged pleural effusion or ascites, cyanosis, and low cardiac output syndrome (LCOS). Transcatheter interventions offer an alternative to early re-surgery for treating these complications. Over a 13-year period, early catheter angiography, performed within 30 days post-index procedure, was administered to 41 patients, identifying anatomical issues that necessitated re-intervention in 39 cases. This led to transcatheter interventions in 37 (10.4%) of the 344 Fontan surgery patients. The median age was 4.8 years (IQR: 4-9.4), and the median weight was 16.5 kg (IQR: 15-25.2), with females comprising 51.4% (19/37) of this group. The primary indications for the procedures were persistent pleural effusion or ascites in 27 patients (66%), LCOS in 8 patients (20%), and cyanosis in 6 patients (14%). Among the 37 undergoing transcatheter intervention, 30 were treated solely with this method and discharged, three died in ICU follow-up, and four required early re-surgery. No procedural mortality was observed. Our findings demonstrate that transcatheter interventions, including stent implantation, balloon angioplasty, and fenestration dilation, are safe and effective in the early post-Fontan period. Therefore, they should be considered an integral part of the management strategy for this patient group.

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.

EASL-ERN position paper on liver involvement in patients with Fontan-type circulation

Fontan-type surgery is the final step in the sequential palliative surgical treatment of infants born with a univentricular heart. The resulting long-term haemodynamic changes promote liver damage, leading to Fontan-associated liver disease (FALD), in virtually all patients with Fontan circulation. Owing to the lack of a uniform definition of FALD and the competitive risk of other complications developed by Fontan patients, the impact of FALD on the prognosis of these patients is currently debatable. However, based on the increasing number of adult Fontan patients and recent research interest, the European Association for The Study of the Liver and the European Reference Network on Rare Liver Diseases thought a position paper timely. The aims of the current paper are: (1) to provide a clear definition and description of FALD, including clinical, analytical, radiological, haemodynamic, and histological features; (2) to facilitate guidance for staging the liver disease; and (3) to provide evidence- and experience-based recommendations for the management of different clinical scenarios.

Arrhythmic and thromboembolic outcomes in adults with coarctation of the aorta

BACKGROUND

Adults with congenital heart disease (ACHD) experience a high prevalence of atrial arrhythmia (AA) and thromboembolic cerebrovascular complications. However, data on AA and associated long-term outcomes are limited in ACHD patients with coarctation of the aorta (CoA).

OBJECTIVES

This study aimed to characterize the prevalence and risk factors for AA and thromboembolic complications in adults with CoA.

METHODS

We conducted a retrospective cohort study in a tertiary ACHD care center and included consecutive CoA patients older than 18 years old with more than one year of follow-up.

RESULTS

Two hundred seventy patients with CoA were followed for 7.2 ± 3.95 years. The mean age was 35.3 ± 11.1 and 55.2% were male. Patients had a mean of 2.1 ± 1.8 cardiovascular surgical or transcatheter procedures. Thirty-five patients (13%) had AA. Ten subjects (3.8%) had a thromboembolic cerebrovascular event, of which four (1.4%) had AA. In univariate analysis, age (p = 0.005) and total intracardiac interventions (p = 0.007) were associated with the presence of AA. Age (p = 0.021), history of heart failure (p = 0.022), and dyslipidemia (p = 0.019) were associated with thromboembolism. In multivariate analysis, age (p < 0.001) and intracardiac interventions (p = 0.007) were associated with AA.

CONCLUSIONS

The rate of AA is higher in adults with CoA than in the general population but lower than in other ACHD. Increasing age and intracardiac interventions were associated with AA. The rate of thromboembolic events was low. Some traditional risk factors for stroke may apply. Larger studies are needed to validate predictors for stroke in this population.

Hemostasis assessment in Fontan patients using the new thrombodynamics test

BACKGROUND

Thromboembolic events are a well-known risk for Fontan patients and often lead to morbidity and mortality in cyanotic patients and patients with a single ventricle. Coagulopathy and thrombophilia, in addition to disturbed Fontan blood flow and endothelial injury, are major contributors to thromboembolic complications. However, there is currently no consensus regarding the optimal medication to prevent or treat these events. Identification of coagulation disorders is therefore crucial for selecting appropriate management strategies and evaluating long-term outcomes in these patients.

CASE PRESENTATION

We present the case of a 35-year-old male who underwent the Fontan procedure with a total cavopulmonary modification during childhood due to tricuspid atresia. He was admitted with complaints of headaches and visual disturbances, but no clear cardiovascular cause was identified. Standard coagulation test parameters were normal, but the thrombodynamics test indicated severe hypercoagulation and spontaneous clot formation. Anticoagulation therapy was initiated, and a subsequent thrombodynamics assay showed normalization of the coagulation parameters. The patient remained asymptomatic during the six-month follow-up period.

CONCLUSIONS

The thrombodynamics test is a valuable tool for the diagnosis of coagulation disorders, as it can assess coagulation parameters and clot growth in vitro. This method can also aid in the optimization of antithrombotic therapy. The presented clinical case highlights the potential use of the thrombodynamics test in Fontan patients to diagnose coagulation disorders and improve long-term outcomes.

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.

Fontan-associated liver disease: Diagnosis, surveillance, and management

The Fontan operation is a lifesaving procedure for patients with functional single-ventricle congenital heart disease, where hypoplastic left heart syndrome is the most frequent anomaly. Hemodynamic changes following Fontan circulation creation are now increasingly recognized to cause multiorgan affection, where the development of a chronic liver disease, Fontan-associated liver disease (FALD), is one of the most important morbidities. Virtually, all patients with a Fontan circulation develop liver congestion, resulting in fibrosis and cirrhosis, and most patients experience childhood onset. FALD is a distinctive type of congestive hepatopathy, and its pathogenesis is thought to be a multifactorial process driven by increased nonpulsatile central venous pressure and decreased cardiac output, both of which are inherent in the Fontan circulation. In the advanced stage of liver injury, complications of portal hypertension often occur, and there is a risk of developing secondary liver cancer, reported at young age. However, FALD develops with few clinical symptoms, a surprisingly variable degree of severity in liver disease, and with little relation to poor cardiac function. The disease mechanisms and modifying factors of its development are still not fully understood. As one of the more important noncardiac complications of the Fontan circulation, FALD needs to be diagnosed in a timely manner with a structured monitoring scheme of disease development, early detection of malignancy, and determination of the optimal time point for transplantation. There is also a clear need for consensus on the best surveillance strategy for FALD. In this regard, imaging plays an important role together with clinical scoring systems, biochemical workups, and histology. Patients operated on with a Fontan circulation are generally followed up in cardiology units. Ultimately, the resulting multiorgan affection requires a multidisciplinary team of healthcare personnel to address the different organ complications. This article discusses the current concepts, diagnosis, and management of FALD, with special emphasis on the role of different imaging techniques in the diagnosis and monitoring of disease progression, as well as current recommendations for liver disease surveillance.

Mild Acquired von Willebrand Syndrome and Cholestasis in Pediatric and Adult Patients with Fontan Circulation

Background: Hemodynamic alterations in Fontan patients (FP) are associated with hemostatic dysbalance and Fontan-associated liver disease. Studies of other hepatopathologies indicate an interplay between cholestasis, tissue factor (TF), and von Willebrand factor (VWF). Hence, we hypothesized a relationship between the accumulation of bile acids (BA) and these hemostatic factors in FP. Methods: We included 34 FP (Phenprocoumon n = 15, acetylsalicylic acid (ASA) n = 16). BA were assessed by mass spectrometry. TF activity and VWF antigen (VWF:Ag) were determined by chromogenic assays. VWF collagen-binding activity (VWF:CB) was assessed via ELISA. Results: Cholestasis was observed in 6/34 FP (total BA ≥ 10 µM). BA levels and TF activity did not correlate (p = 0.724). Cholestatic FP had lower platelet counts (p = 0.013) from which 5/6 FP were not treated with ASA. VWF:Ag levels were increased in 9/34 FP and significantly lower in FP receiving ASA (p = 0.044). Acquired von Willebrand syndrome (AVWS) was observed in 10/34-FP, with a higher incidence in cholestatic FP (4/6) (p = 0.048). Conclusions: Cholestasis is unexpectedly infrequent in FP and seems to be less frequent under ASA therapy. Therefore, ASA may reduce the risk of advanced liver fibrosis. FP should be screened for AVWS to avoid bleeding events, especially in cholestatic states.

Thromboprophylaxis in Patients With Fontan Circulation

BACKGROUND

The optimal strategy for thromboprophylaxis in patients with a Fontan circulation is unknown.

OBJECTIVES

The aim of this study was to compare the efficacy and safety of aspirin, warfarin, and nonvitamin K oral anticoagulants (NOACs) in a network meta-analysis.

METHODS

Relevant studies published by February 2022 were included. The primary efficacy outcome was thromboembolic events; major bleeding was a secondary safety outcome. Frequentist network meta-analyses were conducted to estimate the incidence rate ratios (IRRs) of both outcomes. Ranking of treatments was performed based on probability (P) score.

RESULTS

A total of 21 studies were included (26,546 patient-years). When compared with no thromboprophylaxis, NOAC (IRR: 0.11; 95% CI: 0.03-0.40), warfarin (IRR: 0.23; 95% CI: 0.14-0.37), and aspirin (IRR: 0.24; 95% CI: 0.15-0.39) were all associated with significantly lower rates of thromboembolic events. However, the network meta-analysis revealed no significant differences in the rates of major bleeding (NOAC: IRR: 1.45 [95% CI: 0.28-7.43]; warfarin: IRR: 1.38 [95% CI: 0.41-4.69]; and aspirin: IRR: 0.72 [95% CI: 0.20-2.58]). Rankings, which simultaneously analyze competing interventions, suggested that NOACs have the highest P score to prevent thromboembolic events (P score 0.921), followed by warfarin (P score 0.582), aspirin (P score 0.498), and no thromboprophylaxis (P score 0.001). Aspirin tended to have the most favorable overall profile.

CONCLUSIONS

Aspirin, warfarin, and NOAC are associated with lower risk of thromboembolic events. Recognizing the limited number of patients and heterogeneity of studies using NOACs, the results support the safety and efficacy of NOACs in patients with a Fontan circulation.

27 years of experience with the Fontan procedure: characteristics and clinical outcomes of children in a tertiary referral hospital

BACKGROUND

The Fontan operation has improved the survival of children born with congenital heart disease with single ventricle physiology. The most widely adopted variations of the Fontan procedure are the extracardiac conduit, the lateral tunnel ve the intra/extracardiac conduit with fenestration. Despite advances in the treatment and prevention of early and late complications that may develop after Fontan surgery, morbidity still remains an important problem.

METHODS

304 patients who underwent Fontan surgery in our center between 1995 and 2022 were included in our study. The complications that developed in patients who underwent primary Fontan or lateral tunnel surgery and extracardiac conduit Fontan application were compared.

RESULTS

Classic Fontan surgery and lateral tunnel surgery were performed in 26 of the patients, and extracardiac Fontan surgery was performed in 278 patients. 218 of 304 cases were patients with single ventricular pathology. 86 cases were patients with two ventricular morphologies but complex cardiac pathology. Fenestration was performed in only 6 patients, other patients did not require fenestration. The mean follow-up period of our patients was 12 years (3 months-27 years). When the complications between Fontan procedures were compared in our study, it was found that the length of hospital stay and mortality were statistically significantly reduced in patients who underwent extracardiac Fontan surgery. There was no significant difference in terms of complications that can be seen after Fontan surgery and the length of stay in the intensive care unit.

CONCLUSION

Fontan complex is a palliative surgery for children with complex heart disease. Palliative surgical operations aimed at the preparation of the Fontan circulation lead to the preparation of the pulmonary vascular bed and the preservation of ventricular function. The techniques applied in Fontan surgery affect the early and long-term complications and the survival of the patients. In our study, when we examined the patients who extracardiac conduit Fontan procedure for the non-cardiac route, we found that mortality and morbidity were minimal.

Dissimilarity in coagulation system in adults after Fontan surgery based on thrombin generations

OBJECTIVES

The Fontan procedure is the treatment of choice in congenital cardiac malformations defined as the single ventricle. Fontan patients are at high risk of thromboembolism, but the exact mechanism of this is poorly understood. The aim of this study was to evaluate an involvement of thrombin generations and microparticles (MPs) in prothrombotic state in adults with Fontan circulation.

METHODS

This study included hospitalized patients after Fontan procedure and healthy volunteers. We assessed laboratory tests including thrombin generation by calibrated automated thrombography in three variants [platelet-poor plasma (impact of coagulation factors), platelet-rich plasma (PRP) (influence of platelets) and related with MPs]. The technique allows for a comprehensive evaluation of the coagulation system.

RESULTS

The study groups consisted of 81 adult Fontan patients [41 females (50.6%); median age 22 interquartile range [20-27] years] and 54 control subjects. In patients with Fontan circulation, higher values of endogenous thrombin potential and peak values were observed for both platelet-poor plasma (+17% and +33%) and MPs (+29% and 41%) compared to controls (all P < 0.05). Moreover, in the Fontan group, we found a 64.9% shorter lag time and a 70.4% time to peak for MP variant (both P < 0.001). Contrarily, analysis in the PRP showed 17.1% of reduced endogenous thrombin potential in Fontan. Furthermore, there were no differences in thrombin synthesis in PRP in Fontan patients receiving aspirin or those with thrombocytopaenia (all P > 0.05).

CONCLUSIONS

This study for the first time showed that thrombin generation associated with MPs may be an important contributor to the prothrombotic state in the Fontan population.

Reproductive Issues in Patients With the Fontan Operation

Patients with the Fontan operation have a unique circulation, with a limited ability to increase cardiac output, and high central venous pressure. They may have diastolic and/or systolic ventricular dysfunction, arrhythmias, thromboembolic complications, or multiorgan dysfunction. All of these factors contribute to reproductive issues, including menstrual irregularities, infertility, recurrent miscarriage, and complications during pregnancy. Although atrial arrhythmias are the most common cardiac complications during pregnancy, patients can develop heart failure and thromboembolic events. Obstetric bleeding, including postpartum hemorrhage, is common. In addition to maternal complications, adverse fetal and neonatal events, such as prematurity and low birthweight, are very common. Counselling about these reproductive issues should begin early. For those who become pregnant, care should be provided by a multidisciplinary cardio-obstetric team familiar with the specific issues and needs of the Fontan population. In this review, we discuss infertility, contraception, and pregnancy in patients with the Fontan operation.

Coagulation and Anticoagulation in Fontan Patients

Patients with a Fontan circulation for single-ventricle physiology are at increased risk of developing thromboembolic events. Thromboembolic events can lead to failure of the Fontan circulation, chronic sequelae in case of stroke, and early mortality. Controversies exist regarding the substrates, risk factors, and optimal detection methods for thromboembolic events. Despite the major clinical implications, there is currently no consensus regarding the optimal antithrombotic therapy to prevent or treat thromboembolic events after the Fontan procedure. In this review we aimed to untangle the available literature regarding antithrombotic prophylaxis and treatment for pediatric and adult Fontan patients. A decision-tree algorithm for thromboprophylaxis in Fontan patients is proposed. Additionally, the current state of knowledge is reviewed with respect to the epidemiology, pathophysiology, and detection of thromboembolic events in Fontan patients, and important evidence gaps are highlighted.

The absence of warfarin treatment and situs inversus are associated with the occurrence of hepatocellular carcinoma after Fontan surgery

BACKGROUND

Hepatocellular carcinoma (HCC) is a long-term complication of Fontan-associated liver disease (FALD). However, risk factors for HCC in patients with FALD remain unclear. This study aimed to identify factors associated with HCC development post-Fontan procedure.

METHODS

We retrospectively examined 103 post-Fontan patients who underwent hepatic imaging at our institution. HCC incidence and patient characteristics were analyzed. A Cox proportional hazards model was used to identify risk factors for HCC.

RESULTS

The median interval between Fontan surgery and final hepatic imaging was 19.6 (1.0-37.7) years. Among 103 patients, nine developed HCC. The cumulative incidence rates of HCC at 10, 20, and 30 years postoperatively were 0%, 7%, and 13%, respectively. In the univariate analysis, age at Fontan surgery, situs inversus, and warfarin absence were associated with HCC occurrence. The multivariate analysis identified the warfarin absence (adjusted hazard ratio [aHR], 22.71; 95% confidence interval: 3.29-507.1; p = 0.0005) and situs inversus (aHR, 14.36; 95% confidence interval: 2.75-105.5; p = 0.002) as risk factors. The prevalence of situs inversus and the warfarin absence was 12% and 50%, respectively. The 20- and 30-year incidence rates of HCC among patients who received warfarin were 0% and 7%, respectively, while those among patients who did not receive warfarin were 14% and 21%, respectively. HCC incidence was significantly higher in the non-warfarin group than in the warfarin group (p = 0.006) and among patients with situs inversus than among those with situs solitus (p = 0.004).

CONCLUSIONS

Warfarin absence and situs inversus were associated with HCC development post-Fontan procedure.

Prevalent pharmacotherapy of US Fontan survivors: A study utilizing data from the MarketScan Commercial and Medicaid claims databases

BACKGROUND

Survivors of Fontan palliation are at life-long risk of thrombosis, arrhythmia, and circulatory failure. To our knowledge, no studies have evaluated current United States pharmaceutical prescription practice in this population.

METHODS

A retrospective observational study evaluating the prevalent use of prescription medications in children and adolescents with hypoplastic left heart syndrome or tricuspid atresia after Fontan completion (identified using ICD9/10 codes) was performed using data contained in the MarketScan Commercial and Medicaid databases for the years 2013 through 2018. Cardiac pharmaceuticals were divided by class. Anticoagulant agents other than platelet inhibitors, which are not uniformly a prescription medication, were also studied. Associations between increasing age and the likelihood of a filled prescription for each class of drug were evaluated. Annualized retail costs of pharmaceutical regimens were calculated.

RESULTS

A cohort of 4,056 subjects (median age 12 years [interquartile range: 8-16], 61% male, 60% commercial insurance) was identified. Of the cohort, 50% received no prescription medications. Angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEi/ARB) (38%), diuretics (15%), and mineralocorticoid receptor antagonists (8%) were prescribed with the highest frequency. Pulmonary vasodilators were received by 6% of subjects. Older age was associated with increased likelihood of filled prescriptions for anticoagulants (P = .008), antiarrhythmic agents, digoxin, ACEi/ARB, and beta blockers (each P < .0001), but also lower likelihood of filled prescriptions for pulmonary vasodilators, conventional diuretics (both P < .0001), and mineralocorticoid receptor antagonists (P = .02).

CONCLUSIONS

Pharmaceuticals typically used to treat heart failure and pulmonary hypertension are the most commonly prescribed medications following Fontan palliation. While the likelihood of treatment with a particular class of medication is associated with the age of the patient, determining the optimal regimen for individual patients and the population at large is an important knowledge gap for future research.

Complications and management of functional single ventricle patients with Fontan circulation: From surgeon's point of view

Fontan surgery by step-wise completing the isolation of originally mixed pulmonary and systemic circulation provides an operative approach for functional single-ventricle patients not amenable to biventricular repair and allows their survival into adulthood. In the absence of a subpulmonic pumping chamber, however, the unphysiological Fontan circulation consequently results in diminished cardiac output and elevated central venous pressure, in which multiple short-term or long-term complications may develop. Current understanding of the Fontan-associated complications, particularly toward etiology and pathophysiology, is extremely incomplete. What's more, ongoing efforts have been made to manage these complications to weaken the Fontan-associated adverse impact and improve the life quality, but strategies are ill-defined. Herein, this review summarizes recent studies on cardiac and non-cardiac complications associated with Fontan circulation, focusing on significance or severity, etiology, pathophysiology, prevalence, risk factors, surveillance, or diagnosis. From the perspective of surgeons, we also discuss the management of the Fontan circulation based on current evidence, including post-operative administration of antithrombotic agents, ablation, pacemaker implantation, mechanical circulatory support, and final orthotopic heart transplantation, etc., to standardize diagnosis and treatment in the future.

Current Treatment Options for the Failing Fontan Circulation

The Fontan operation was introduced in 1968. For congenital malformations, where biventricular repair is unsuitable, the Fontan procedure has provided a long-term palliation strategy with improved outcomes compared to the initially developed procedures. Despite these improvements, several complications merely due to a failing Fontan circulation, including myocardial dysfunction, arrhythmias, increased pulmonary vascular resistance, protein-losing enteropathy, hepatic dysfunction, plastic bronchitis, and thrombo-embolism, may occur, thereby limiting the life-expectancy in this patient cohort. This review provides an overview of the most common complications of Fontan circulation and the currently available treatment options.

Long-term management of Fontan patients: The importance of a multidisciplinary approach

The Fontan operation is a palliative procedure that leads to increased survival of patients with a functional single ventricle (SV). Starting from 1967 when the first operation was performed by Francis Fontan, more and more patients have reached adulthood. Furthermore, it is expected that in the next 20 years, the population with Fontan circulation will reach 150,000 subjects. The absence of right ventricular propulsion and the inability to improve cardiac output because of the low cardiac reserve are the main issues with the Fontan circulation; however, potential complications may also involve multiple organ systems, such as the liver, lungs, brain, bones, and the lymphatic system. As these patients were initially managed mainly by pediatric cardiologists, it was important to assure the appropriate transition to adult care with the involvement of a multidisciplinary team, including adult congenital cardiologists and multiple subspecialists, many of whom are neither yet familiar with the pathophysiology nor the end-organ consequences of the Fontan circulation. Therefore, the aim of our work was to collect all the best available evidence on Fontan's complications management to provide "simple and immediate" information sources for practitioners looking for state of the art evidence to guide their decision-making and work practices. Moreover, we suggest a model of follow-up of patients with Fontan based on a patient-centered multidisciplinary approach.

Use of Pulmonary Arterial Hypertension Therapies in Patients with a Fontan Circulation: Current Practice Across the United Kingdom

Background

The Fontan circulation is a successful operative strategy for abolishing cyanosis and chronic volume overload in patients with congenital heart disease with single ventricle physiology. “Fontan failure” is a major cause of poor quality of life and mortality in these patients. We assessed the number and clinical characteristics of adult patients with Fontan physiology receiving pulmonary arterial hypertension (PAH) therapies across specialist centers in the United Kingdom.

Methods and Results

We identified all adult patients with a Fontan‐type circulation under active follow‐up in 10 specialist congenital heart disease centers in England and Scotland between 2009 and 2019. Patients taking PAH therapies were matched to untreated patients. A survey of experts was also performed. Of 1538 patients with Fontan followed in specialist centers, only 76 (4.9%) received PAH therapies during follow‐up. The vast majority (90.8%) were treated with a phosphodiesterase‐5 inhibitor. In 33% of patients, PAH therapies were started after surgery or during hospital admission. In the matched cohort, treated patients were more likely to be significantly limited, have ascites, have a history of protein‐losing enteropathy, or receive loop diuretics (P<0.0001 for all), also reflecting survey responses indicating that failing Fontan is an important treatment target. After a median of 12 months (11–15 months), functional class was more likely to improve in the treated group (P=0.01), with no other changes in clinical parameters or safety issues.

Conclusions

PAH therapies are used in adult patients with Fontan circulation followed in specialist centers, targeting individuals with advanced disease or complications. Follow‐up suggests stabilization of the clinical status after 12 months of therapy.

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.

Atrial pacing in Fontan patients: The effect of transvenous lead on clot burden

BACKGROUND

Transvenous permanent pacemaker (PPM) implantation is an available option for Fontan patients with sinus node dysfunction. However, the thrombogenic potential of leads within the Fontan baffle is unknown.

OBJECTIVE

The purpose of this study was to compare the clot burden in Fontan patients with a transvenous atrial PPM to those without a PPM and those with an epicardial PPM.

METHODS

This was a retrospective cohort study of all transvenous PPM implantations in Fontan patients followed at our institution (2000-2018). We performed frequency matching on Fontan type and age group. Primary outcome was identification of intracardiac clot, pulmonary embolus, or embolic stroke.

RESULTS

Of 1920 Fontan patients, 58 patients (median age 23 years; interquartile range [25th-75th percentiles] 14-33) at the time of transvenous PPM implantation and 174 matched subjects formed our cohort. The type of Fontan performed in case subjects was right atrium-pulmonary artery or right atrium-right ventricle conduit (54%), lateral tunnel (43%), and extracardiac (3%). The cumulative incidence of clot was highest in patients with transvenous PPM, followed by patients with epicardial PPM and no PPM (1.2 vs 0.87 vs 0.67 per 100 person-years of follow-up, respectively). In multivariable analysis, anticoagulation and/or antiplatelet therapy were protective against clot and resulted in reduction of clot risk by 3-fold (incidence rate ratio 0.33; 95% confidence interval 0.21-0.53; P <.001).

CONCLUSION

In a large cohort of Fontan patients matched for age and Fontan type, patients with transvenous PPM had a higher but not statistically significant incidence of clot compared to those with no PPM and epicardial PPM. Patients treated with warfarin/aspirin had lower clot risk.

Cross-sectional assessment of haemostatic profile and hepatic dysfunction in Fontan patients

Background

Fontan-associated liver disease is accompanied by a hypercoagulable state. While hepatic dysfunction in Fontan patients is common, its relationship with haemostatic changes and clinical outcomes in this patient population remains unclear.

Objective

To correlate liver dysfunction and haemostatic profiles with clinical outcomes in the Fontan population.

Patients/methods

Patients were enrolled in a multicentre, cross-sectional study in Australia and New Zealand. Hepatic structure and function were assessed using serum-based calculations (Fibrotest and model for end-stage liver disease excluding international normalised ratio scores). Haemostatic profiles were assessed by Thrombin Generation. Platelet function was assessed via Platelet Factor 4 (PF4) and P-selectin (P-SEL). Clinical outcomes were obtained from the Australian and New Zealand Fontan Registry.

Results

Seventy-three patients participated in the study (mean age 18.9±8.5 years with a mean of 13.5±6.9 years post-Fontan). The Endogenous Thrombin Potential (ETP) for patients who suffered thrombotic events (TE) (1366.4±66.2 nM/min) was higher compared with patients with major bleeding events (1011.1±138.4 nM/min) (p=0.03). Except for a negative correlation between Fibrotest-score and PF4 (p=0.045), PF4 and P-SEL concentrations did not correlate with markers of hepatic dysfunction or structural abnormality.

Conclusions

Increased ETP is associated with TE during clinical follow-up after Fontan. This study reinforces that hepatic dysfunction may contribute to the derangement of coagulation factors, impacting the individual risk of haemostatic complications for the Fontan population.

Perioperative and long-term management of Fontan patients

A Fontan circulation requires a series of three-staged operations aimed to palliate patients with single-ventricle CHD. Currently, the most frequent technique is the extracardiac total cavopulmonary connection, an external conduit connecting the IVC and right pulmonary artery, bypassing the right side of the heart. Fontan candidates must meet strict criteria; they are assessed utilising both cardiac catheterisation and cardiac magnetic resonance. Postoperatively, treatment protocols prioritise antibiotic prophylaxis, diuretics, angiotensin-converting enzyme inhibitors, anticoagulation, and oxygen therapy with fluid restriction and a low-fat diet. These measures aim to reduce length of stay in the ICU and hospital by preventing acute complications such as infection, venous thromboembolism, low cardiac output, pleural effusion, and acute kidney injury. Late complications of a Fontan procedure include circulation failure, protein-losing enteropathy, plastic bronchitis, and Fontan-associated liver disease. The definitive management is cardiac transplantation, with promising innovations in selective embolisation of lymphatic vessels and Fontan-specific ventricular assist devices. Further research assessing current protocols in the perioperative management of Fontan patients would be beneficial for standardising current practice and improving outcomes.

Abdominal Imaging of Children and Young Adults With Fontan Circulation: Pathophysiology and Surveillance

OBJECTIVE. The Fontan procedure has significantly improved the survival in children with a functional single ventricle, but it is associated with chronically elevated systemic venous pressure that leads to multisystemic complications. Imaging plays an important role in assessing these complications and guiding management. The pathophysiology, imaging modalities, and current surveillance recommendations are discussed and illustrated. CONCLUSION. Significant improvement in survival of patients with Fontan circulation is associated with ongoing cardiac and extracardiac comorbidities and multisystemic complications. The liver and intestines are particularly vulnerable to damage. In addition, this patient population has been shown to be at increased risk of certain malignancies such as hepatocellular carcinoma and neuroendocrine tumors. Familiarity with imaging findings of Fontan-associated liver disease and other abdominal complications of the Fontan circulation is essential for radiologists because we are likely to encounter these patients in our general practice.

Perioperative Management of the Fontan Patient for Cardiac and Noncardiac Surgery

The Fontan circulation is the single-ventricle approach to surgical palliation of complex congenital heart disease wherein biventricular separation and function cannot be safely achieved. Incremental improvements in this surgical technique, along with improvements in the long-term medical management of these patients, have led to greater survival of these patients and a remarkably steady increase in the number of adults living with this unusual circulation and physiology. This has implications for healthcare providers who now have a greater chance of encountering Fontan patients during the course of their practice. This has particularly important implications for anesthesiologists because the effects of their interventions on the finely balanced Fontan circulation may be profound. The American Heart Association and American College of Cardiology recommend that, when possible, elective surgery should be performed in an adult congenital heart disease center, although this may not be feasible in the provision of true emergency care. This review article summarizes the pathophysiology pertinent to the provision of anesthesia in this complex patient group and describes important modifications to anesthetic technique and perioperative management.

Low-dose aspirin-induced gastric mucosal injury after Fontan surgery in an adolescent

Low-dose aspirin (LDA)-induced gastric mucosal injury always requires rigorous follow-up while taking LDA, even in adolescents, and after a long time from the start of LDA.

Early Thromboprophylaxis Initiation is Associated With Reduced Fontan Thromboses in the Early Postoperative Period

Fontan circuit thrombosis is a significant cause of early postoperative morbidity and mortality. Thrombosis incidence and relationship to thromboprophylaxis choice and timing of initiation are not well established. We sought to evaluate the incidence of Fontan circuit thrombosis in the first 30 postoperative days and its relationship to thromboprophylaxis choice and timing. Patients undergoing Fontan surgery, 2006-2016, were reviewed. Fontan circuit thrombosis was defined by sonographic detection of intracardiac or deep venous thrombi. Logistic regression was used to assess relationships between thromboprophylaxis characteristics and thrombosis. One hundred ninety-two patients underwent Fontan. Fontan thrombosis occurred in 19 (10%) patients. 54% were started on aspirin, 27% coumadin, 4% heparin, and 7% none. There was no relationship between thrombosis and baseline anatomy, Fontan type or fenestration. Median time to thromboprophylaxis initiation was 4 days (interquartile range 2-6). Patients not started on thromboprophylaxis had 44.8 times the odds of thrombosis as those on thromboprophylaxis (confidence interval 6.4-311.7, P < 0.01); no children starting thromboprophylaxis before postoperative day 2 developed thromboses. For every day that thromboprophylaxis was delayed, odds of thrombosis increased by 30% (odds ratio 1.3; CI 1.1-1.6, P < 0.01). There was no difference in the odds of thrombosis between children taking aspirin vs other thromboprophylaxis types. Odds of early postoperative Fontan circuit thrombosis are increased in patients in whom thromboprophylaxis is delayed beyond the second postoperative day, with no difference in the odds of thrombosis between patients initiated on aspirin vs other thromboprophylaxis. Early aspirin institution post Fontan is recommended to reduce morbidity. Ultra-mini-Abstract: Odds of early postoperative Fontan circuit thrombosis are increased in patients in whom thromboprophylaxis is delayed beyond the second postoperative day, with no difference in the odds of thrombosis between patients initiated on aspirin vs other thromboprophylaxis. Early aspirin institution post Fontan is recommended to reduce morbidity and resource utilization.

Direct oral anticoagulant use and outcomes in adult patients with Fontan circulation: A multicenter retrospective cohort study

BACKGROUND

Many adult patients with Fontan circulation are treated with antithrombotic agents, including direct oral anticoagulants (DOACs). However, few studies have investigated the efficacy, feasibility, and safety of DOACs in adult patients with Fontan circulation.

METHODS AND RESULTS

In this retrospective cohort study, clinical records of 139 adult patients with Fontan circulation (70 females, 50.4%) from April 2015 to March 2018 were reviewed and classified into five groups according to the therapeutic agents used: DOAC (n = 36), vitamin K antagonist (VKA; n = 41), antiplatelet drug (n = 43), combination of an antiplatelet and anticoagulant (n = 14), and no-antithrombotic prophylaxis (n = 5). In a 1114-patient-year follow-up, 28 major events occurred, including 10 thrombotic and 18 bleeding events; 11 of 18 (61%) female patients had severe menorrhagia. The incidence (% patient-years) of major events was 0.6, 1.42, 3.74, and 5.13 in the DOAC, antiplatelet, VKA, combination, and no-antithrombotic groups, respectively. The Cox proportional hazards analysis revealed that the DOAC group had a lower rate of primary endpoints than the VKA group in males.

CONCLUSIONS

DOAC may be a safe antithrombotic agent for use in adult patients with Fontan circulation, particularly in males. However, these findings should be confirmed in multi-institutional prospective studies.

Management of Fontan circulation in pregnancy: a multidisciplinary approach to care

The Fontan operation was first performed in 1968 and is a palliative procedure for children born with single ventricle forms of congenital heart disease. Today, 70,000 patients worldwide have Fontan circulation today, half of them women, and with an expected 30-year survival of >80%, this population is expected to double in the next 20 years. The Fontan operation surgically redirects systemic venous blood return directly to the pulmonary circulation, bypassing the single ventricle. This abnormal anatomy results in significant challenges for the cardiovascular system and is marked by a sustained, abnormally elevated systemic venous pressure combined with decreased cardiac output. As more women with Fontan circulation reach childbearing age, understanding the unique risks of pregnancy to the mother and fetus and how to best provide clinical care for these women during pregnancy is imperative. However, there are limited clinical data to guide counseling and management in this population. This expert review offers an analysis of the literature about Fontan circulation during pregnancy and describes our center's current multidisciplinary approach to care for these women in the preconception, antepartum, intrapartum, and postpartum periods.

Thromboembolic complications in adult congenital heart disease: the knowns and the unknowns

Despite impressive improvement in long-term survival, adults with congenital heart disease (CHD) remain exposed to a significant cardiovascular morbidity over lifetime. Thromboembolic events (TE) are a major issue. Specific anatomic groups have been shown a particular high risk of TE, including cyanotic heart disease and Fontan circulation. Many intercurrent clinical factors add a substantial risk such as intracardiac medical devices, atrial arrhythmia, endocarditis, or pregnancy. Nevertheless, what is unknown exceeds what is known, especially regarding the management of this heterogenous patient population. Anticoagulation decision should always be individualized weighing balanced with the alternative risk of hemorrhagic complications. In this review, we aim to synthetize existing literature on TE in adults with CHD, discuss management issues, highlight gaps in knowledge, and intend to suggest high priority research.

Coronary artery embolism in a patient with Fontan palliation: a rare complication

Coronary artery embolism is extremely rare in children with Fontan palliation. We report a 10-year-old boy with hypoplastic left heart syndrome post-Fontan procedure who presented with acute onset chest pain and ST-segment changes on electrocardiogram. Cardiac catheterisation revealed coronary artery emboli requiring stent placement. Our case highlights the importance of evaluating chest pain in a systematic manner in Fontan patients as acute coronary artery embolism can be a part of the spectrum of well-known thromboembolic complications.

Non-Vitamin K Oral Anticoagulants in Adults with Congenital Heart Disease: A Systematic Review

Adults with congenital heart disease (ACHD) experience more thromboembolic complications than the general population. We systematically searched and critically appraised all studies on the safety and efficacy of non-vitamin-K oral anticoagulants (NOACs) in adult patients with various forms of congenital heart disease. PubMed and the Cochrane Central Register of Controlled Trials (CENTRAL) were used, with duplicate extraction of data and risk of bias assessment. The Newcastle-Ottawa quality assessment scale was used to assess study quality. Three studies fulfilled the inclusion criteria and were analyzed. The total number of participants was 766, with a total follow-up of 923 patient-years. The majority of patients (77%) received a NOAC for atrial arrhythmias, while the remainder were prescribed NOACs for secondary (19%) or primary (4%) thromboprophylaxis. The annual rate of thromboembolic and major bleeding events was low: 0.98% (95% CI: 0.51-1.86) and 1.74% (95% CI: 0.86-3.49) respectively. In Fontan patients, the annual rate of thromboembolic and major bleeding events was 3.13% (95% CI: 1.18-8.03) and 3.17% (95% CI: 0.15-41.39) respectively. NOACs appear safe and effective in ACHD without mechanical prostheses. Additional studies are, however, needed to confirm their efficacy in complex ACHD, especially those with a Fontan-type circulation.

Single-Ventricle Physiology

Single-ventricle physiology occurs in patients with hypoplastic ventricular heart defects, either on the right or left, who have undergone stepwise palliation surgeries ending with the Fontan procedure. After Fontan completion, these patients are dependent on passive venous return to the pulmonary circulation. The implications of passive flow are potentially devastating to the patient. We discuss some of the basic changes to the patient’s experience after a Fontan procedure, as well as the common complications. We also touch on some of the emerging management strategies for the common complications.