Incremental value of machine learning for risk prediction in tetralogy of Fallot.

OBJECTIVE: Machine learning (ML) can facilitate prediction of major adverse cardiovascular events (MACEs) in repaired tetralogy of Fallot (rTOF). We sought to determine the incremental value of ML above expert clinical judgement for risk prediction in rTOF. METHODS: Adult congenital heart disease (ACHD) clinicians (≥10 years of experience) participated (one cardiac surgeon and four cardiologists (two paediatric and two adult cardiology trained) with expertise in heart failure (HF), electrophysiology, imaging and intervention). Clinicians identified 10 high-yield variables for 5-year MACE prediction (defined as a composite of mortality, resuscitated sudden death, sustained ventricular tachycardia and HF). Risk for MACE (low, moderate or high) was assigned by clinicians blinded to outcome for adults with rTOF identified from an institutional database (n=25 patient reviews conducted by five independent observers). A validated ML model identified 10 variables for risk prediction in the same population. RESULTS: Prediction by ML was similar to the aggregate score of all experts (area under the curve (AUC) 0.85 (95% CI 0.58 to 0.96) vs 0.92 (0.72 to 0.98), p=0.315). Experts with ≥20 years of experience had superior discriminative capacity compared with <20 years (AUC 0.98 (95% CI 0.86 to 0.99) vs 0.80 (0.56 to 0.93), p=0.027). In those with <20 years of experience, ML provided incremental value such that the combined (clinical+ML) AUC approached ≥20 years (AUC 0.85 (95% CI 0.61 to 0.95), p=0.055). CONCLUSIONS: Robust prediction of 5-year MACE in rTOF was achieved using either ML or a multidisciplinary team of ACHD experts. Risk prediction of some clinicians was enhanced by incorporation of ML suggesting that there may be incremental value for ML in select circumstances.

Impact of a quality improvement initiative with a dedicated anesthesia team on outcomes after surgery for adult congenital heart disease.

Objectives: A quality improvement initiative was introduced to the adult congenital cardiac surgery program at Toronto General Hospital in January 2016. A dedicated Adult Congenital Anesthesia and intensive care unit team was introduced within the cardiac group. The use of factor concentrates was introduced. The study compares perioperative mortality, adverse events, and transfusion burden before and after this process change. Methods: We performed a retrospective analysis of all adult congenital cardiac surgeries from January 2004 to July 2019. Two groups were analyzed: patients undergoing operation before and after 2016. The primary outcome was in-hospital mortality. One-year mortality and prevalence of key morbidities were analyzed as secondary outcomes. A separate analysis looked at patients who had and had not attended an anesthesia-led preassessment clinic. Results: In-hospital mortality was significantly reduced in patients undergoing operation after 2016 (1.1% vs 4.3%, P = .003) despite a higher risk profile. One-year mortality (1.3% vs 5.8%, P = .003) and ventilation times (5.5 hours [3.4-13.0] vs 6.3 hours [4.2-16.2], P = .001) were also reduced. The incidence of stroke and renal failure was similar between groups. Blood product exposure was comparable, but the incidence of chest reopening decreased (1.8% vs 4.8%, P = .022), despite more patients with multiple previous chest wall incisions, on anticoagulation, and with more complex cardiac anatomy. There were no significant outcome differences between those who did or did not attend the preassessment clinic. Conclusions: Both in-hospital and 1-year mortality were significantly reduced after the introduction of a quality improvement program, despite a higher risk profile. Blood product exposure remained unchanged, but there were less chest reopenings.

Long-Term Outcomes of Unrepaired Isolated Partial Anomalous Pulmonary Venous Connection With an Intact Atrial Septum.

The natural history of an unrepaired isolated partial anomalous pulmonary venous connection(s) (PAPVC) and the absence of other congenital anomalies remains unclear. This study aimed to expand the understanding of the clinical outcomes in this population. Isolated PAPVC with an intact atrial septum is a relatively uncommon condition. There is the perception that patients with isolated PAPVC are usually asymptomatic, that the lesion generally has a limited hemodynamic impact, and that surgical repair is rarely justified. For this retrospective study, we reviewed our institutional database to identify patients with either 1 or 2 anomalous pulmonary veins that drain a portion of but not the complete ipsilateral lung. Patients with previous surgical cardiac repair, coexistence of other congenital cardiac anomalies that would result in either pretricuspid or post-tricuspid loading of the right ventricle (RV), or scimitar syndrome were excluded. We reviewed their clinical course over the follow-up period. We identified 53 patients; 41 with a single and 12 with 2 anomalous PAPVC. A total of 30 patients (57%) were men, with a mean age at the latest clinic visit of 47 ± 19 years (18 to 84 years). Turner syndrome (6 of 53, 11.3%), bicuspid aortic valve (6 of 53, 11.3%), and coarctation of the aorta (5 of 53, 9.4%) were commonly associated anomalies. A single anomalous left upper lobe vein was the most commonly identified variation. More than half of the patients were asymptomatic. Cardiopulmonary exercise test demonstrated a maximal oxygen consumption of 73 ± 20% expected (36 to 120). Transthoracic echocardiography demonstrated a mean RV basal diameter of 4.4 ± 0.8 cm, RV systolic pressure of 38 ± 13 (16 to 84) mm Hg. A total of 8 patients (14.8%) had ≥moderate tricuspid regurgitation. Cardiac magnetic resonance in 42 patients demonstrated a mean RV end-diastolic volume index of 122 ±3 0 ml/m2 (66 to 188 ml/m2), of which in 8 (14.8%), it was >150 ml/m2. Magnetic resonance imaging-based Qp:Qs was 1.6 ± 0.3. A total of 5 patients (9.3%) had established pulmonary hypertension (mean pulmonary artery pressure ≥25 mm Hg). In conclusion, isolated single or dual anomalous pulmonary venous connection is not necessarily a benign congenital anomaly because a proportion of patients develop pulmonary hypertension and/or RV dilation. Regular follow-up and on-going patient surveillance with cardiac imaging is advised.

Machine Learning for Prediction of Adverse Cardiovascular Events in Adults With Repaired Tetralogy of Fallot Using Clinical and Cardiovascular Magnetic Resonance Imaging Variables.

BACKGROUND: Existing models for prediction of major adverse cardiovascular events (MACE) after repair of tetralogy of Fallot have been limited by modest predictive capacity and limited applicability to routine clinical practice. We hypothesized that an artificial intelligence model using an array of parameters would enhance 5-year MACE prediction in adults with repaired tetralogy of Fallot. METHODS: A machine learning algorithm was applied to 2 nonoverlapping, institutional databases of adults with repaired tetralogy of Fallot: (1) for model development, a prospectively constructed clinical and cardiovascular magnetic resonance registry; (2) for model validation, a retrospective database comprised of variables extracted from the electronic health record. The MACE composite outcome included mortality, resuscitated sudden death, sustained ventricular tachycardia and heart failure. Analysis was restricted to individuals with MACE or followed ≥5 years. A random forest model was trained using machine learning (n=57 variables). Repeated random sub-sampling validation was sequentially applied to the development dataset followed by application to the validation dataset. RESULTS: We identified 804 individuals (n=312 for development and n=492 for validation). Model prediction (area under the curve [95% CI]) for MACE in the validation dataset was strong (0.82 [0.74-0.89]) with superior performance to a conventional Cox multivariable model (0.63 [0.51-0.75]; P=0.003). Model performance did not change significantly with input restricted to the 10 strongest features (decreasing order of strength: right ventricular end-systolic volume indexed, right ventricular ejection fraction, age at cardiovascular magnetic resonance imaging, age at repair, absolute ventilatory anaerobic threshold, right ventricular end-diastolic volume indexed, ventilatory anaerobic threshold % predicted, peak aerobic capacity, left ventricular ejection fraction, and pulmonary regurgitation fraction; 0.81 [0.72-0.89]; P=0.232). Removing exercise parameters resulted in inferior model performance (0.75 [0.65-0.84]; P=0.002). CONCLUSIONS: In this single-center study, a machine learning-based prediction model comprised of readily available clinical and cardiovascular magnetic resonance imaging variables performed well in an independent validation cohort. Further study will determine the value of this model for risk stratification in adults with repared tetralogy of Fallot.

Tetralogy of Fallot Across the Lifespan: A Focus on the Right Ventricle.

Tetralogy of Fallot is a cyanotic congenital heart disease, for which various surgical techniques allow patients to survive to adulthood. Currently, the natural history of corrected tetralogy of Fallot is underlined by progressive right ventricular (RV) failure due to pulmonic regurgitation and other residual lesions. The underlying cellular mechanisms that lead to RV failure from chronic volume overload are characterized by microvascular and mitochondrial dysfunction through various regulatory molecules. On a clinical level, these cardiac alterations are commonly manifested as exercise intolerance. The degree of exercise intolerance can be objectified and aid in prognostication through cardiopulmonary exercise testing. The timing for reintervention on residual lesions contributing to RV volume overload remains controversial; however, interval assessment of cardiac function and volumes by echocardiography and magnetic resonance imaging may be helpful. In patients who develop clinically important RV failure, clinicians should aim to maintain a euvolemic state through the use of diuretics while paying particular attention to preload and kidney function. In patients who develop signs of cardiogenic shock from right heart failure, stabilization through the use of inotropes and pressor is indicated. In special circumstances, the use of mechanical support may be appropriate. However, cardiologists should pay particular attention to residual lesions that may impact the efficacy of the selected device.

De nombreuses techniques chirurgicales permettent aux patients présentant une tétralogie de Fallot (TF), une forme de cardiopathie congénitale, de survivre jusqu'à l'âge adulte. À l'heure actuelle, l'évolution naturelle de la TF corrigée est caractérisée par une insuffisance ventriculaire droite (VD) progressive attribuable à une régurgitation pulmonaire et à d'autres lésions résiduelles. Les mécanismes cellulaires sous-jacents qui mènent à l'insuffisance VD due à une surcharge volumique chronique sont caractérisés par une dysfonction microvasculaire et mitochondriale faisant intervenir diverses molécules régulatrices. Sur le plan clinique, ces atteintes cardiaques se manifestent par une intolérance à l'effort qui peut être évaluée au moyen d'une épreuve d'effort cardiorespiratoire, ce qui permet de faciliter l'établissement d'un pronostic. Le moment propice pour une réintervention en cas de lésions résiduelles contribuant à la surcharge volumique du ventricule droit demeure controversé; toutefois, il peut être utile d'évaluer régulièrement la fonction et les volumes cardiaques au moyen d'une échocardiographie et de tests d'imagerie par résonance magnétique. En présence d'une insuffisance VD cliniquement importante, les cliniciens doivent tenter de maintenir les patients dans un état euvolémique en utilisant des diurétiques, tout en accordant une attention particulière à la précharge et à la fonction rénale. Si les patients manifestent des signes de choc cardiogénique associé à une insuffisance cardiaque droite, il convient de leur administrer des inotropes et des vasopresseurs pour stabiliser leur état. Dans certains cas, l'utilisation d'un dispositif d'assistance mécanique peut être appropriée. Cependant, les cardiologues doivent être attentifs aux lésions résiduelles, car elles peuvent influencer l'efficacité de ce dispositif.

Management of Heart Failure With Arrhythmia in Adults With Congenital Heart Disease: JACC State-of-the-Art Review.

Together, heart failure and arrhythmia represent the most important cardiovascular sources of morbidity and mortality among adults with congenital heart disease (ACHDs). Although traditionally conceptualized as operating within 2 distinct clinical silos, these scenarios frequently coexist within the same individual; consequently the mechanistic, therapeutic, and prognostic overlap between them demands increased recognition. In fact, given the near ubiquity of heart failure and arrhythmia among ACHDs, there is perhaps no other arena within cardiology where this critical intersection is more frequently observed. Optimal care for ACHDs therefore requires a heightened awareness of the relevant interactions as well as the pharmacologic and interventional resources that are increasingly available to the treating cardiologist. This review explores and highlights the overlap between these 2 fields to recommend a parallel, yet interactive, multidisciplinary approach to clinical management. Congenital heart disease categories are broken down into their archetypal subtypes to highlight subtleties of the pathophysiology, evaluation, and therapeutic approach.

Heart Transplant Indications, Considerations, and Outcomes in Fontan Patients: Age-Related Nuances, Transplant Listing, and Disease-Specific Indications.

In the current era, 5%-10% of Fontan patients die or need a transplant in childhood, and approximately 50% will experience the same fate by age 40 years. Heart transplant (HTx) can be successful for selected children and adults with Fontan circulatory failure of any mechanism, with a 1-year post-transplant survival rate approaching 90% in children and 80% in the largest single-centre adult Fontan HTx experience. Protein-losing enteropathy and plastic bronchitis can be expected to resolve post-transplant, and limited data suggest patients with Fontan-associated liver disease who survive HTx can expect improvement in liver health. Early Fontan failure, within 12 months of Fontan completion, is not easily rescued by HTx, and late referrals and failure to refer adult patients remain problematic. Very little is known about the numbers of patients who are not referred, are turned down following assessment for HTx, or die on the waiting list-numbers that are needed to understand the complete picture of HTx in the Fontan population and to identify where best to focus quality-improvement efforts. Recent revisions to listing prioritization in Canada with considerations specific to the Fontan population aim to mitigate the fact that the status-listing criteria are not tailored to the congenital heart population. Transplanting high-risk children prior to Fontan completion, developing adult congenital heart disease transplant centres with expertise that can also offer combined heart-liver transplant when appropriate, and improving single-ventricle mechanical support options and criteria for both adults and children may help mitigate the early post-listing mortality.

Outcome and right ventricle remodelling after valve replacement for pulmonic stenosis.

BACKGROUND: Complications and need for reinterventions are frequent in patients with pulmonary valve stenosis (PVS). Pulmonary regurgitation is common, but no data are available on outcome after pulmonary valve replacement (PVR). METHODS: We performed a retrospective analysis of 215 patients with PVS who underwent surgical valvotomy or balloon valvuloplasty. Incidence and predictors of reinterventions and complications were identified. Right ventricle (RV) remodelling after PVR was also assessed. RESULTS: After a median follow-up of 38.6 (30.9-49.4) years, 93% of the patients were asymptomatic. Thirty-nine patients (18%) had at least one PVR. Associated right ventricular outflow tract (RVOT) intervention and the presence of an associated defect were independent predictors of reintervention (OR: 4.1 (95% CI 1.5 to 10.8) and OR: 3.6 (95% CI 1.9 to 6.9), respectively). Cardiovascular death occurred in 2 patients, and 29 patients (14%) had supraventricular arrhythmia. Older age at the time of first intervention and the presence of an associated defect were independent predictors of complications (OR: 1.0 (95% CI 1.0 to 1.1) and OR: 2.1 (95% CI 1.1 to 4.2), respectively). In 16 patients, cardiac magnetic resonance before and after PVR was available. The optimal cut-off values for RV volume normalisation were 193 mL/m2 for RV end-diastolic volume indexed(sensitivity 80%, specificity 64%) and 100 mL/m2 for RV end-systolic volume indexed(sensitivity 80%, specificity 56%). CONCLUSIONS: Previous RVOT intervention, presence of an associated defect and older age at the time of first repair were predictors of outcome. More data are needed to guide timing of PVR, and extrapolation of tetralogy of Fallot guidelines to this population is unlikely to be appropriate.

Lumped parameter models for two-ventricle and healthy and failing extracardiac Fontan circulations.

Fontan circulations are surgical strategies to treat infants born with single ventricle physiology. Clinical and mathematical definitions of Fontan failure are lacking, and understanding is needed of parameters indicative of declining physiologies. Our objective is to develop lumped parameter models of two-ventricle and single-ventricle circulations. These models, their mathematical formulations and a proof of existence of periodic solutions are presented. Sensitivity analyses are performed to identify key parameters. Systemic venous and systolic left ventricular compliances and systemic capillary and pulmonary venous resistances are identified as key parameters. Our models serve as a framework to study the differences between two-ventricle and single-ventricle physiologies and healthy and failing Fontan circulations.

Outcomes and healthcare resource utilization in adult congenital heart disease patients with heart failure.

AIMS: While heart failure (HF) is a leading cause of death in adults with congenital heart disease (ACHD), few studies report contemporary outcomes after the first HF hospitalization. We examined outcomes of ACHD patients newly admitted for HF compared with ACHD patients without HF and the general HF population without ACHD. METHODS AND RESULTS: Using population databases from a single-payer health system from 1994 to 2018, ACHD patients newly admitted for HF were matched 1:1 to ACHD patients without HF (n = 4030 matched pairs). Similarly, ACHD patients newly admitted for HF were matched 1:1 to HF patients without ACHD (n = 4336 matched pairs). Patients with ACHD and HF (median age 68 years, 45% women) experienced higher mortality in short-term [30 day adjusted hazard ratio (HR) 4.68, 95% confidence interval (CI) 4.06, 5.43, P < 0.001], near-term (1 year HR 3.87, 95% CI 3.77, 4.92, P < 0.001), and long-term (24 year HR 1.59, 95% CI 1.13, 2.36, P = 0.008) follow-up. Patients with ACHD and HF had fewer baseline cardiovascular comorbidities than non-ACHD HF but demonstrated higher 30 day (HR 1.56, 95% CI 1.41, 1.73, P < 0.001), 1 year (HR 1.30, 95% CI 1.20, 1.40, P < 0.001), and 24 year (HR 2.40, 95% CI 1.73, 3.38, P < 0.001) mortality. Those with ACHD and HF also exhibited higher cardiovascular readmission rates at 30 days with HRs 9.15 (95% CI; 8.00, 10.48, P < 0.001) vs. ACHD without HF, and 1.71 (95% CI; 1.54, 1.85, P < 0.001) vs. HF without ACHD, and the higher readmission risk extended to 10 year follow-up. CONCLUSIONS: Adults with congenital heart disease patients with new HF have high risks of death and cardiovascular hospitalization, and preventative strategies to improve outcomes are urgently needed.

Maternal and Fetal Hemodynamic Adaptations to Pregnancy and Clinical Outcomes in Maternal Cardiac Disease.

BACKGROUND: Although insufficient maternal cardiac output (CO) has been implicated in poor outcomes in mothers with heart disease (HD), maternal-fetal interactions remain incompletely understood. We sought to quantify maternal-fetal hemodynamics with the use of magnetic resonance imaging (MRI) and explore their relationship with adverse events. METHODS: Pregnant women with moderate or severe HD (n = 22; mean age 32 ± 5 years) were compared with healthy control women (n = 21; 34 ± 3 years). An MRI was performed during the third trimester at peak output (maternal-fetal) and 6 months postpartum with return of maternal hemodynamics to baseline (reference). Phase-contrast MRI was used for flow quantification and was combined with T1/T2 relaxometry for derivation of fetal oxygen delivery/consumption. RESULTS: Third-trimester CO and cardiac index (CI) measurements were similar in HD and control groups (CO 7.2 ± 1.5 vs 7.3 ± 1.6 L/min, P = 0.79; CI 4.0 ± 0.7 vs 4.3 ± 0.7 L/min/m,2P = 0.28). However, the magnitude of CO/CI increase (Δ, peak pregnancy - reference) in the HD group exceeded that in the control group (CO 46 ± 24% vs 27 ± 16% [P = 0.007]; CI 51 ± 28% vs 28 ± 17% [P = 0.005]). Fetal growth and oxygen delivery/consumption were similar between groups. Adverse cardiovascular outcomes (nonmutually exclusive) in 6 HD women included arrhythmia (n = 4), heart failure (n = 2), and hypertensive disorder of pregnancy (n = 1); premature delivery was observed in 2 of these women. The odds of a maternal cardiovascular event were inversely associated with peak CI (odds ratio 0.10, 95% confidence interval 0.001-0.86; P = 0.04) and Δ,CI (0.02, 0.001-0.71; P = 0.03). CONCLUSIONS: Maternal-fetal hemodynamics can be well characterised in pregnancy with the use of MRI. Impaired adaptation to pregnancy in women with HD appears to be associated with development of adverse outcomes of pregnancy.

Mechanical Circulatory Support for the Failing Sub-Aortic Right Ventricle in Adults.

Patients with ccTGA or d-TGA managed via atrial switch (Mustard or Senning operations) have biventricular circulations with a sub-aortic right ventricle (2V-RV). Other than in a tiny percentage of ccTGA patients, premature heart failure (HF) is common, driven by chronic RV dilatation and dysfunction and/or tricuspid regurgitation. These patients are different from the general HF population in that they are younger, more heterogeneous, are predisposed to pulmonary hypertension and present unique and complex surgical challenges. Despite their young age, they experience disproportionately poor access to advanced therapies and are often disqualified for transplant by pulmonary hypertension, HLA sensitization, program risk-tolerance and psychosocial issues. Mechanical support of the subaortic RV with ventricular assist device (subaortic RVAD, also known as SVAD), although technically challenging, can be an effective alternative to palliative care and offers high likelihood of bridging patients to heart transplant candidacy. In addition, temporary trans-catheter SVAD Impella support has been advantageous for stabilization of decompensated 2V-RV patients or as bridge to durable SVAD support. Improved awareness of and access to specialist ACHD-HF teams offering mechanical support (and transplantation) for 2V-RV patients is increasingly urgent for this aging population, and will improve options and outcomes for these patients as HF emerges.

Safety and Long-term Outcomes of Defibrillator Therapy in Patients With Right-Sided Implantable Cardiac Devices in Adults With Congenital Heart Disease.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) have been proven to prevent sudden cardiac death in adult congenital heart disease (ACHD) patients. Although the left side is chosen by default, implantation from the right side is often required. However, little is known about the efficacy and safety of right-sided ICDs in ACHD patients. METHODS: In this study we reviewed a total of 191 ACHD patients undergoing ICD/cardioverter resynchronisation therapy-defibrillator (CRT-D) implantation at our hospital between 2001 and 2019 (134 men and 57 women; age [mean ± standard deviation], 41.5 ± 14.8 years). RESULTS: Twenty-seven patients (14.1%) had right-sided devices. The most common causes of right-sided implantation were persistent left superior vena cava and vein occlusion (37.0%). Although procedure time (202.8 ± 60.5 minutes vs 143.8 ± 69.1 minutes, P = 0.008) was longer and the procedural success was lower (92.6% vs 99.4%, P = 0.008) for right-sided devices, no difference in R-wave and pacing threshold were noted. Among the 47 patients (24.6%) who underwent defibrillation threshold testing (DFT), no difference in DFT was observed (25.2 ± 5.3 J vs 23.8 ± 4.1 J, P = 0.460). During the median follow-up of 42.4 months, appropriate ICD therapy was observed in 5 (18.5%) and 30 (18.3%) patients for right- and left-sided ICDs/CRTDs, respectively (P = 0.978). No significant difference was seen in complications between them. CONCLUSIONS: Implantation of an ICD on the right side is technically challenging, but it is feasible as an alternative approach for ACHD patients with contraindications to left-sided device implantation.

Risk prediction models for heart failure admissions in adults with congenital heart disease.

BACKGROUND: Heart failure (HF) is the leading cause of death in adult patients with congenital heart disease (ACHD). No risk prediction model exists for HF hospitalization (HFH) for ACHD patients. We aimed to develop a clinically relevant one-year risk prediction system to identify ACHD patients at high risk for HFH. METHODS: Data source was the Quebec CHD Database. A retrospective cohort including all ACHD patients aged 18-64 (1995-2010) was constructed for assessing the cumulative risk of HFH adjusting for competing risk of death. To identify one-year predictors of incident HFH, multivariable logistic regressions were employed to a nested case-control sample of all ACHD patients aged 18-64 in 2009. The final model was used to create a risk score system based on adjusted odds ratios. RESULTS: The cohort included 29,991 ACHD patients followed for 648,457 person-years. The cumulative HFH risk by age 65 was 12.58%. The case-control sample comprised 26,420 subjects, of whom 189 had HFHs. Significant one-year predictors were age ≥ 50, male sex, CHD lesion severity, recent 12-month HFH history, pulmonary arterial hypertension, chronic kidney disease, coronary artery disease, systemic arterial hypertension, and diabetes mellitus. The created risk score ranged from 0 to 19. The corresponding HFH risk rose rapidly beyond a score of 8. The risk scoring system demonstrated excellent prediction performance. CONCLUSIONS: One eighth of ACHD population experienced HFH before age 65. Age, sex, CHD lesion severity, recent 12-month HFH history, and comorbidities constructed a risk prediction model that successfully identified patients at high risk for HFH.

Cardiovascular and abdominal flow alterations in adults with morphologic evidence of liver disease post Fontan palliation.

BACKGROUND: Although morphologic abnormalities in the liver are commonly encountered post Fontan palliation, the relationships between hepatic morphology, vascular flows, and clinical status remain incompletely understood. We therefore aimed to explore flow characteristics in hepatic and intestinal vessels and to examine cardiovascular associations with liver disease. METHODS: This was a retrospective study of adults post Fontan palliation undergoing clinically indicated cardiovascular magnetic resonance imaging (MRI). Patients were included if MRI flow quantification was available for cardiac, hepatic and intestinal vessels; patients were excluded if phase-contrast flow imaging was insufficient for analysis. RESULTS: Thirty patients were studied (median age at MRI 28.5 years [range 19-47]). Eighteen subjects (60%) were classified as having morphologic liver disease according to validated criteria based on available MRI imaging. Abdominal and cardiovascular flows were quantified. Patients with morphologic liver disease had a 41% reduction in superior mesenteric artery (211 ± 124 versus 358 ± 181 mL/min/m2, p = .004), a 36% reduction in hepatic vein (496 ± 247 versus 778 ± 220 mL/min/m2, p = .01), a 31% reduction in portal vein (399 ± 133 versus 580 ± 159 mL/min/m2, p = .004), and an 18% reduction in Fontan pathway flows (1358 ± 429 versus 1651 ± 270 mL/min/m2, p = .04) compared with the remaining population. Adverse cardiovascular events were not associated with morphologic liver disease. CONCLUSION: Morphologic liver disease appears to be associated with flow alterations within the heart, liver and intestine post Fontan palliation. These novel observations suggest that a potential relationship exists between morphologic disease and vascular flows thereby providing further insights into the pathophysiology of liver disease in this high-risk population.

Lateral tunnel Fontan atrial tachycardia ablation trans-baffle access is not mandatory as the initial strategy.

BACKGROUND: Mapping and ablation of atrial tachycardia (AT) is commonly performed in lateral tunnel Fontan (LTF) patients, yet there is little information on the need of baffle puncture to access the pulmonary venous atrium (PVA). This study aimed to evaluate the most common chamber location of critical sites for majority of AT in LTF patients. METHODS: Consecutive LTF patients underwent catheter-based high-density mapping and ablation of AT from Nov. 2015 to Mar. 2019. Critical sites were identified by a combination of activation and entrainment mapping. Acute procedural success was defined as AT termination with ablation and non-inducibility of any AT. Predictors for ablation failure were evaluated in retrospect. RESULTS: Fifteen catheter ablation procedures were performed in 9 patients. A total of 15 clinical ATs (mean TCL 369 ± 91 ms) were mapped. The mechanism was macro re-entry in 11 (73%) and micro re-entry in 2. In 11 ATs (73%), 94 ± 5% of tachycardia cycle length (TCL) were mapped inside the tunnel. The commonest site of successful ablation in the tunnel was on the lateral wall (60%). Trans-baffle access was obtained during 5 of 15 procedures (33%). Overall, procedural success was achieved in 9 of 15 procedures (60%). There were no complications. Recurrence of AT was 42% over a follow-up period of 4.3 ± 3.2 years. Faster TCL of 200-300 ms showed a trend towards ablation failure, (OR 17, 95% CI 0.7 to 423, p = 0.08). CONCLUSIONS: Catheter ablation can be performed effectively for ATs in LTF patients usually from inside the tunnel. ATs with critical sites in the PVA are uncommon. This information will help plan ablation in LTF patients without resorting to initial trans-baffle access.