Fontan-Associated Dyslipidemia

Background Hypocholesterolemia is a marker of liver disease, and patients with a Fontan circulation may have hypocholesterolemia secondary to Fontan-associated liver disease or inflammation. We investigated circulating lipids in adults with a Fontan circulation and assessed the associations with clinical characteristics and adverse events. Methods and Results We enrolled 164 outpatients with a Fontan circulation, aged ≥ 18 years, in the Boston Adult Congenital Heart Disease Biobank and compared them with 81 healthy controls. The outcome was a combined outcome of nonelective cardiovascular hospitalization or death. Participants with a Fontan (median age, 30.3 [interquartile range, 22.8–34.3 years], 42% women) had lower total cholesterol (149.0±30.1 mg/dL versus 190.8±41.4 mg/dL, P\u3c 0.0001), low‐density lipoprotein cholesterol (82.5±25.4 mg/dL versus 102.0±34.7 mg/dL, P\u3c 0.0001), and high‐density lipoprotein cholesterol (42.8±12.2 mg/dL versus 64.1±16.9 mg/dL, P\u3c 0.0001) than controls. In those with a Fontan, high‐density lipoprotein cholesterol was inversely correlated with body mass index (r=−0.30, P\u3c 0.0001), high‐sensitivity C‐reactive protein (r=−0.27, P=0.0006), and alanine aminotransferase (r=−0.18, P=0.02) but not with other liver disease markers. Lower high‐density lipoprotein cholesterol was independently associated with greater hazard for the combined outcome adjusting for age, sex, body mass index, and functional class (hazard ratio [HR] per decrease of 10 mg/dL, 1.37; 95% CI, 1.04–1.81 [P=0.03]). This relationship was attenuated when log high‐sensitivity C‐reactive protein was added to the model (HR, 1.26; 95% CI, 0.95–1.67 [P=0.10]). Total cholesterol, low‐density lipoprotein cholesterol, and triglycerides were not associated with the combined outcome. Conclusions The Fontan circulation is associated with decreased cholesterol levels, and lower high‐density lipoprotein cholesterol is associated with adverse outcomes. This association may be driven by inflammation. Further studies are needed to understand the relationship between the severity of Fontan‐associated liver disease and lipid metabolism

Associations Between Characteristics of Individuals With Fontan Circulation With Blood and Urine Biomarkers of Kidney Injury and Dysfunction

Background Fontan circulation is associated with kidney injury and dysfunction, often unappreciated until Fontan circulatory failure. We hypothesized that cystatin C‐estimated glomerular filtration rate (eGFR) would identify chronic kidney disease more frequently and that urine kidney injury biomarkers would be higher with declining Fontan physiological features. Methods and Results We enrolled 100 ambulatory individuals. Blood and urinary laboratory measurements were compared with demographics and clinically obtained data. Different eGFR equations were used for individuals aged ≥19 years and <19 years. Chronic kidney disease was defined as eGFR <90 mL/min per 1.73 m2. Median (25th–75th percentile) age was 19 (14–26) years, and 43% were female patients. Cystatin C eGFR detected chronic kidney disease (37%) in more patients than creatinine eGFR (11%). Cystatin C eGFR was positively associated, and skeletal muscle mass was negatively associated, with creatinine eGFR in both univariate (cystatin C eGFR β=0.44±0.12, P=0.0006; skeletal muscle mass β=−0.72±0.32, P=0.03) and multivariable analysis (cystatin C eGFR β=0.43±0.12, P=0.0005; skeletal muscle mass β=−0.69±0.29, P=0.02). Urine neutrophil gelatinase‐associated lipocalin concentration correlated with Fontan pressure (r=0.28; P=0.04), ventricular end‐diastolic pressure (r=0.28; P=0.04), and body fat mass (r=0.26; P=0.03). Conclusions Cystatin C eGFR identified more kidney dysfunction, likely attributable to creatinine eGFR being confounded by skeletal muscle mass. Elevated urine neutrophil gelatinase‐associated lipocalin was associated with worse Fontan hemodynamics and higher percentage body fat, suggesting that higher venous pressure and higher adiposity are associated with ongoing kidney injury

Risk Factors for Mortality and Ventricular Tachycardia in Patients With Repaired Tetralogy of Fallot: A Systematic Review and Meta-analysis

Background: Patients with repaired tetralogy of Fallot (rTOF) have increased risk for mortality, sudden cardiac death, and ventricular tachycardia (VT). The aim of this systematic review and meta-analysis is to offer an updated analysis of risk factors following significant changes in surgical and perioperative management. Methods: A meta-analysis based on the published literature between 2008 and 2018 was conducted. Endpoints were VT, cardiac mortality/VT, and all-cause mortality/VT. Studies with ≥100 patients and ≥10 events were included. Results: Fifteen studies including 7218 patients (average age 27.5 years) were analyzed. Risk factors for VT included older age (per 1 year, odds ratio [OR]: 1.039; 95% confidence interval [CI]: 1.025-1.053), older age at corrective surgery (per 1 year, OR: 1.034; CI: 1.017-1.051), previous palliative shunt (OR: 3.063; CI: 1.525-6.151), number of thoracotomies (OR: 1.416; CI: 1.249-1.604), longer QRS duration (per 1 ms, OR: 1.031; CI: 1.008-1.055), and at least moderate right-ventricular dysfunction (OR: 2.160; CI_ 1.311-3.560). Additional risk factors for cardiac death/VT were previous ventriculotomy (OR: 2.269; CI: 1.226-4.198), lower left-ventricular ejection fraction (per 1%, OR: 1.049; CI: 1.029-1.071), and higher right-ventricular end diastolic volume (per 1 mL/m2, OR: 1.009; CI: 1.002-1.016). Supraventricular tachycardia/atrial fibrillation was an additional risk factor for all-cause mortality/VT (OR: 1.939; CI: 1.088-3.457). Conclusions: The study highlights the importance of preservation of biventricular systolic function on late outcomes. Ventricular function appears to have a greater impact on outcomes than the severity of pulmonary regurgitation alone in this patient population

The impact of the COVID-19 pandemic on individuals with Fontan circulation: Focus on gaps in care

Background: Gaps in subspecialty cardiology care could potentially delay identification and care for multi-organ complications common in patients with Fontan circulation. This study analyzed the frequency of gaps in care for individuals with Fontan circulation during the COVID-19 pandemic and associated demographic and clinical factors. Methods: This retrospective study evaluated individuals with Fontan circulation followed at our center since 2010. A gap in care was defined as an absence of any formal cardiology provider-patient contact (clinic visit or telehealth) for >15 months. Results: Over a third of 308 patients with Fontan circulation experienced at least one gap in care between 2010 and 2022, and 77 experienced a gap in care during the COVID-19 pandemic. Of this latter group, 27 (35%) had never experienced a prior gap in cardiology care until the pandemic. Those who experienced gaps in care during the pandemic were on average older (18.0 [IQR 9.6–25.6] vs. 14.2 [7.2–21.2] years, p = 0.01), more likely to be of Black/African American race (23.4% vs 7.4%, p = 0.001), and less likely to have a diagnosis of protein-losing enteropathy or plastic bronchitis (0% vs. 8.6%, p = 0.005). Those without a gap in care during the pandemic were more likely to have utilized telehealth visits (13% vs 3%, p = 0.02). Conclusion: Gaps in care are common and appear to have been exacerbated by the COVID-19 pandemic in those with a Fontan circulation. Such gaps are particularly common among African American and adult patients, and may potentially be mitigated by expanding telehealth access

MELD-XI score is not associated with adverse outcomes in ambulatory adults with a Fontan circulation

Background: The Model for End-stage Liver Disease excluding INR (MELD-XI) is commonly used to identify patients with a Fontan circulation at increased risk of adverse events, However, this approach has not been evaluated in unselected ambulatory adults. Methods: We enrolled a cohort of 163 outpatients with a Fontan circulation aged ≥18-years in the Boston Adult Congenital Heart Disease Biobank from 2012 to 2018. Survival analysis was performed to assess the relationship between MELD-XI with both all-cause mortality and a composite outcome of mortality or non-elective cardiovascular hospitalization. Results: Mean age was 30.2±9.7 years, and 41.1% were women. Most had a lateral tunnel Fontan (62.6%). MELD-XI score averaged 10.6±2.1 (median = 13). Both creatinine and total bilirubin were ≤1.0 mg/dL in 94/163 (57.7%), translating to the lowest possible score. MELD-XI18. During follow-up of 3.2±2.2 years, the composite outcome occurred in 58 patients (35.6%), with 16 deaths (9.8%). Most deaths (n = 11, 68.8%) and composite outcomes (n = 39, 67.2%) occurred among patients with MELD-XI less than the median. MELD-XI score did not differ between those who did and did not have events (death: 10.8±2.2 vs. 10.6±2.1; p = 0.92; composite outcome: 10.6±2.2 vs. 10.7±2.1, p = 0.45). Likewise, survival analysis did not suggest an association between MELD-XI and either outcome. Conclusions: MELD-XI score does not appear to be associated with risk for adverse outcomes in an unselected cohort of outpatients with a Fontan circulation. Prior findings may reflect conditioning on a clinical referral for laboratory testing

Thromboembolic Events Are Independently Associated with Liver Stiffness in Patients with Fontan Circulation

Background: Thromboembolism (TE) and Fontan-associated liver disease (FALD) are common and lead to significant morbidity in Fontan circulations. Risk factors for TE and the potential link between TE and FALD are not well understood. The objective of this study was to evaluate the association between TE and the severity of FALD based on radiologic liver stiffness. Methods: Using a retrospective cohort study design, 85 Fontan patients (aged 27.7 &plusmn; 8.2 years) who had liver stiffness measurement were included. Multivariable logistic regression was used to determine independent associations with TE. Results: Sixteen patients (19%) had a history of TE after the Fontan procedure at a mean age of 21.4 &plusmn; 15.0 years. Patients with TE were significantly older at the time of the last evaluation (33.8 &plusmn; 11.7 vs. 26.3 &plusmn; 6.5 years, p = 0.03). Liver stiffness by MRI and ultrasound was higher in the TE group (5.1 &plusmn; 1.4 vs. 4.3 &plusmn; 1.2 kPa, p = 0.04 and 2.8 &plusmn; 0.4 vs. 2.4 &plusmn; 0.5 m/s, p = 0.04, respectively). On multivariable analysis, higher liver stiffness (odds ratio (OR): 2.12, p = 0.03) and older age (OR: 1.11, p = 0.03) were associated with TE. Conclusions: This study found an association between TE, age, and radiologic liver stiffness

Isosorbide dinitrate effect on hemodynamic profile, liver stiffness, and exercise tolerance in Fontan circulation (the NEET clinical trial)

After Fontan operation, decreased venous capacitance and venoconstriction are adaptive mechanisms to maintain venous return and cardiac output. The consequent higher venous pressure may adversely impact end-organ function, exercise capacity and result in worse clinical outcomes. This pilot study evaluated the safety and effect of isosorbide dinitrate (ISDN), a venodilator, on exercise capacity, peripheral venous pressure (PVP), and liver stiffness in patients with Fontan circulation. In this prospective single-arm trial, 15 individuals with Fontan circulation were evaluated at baseline and after 4 weeks of therapeutic treatment with ISDN. Primary aims were to assess the safety of ISDN and the effect on maximal exercise. We also aimed to evaluate the effect of ISDN on ultrasound-assessed liver stiffness, markers of submaximal exercise, and PVP at rest and peak exercise. Repeated measures t-tests were used to assess change in variables of interest in response to ISDN. Mean age was 23.5 ± 9.2 years (range 11.2–39.0 years), and 10/15 (67%) were male. There was no statistically significant change in peak VO2 (1401 ± 428 to 1428 ± 436 mL/min, p = 0.128), but VO2 at the anaerobic threshold increased (1087 ± 313 to 1115 ± 302 mL/min, p = 0.03). ISDN was also associated with a lower peak exercise PVP (22.5 ± 4.5 to 20.6 ± 3.0 mmHg, p = 0.015). Liver stiffness was lower with ISDN, though the difference was not statistically significant (2.3 ± 0.4 to 2.1 ± 0.5 m/s, p = 0.079). Of the patients completing the trial, mild headache was common (67%), but there were no major adverse events. Treatment with ISDN for 4 weeks is well-tolerated in patients with a Fontan circulation. ISDN is associated with an increase in VO2 at anaerobic threshold, lower peak PVP, and a trend toward lower liver stiffness. Larger, longer duration studies will be necessary to define the impact of ISDN on clinical outcomes in the Fontan circulation. Clinical Trial Registration: URL: https://clinicaltrials.gov. Unique identifier: NCT04297241