Fred Wu

MELD-XI score and cardiac mortality or transplantation in patients after Fontan surgery

Objective The Fontan operation is a staged palliation for complex congenital heart disease and single ventricle physiology. Perioperative survivors of the Fontan operation experience long-term cardiac complications, including death. Liver and renal dysfunction are reported in these patients and have a direct effect on morbidity and mortality. This study aims to investigate whether the Model for End-stage Liver Disease eXcluding INR score (function of creatinine and total bilirubin, MELD-XI) predicts risk for cardiac mortality or transplantation in patients with Fontan circulation. Design and setting Retrospective, single-centre study. Time of first evaluation was the time of the earliest available MELD-XI score measurement, and follow-up was terminated by a cardiac event or by the last clinical evaluation. Patients Patients surviving after Fontan surgery and evaluated at Boston Childrens Hospital between 1993 and 2008. Main outcome measure Composite endpoint of sudden death, death from congestive heart failure or cardiac transplantation. Results The MELD-XI score was calculated as MELD-XI=11.76(loge creatinine)+5.112(loge total bilirubin)+9.44. Ninety-six patients were included (52 male, median age 26 years). After a mean follow-up period of 5.7 years, 18 patients (19%) experienced the composite end point. Baseline MELD-XI score was independently and directly related to the incidence of the composite endpoint (HR for high MELD-XI score group of 7.76, 95% CI 2.05 to 29.33, p=0.008). Conclusions Fontan patients with a higher MELD-XI score have shorter freedom from sudden cardiac death, death from congestive heart failure and cardiac transplantation.

Liver Disease in the Patient with Fontan Circulation

The Fontan procedure has undergone many modifications since first being performed on a patient with tricuspid valve atresia in 1968. It is now the procedure of choice for individuals born with single-ventricle physiology or for those in whom a biventricular repair is not feasible. Forty years of experience with the Fontan procedure have gradually revealed the shortfalls of such a circulatory arrangement. Sequelae related to the underlying congenital anomaly or to the altered physiology of passive, nonpulsatile flow through the pulmonary arterial bed can result in failure of the Fontan circulation over time. Liver abnormalities including abnormalities in the clotting cascade have been well documented in Fontan patients. The clinical significance of these findings, however, has remained poorly understood. As Fontan survivors have increased in age and number, we have begun to better recognize subclinical hepatic dysfunction and the contribution of liver disease to adverse outcomes in this population. The purpose of this review is to summarize the existing data pertaining to liver disease in the Fontan population and to identify some questions that have yet to be answered.

Transient Elastography May Identify Fontan Patients with Unfavorable Hemodynamics and Advanced Hepatic Fibrosis

BACKGROUND Transient elastography (TE) offers a noninvasive correlate with the degree of hepatic fibrosis. However, factors other than fibrosis affect liver stiffness. We sought to determine whether hepatic congestion related to hemodynamics in Fontan circulation influences liver stiffness measurement (LSM) assessed by TE. METHODS We studied 45 subjects with Fontan circulation undergoing cardiac catheterization with or without simultaneous liver biopsy. Subjects underwent TE within 5 days before catheterization. Clinical history, hemodynamic and biopsy data, and hepatic biomarkers were collected. Five subjects who had previously undergone liver biopsy and TE were also included. RESULTS Median age was 13.1 years (range 2.4-57.8); median time since Fontan was 9.9 years (range 0.1-32.5). No subject had known hepatitis C. Mean LSM for the entire cohort was 21.4 ± 10.8 kPa. Univariate regression analysis using LSM as a continuous outcome variable shows significant correlations with age (R = 0.35, P = .01), time since Fontan (R = 0.41, P = .003), Fontan pressure (R = 0.31, P = .04), cardiac index (R = 0.33, P = .03), pulmonary vascular resistance (R = 0.34, P = .03), systemic arterial oxygen saturation (R = 0.31, P = .04), and platelet count (R = 0.29, P = .05). On multiple regression analysis, Fontan pressure (β = 0.901, P = .03) and cardiac index (β = 2.703, P = .02) were significant predictors of LSM with overall model R(2) = 0.206. Univariate analysis shows LSM to be associated with more severe centrilobular fibrosis (P = .05). CONCLUSIONS Higher LSM is associated with unfavorable Fontan hemodynamics and advanced centrilobular hepatic fibrosis. TE may be a useful tool for identifying Fontan patients who warrant invasive testing.

Portal and centrilobular hepatic fibrosis in Fontan circulation and clinical outcomes

BACKGROUND The Fontan operation redirects venous blood flow directly to the pulmonary circulation in subjects with single ventricle anatomy. Congestive hepatopathy and cirrhosis have been described in subjects with Fontan circulation, but the prevalence of and predictors for liver disease remain unknown. METHODS We performed a retrospective study of liver histopathology in Fontan subjects who had liver biopsy or autopsy. All specimens were graded using a pre-determined protocol. Additional data were collected through chart review. Among 68 subjects, specimens were obtained at a median age of 23.2 years (range 5.0 to 52.7 years). Median time since Fontan was 18.1 years (range 1.2 to 32.7 years). RESULTS Centrilobular fibrosis was seen in every specimen, with 41.2% showing Grade 4 centrilobular fibrosis. Portal fibrosis was seen in 82.3% of specimens, with 14.7% showing cirrhosis. Megamitochondria were seen in 58.8% of specimens. Centrilobular fibrosis grade was greater in those with a dominant left or right ventricle than in those with a combined right and left systemic ventricle (p = 0.008). Portal fibrosis grade correlated with alkaline phosphatase (p = 0.04) and mode of biopsy (p = 0.02). Neither centrilobular fibrosis nor portal fibrosis grade was predictive of transplant-free survival or overall survival. CONCLUSIONS Individuals with Fontan physiology have a high prevalence of hepatic fibrosis. Signs and symptoms of liver disease did not predict histopathologic findings. Few risk factors for advanced disease were identified. Histopathology findings did not predict transplant-free survival. The role of liver biopsy in this population remains uncertain.

Abnormal spirometry after the Fontan procedure is common and associated with impaired aerobic capacity

Impaired exercise capacity is common after the Fontan procedure and is attributed to cardiovascular limits. The Fontan circulation, however, is also distinctively vulnerable to unfavorable lung mechanics. This study aimed to define the prevalence and physiological relevance of pulmonary dysfunction in patients with Fontan physiology. We analyzed data from the Pediatric Heart Network Fontan Cross-Sectional Study to assess the prevalence and pattern of abnormal spirometry in Fontan patients (6-18 yr old) and investigated the relationship between low forced vital capacity (FVC) and maximum exercise variables, including peak O2 consumption (Vo2peak), among those who demonstrated adequate effort (n = 260). Average ages at the time of exercise testing and Fontan completion were 13.2 ± 3.0 and 3.5 ± 2.2 yr old, respectively. Aerobic capacity was reduced (Vo2peak: 67.3 ± 15.6% predicted). FVC averaged 79.0 ± 14.8% predicted, with 45.8% having a FVC less then the lower limit of normal. Only 7.8% demonstrated obstructive spirometry. Patients with low FVC had lower Vo2peak (64.4 ± 15.9% vs. 69.7 ± 14.9% predicted, P < 0.01); low FVC independently predicted lower Vo2peak after adjusting for relevant covariates. Among those with Vo2peak < 80% predicted (n = 204/260), 22.5% demonstrated a pulmonary mechanical contribution to exercise limitation (breathing reserve < 20%). Those with both low FVC and ventilatory inefficiency (minute ventilation/CO2 production > 40) had markedly reduced Vo2peak (61.5 ± 15.3% vs. 72.0 ± 14.9% predicted, P < 0.01) and a higher prevalence of pulmonary mechanical limit compared with patients with normal FVC and efficient ventilation (36.1% vs. 4.8%). In conclusion, abnormal FVC is common in young patients after the Fontan procedure and is independently associated with reduced exercise capacity. A large subset has a pathologically low breathing reserve, consistent with a pulmonary mechanical contribution to exercise limitation.

Pheochromocytoma and Paraganglioma in Cyanotic Congenital Heart Disease

CONTEXT Aberrant cellular oxygen sensing is a leading theory for development of pheochromocytoma (PHEO) and paraganglioma (PGL). OBJECTIVE The objective of the study was to test the hypothesis that chronic hypoxia in patients with cyanotic congenital heart disease (CCHD) increases the risk for PHEO-PGL. DESIGN/SETTING/PARTICIPANTS We investigated the association between CCHD and PHEO-PGL with two complementary studies: study 1) an international consortium was established to identify congenital heart disease (CHD) patients with a PHEO-PGL diagnosis confirmed by pathology or biochemistry and imaging; study 2) the 2000-2009 Nationwide Inpatient Survey, a nationally representative discharge database, was used to determine population-based cross-sectional PHEO-PGL frequency in hospitalized CCHD patients compared with noncyanotic CHD and those without CHD using multivariable logistic regression adjusted for age, sex, and genetic PHEO-PGL syndromes. RESULTS In study 1, we identified 20 PHEO-PGL cases, of which 18 had CCHD. Most presented with cardiovascular or psychiatric symptoms. Median cyanosis duration for the CCHD PHEO-PGL cases was 20 years (range 1-57 y). Cases were young at diagnosis (median 31.5 y, range 15-57 y) and 7 of 18 had multiple tumors (two bilateral PHEO; six multifocal or recurrent PGL), whereas 11 had single tumors (seven PHEO; four PGL). PGLs were abdominal (13 of 17) or head/neck (4 of 17). Cases displayed a noradrenergic biochemical phenotype similar to reported hypoxia-related PHEO-PGL genetic syndromes but without clinical signs of such syndromes. In study 2, hospitalized CCHD patients had an increased likelihood of PHEO-PGL (adjusted odds ratio 6.0, 95% confidence interval 2.6-13.7, P < .0001) compared with those without CHD; patients with noncyanotic CHD had no increased risk (odds ratio 0.9, P = .48). CONCLUSIONS There is a strong link between CCHD and PHEO-PGL. Whether these rare diseases coassociate due to hypoxic stress, common genetic or developmental factors, or some combination requires further investigation.

Single ventricle anatomy is associated with increased frequency of nonalcoholic cirrhosis.

BACKGROUND Single ventricle (SV) patients with Fontan physiology have multiple risk factors for liver disease but the prevalence of liver disease remains unknown in this population. We sought to determine whether hospitalized patients with a SV diagnosis have higher rates of nonalcoholic cirrhosis than patients without congenital heart disease. METHODS We used the 1998-2009 Healthcare Cost and Utilization Projects Nationwide Inpatient Sample, a nationally representative dataset, to identify patients 18-49 years old admitted to an acute care hospital. We compared the rate of nonalcoholic cirrhosis between those with a SV diagnosis and patients without congenital heart disease. RESULTS There were 7968 hospitalizations of patients with a SV diagnosis and 13,602,149 hospitalizations of patients without congenital heart disease. SV patients were more likely to have nonalcoholic cirrhosis than those without congenital heart disease (4.3 ± 0.7 vs. 0.3 ± 0.01%, univariate OR 15.2, 95%CI 10.9-21.3), even after adjusting for viral or chronic hepatitis and other cirrhosis risk factors (multivariable OR 21.6, 95%CI 4.3-32.5). The proportion of all hospitalizations among SV patients for nonalcoholic cirrhosis increased by 173% between 1998/9 and 2008/9, from 2.3% to 6.2% (p=0.009). Among those with nonalcoholic cirrhosis, SV patients were more likely to have congestive hepatopathy (6.6 ± 3.1 vs. 0.1 ± 0.0001%, OR 63.2, 95%CI 19.2-207.8), longer hospital stays and higher hospital charges. CONCLUSIONS A single ventricle diagnosis is associated with markedly higher risk for nonalcoholic cirrhosis in a population-based sample of hospitalized patients. The proportion of patients with single ventricle anatomy admitted for nonalcoholic cirrhosis or its complications is increasing rapidly.

Liver health in adults with Fontan circulation: A multicenter cross-sectional study

Objectives: Liver disease is an important contributor to morbidity and mortality in patients after Fontan surgery. There has been no large‐scale survey of liver health in this population. We sought to explore the prevalence and predictors of liver disease in a multicenter cohort of adults with Fontan physiology. Methods: Subjects were recruited from 6 adult congenital heart centers. Demographics; clinical history; and laboratory, imaging, and histopathology data were obtained. Results: Of 241 subjects (median age 25.8 years [11.8‐59.4], median time since Fontan 20.3 years [5.4‐34.5]), more than 94% of those who underwent testing (208 of 221) had at least 1 abnormal liver‐related finding. All hepatic imaging (n = 54) and liver histology (n = 68) was abnormal. Subjects with abnormal laboratory values had higher sinusoidal fibrosis stage (2 vs 1, P = .007) and higher portal fibrosis stage (3 vs 1, P = .003) compared with those with all normal values. Low albumin correlated with lower sinusoidal fibrosis stage (1 vs 2; P = .02) and portal fibrosis stage (0 vs 3, P = .002); no other liver studies correlated with fibrosis. Regenerative nodules were seen on 33% of histology specimens. Conclusions: Regardless of modality, findings of liver disease are common among adults with Fontan circulation, even those appearing clinically well. Cirrhosis is present in up to one‐third of subjects. Correlations between hepatic fibrosis stage and clinical history or findings on noninvasive testing are few. Further research is needed to identify patients at risk for more severe liver disease and to determine the best methods for assessing liver health in this population.

Galectin‐3 Is Elevated and Associated With Adverse Outcomes in Patients With Single‐Ventricle Fontan Circulation

Background Galectin‐3 may play a role in cardiac and noncardiac fibrosis, and elevated circulating levels of this protein predict adverse outcomes in patients with heart failure who do not have congenital heart disease. We investigated galectin‐3 in adults with single‐ventricle Fontan circulation, patients who are prone to premature clinical deterioration in the context of extensive multiorgan fibrosis. Methods and Results We measured plasma galectin‐3 concentrations in 70 ambulatory adult Fontan patients and 21 age‐ and sex‐matched control participants. Galectin‐3 level was significantly higher in the Fontan group (11.85 ng/mL, interquartile range 9.9 to 15.0 ng/mL) versus the control group (9.4 ng/mL, interquartile range 8.2 to 10.8 ng/mL; P<0.001). Among Fontan patients, galectin‐3 was positively correlated with age, uric acid, and high‐sensitivity C‐reactive protein and negatively correlated with estimated glomerular filtration rate. There was no significant relationship between galectin‐3 and oxygen saturation, Fontan type, or ventricular morphology. Over a median follow‐up of 461 days, 15 events occurred among the Fontan patients: 12 nonelective hospitalizations (with 2 subsequent deaths) and 3 deaths without prior hospitalization. Patients with elevated galectin‐3 (n=19, defined as >2 SD above the control group mean value) had a higher risk of nonelective hospitalization or death (hazard ratio 6.0, 95% CI 2.1 to 16.8, P<0.001). This relationship persisted after individual adjustment for covariates including age, New York Heart Association functional class, C‐reactive protein, and estimated glomerular filtration rate and after multivariable adjustment for independently predictive covariates (hazard ratio 9.2, 95% CI 2.4 to 35.2, P=0.001). Conclusions Galectin‐3 concentrations are elevated among adults with a Fontan circulation, and elevated galectin‐3 is associated with an increased risk of nonelective cardiovascular hospitalization or death.

Predictive value of biomarkers of hepatic fibrosis in adult Fontan patients

BACKGROUND Hepatic fibrosis is highly prevalent in individuals with Fontan circulation. FibroSure (LabCorp, Burlington, NC) and hyaluronic acid (HA) have been validated for assessment of hepatic fibrosis in several forms of liver disease. We sought to determine whether these tests could identify Fontan patients with advanced hepatic fibrosis or cirrhosis. METHODS Subjects who had liver biopsy and FibroSure or HA testing within 6 months of biopsy were identified from the Alliance for Adult Research in Congenital Cardiology Fontan Liver Health study. Biopsy specimens were scored for degree of sinusoidal and portal fibrosis on a 3- and 5-point scale, respectively. Histologic findings were correlated with FibroSure and HA results. RESULTS The study included 27 subjects. Median age was 26.8 years (range, 17.4-59.8 years), and the median time since the Fontan surgery was 20.4 years (range, 12.0-31.3 years). FibroSure scores were elevated (>0.21) in 21 of 23 subjects (91%), and the scores for 3 (13%) suggested cirrhosis (>0.74). HA suggested cirrhosis (>46 ng/mL) in 3 of 17 subjects (18%). One subject died during the collection period. Eleven of 26 subjects (42%) had 4/5 or 5/5 portal fibrosis, consistent with cirrhosis; 17 (63%) had 3/3 sinusoidal fibrosis involving >66% of sinusoids. The FibroSure score and HA levels did not correlate with the degree of hepatic fibrosis and did not predict cirrhosis. CONCLUSIONS Abnormal biomarkers of hepatic fibrosis and specimen-proven hepatic fibrosis are common in adults with Fontan circulation. However, FibroSure and HA do not accurately predict the degree of histologic hepatic fibrosis. Further studies are needed to guide strategies for surveillance of liver disease in this population.