Study of Placebo or Bosentan to Treat Patients With Single Ventricle Physiology.

Study Overview
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Brief Summary
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The purpose of this study is to determine whether Bosentan is an effective and safe treatment to adolescent and adult (15 years and older) patients, born with one ventricle of the heart instead of two (single ventricle physiology) and who have undergone TCPC as a palliative surgical treatment. The aim of the TCPC operation is to use the one functioning ventricle to pump the blood flow to the body, while the blood to the lungs is received directly from the caval veins, and is thus a passive flow, without the aid of a ventricle to actively pump the blood through the pulmonary circulation. The resistance in the pulmonary circulation is therefore critical to these patients. These patients have markedly lower work capacity in bicycle test than the general public. Furthermore they have a high risk of developing complications e.g. loss of protein from the intestines. Bosentan is a medication that lowers the resistance in the pulmonary circulation. It is routinely used for patients with pulmonary hypertension. Some studies have shown that drugs that lower the pulmonary resistance can increase exercise capacity significantly in patients with single ventricle physiology. In this study 80 patients will receive either placebo or Bosentan for 14 weeks. Before and after the treatment, bicycle test along with blood samples, stool samples and quality of life interviews will be performed. Every four weeks during the study blood samples, physical exam and interviews will be performed to ensure the safety of the treatment. The investigators expect to find a significant increase in work capacity after 14 weeks in the treatment group compared with the placebo group. Moreover the investigators hope to find a decrease in intestinal protein loss and an improved quality of life.

Detailed Description
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In the statistical analysis the investigators wish to analyse interactions between the primary endpoint and predefined subgroups in order to distinguish responders from non-responders to the treatment. The predefined subgroups are: NT-proBNP > 100 (yes/no) Ventricular anatomy (RV/LV) CT-proEndothelin-1. In the latter, the investigators do not wish to predefine a specific value, due to limited experience with this analysis. We wish to use the data from the study to find a cut-off value, that is able to predict positive response to treatment.

Official Title
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Treatment With Endothelin Antagonist to Tcpc Patients; a Multicenter, Randomized, Prospective Study Measuring Maximal O2 Uptake in Ergometer Bicycle Test

Conditions
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Hypoplastic Left Heart Syndrome, Tricuspid Atresia, Other Specified Congenital Anomalies of Heart

Intervention / Treatment
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* Drug: Bosentan
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: TCPC operated Age > 15 years old Clinical stability > 3 months, evaluated by investigator from clinical record For women: Negative s-hCG and use of contraception Exclusion Criteria: Severe heart failure (NYHA-class IV) Oxygen saturation < 85 % at rest Pre-existing liver condition (transaminases 2x > reference) Renal failure (creatinin > 150 mmol/l) Obstruction of TCPC circulation History of work induced severe arrhythmia Systolic blood pressure below 80% of reference (BT < 88 mmHg) Use of any of following drugs: Fluconazol, Ketoconazole, CiclosporinA, Lopinavir, Ritonavir, Rifampicin, Carbamazepin and Phenytoin Significant extra-cardiac condition e.g. neurological impairment

Ages Eligible for Study
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Minimum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Bosentan<br> | Drug: Bosentan<br>* tablets Bosentan 62,5 mg x 2 daily for two weeks, then 125 mg x 2 daily for 12 weeks<br>* Other names: Bosentan: Tracleer;|
| Placebo Comparator: Placebo<br> | Drug: Placebo<br>* Placebo tablets 2 x daily for 2 weeks, then change to different placebo tablets to match Bosentan group, 2 x daily for 12 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in VO2max at 14 weeks | Maximal O2 uptake in ml/min/kg in ergometer bicycle test | Baseline and 14 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in blood samples at 14 weeks | blood samples measured: plasma CT pro endothelin-1, IgG, IgA, NT pro BNP, albumin, free protein | Baseline and 14 weeks | 
| Change from baseline in SF36 questionnaire score at 14 weeks | SF36 quality of life interview | Baseline and 14 weeks | 
| Change from baseline in feces alfa 1 antitrypsin at 14 weeks | Fecal alfa 1 antitrypsin in mg/g | Baseline and 14 weeks | 
| Number of participants with adverse events | general interview on adverse effects, and questions with special focus on typical adverse effects in Bosentan | 2, 6, 10 and 14 weeks after start of treatment | 
| Change from baseline in vital signs | Systemic bloodpressure in mmHg, Pulse in min-1, Oxygen saturation in percent | Baseline, 2, 6, 10 and 14 weeks | 
| Change from baseline in control blood samples | Liver and renal biomarkers, Hb, PCV, trc and hCG for women | Baseline, 2, 6, 10 and 14 weeks | 
| Change from baseline in cardiac output/pulmonary blood flow | CO measured by Stringer Wassermann method during ergometer bicycle test | Baseline and 14 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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single ventricle physiology, Fontan procedure