BICYCLE trial.

Rationale:

Pulmonary arterial hypertension (PAH) can be a rapidly progressive disorder and is associated with a high mortality rate, despite medical intervention. With the availability of effective therapy, early disease detection is an important strategic objective to improve treatment outcomes. Resting echocardiography is currently the recommended screening modality for high-risk population groups. However, it is clear that abnormalities in resting hemodynamics (and symptoms) are late sequelae of the pathobiological processes that begin in the distal pulmonary arteries. Exercise stress may unmask early pulmonary vascular dysfunction, however the definition, clinical significance, and natural history of ‘exercise PAH’ remain undefined. However, based on clinical experience and literature the prevalence is estimated at ~ 20%.Treatment with endothelin receptor blockers has shown a beneficial influence on the clinical performance in patients with exercise induced PAH due to systemic sclerosis and primary pulmonary hypertension. Whether endothelin receptor blockers decrease pulmonary pressures and improve clinical outcome in patients with exercise induced pulmonary arterial hypertension due to congenital heart disease is unknown.



Objective:

Identify congenital heart disease patients with exercise-induced pulmonary arterial hypertension. Analyze changes in pulmonary arterial pressures at peak exercise in patients with exercise induced pulmonary arterial hypertension before and after treatment with bosentan, compared to placebo.



Study design:

Randomized placebo controlled trial with a study period of 26 weeks.



Study population:

Adult congenital heart disease patients with exercise induced pulmonary arterial hypertension (n=40) from the Academic Medical Centre, Amsterdam.



Intervention:

After randomization one group (n=20) receives a 125 mg tablet of Bosentan twice daily for 6 months. The other group (n=20) receives placebo for 6 months.



Main study parameters/endpoints:

To determine wether bosentan (endothelin receptor inhibitor) decreases mean pulmonary arterial pressure at peak exercise in adult congenital heart disease patients with exercise induced pulmonary arterial hypertension. Furthermore the change in cardiopulmonary exercise capacity and right ventricular function will be investigated.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

All investigations, blood analysis excepted, are non-invasive and free of risk. The burden for the patients mainly consists of the time that is consumed by the investigations, namely: history taking + physical examination (15 min); Quality-of-Life- score (15 min); laboratory tests (electrolytes, creatinine, urea, albumin and neurohormones, troponin T); 12 lead electrocardiogram (10 min); exercise echocardiography (30 min); cardiovascular exercise testing (30 min).

The trial medication has a potential risk of liver damage, which will be monitored regularly by laboratory testing of liver transaminases.

In adult congenital heart disease patients with exercise-induced pulmonary arterial hypertension, treatment with bosentan lowers the mean pulmonary arterial pressure, which may result in improvement of the cardiopulmonary circulation, cardiopulmonary exercise capacity and quality of life.

Patients are requested to visit the outpatient clinic at baseline, at 3 and 6 months follow-up.

When all baseline procedures have been performed and the investigator has observed that all inclusion and none of the exclusion criteria apply, patients are randomised by the investigator using a computerized randomisation tool. Randomisation is performed by the investigator after informed consent has been contained. Eligible patients are randomly assigned to one of the following treatment arms:

1. 6 months of treatment with bosentan 125 mg twice a day;

2. 6 months of treatment with placebo twice a day.

The starting dosage of bosentan is 62,5 mg twice a day. Trial medication is doubled after 4 weeks to reach study dose, after checking liver parameters.