* Medication which is not compatible with bosentan or interferes with its metabolism (inhibitors or inducers of CYP2C9, CYP3A4) or medication which may interfere with bosentan treatment according to the investigator
You may not be if
Incapable of giving informed consent
Pregnancy or lactation (a pregnancy test is offered to every female patient within fertile age)
Women of child-bearing age who are sexually active without practising reliable methods of contraception. The use of oral contraceptives only, is not considered reliable. Reliable methods include concomitant use of oral contraceptives and condoms ("Double Dutch"), and those methods with a less than 1% chance of pregnancy during typical use20, including intrauterine contraceptives (Copper T, Mirena), Implanon, and sterilization.
Substance abuse (alcohol, medicines, drugs)
Subjects who are not able to perform cardiopulmonary exercise testing
Any cardiac operation \< 6 months before inclusion
