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What is CTEPH?

Chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) (WHO Group 4) is a type of high blood pressure in the arteries (blood vessels) of your lungs caused by blood clots that narrow or block blood flow.

Adempas is approved to treat adults with CTEPH (WHO Group 4) that was treated with surgery but who continue to have high pulmonary blood pressure (persistent) or it comes back after surgery (recurrent), or that cannot be treated with surgery (inoperable). The Adempas clinical studies included mostly patients with WHO functional class II-III symptoms. It is not known if Adempas is safe and effective in children.

WHO=World Health Organization


In most cases of CTEPH, blood clots in the blood vessels of your legs break off and travel to the lungs. Sometimes, blood clots or tissue growth may form in the blood vessels of the lungs. Over time, extra tissue forms over these clots and creates a blockage that can’t be removed with blood thinners alone.
Normal blood vessel

What does CTEPH feel like?


During the beginning stages you might not feel like anything is wrong. Not everybody experiences all of the symptoms in the illustration below. As in many diseases, you may also experience a depressed mood, low self-esteem, frustration, anxiety, or worry as a part of your condition.


Shortness of breath with exercise

Shortness of breath with exercise

Fainting or feeling tired or dizzy

Fainting or feeling tired or dizzy

Swelling in the ankles, arms, or stomach area

Swelling in the ankles, arms, or stomach area

Chest pain

Chest pain

Diagnosis and treatment of CTEPH

How is CTEPH diagnosed?

Some of the tests used to diagnose CTEPH are echocardiography, right-heart catheterization, ventilation/perfusion (V/Q) scan (measures the amount of air and blood flowing through the lungs), and computed tomography (CT) angiography (computerized imaging of the blood vessels in the heart and lungs).

Can CTEPH be treated?

CTEPH may be treated with an operation called pulmonary endarterectomy (shortened as PEA). During this very specialized operation, clots and other blockages of the pulmonary arteries are removed. CTEPH is potentially cured after the surgical procedure.

However, if you are not a candidate for PEA surgery (inoperable), or your high pulmonary blood pressure continued (persistent) or came back (recurrent) after PEA surgery, your doctor can treat your CTEPH (WHO Group 4) with Adempas. Clinical studies of Adempas included mostly patients with WHO functional class II–III symptoms.

Can CTEPH become more serious?

As CTEPH progresses, symptoms get worse. The WHO developed a scale for doctors to rate the severity of CTEPH symptoms. Your doctor will determine which WHO functional class you belong to. A lower class number (I or II) means that you have less severe symptoms. Identifying your WHO functional class is one of the ways your doctor determines your best course of treatment.

WHO functional classes of CTEPH

Class I

Patients have no limitation of usual physical activity.

Class II

Patients have mild limitation of usual physical activity.
Patients are comfortable at rest.

Class III

Patients have severe limitation of usual physical activity.
Patients are comfortable at rest.

Class IV

Patients are unable to carry out any physical activity without symptoms.

Questions about CTEPH

Questions about CTEPH?

Learn more in the FAQ section here.


Adempas can cause serious birth defects if taken during pregnancy.

  • Females must not be pregnant when they start taking Adempas (riociguat) tablets or become pregnant during treatment with Adempas.
  • Females who are able to get pregnant must have a negative pregnancy test before beginning treatment with Adempas, each month during treatment, and 1 month after you stop treatment with Adempas. Talk to your doctor about your menstrual cycle. Your doctor will decide when to do the test.
    • Females who are able to get pregnant are females who:
      • Have entered puberty, even if they have not started their period, have a uterus, and have not gone through menopause (have not had a period for at least 12 months for natural reasons, or have had their ovaries removed).
    • Females who are not able to get pregnant are females who:
      • Have not yet entered puberty, do not have a uterus, or have gone through menopause.

Females who are able to get pregnant must use two acceptable forms of birth control, during Adempas treatment and for one month after stopping Adempas.

  • If you have had a tubal sterilization, have a progesterone implant, or have an IUD (intrauterine device), these methods can be used alone and no other form of birth control is needed.
  • Talk with your doctor or gynecologist (a doctor who specializes in female reproduction) to find out how to prevent pregnancy during treatment with Adempas.
    • Do not have unprotected sex. Talk to your doctor or pharmacist right away if you have unprotected sex or if you think your birth control has failed. Your doctor may tell you to use emergency birth control.
    • Tell your doctor right away if you miss a menstrual period or think you may be pregnant for any reason.

If you are the parent or caregiver of a female child who started taking Adempas before reaching puberty, you should check your child regularly to see if she is developing signs of puberty. Tell your doctor right away if you notice that she is developing breast buds or any pubic hair. Your doctor should decide if your child has reached puberty. Your child may reach puberty before having her first menstrual period.

Females can only receive Adempas through a restricted program called the Adempas Risk Evaluation and Mitigation Strategies (REMS) program. If you are a female who can become pregnant, you must talk to your doctor, understand the benefits and risks of Adempas, and agree to all of the instructions in the Adempas REMS program. Males can receive Adempas without taking part in the Adempas REMS program.

Do not take Adempas if:

  • you are pregnant, plan to become pregnant, or become pregnant during treatment with Adempas. Adempas can cause serious birth defects.
  • you take:
    • a nitrate medicine to treat high blood pressure or heart disease, such as nitroglycerin, or a medicine called a nitric oxide donor, such as amyl nitrite
    • certain other medicines that contain sildenafil (Revatio or Viagra), tadalafil (Adcirca or Cialis), vardenafil (Levitra or Staxyn), dipyridamole, or theophylline. Revatio and Adcirca are also used to treat PAH
  • you have pulmonary hypertension associated with idiopathic interstitial pneumonias (PH-IIP).

Ask your doctor or pharmacist if you are not sure if you take any of the medicines listed above.

Before you take Adempas, tell your doctor if you:

  • smoke; have recently had serious bleeding from your lungs, or if you have had a medical procedure called bronchial arterial embolization to stop you from coughing up blood; have problems with your heart or blood circulation; have low blood pressure; have liver problems; have kidney problems or are on dialysis; have narrowing of the pulmonary veins, a condition called pulmonary veno-occlusive disease or PVOD; have any other medical conditions.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
Adempas and other medicines may affect each other causing side effects. Do not start any new medicine until you check with your doctor.

What should I avoid while taking Adempas?

  • Do not get pregnant while taking Adempas. If you miss a menstrual period, or think you might be pregnant, call your doctor right away.
  • It is not known if Adempas passes into your breast milk. You should not breastfeed if you take Adempas. Talk to your doctor about the best way to feed your baby if you take Adempas.
  • Adempas may make you feel dizzy. Do not drive, operate machinery, or do other activities that require mental alertness or coordination until you know how Adempas affects you. Talk with your doctor if you are concerned about when it is safe for you to do these activities.
  • Smoking. Adempas may not work as well if you smoke during treatment. Tell your doctor if you stop smoking or start smoking during treatment with Adempas, because your dose of Adempas may need to be changed.

Adempas can cause serious side effects including:

  • Serious birth defects.
  • Reduced blood pressure. This may cause symptoms of low blood pressure, such as lightheadedness, chest pain, and dizziness especially in people who are dehydrated, have a severe blockage of blood flow out of the heart, or have certain other medical problems. Your doctor will check you for any of these problems.
  • Increased risk of bleeding, including bleeding from the respiratory tract. Tell your doctor right away if you cough up blood during treatment with Adempas.
  • Worsening of symptoms in people with Pulmonary Veno-Occlusive Disease (PVOD). If you have PVOD, treatment with Adempas may cause a build-up of fluid in your lungs (pulmonary edema) which may result in shortness of breath. Your doctor may tell you to stop taking Adempas and switch you to a different medicine.

The most common side effects of Adempas are:

  • Headache; dizziness; indigestion; swelling of your hands, legs, feet, and ankles (peripheral edema); nausea; diarrhea; and vomiting

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of Adempas.