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How Is Risk Assessed for Pulmonary Arterial Hypertension?

Posted on March 01, 2021
Medically reviewed by
Allen J. Blaivas, D.O.
Article written by
Bethany J. Sanstrum, Ph.D.

  • Risk assessment for pulmonary arterial hypertension (PAH) is based on your health factors, as well as the results of several tests.
  • PAH symptoms, exercise capacity, cardiac imaging, right heart catheterization, and brain natriuretic peptide (BNP) levels are used to predict the risk of death within one year.
  • Risk assessment is one of the most important tools used to manage PAH.

For people with pulmonary arterial hypertension (PAH), doctors use guidelines to assess the risk of death within one year. The results of this risk assessment can help your doctor determine your PAH prognosis and monitor your response to treatment. Risk assessment is a regular part of PAH follow-up appointments every three to six months.

Risk assessment for PAH is classified as low, intermediate, or high:

  • Low-risk PAH — The risk of death within one year is lower than 5 percent.
  • Intermediate-risk PAH — The risk of death within one year is between 5 percent and 10 percent.
  • High-risk PAH — The risk of death within one year is greater than 10 percent.

There are several risk factors and lab tests associated with a higher or lower risk of mortality. Read more about predictive models used to assess risk in PAH.

Risk Factors and PAH Subtype

Like many diseases, PAH prognosis is influenced by demographic information. Factors such as age and sex are incorporated into risk assessment. For instance, being a man and being older are both associated with a poorer outcome.

Other factors include the cause and type of PAH. PAH may be caused by a genetic mutation (known as heritable or familial PAH) or another health condition, such as systemic sclerosis. When the cause of PAH is unknown, it is called idiopathic PAH (iPAH).

Genetics and Risk Assessment

Mutation of a gene called bone morphogenetic protein receptor 2 (BMPR2) is the most common genetic cause of heritable PAH. Mutation in the BMPR2 gene is associated with a worse PAH risk assessment outcome, partially because people with this mutation typically have a higher pulmonary arterial pressure and pulmonary vascular resistance at the time of diagnosis.

Associated Conditions and Risk Assessment

PAH caused by another health condition is called associated PAH. Congenital heart disease, chronic liver disease, and connective tissue conditions — including scleroderma and lupus — are sometimes associated with PAH. Scleroderma or systemic sclerosis-associated PAH (SSc-PAH) also predicts a poorer outcome. Clinical studies have shown that SSc-PAH tends to improve less with treatment compared to iPAH.

PAH Complications and Increased Risk

As time passes, PAH can cause other conditions to develop that complicate PAH treatment and affect risk assessment. Accordingly, these conditions are called complications. Right heart failure is a common complication of PAH that can occur when buildup of pulmonary arterial pressure makes the right ventricle of the heart work harder to move blood to the lungs. Blood from the body returns to the right side of the heart. When right heart failure occurs, fluid can build up in the venous system and overwhelm the heart’s ability to pump enough blood.

During a physical examination, several signs may indicate right heart failure and cardiovascular damage. These include:

  • Swelling in the legs or abdomen
  • Changes in the sound of the heart
  • Fainting

Your doctor may ask about the frequency of fainting episodes and what activities were being performed beforehand. If right heart failure is identified, it will be included in the risk assessment.

PAH Functional Class and Capacity

Symptoms of PAH and right heart failure are more likely to happen when the heart has to work harder, such as during physical activity. The World Health Organization functional class (WHO-FC) system was developed to determine how PAH symptoms affect day-to-day activities. WHO-FC is a somewhat subjective measure based on the amount of physical activity a person can perform without experiencing symptoms such as fainting, fatigue, and chest pain.

There are four classes ranging from no symptoms with normal physical activity (class 1) to symptoms at rest or during minimal physical activity (class 4). Despite the subjectivity of the WHO-FC system, class has been shown to correlate with PAH survival rates, with the lower classes predicting longer survival.

Tests Used in PAH Risk Assessment

Your doctor may order one or more tests to help assess risk in PAH during regular follow-up appointments.

Exercise Capacity

A regular part of PAH assessment to test the functional capacity of the heart and lungs is the ability to perform exercise. Two well-accepted, noninvasive tests are routinely used to measure exercise capacity:

  • The six-minute walk test (6MWT)
  • The cardiopulmonary exercise test (CPET)

The 6MWT is a simple test that measures the distance walked during a six-minute time period. CPET is performed on a treadmill or stationary bicycle for a set amount of time or until symptoms arise. Systolic blood pressure, electrocardiogram, and oxygen saturation level during physical activity can be measured with easy, noninvasive techniques.

In general, higher exercise capacity indicates a lower mortality risk due to PAH.

Cardiac Imaging

Echocardiography and MRI are common tools used to visualize the structure and function of the heart. Imaging can detect and monitor the disease progression of heart failure. Additionally, increased pressure in the heart can cause fluid to build up around the heart, which is called pericardial effusion. Cardiac imaging can detect pericardial effusion so the fluid accumulation can be treated.

Cardiac output, the volume of blood the heart can pump in one minute, is an important cardiac index that can be measured from an echocardiogram. Reduced cardiac output is associated with heart failure and is a sign of PAH.

Right Heart Catheterization

Right heart catheterization (RHC) is another measure of clinical worsening in PAH. During RHC, a small catheter is inserted into a vein in the neck, arm, or groin. The catheter is slowly guided to the right side of the heart and pulmonary arteries to measure the pressure in the heart and lungs. The procedure typically takes one hour. Doctors may perform RHC during yearly follow-up exams.

RHC can give the doctor a direct measurement of blood pressure within the heart and lung at baseline — not during exercise. This can be helpful to monitor PAH progression.

Brain Natriuretic Peptide and N-Terminal-Prohormone BNP

Brain natriuretic peptide (BNP) and N-terminal-prohormone (NT-proBNP) are proteins released by the ventricles of the heart in response to high pressure. These proteins act to reduce the pressure load on the heart. Levels of BNP and NT-proBNP are measured from a blood sample. High levels can indicate heart failure. Levels also rise as heart failure worsens and decrease as heart failure stabilizes.

Clinical trials indicate that low levels of BNP and NT-proBNP are associated with better long-term PAH prognosis.

Why Are Risk Assessments Important?

Because PAH can change rapidly, regular risk assessments and disease monitoring are vital. Even if you cannot make it to a clinic in person, there are many tools and approaches your doctor can use to perform risk assessments during telehealth visits.

Disease management can make a huge difference for people living with PAH. During the COVID-19 pandemic, it has become more important than ever to keep regularly scheduled visits and open communication with your health care provider.

Read more about using telehealth for PAH risk assessment.

Talk With Others Who Understand

On myPHteam, the social network for people with pulmonary hypertension and their loved ones, more than 46,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.

Are you living with pulmonary arterial hypertension? Share your experience in the comments below, or start a conversation by posting on your Activities page.

All updates must be accompanied by text or a picture.
Allen J. Blaivas, D.O. is certified by the American Board of Internal Medicine in Critical Care Medicine, Pulmonary Disease, and Sleep Medicine. Review provided by VeriMed Healthcare Network. Learn more about him here.
Bethany J. Sanstrum, Ph.D. holds a doctorate in cell and molecular biology with a specialization in neuroscience from the University of Hawaii at Manoa. Learn more about her here.

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