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5 Tests That Measure PAH Disease Progression

Updated on December 28, 2022
Medically reviewed by
Allen J. Blaivas, D.O.
Medically reviewed by
Steven C. Pugliese, M.D.
Article written by
Bethany J. Sanstrum, Ph.D.
Article written by
Joan Grossman

Pulmonary arterial hypertension (PAH) is a chronic disease that gets worse over time. For people with PAH, doctors will perform a variety of tests to measure how advanced the disease is and the extent of damage to their heart and lungs. These tests are a regular part of PAH follow-up appointments and are recommended every three to six months.

Tests that measure PAH disease progression are a part of risk assessment — an essential tool in the management of PAH. They help PAH specialists predict your mortality risk (risk of dying from PAH) and detect and treat the clinical worsening of the condition. Doctors also use test results to set a treatment plan and evaluate your response to different PAH medications.

From a risk assessment, your doctor will classify your PAH as low, intermediate, or high risk:

  • 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.

Testing results also let you know which World Health Organization (WHO) functional class your PAH is considered to be. This classification system includes four classes — ranging from having no symptoms with normal physical activity (class 1) to having symptoms at rest or during minimal physical activity (class 4). Functional class has been shown to correlate with PAH survival rates, with the lower classes predicting longer survival.

If you are living with PAH, your doctor will regularly conduct one or more of the following tests to help assess your PAH risk.

1. Exercise Capacity Tests

Testing a person’s ability to exercise is a regular part of assessing the functional capacity of their heart and lungs. Two well-accepted, noninvasive types of exercise testing are routinely used to measure exercise capacity:

  • The six-minute walk test (6MWT) — This simple test measures the distance walked during a six-minute time period.
  • The cardiopulmonary exercise test (CPET) — During this type of test, a person walks on a treadmill or rides a stationary bicycle for a set amount of time or until symptoms arise.

During these physical activities, your systolic blood pressure, electrical signals in the heart, and oxygen saturation level can be measured with easy, noninvasive techniques.

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

2. Cardiac Imaging Exams

Echocardiography and magnetic resonance imaging (MRI) are common tools used to visualize the structure and function of the heart. These imaging tools can detect and monitor disease progression and signs of heart failure. Increased atrial pressure in the heart can cause fluid to build up around the organ, which is called pericardial effusion. Cardiac imaging can detect pericardial effusion so that any fluid accumulation can be treated.

Cardiac output is the volume of blood the heart can pump in one minute, and it can be estimated from an echocardiogram. Insufficient or reduced cardiac output in PAH is associated with heart failure.

3. Right Heart Catheterization

Right heart catheterization (RHC) is another risk assessment tool that can measure disease progression and ventricular dysfunction in PAH. During an RHC, a small catheter is inserted into a vein in the neck, arm, or groin. The catheter is slowly guided through the right side of the heart, the right ventricle, and the pulmonary arteries to measure pulmonary artery pressure and hemodynamics (blood flow) in the heart and lungs.

The procedure typically takes one hour. Doctors may perform RHC during yearly follow-up exams.

4. Blood Tests To Measure 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.

5. High-Resolution Lung Scans

Two types of lung scans can be used to detect changes in lung function. A ventilation/perfusion (V/Q) lung scan measures blood and airflow in the lungs. It may be used in the diagnosis phase to rule out chronic thromboembolic pulmonary hypertension. This imaging tool can also reveal small defects in lung tissue in people with PAH. A chest X-ray may be performed before or after a ventilation and perfusion scan.

High-resolution computed tomography (CT) scans may be used to help determine the type of PAH you have. A CT scan is similar to a chest X-ray, but it provides more detailed images of the lungs.

Other Considerations in Diagnosing PAH

Other factors like the type of PAH and demographic characteristics can influence PAH outlook. Although doctors don’t test these factors regularly, they’ll record them when they make an initial PAH diagnosis and try to understand your risk level. For example, when you’re first diagnosed with PAH, doctors may try to determine the type of PAH, whether it’s heritable PAH, idiopathic pulmonary arterial hypertension (IPAH, PAH of an unknown cause), or PAH associated with other medical conditions or drug use.

Demographics

During prognostic (predictive) testing, a health care provider will note risk factors like your age, sex, race, and ethnicity in your medical record. In general, PAH is more common in females between the ages of 30 to 60, according to NORD. Research studies have also found differences in the type of PAH by racial and ethnic groups.

Genetics

When you’re first diagnosed with PAH, your doctor may conduct genetic testing to check if you have a genetic mutation that’s causing your PAH. Genetic testing usually involves a blood or saliva sample to examine your DNA.

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 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

PAH caused by another health condition is called associated PAH. They can include

  • Congenital heart disease
  • Chronic liver disease
  • Human immunodeficiency virus (HIV)
  • Connective tissue diseases — including scleroderma and lupus

Scleroderma or systemic sclerosis-associated PAH (SSc-PAH) are also predictors of poorer PAH outcome.

When trying to determine the cause of your PAH, doctors may ask whether you have any health conditions that are associated with PAH. If you are unsure but have symptoms of other conditions, your doctor may run medical tests to determine whether you have any diseases or infections associated with PAH. Having associated conditions will affect decisions around treatment and disease management.

Talk With Others Who Understand

On myPHteam, the social network for people with pulmonary hypertension and their loved ones, more than 48,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.

Have you had risk assessment tests to measure your disease progression? What tests did you have at your last risk assessment? 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.
Steven C. Pugliese, M.D. is affiliated with the Hospital of the University of Pennsylvania in Philadelphia, serving as the director of the pulmonary embolism response team, co-director of the comprehensive pulmonary embolism program, and an assistant professor of clinical 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.
Joan Grossman is a freelance writer, filmmaker, and consultant based in Brooklyn, NY. Learn more about her here.

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