You’ve recently gone to your doctor after experiencing shortness of breath when you exercise. They diagnose you with borderline pulmonary hypertension (PH) — a condition that causes elevated pressure in the arteries leading to your lungs. You’re left with many questions, like what is borderline PH and how is it different from PH? What does this mean for your health?

“How many of you were diagnosed with mild or borderline PH? What were your thoughts at the time? How can I prevent progression?” one myPHteam member asked.

In this article, we’ll discuss six things to know about borderline PH, including what causes it, how it’s diagnosed, and treatment options. It’s important to work closely with your doctor and team of specialists to treat your elevated blood pressure and help prevent it from worsening.

1. Borderline PH Is Now Considered PH

PH is diagnosed by measuring your mean pulmonary artery pressure (mPAP) — that is, the blood pressure of your pulmonary arteries, which are responsible for transporting oxygen-poor blood from your heart toward your lungs. There, the blood is replenished with oxygen and sent back out to the rest of your body.

When you have PH, the blood pressure in your pulmonary arteries is too high. This causes the blood vessels to narrow, making it harder to pump blood through them. Your heart has to work overtime to push the same amount of blood through a smaller space. Over time, this weakens the right side of the heart and can lead to serious problems.

An mPAP reading is measured using millimeters of mercury (mm Hg). A healthy mPAP is between 11 and 20 mm Hg.

In April 2023, the American Heart Association made some changes to the definitions of pulmonary hypertension in the U.S. According to the old definition, an mPAP between 21 and 24 mm Hg was the criteria for a diagnosis of borderline PH, and it was considered a mild form of the condition. Those with an mPAP of 25 mm Hg or higher were diagnosed with PH.

However, according to the updated definition of PH, anyone with an mPAP greater than 20 mm Hg simply has PH. Their reasoning for the change was to identify people early in the course of the disease.

Because of these changes, if you were diagnosed with borderline PH, it’s a good time to check back in with your doctor or cardiologist. They can retest your mPAP and advise you on the next steps for treatment and preventing disease progression.

2. Several Health Conditions Can Lead to Borderline PH

The same health conditions that cause PH can also lead to what was considered borderline PH. The World Health Organization (WHO) classifies PH into five different groups based on what’s causing it.

Group 1 PH is known as pulmonary arterial hypertension (PAH). With PAH, your pulmonary arteries become thick, stiff, and narrow, making it hard for blood to flow through. PAH may develop from an unknown cause or can be associated with connective tissue diseases like scleroderma.

Group 2 PH is caused by problems with the left side of your heart (left heart disease). The left side of the heart is responsible for pumping oxygen-rich blood out the rest of your body. When it can’t pump properly, blood begins pooling in your heart. As a result, the blood pressure level in your pulmonary arteries increases.

Long-term or chronic lung diseases are responsible for group 3 PH. Obstructive lung diseases block the airways and make it hard to breathe. Hypoxia (low oxygen levels) leads to narrowing in the pulmonary arteries and raises blood pressure. Examples of diseases related to group 3 PH include:

• Interstitial lung disease
• Pulmonary fibrosis (lung scarring)
• Chronic obstructive pulmonary disease (COPD)
• Sleep apnea

Group 4 PH is also known as chronic thromboembolic pulmonary hypertension (CTEPH). This is because it’s caused by blood clots that create scar tissue in the lungs. Blood can’t easily flow through these scarred arteries, which raises blood pressure.

Lastly, group 5 PH refers to PH from an unknown cause.

3. Research Is Mixed on Who’s Most Affected by Borderline PH

There seem to be some mixed results about who is (or was) more likely to be diagnosed with borderline PH. Researchers have compared people with healthy mPAP levels and those with what was called borderline PH in large studies to find out who’s at risk.

One group of researchers found that there were no measurable differences in age, body mass index (BMI), and underlying health conditions in people with borderline PH and those without. On the other hand, another study found that people with borderline PH were older and tended to have worse lung function or other heart problems.

In order for doctors to better understand who may develop PH, more studies are needed.

4. Borderline PH Is Diagnosed Using Right-Heart Catheterization

If you were diagnosed with borderline PH, you may experience some symptoms like shortness of breath with exercise, fatigue, dizziness, and chest pain. Be sure to let your doctor know about these symptoms — they can refer you to a cardiologist (heart specialist) or pulmonologist (lung specialist) to run some additional tests.

The best way to accurately diagnose PH is by measuring blood pressure in your pulmonary arteries. Your doctor will use a technique known as right-heart catheterization or cath. During this test, they’ll insert a long, thin tube known as a catheter into the right side of your heart.

The catheter is then guided to your pulmonary artery to take an mPAP reading and look at how blood flows through your heart. Your doctor may also measure the amount of blood your heart pumps each minute to check your heart health. If your mPAP is between 21 and 24 mm Hg, you’ll be diagnosed with borderline PH (or simply PH, depending on which criteria your doctor is using).

Other tests your doctor may run to determine what’s causing your PH symptoms include echocardiography to look at your heart, blood tests, and a chest X-ray. “I had an echocardiogram about four years ago to determine the cause of my dizzy spells. It showed borderline PH,” shared one myPHteam member.

5. More Research Is Needed To Find the Best Borderline PH Treatment

Currently, there aren’t many treatment recommendations for people diagnosed with borderline PH. Some myPHteam members noted they hadn’t received any treatment. “Here where I live, if it’s mild or borderline, they just send you on your way and see you next year,” wrote a member.

Doctors and researchers are working on finding the best treatments for controlling early PH to help prevent it from progressing. One study from 2019 looked at treating people diagnosed with borderline PH and systemic sclerosis with the PH drug ambrisentan (Letairis) or a placebo (sugar pill). They found that both groups had similar mPAP levels, meaning the treatment didn’t help lower blood pressure in the lungs. However, they did note that ambrisentan helped improve blood flow from the pulmonary arteries to the heart. Research for treating borderline PH is limited, and more studies are needed to find the best therapies.

For people with mPAP between 21 to 24 mm Hg, the American Heart Association recommends the following:

• Identifying the cause of pulmonary hypertension
• Reducing risk factors that increase pulmonary arterial pressure
• Closely following symptom progression

Your doctor may choose to use medications prescribed for PH to help you manage your symptoms. Many medications work by relaxing and opening your blood vessels. This lowers blood pressure in the lungs to relieve symptoms.

6. Borderline PH Can Progress and Lead to Disease Complications

If you were diagnosed with borderline PH, your doctor will continue monitoring your condition. If left alone, your PH may eventually progress and your symptoms may worsen. One study found that people with scleroderma and borderline PH were at a higher risk of developing PAH in the future. Others have noted that people with borderline PH and lung diseases may have a worse disease prognosis (outlook) or outcome.

Ask your doctor about how they plan to treat your PH and what lifestyle changes you can make to lower your risk of PH.

Talk With Others Who Understand

On myPHteam, the social network for people with pulmonary hypertension and their loved ones, more than 51,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.

Have you been diagnosed with borderline or mild pulmonary hypertension? What treatments are you taking to manage it? Share your experience in the comments below, or start a conversation on your Activities page.