Understanding Treatment-Resistant Hypertension

Every time your heart beats, it pumps blood through your blood vessels to supply your body with oxygen. Blood pressure is the measurement of the force with which blood pushes against the walls of these blood vessels.¹

High blood pressure is a health condition that is also known as hypertension. Hypertension impacts nearly half of all U.S. adults, or about 119 million people. Hypertension is often called a "silent killer" because it can cause serious damage without showing any symptoms.²

For most people, changing their diet or taking medicine can lower their blood pressure to a safe level. However, some people have treatment-resistant hypertension. Understanding this medical challenge is vital for protecting long-term heart health.¹

Who does hypertension affect?

Anyone can develop high blood pressure, but certain groups of people are at a much higher risk.

Studies show that older adults face the highest risk because blood vessels naturally stiffen over time. Middle-aged men are more likely than middle-aged women to develop hypertension. However, among older adults, women are more likely than men to have high blood pressure.⁴

Compared to other ethnic groups, Black adults tend to have higher-than-average blood pressure readings and get high blood pressure earlier in life. During pregnancy, Black women are more likely than white women to develop preeclampsia, a pregnancy-related disorder that causes sudden hypertension, kidney problems, and liver problems.⁴

Other people at higher risk for hypertension are those who have certain health conditions, including:⁴

• Obesity
• Chronic kidney disease
• Metabolic syndrome
• Thyroid problems
• Sleep apnea

How is hypertension diagnosed?

Doctors measure blood pressure using 2 numbers. The top number, called systolic pressure, measures the force when the heart squeezes. The bottom number, called diastolic pressure, measures the force when the heart rests between beats.³

When a person's blood pressure reading is consistently 130/80 mmHg or higher, they are diagnosed with hypertension. This constant extra pressure strains the blood vessels and forces the heart to work much harder than it should.³

What is treatment-resistant hypertension?

When a person's high blood pressure does not respond to standard treatments, it is known as treatment-resistant. About 25 percent of people with treatment-resistant hypertension have primary or essential hypertension, a term used when there is no known medical cause for high blood pressure. The other 75 percent are said to have secondary hypertension, when high blood pressure is caused by another medical condition.¹

What causes treatment-resistant hypertension?

A few common conditions that may cause secondary hypertension include:¹

• Sleep apnea — When a person periodically stops breathing for seconds at a time during sleep
• Renal (kidney) artery stenosis — A narrowing of the artery that sends blood to the kidneys
• Kidney failure
• Primary aldosteronism — An adrenal gland disorder that raises blood pressure
• Hyperthyroidism or hypothyroidism — An overactive or underactive thyroid

Lifestyle factors can also contribute to secondary hypertension. A few of these include:⁴

• A diet that is high in salt and low in potassium
• Drinking too much alcohol or caffeine
• Low physical activity
• Not enough good quality sleep
• Exposure to chronic stress
• Substance misuse

How is treatment-resistant hypertension diagnosed?

To diagnose treatment-resistant hypertension, doctors must first rule out "pseudo-resistance," which is false resistance. Sometimes, blood pressure appears high simply because a patient feels anxious at the clinic — a phenomenon known as "white coat hypertension" or "white coat effect."¹

Other causes of pseudo-resistance include:¹

• Taking the wrong medicine or the wrong dose
• Medicines and supplements that may increase blood pressure
• Lifestyle factors
• Stiffening of the arteries

Once pseudo-resistance is ruled out, doctors often use a diagnostic method called ambulatory blood pressure monitoring (ABPM). For this test, the patient wears a portable blood pressure cuff that automatically inflates and measures their pressure every 20 to 30 minutes at home over a full 24-hour period while they go about their day.¹

Other tests that a doctor may use to diagnose treatment-resistant hypertension include:¹

• Physical exam and full medical history
• Tests for secondary conditions
• Tests for organ damage caused by hypertension
• Fundoscopic eye exam to check for damaged blood vessels inside the eye
• Urinalysis to test for kidney damage
• Chest X-ray

Doctors confirm a diagnosis of treatment-resistant hypertension when all of the following criteria are met:^1,5

• A patient is taking 3 or more medications at the highest tolerable doses
• One of these medications is a diuretic (removes fluid and salt from the body)
• The patient's blood pressure remains above 130/80 mmHg

Do people with treatment-resistant hypertension have options?

Even though this type of hypertension is resistant to standard treatments, there are options that can help get blood pressure back under control. Treatment will depend on what is causing the resistant hypertension and what kinds of treatment can be safely tolerated. For example, certain drugs may help treat the underlying causes of treatment resistance, such as spironolactone for those with aldosteronism. A new type of medication, called an aldosterone synthase inhibitor (ASI), lowers blood pressure by stopping the body's production of aldosterone.^1,5,6

In addition to addressing any potential underlying causes, certain lifestyle changes may help, including:¹

• Sticking to your medication schedule and dosage
• Reducing salt intake
• Quitting smoking
• Reducing alcohol intake
• Increasing physical activity
• Avoiding substances that increase blood pressure

Medical researchers are also developing surgical procedures such as renal denervation. This minimally invasive procedure uses radio waves to calm down overactive nerves near the kidneys that signal the body to keep blood pressure high.⁵

What is the prognosis of treatment-resistant hypertension?

Treatment-resistant hypertension is a serious condition, but management of treatment resistance is possible. Identifying underlying causes, understanding risk factors, and controlling blood pressure with medication and healthy lifestyle choices can help people successfully lower their blood pressure and lead long, healthy lives.