PAH is rare, estimated to affect 15–60 people per million in the general population, with an incidence of about 5–10 new cases per million per year. It occurs two to four times more often in women than men, and can appear at any age, though idiopathic PAH is most often diagnosed in the 30s–60s. Improved awareness and therapies have increased the number of diagnosed patients.

PAH results from abnormal remodeling and narrowing of the pulmonary arteries. Causes include:

• Idiopathic – no identifiable cause, accounting for about half of all PAH cases.

• Heritable – linked to gene mutations involved in pulmonary vascular development, most commonly BMPR2, but also ACVRL1, ALK1, ENG, SMAD9, CAV1, KCNK3 and others. These genes encode proteins that are part of key signaling pathways such as TGF-β/BMP9 (transforming growth factor, bone morphogenic protein), P13K/AT (involved in pulmonary smooth muscle proliferation) or the potassium ion channel.

• Drug- or toxin-induced – associated with certain appetite suppressants, some chemotherapy agents, and amphetamines.

• Associated with other conditions, including:

  • Connective tissue diseases (systemic sclerosis, scleroderma, lupus or mixed connective tissue disease)

  • HIV infection

  • Portal hypertension

  • Congenital heart disease with systemic-to-pulmonary shunts

  • Schistosomiasis

  • Certain inherited metabolic disorders.

Symptoms of PAH are often non-specific, develop slowly and may be mistaken for other heart or lung conditions, delaying diagnosis. They include:

• Dyspnea: Shortness of breath, initially during exercise and eventually at rest.

• Fatigue: Excessive tiredness.

• Dizziness or Syncope: Fainting spells, especially during physical activity;  heart palpitations.

• Chest Pain: Pressure or pain in the chest (angina).

• Edema: Swelling in the ankles, legs, and eventually the abdomen (ascites).

• Cyanosis: A bluish tint to the lips or skin.

As the disease progresses:

• Right-sided heart failure, including symptoms such as fatigue, swelling in the legs and shortness of breath.

• Reduced exercise tolerance

• Severe fluid retention

• Oxygen dependence in advanced disease

Because symptoms are nonspecific, diagnosis often requires a series of tests to rule out other conditions:

• Echocardiogram – initial screening tool; estimates pulmonary artery pressure and assesses right heart function.

• Right heart catheterization – the gold standard, directly measuring pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac output. PAH is defined by a mean pulmonary artery pressure >20 mmHg, pulmonary artery wedge pressure ≤15 mmHg, and pulmonary vascular resistance >2 Wood units.

• Pulmonary function tests and chest imaging – CT or MRI to visualize heart and lung structure; Ventilation/Perfusion (V-Q scan) to rule out blood clots in the lungs.

• Blood tests – including autoimmune panels, HIV testing, and BNP/NT-proBNP as a marker of right heart strain.

• Six-minute walk test – functional capacity assessment used for both diagnosis workup and risk stratification.

• Genetic testing – considered in heritable or idiopathic cases.

While there is currently no cure for PAH, treatments have advanced significantly to improve survival and quality of life:

• Oral Medications: Vasodilating phosphodiesterase-5 inhibitors (sildenafil, tadalafil), endothelin receptor antagonists that block vasoconstriction (bosentan, ambrisentan, macietentan), and soluble guanylate cyclase stimulators that promote vasodilation (riociguat).

• Infused Medications: Prostanoids (epoprostenol) help open narrowed blood vessels;  sotatercept (inhibits activin, a molecule involved in vascular remodeling) has shown recent promise in PAH treatment.

• Supportive Therapy: Oxygen therapy, diuretics (to reduce fluid buildup), and anticoagulants (blood thinners).

• Surgical Options: In severe cases, a lung or heart-lung transplant may be necessary.

PAH remains a serious, potentially life-shortening condition, though outcomes have improved considerably with newer targeted therapies. With early detection and treatment, many patients survive 7-10 years or longer after diagnosis. Historical untreated survival was approximately 2.8 years.

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4. National Organization for Rare Disorders (NORD):  Pulmonary arterial hypertension.

5. Pulmonary Hypertension Association:  What is pulmonary hypertension?