How is pulmonary arterial hypertension (PAH) diagnosed?

Some of the early symptoms of PAH may be easily confused with those of other conditions, such as asthma. That's why tests must be performed to rule out other conditions and confirm PAH.

Because PAH is a progressive disease (meaning that it gets worse over time), the sooner it is diagnosed and treated, the better the outcome. Patients with undiagnosed PAH who do not get treatment may experience more rapid clinical deterioration (worsening of symptoms or physical condition) than patients who are on a doctor-prescribed treatment plan.

From suspicion to diagnosis: four important steps

Diagnosing PAH is a process that begins with a suspicion that the disease may be causing a patient's symptoms—such as shortness of breath, fainting, fatigue, dizziness and more—and finishes with an actual diagnosis of PAH.

It is recommended that doctors follow four important steps along the way:

1. Suspect—to assess the patient's signs and symptoms, which can include:

Breathlessness
Chronic fatigue
Chest pain
Swelling
Dizziness
Fainting

2. Identify—to determine how well the heart and lungs are working and focus on PAH as a possible cause; tests may include:

Echocardiogram with Doppler
Chest X-ray
Pulmonary function tests (helps rule out certain kinds of lung disease)
Six-minute walk test (helps determine functional limitations)
Laboratory tests (help identify potential risk factors for PAH such as connective tissue disease, HIV, or other conditions)

3. Rule Out—to exclude other causes; tests may include:

A V/Q lung scan (helps rule out an embolism or lung disease)

4. Confirm—to accurately establish the diagnosis of PAH the test most often used:

Right heart catheterization (if other tests rule out a diagnosis of PAH, this test is not necessary; see more below)

Important information about the right heart catheterization

The only test for confirming a precise diagnosis of PAH and assessing the disease severity is the right heart catheterization, which directly measures the pressures in your pulmonary arteries.

It's an invasive procedure—involving the insertion of a thin flexible tube into the right side of the heart—that takes 1 to 2 hours and often requires sedation. So your doctor may first perform a number of non-invasive tests like the electrocardiogram, chest X-ray, and echocardiogram mentioned above. It's important to remember that if previous diagnostic tests rule out PAH, the right heart catheterization is not necessary.

The last step is determining the World Health Organization (WHO) Functional Class.

Once a diagnosis of PAH has been established, doctors need to determine a patient’s WHO Functional Class. This is a rating of someone’s ability to perform ordinary physical activities, such as walking, without shortness of breath. Placing patients into WHO Functional Classes helps the healthcare team make certain treatment decisions and prescribe the correct medications.

The WHO Functional Class scale is divided into 4 categories and considers how symptoms such as tiredness, shortness of breath, chest pain or light-headedness limit physical activity.1 The lower the WHO Functional Class, the less severe the PAH.

The WHO Functional Class Scale

Functional Class I:
No limitation in usual physical activity (ordinary activity does not increase symptoms).

Functional Class II:
Some limitation in physical activity (no discomfort at rest, but normal activity increases symptoms).

Functional Class III:
Significant limitation in physical activity (no discomfort at rest, but less than normal activity increases symptoms).

Functional Class IV:
Symptoms are present with any activity or even at rest.

IMPORTANT SAFETY INFORMATION

Because of the risks associated with Tracleer, this medication may be prescribed only by your doctor through the Tracleer Access Program. Liver damage: Tracleer can cause serious liver damage, including in rare cases liver failure and, in situations with regular liver testing, unexplained liver cirrhosis. So you must have a blood test to check your liver function before you start Tracleer and each month after that. Call your doctor right away if you have any of these symptoms of liver problems: nausea, vomiting, fever, unusual tiredness, abdominal (stomach area) pain, or yellowing of the skin or the whites of your eyes (jaundice). Serious birth defects: Tracleer is very likely to cause serious birth defects. It is important not to be or to become pregnant while taking Tracleer and to have a pregnancy test before you start the drug and each month thereafter. It is very important for you to use reliable forms of birth control while taking Tracleer. Hormonal contraceptives should not be used alone because they may not be effective in patients taking Tracleer.
Do not take Tracleer with glyburide or cyclosporine-A because they may increase your chance of side effects.

Please see full Prescribing Information, including BOXED WARNING and Medication Guide.



	What is PAH?

	World Health Organization (WHO) Category 1: PAH

	Treatments for PAH and related conditions

REFERENCES

1. Barst RJ, McGoon M, Torbicki A et al. Diagnosis and differential assessment of pulmonary arterial hypertension. J Am Coll Cardiol. 2004; 43(Suppl S): 40S-47S.