Diagnosing PAH

Diagnostic algorithm
Symptoms of PAH
Echo measures suggest PAH
Right heart cath required for diagnosis of PAH

PAH diagnostic criteria

Diagnosing pulmonary arterial hypertension (PAH) involves a series of tests, starting with an initial evaluation of symptoms, lab work, and imaging to assess heart and lung function. This process concludes with right heart catheterization (cath), the definitive step to confirm PAH by measuring pulmonary pressures directly from the right heart.¹

Symptom onset

Symptoms are related to right ventricular dysfunction²

Typical presentation includes exertional symptoms²

Dyspnea
Fatigue

Due to nonspecific symptoms, the time between symptom onset and diagnosis is often >2 years³

Diagnosis

As disease progresses, symptoms start to occur at rest as the RV fails to compensate against the increased PVR^2,4

Syncope
Lower extremity edema
Abdominal distention
Angina

Misdiagnoses/Comorbid conditions

Common misdiagnoses or comorbid conditions that delay diagnosis^5,6:

PH-LHD
COPD
Asthma
Obesity

Diagnostic algorithm

The diagnostic process begins after clinical suspicion of PH based on symptoms and physical examination.¹

Although many tests can hone suspicion of PAH, a right heart cath must be performed to definitively diagnose PAH. Current treatment guidelines recommend that patients be evaluated at a PH Expert Center for confirmation.^1,2

Download a step-by-step guide of testing and decision-making to help reach a possible diagnosis of PAH.

Download of the diagnostic algorithm flowchart to help reach a possible diagnosis of PAH

Download Diagnostic Flowchart

Symptoms of PAH are often nonspecific⁷

Patients with PAH often present with nonspecific symptoms resulting from the decompensation of the RV. The delay in symptom presentation and the nonspecific symptoms of PAH lead to delay in diagnosis.^3,7,8

Early symptoms^2,6,9

1
Dizzness
2
SOB (dyspnea)
3
Palpitations
4
Fatigue
5
Edema

Body illustration showing non specific clinical characteristics, labeled by number based on the criteria evaluated in the diagnosis of PAH

Late symptoms^6,8,9

6
Syncope
7
Jugular venous distension
8
SOB
9
Chest pain
10
Hepatomegaly
11
Swollen abdomen
12
Low blood pressure

Screening for PAH¹

Cardiac

EKG
Echo
Cardiac MRI

Respiratory

Pulmonary function test
Arterial blood gases
Overnight oximetry

Blood

Laboratory tests (eg, blood counts, electrolytes, kidney function, uric acid, liver parameters, iron, BNP/NT-proBNP, thyroid testing)
Immunology tests (anti-nuclear antibodies, anti-centromere antibodies, and anti-Ro)
Serologic testing (hepatitis, HIV)

Exercise

CPET

Imaging

Chest radiograph
V/Q lung scan
Non-contrast and contrast-enhanced CT
CTPA
Abdominal ultrasound

Exam findings that may indicate PAH

Extracardiac exam findings⁴

Jugular vein distension
Hepatomegaly
Peripheral edema
Ascites
Lung examination is usually normal

Heart illustration of the right ventricular

Cardiac findings reflecting functional and structural changes of the right ventricle^4,10

Left parasternal shift
Loud pulmonary component of the second heart sound
Pansystolic murmur of tricuspid regurgitation
Diastolic murmur of pulmonary insufficiency
RV third heart sound

Echo measurements may suggest PAH

A right heart Echo can assess the probability of pulmonary hypertension based on peak tricuspid regurgitant velocity and presence of other suggestive signs of the disease. However, right heart cath is required to confirm the diagnosis.¹

Echo evaluation to hone PAH probability¹¹

One way to investigate the probability of PAH based on Echo findings is to use VEST scoring. The VEST score uses routine variables from an Echo report to help determine the probability that a patient may have PAH.

Scores range from -3 to +3. If your patient has 1 “yes,” there is a probability that they may have PAH, and the more "yes" results, the higher the probability.

Patients with more "yes" results should be referred to PH Expert Centers for more comprehensive diagnostic investigations, including right heart cath.

Echocardiographic parameter

Yes

Mitral E:e′, lateral ≤10 (or E ≤90 cm/s)

−1

Qualitative left atrial size normal or mildly enlarged

−1

Systolic interventricular septal flattening

−1

Echo images may suggest PAH

These Echos show the progressive dilation of the RV and RA in PAH.

In end-stage PAH, the RV may cause the interventricular septum to bow outward and compress the LV.

Other signs of RV dysfunction that can be found on Echo include^1,12,13:

Tricuspid regurgitation
Ratio between RV and LV basal diameter >1
Loss of IVC inspiratory collapse
TAPSE
Increased RV systolic dysfunction
Presence of pericardial effusion

Echo of the heart that the progressive dilation of the RV and RA in PAH

Images courtesy of Anjali Vaidya, MD, FACC, FASE, FACP. Pulmonary Hypertension, Right Heart Failure & CTEPH Program, Temple University Hospital.

Explore the 2025 ASE Guidelines for Echo assessment of the right heart

Access 2025 ASE Guidelines

Right heart cath is required for a definitive diagnosis¹

The 2022 ESC/ERS Treatment Guidelines recommend that patients with unexplained exertional dyspnea, syncope, and/or signs of RV dysfunction should be assessed for suspected PH/PAH using transthoracic echocardiography with a confirmed diagnosis ultimately dependent on hemodynamic results obtained from right heart cath.¹

Hemodynamic values obtained during right heart cath^1,14

Confirm diagnosis of PAH
Evaluate severity of PAH
Assess congenital heart defects
Exclude left-side heart disease
Assess response to vasodilator challenge
Assess key hemodynamic parameters
Guide treatment decisions

Illustration of right heart catheterization definitive diagnosis of WHO Group 1 PAH

*PVR = (mPAP – PAWP) / CO.

Image Description

PAWP ≤15 mm Hg
PVR* >2 WU
mPAP >20 mm Hg

Normal¹⁵: 14 ± 3 mm Hg

Learn about PAH prognosis

Explore PAH Prognosis

ASE=American Society of Echocardiography; CO=cardiac output; COPD=chronic obstructive pulmonary disease; CPET=cardiopulmonary exercise test; CT=computed tomography; CTEPH=chronic thromboembolic pulmonary hypertension; CTPA=CT pulmonary angiogram; E:e′=early diastolic flow peak velocity of mitral valve:early diastolic peak velocity of mitral valve annulus; Echo=echocardiography; EKG=electrocardiography; ERS=European Respiratory Society; ESC=European Society of Cardiology; HIV=human immunodeficiency virus; IVC=inferior vena cava; LV=left ventricle/left ventricular; mPAP=mean pulmonary arterial pressure; MRI=magnetic resonance imaging; NT-proBNP=N-terminal pro–B-type natriuretic peptide; PAWP=pulmonary arterial wedge pressure; PH=pulmonary hypertension; PH‑LHD=pulmonary hypertension due to left heart disease; PVR=pulmonary vascular resistance; RA=right atrium/right atrial; RV=right ventricle/right ventricular; SOB=shortness of breath; TAPSE=tricuspid annular plane systolic excursion; V/Q=ventilation/perfusion; VEST=virtual echocardiography screening tool; WU=Wood unit.

References: 1. Humbert M, et al. Eur Heart J. 2022;43(38):3618-3731. 2. Lai YC, et al. Circ Res. 2014;115(1):115-130. 3. Rich S, et al. Ann Intern Med. 1987;107(2):216-223. 4. Rich JD, Rich S. Circulation. 2014;130(20):1820-1830. 5. Hussain N, et al. Pulm Circ. 2016;6(1):3-14. 6. Brown LM, et al. Chest. 2011;140(1):19-26. 7. Vachiéry J, Gaine S. Eur Respir Rev. 2012;21(126):313-320. 8. McLaughlin VV, et al. J Am Coll Cardiol. 2009;53(17):1573-1619. 9. Oldroyd SH, et al. In: StatPearls [Internet]. Updated May 1, 2024. Accessed April 30, 2025. https://pubmed.ncbi.nlm.nih.gov/29494070/ 10. Mukherjee M, et al. J Am Soc Echocardiogr. 2025;38(3):141-186. 11. Vaidya A, et al. Pulm Circ. 2020;10(3):2045894020950225. 12. Forfia PR, Vachiéry J. Am J Cardiol. 2012;110(6 suppl):16S-24S. 13. Roberts JD, Forfia PR. Pulm Circ. 2011;1(2):160-181. 14. Rosenkranz S, Preston IR. Eur Respir Rev. 2015;24(138):642-652. 15. Galiè N, et al. Eur Heart J. 2016;37(1):67-119.

Diagnosing PAH

PAH diagnostic criteria

Diagnostic algorithm

Symptoms of PAH are often nonspecific7

Early symptoms2,6,9

Late symptoms6,8,9

Screening for PAH1