What is the mean pulmonary arterial pressure threshold for diagnosing pulmonary hypertension, more than 20 mmHg or more than 25 mmHg?

From the Guidelines

The mean pulmonary arterial pressure threshold for diagnosing pulmonary hypertension is more than 20 mmHg. This represents a change from the previous diagnostic threshold of 25 mmHg, which was used for many years. The revised definition was established based on evidence that even mildly elevated pulmonary pressures (between 21-24 mmHg) are associated with increased morbidity and mortality, as noted in the 2022 update of the ACR Appropriateness Criteria for suspected pulmonary hypertension 1. This lower threshold allows for earlier detection and intervention in patients with pulmonary hypertension.

Key Considerations

• The diagnosis of pulmonary hypertension requires right heart catheterization for accurate measurement of pulmonary pressures, as echocardiography can estimate but not definitively measure these pressures.
• When evaluating a patient with suspected pulmonary hypertension, it's essential to also assess for underlying causes, which may include left heart disease, lung disease, chronic thromboembolic disease, or various other conditions that can lead to elevated pulmonary pressures.
• The 2019 guidelines from the American Society of Hematology also support the use of a mean pulmonary artery pressure threshold of >20 mmHg for diagnosing pulmonary hypertension, highlighting the importance of early detection and treatment in patients with sickle cell disease 1.

Diagnostic Criteria

• The diagnosis of pulmonary arterial hypertension (PAH) includes a mean pulmonary arterial pressure >20 mmHg, a pulmonary artery wedge pressure ≤15 mmHg, and a pulmonary vascular resistance ≥3 Wood units.
• The clinical classification of pulmonary hypertension has been simplified and now includes five groups, with PAH being group 1, and the diagnosis requires careful evaluation of the patient's symptoms, medical history, and hemodynamic measurements.

Clinical Implications

• The revised definition of pulmonary hypertension allows for earlier detection and intervention, potentially improving outcomes for patients with this condition.
• Clinicians should be aware of the updated diagnostic criteria and classification system for pulmonary hypertension to provide optimal care for their patients.

From the Research

Definition of Pulmonary Hypertension

The definition of pulmonary hypertension (PH) is a topic of discussion among researchers.

• According to 2 and 3, PH is defined by a mean pulmonary artery pressure greater than 20 mm Hg.
• However, other studies, such as 4 and 5, define PH as a mean pulmonary arterial pressure over 25 mm Hg at rest or over 30 mm Hg during activity.

Diagnosis of Pulmonary Hypertension

The diagnosis of PH involves a stepwise approach, including:

• Non-invasive tests, such as electrocardiography, chest radiography, and pulmonary function tests 6
• Transthoracic echocardiography to estimate the probability of PH 6
• Right-sided heart catheterization for accurate diagnosis and classification 2, 6, 3
• Invasive and non-invasive markers of disease severity, such as biomarkers or physiological parameters 4

Classification of Pulmonary Hypertension

PH is classified into 5 clinical subgroups:

• Pulmonary arterial hypertension (PAH) 2, 6, 3
• PH due to left-sided heart disease 6
• PH due to chronic lung disease 6
• Chronic thromboembolic PH (CTEPH) 6
• PH with an unclear and/or multifactorial mechanisms 6