From the Guidelines
Pulmonary hypertension is classified as pre-capillary or post-capillary based on hemodynamic measurements obtained during right heart catheterization, with pre-capillary pulmonary hypertension defined by a mean pulmonary artery pressure (mPAP) ≥20 mmHg, pulmonary artery wedge pressure (PAWP) ≤15 mmHg, and pulmonary vascular resistance (PVR) ≥3 Wood units, as stated in the 2022 update of the ACR Appropriateness Criteria for suspected pulmonary hypertension 1. The main differences between pre-capillary and post-capillary pulmonary hypertension are:
- Pre-capillary pulmonary hypertension is characterized by mPAP ≥20 mmHg, PAWP ≤15 mmHg, and PVR ≥3 Wood units, and includes pulmonary arterial hypertension (Group 1), pulmonary hypertension due to lung diseases (Group 3), chronic thromboembolic pulmonary hypertension (Group 4), and pulmonary hypertension with unclear mechanisms (Group 5) 1.
- Post-capillary pulmonary hypertension is characterized by mPAP ≥20 mmHg with PAWP >15 mmHg and can be isolated (PVR <3 Wood units) or combined with pre-capillary components (PVR ≥3 Wood units), and is primarily caused by left heart disease (Group 2) 1. The treatment for pre-capillary pulmonary hypertension typically involves disease-specific therapies such as phosphodiesterase-5 inhibitors, endothelin receptor antagonists, prostacyclin analogs, and soluble guanylate cyclase stimulators, as recommended by the 2015 ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension 1. In contrast, the treatment for post-capillary pulmonary hypertension focuses on managing the underlying cardiac condition with diuretics, ACE inhibitors, beta-blockers, and potentially valve repair or replacement if indicated, as stated in the 2015 ESC/ERS guidelines 1. It is crucial to distinguish between these types of pulmonary hypertension, as pulmonary vasodilators beneficial in pre-capillary hypertension may worsen outcomes in isolated post-capillary hypertension by increasing pulmonary edema, highlighting the importance of accurate diagnosis and treatment based on the underlying hemodynamic characteristics 1.
From the Research
Differences between Pre-Capillary and Post-Capillary Pulmonary Hypertension
- Pre-capillary pulmonary hypertension is characterized by elevated pulmonary artery pressure and low pulmonary capillary wedge pressure, often seen in idiopathic pulmonary arterial hypertension (IPAH) 2.
- Post-capillary pulmonary hypertension is characterized by elevated pulmonary artery pressure and high pulmonary capillary wedge pressure, often seen in heart failure with preserved ejection fraction (HFpEF) 2.
- The main difference between pre-capillary and post-capillary pulmonary hypertension lies in the location of the obstruction: pre-capillary PH is due to obstruction in the pulmonary arteries, while post-capillary PH is due to obstruction in the pulmonary veins or left heart 3.
Hemodynamic Characteristics
- Pre-capillary PH is defined by a mean pulmonary artery pressure greater than 20 mm Hg, a pulmonary artery wedge pressure of 15 mm Hg or lower, and a pulmonary vascular resistance of 3 Wood units or greater 3.
- Post-capillary PH is characterized by a mean pulmonary artery pressure greater than 20 mm Hg and a pulmonary capillary wedge pressure greater than 15 mm Hg 2.
Clinical Characteristics
- Patients with pre-capillary PH, such as IPAH, tend to be younger and have fewer comorbidities compared to those with post-capillary PH, such as HFpEF 2.
- Patients with post-capillary PH, such as HFpEF, tend to have more comorbidities, such as hypertension, diabetes, and obesity, and are often older than those with pre-capillary PH 2.
Treatment
- Treatment for pre-capillary PH includes drugs that enhance the nitric oxide-cyclic guanosine monophosphate biological pathway, prostacyclin pathway agonists, and endothelin pathway antagonists 3, 4.
- Treatment for post-capillary PH focuses on managing the underlying left heart disease, such as heart failure, and may include diuretics, beta-blockers, and other medications to reduce pulmonary congestion 2.