Identifying Subpopulations of PH and PAH

Considerations for the identification of specific subpopulations of PH and PAH, as well as their impact on outcomes and treatment goals.


Hilary M. DuBrock, MD: Chronic thromboembolic pulmonary hypertension [CTEPH] is Group 4 PH [pulmonary hypertension]. These patients have pulmonary hypertension that develops due to chronic thrombi and organized thrombus that develop in the pulmonary blood vessels. This, over time, can lead to right heart failure and even death if not treated. CTEPH is characterized by precapillary pulmonary hypertension with an elevated mean PA [pulmonary artery] pressure, pulmonary vascular resistance, and a normal pulmonary artery wedge pressure. However, we categorize it differently than idiopathic Group 1 pulmonary arterial hypertension [PAH] because there’s a different approach to treatment of chronic thromboembolic pulmonary hypertension.

Patients with CTEPH need to first and foremost be evaluated for surgical intervention, which is pulmonary thromboendarterectomy. In patients who are not candidates for surgery, either because they have distal disease or because they have comorbidities that would preclude surgical intervention, we consider other options for treatment such as balloon pulmonary angioplasty or medical therapy with medications such as riociguat, a soluble guanylate cyclase stimulator.

Connective tissue disease—associated pulmonary arterial hypertension is a subgroup of Group 1 PAH. Patients with connective tissue disease–associated pulmonary arterial hypertension have PAH that develops in the context of different types of connective tissue disease, such as scleroderma, lupus, mixed connective tissue disease, polymyositis, and dermatomyositis, among other disorders. Patients with connective tissue disease–associated pulmonary arterial hypertension tend to have a worse prognosis and respond less well to PAH-directed therapy when compared to patients with idiopathic pulmonary arterial hypertension. Among patients with connective tissue disease pulmonary arterial hypertension, scleroderma is the most common cause of connective tissue disease that is associated with PAH.

Portopulmonary hypertension refers to a subgroup of Group 1 pulmonary arterial hypertension, in which pulmonary arterial hypertension develops in patients with either cirrhotic or non-cirrhotic portal hypertension. These patients tend to have a worse prognosis compared to idiopathic or connective tissue disease—associated pulmonary arterial hypertension, despite having better hemodynamics at the time of diagnosis. Additionally, a mainstay of treatment goals in patients with portopulmonary hypertension is to improve their eligibility for a procedure such as liver transplantation, if that is needed to treat their underlying liver disease. The treatment goals in portopulmonary hypertension tend to be different from goals in other forms of PAH.

Charles D. Burger, MD: Physicians always love to talk about diagnosis. That’s one of the reasons we get into the field: to figure out what’s going on with the patient to determine the diagnosis and the best treatment recommendations. Really, it starts with your interview with the patient. For example, if you’re looking for the possibility of connective tissue disease like scleroderma with the patient, you may be asking them about symptoms of scleroderma, which include joint pain, changes in their fingers where the skin thickens, or when the hands will turn different colors when exposed to cold. That’s called Raynaud phenomenon, and you’re asking about that.

In a similar way, you’re looking for these findings on physical examination. One of the hallmarks of disease are tiny spider-type reddenings of the skin that are referred to as telangiectasias. If these are prevalent or if they’ve been increasing in incidence recently, you worry about the patient possibly having pulmonary arterial hypertension. Your examination might show signs of this, but you often have to move forward, as you might imagine, to diagnostic evaluation.

Generally, you screen for pulmonary hypertension in someone with scleroderma with an echocardiogram. That might show you elevated right heart pressures. It might show you strain on the right heart. And then, you need to move forward with the confirmatory test, which is a right heart catheterization, regardless of the type of pulmonary hypertension. That will show you a profile that would confirm the presence of Group 1 PAH in a patient with connective tissue disease.

Similarly, if you’re worried about liver disease, there might be a history of risk factors for liver disease, such as having chronic hepatitis. You’re looking for signs on examination that might indicate the liver isn’t functioning properly, such as fluid that will accumulate in the abdomen, or what’s referred to as ascites. As you move forward with screening for pulmonary hypertension, you will use an echocardiogram and a right heart catheterization just as with connective tissue diseases, but it also involves some assessment of liver function, which involves blood tests, imaging of the liver, and generally, consultation with a gastroenterologist with a specific interest in liver disease.

Group 4 chronic thromboembolic disease pulmonary hypertension is a little different, and it can be subtle because not all patients have a history of having a blood clot in their legs or their lungs. They may not be aware that this is the cause. As you’re moving through your diagnostic evaluation, it’s very important for providers to get a ventilation/perfusion lung scan. This is the screening test of choice based on guideline recommendations that would help you uncover the possibility of chronic thromboembolic disease pulmonary hypertension. It will be abnormal in those patients. Additional testing might be required, such as a pulmonary angiogram or a CT [computed tomography] scan with contrast, to further delineate the scope of the problem.

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