On average, there is a time lapse of two years between the appearance of the initial symptoms and diagnosis. An echocardiogram reinforces the suspected diagnosis. Here, signs of right ventricular load indicate an existing pulmonary hypertension.

Following this, using the so-called lung ventilation/perfusion scan (VQ scan), during which a small number of radioactive microscopic small particles are injected into the vein, the blood circulation in the lung is evaluated in order to distinguish between CTEPH with malfunction of the pulmonary circulation and another cause of pulmonary hypertension. In addition, a right heart catheterization and also a so-called pulmonary angiogram, i.e. a catheter imaging test of the pulmonary arteries, are carried out to facilitate the planning of further procedures. 

A new method of displaying CTEPH-typical hypoperfusion of the lung is a test using contrast medium-supported magnetic resonance imaging (MRI). In contrast to the VQ scan, it requires no potentially damaging radiation.