Chronic thromboembolic pulmonary hypertension (CTEPH) is a specific subtype of pulmonary hypertension. Pulmonary ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) is the reference diagnostic examination of CTPEH showing mismatch in at least one segment or two sub-segments.

To investigate the relationship between the extent of pulmonary perfusion defects and hemodynamic, echocardiographic, biological and functional parameters.

Between 2012 and 2019, 46 patients with CTEPH were retrospectively enrolled in the study. The diagnosis of pulmonary hypertension was made by the referral team of the expert centre according European Society of Cardiology and European Respiratory Society guidelines. All patients underwent pulmonary V/Q SPECT, right heart catheterisation, transthoracic echocardiography (TTE), functional tests and natriuretic peptides assays during the same stay.

There was a slight correlation between the extent of pulmonary perfusion defects and pulmonary vascular resistances (r=0.510, P<0.001; Fig. 1). However, there was no correlation between the extent of pulmonary perfusion defects or hemodynamic measurements and right ventricular function assessed by TTE, the functional parameters (6minutes walk distance [6MWD], NYHA class and NT-proBNP level). In contrast, there was a correlation between right ventricular function assessed in TTE (i.e. tricuspid antero-posterior systolic excursion and tricuspid annular S wave) and 6MWD (r=0.586, P<0.001 and r=0.471, P<0.01, respectively), functional class (NYHA III or IV) (r=0.427, P<0.01 and r=0.377, P<0.01, respectively) and the NT-proBNP level (r=0.513, P<0.001 and r=0.485, P<0.001, respectively).

Pulmonary perfusion defects extension by V/Q SPECT can provide information on pulmonary vascular resistances. However, it is not correlated with right ventricular function and functional parameters.