Objective:Chronic thromboembolic pulmonary hypertension (CTEPH), one of the subtypes of pulmonary hypertension. Patients can be effectively treated with pulmonary endarterectomy (PEA). Although defects in diffusion capacity develop in the presence of severe pulmonary hypertension, the pulmonary function tests (PFT) and carbon-monoxide diffusion breathing test (DLCO) are not employed in the diagnosis of CTEPH.  The purpose of this study was to investigate the association between preoperative PFT and DLCO test and postoperative endarterectomy thrombus levels in patients with CTEPH.

Methods:Retrospective evaluations were done on the preoperative PFT and DLCO parameters, as well as the postoperative thrombus level, of CTEPH patients who underwent pulmonary endarterectomy at our center.

Results:143 patients were included in the study. of the 130 patients whose PFT results were avaliable, 94 had DLCO test results. When PFT results are evaluated according to anatomical classification of PEA materials mean expected FEV1 values are 2.05±0.55 L in patient  with PEA material Level 1 (main pulmonary artery emboli) and 2.86±1.33 L in level 4 (subsegmentery emboli) (p=0.053)

Conclusion: No significant relationship could be demostrated between the PFT and DLCO test parameters performed in the preoperative period and the anatomical classification of thrombus. Contrary to literature,DLCO levels tend to be lower in patients with thrombus in the main pulmonary arteries, not in patients with distal disease and prom?nent micro-vasculopathy, in our study.