Chronic thromboembolic pulmonary hypertension (CTEPH) is an important complication after acute pulmonary embolism (PE) with considerable morbidity and mortality. The aim of this study was to estimate the CTEPH incidence in a cohort after the first occurrence of PE.We conducted a 1-year follow-up cohort study between 2015 and 2018 to assess the incidence of CTEPH in 474 patients with their first acute episode of PE. For the diagnosis of CTEPH, patients with unexplained persistent dyspnea during follow-up underwent transthoracic echocardiography, right heart catheterization, ventilation-perfusion lung scanning, and CT pulmonary angiography.Overall, 317 patients were included in the study. The mean age of the patients was 56.5 ± 16 years. One hundred and three patients (32%) had exertional dyspnea at the 1-year follow-up. Patients with evidence of pulmonary hypertension (PH) on echocardiography underwent right heart catheterization. Eleven patients (18%) had no PH (mPAP < 25 mmHg); 47 patients (81%) had mPAP > 25 mmHg. Fifteen patients had PAWP > 15 mmHg, including those with underlying left heart problems or valvular diseases. There were 32 patients with PAH (mPAP > 25 mmHg and PVR > 3 WU) undergoing CTEPH studies; 22 patients (6.9%) had multiple segmental defects suggesting CTEPH on a perfusion scan.The incidence of CTEPH observed in this study 1 year after the first episode of acute PE was approximately 6.9%. This incidence seems to be high in our population, and diagnostic and therapeutic strategies for the early identification of CTEPH are needed.