Chronic thromboembolic pulmonary hypertension (CTPH) is associated with considerable morbidity and mortality. Its incidence after pulmonary embolism and associated risk factors are not well documented in Chinese population. We conducted a prospective, long-term, follow-up study to assess the incidence of symptomatic CTPH in consecutive patients with an acute episode of pulmonary embolism but without prior venous thromboembolism. Patients with unexplained persistent dyspnea during follow-up underwent transthoracic echocardiography and, if supportive findings were present, ventilation-perfusion lung scanning and pulmonary angiography. CTPH was considered to be present if systolic and mean pulmonary-artery pressures exceeded 40 mm Hg and 25 mm Hg, respectively; pulmonary-capillary wedge pressure was normal; and there was angiographic evidence of disease.

Inclusion Criteria:

• Patients with an episode of acute symptomatic pulmonary embolism without prior pulmonary embolism or venous thrombosis

Exclusion Criteria:

• Have other diseases (e.g., systemic sclerosis or severe emphysema) that could have caused nonthromboembolic pulmonary hypertension,
• Have preexisting exertional dyspnea,
• Geographically inaccessible for follow-up,
• Decline to participate in the study.

Consecutive patients with an acute episode of pulmonary embolism but without prior venous thromboembolism.