Chronic Thromboembolic Pulmonary Hypertension: A Narrative Review

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism (PE), which is chronically underdiagnosed. It is characterized by organized thromboembolic lesions within the pulmonary arteries, resulting in both obstruction of pulmonary arterial blood flow and pathologic small vessel remodeling. Patients present with dyspnea and decreased exercise tolerance; however, CTEPH patients are generally very comorbid, and these nonspecific symptoms often fail to initiate the diagnostic investigations. Late presentation results in poor outcomes with pulmonary hypertension and symptomatic right heart failure. Surgical treatment with pulmonary thromboendarterectomy is the gold standard treatment for CTEPH; however, only proximal arterial disease is surgically accessible. Over a third of patients are ineligible for surgery due to a significant burden of distal disease or comorbidities. Other treatment modalities, such as balloon angioplasty and medical therapies, play an important role in the management of these patients. Investigations for the diagnosis and treatment of CTEPH are extensive and require close multidisciplinary collaboration between medical, surgical, and imaging specialists. However, initiating the diagnostic investigations and referral process relies primarily on a high index of suspicion maintained by general practitioners, as early diagnosis is paramount to achieving successful outcomes in this cohort. The objective of this narrative review is to summarize the current knowledge and understanding of CTEPH, including its pathogenesis, presentation, diagnosis, current treatments, and outcomes. We also highlight current areas of uncertainty and ongoing research. Improving awareness and understanding of CTEPH will ultimately lead to better outcomes in the treatment of this disease.