Acute Pulmonary Embolism: not just an acute condition after all

Background: Acute pulmonary embolism (PE) is the third most common cardiovascular disease following myocardial infarction and stroke. Despite diagnostic improvements, the diagnosis of PE is still associated with many difficulties, as the symptoms of an acute PE are nonspecific. Even though an acute PE is associated with a high short-term mortality, less attention has been given to long-term mortality. In addition, the clinical course following an acute PE may be accompanied by substantial morbidity, and one feared complication is chronic thromboembolic pulmonary hypertension (CTEPH), a progressive pulmonary vasculopathy. In addition to CTEPH, increasing evidence suggests that a large proportion of patients report persistent functional impairment several years after an acute PE. Recently, the term chronic thromboembolic pulmonary disease (CTEPD) has been proposed for those with remaining symptoms and signs of residual thrombotic material in the pulmonary arteries. Methods and Results: A nation-wide Swedish cohort of all patients (n= 5793) diagnosed with an acute PE in 2005 was identified. The incidence of PE was 0.6/1000 person-years, and during a 4-year follow-up, the mortality was more than doubled compared with an age- and sex-matched control group. We found that the acute PE associated with multiple comorbidities, and with cardiovascular diseases in particular. All surviving patients in 2007 (n=3510) were invited to answer a questionnaire regarding dyspnea and related comorbidities. We demonstrated a substantially higher prevalence of both exertional dyspnea (53.0% vs. 17.3%) and wake-up dyspnea (12% vs. 1.7%) in patients compared to controls from the Northern Sweden MONICA study. Furthermore, PE associated independently with dyspnea in a multivariable analysis. Through a manual review of approximately 10 % of the patient’s medical records, a positive predictive value of 79% was found for the PE diagnosis. Post-PE patients with remaining dyspnea and/or previously known risk factors for CTEPH development were referred for blood sampling and levels of N-terminal (NT)-prohormone (pro) brain-type natriuretic peptide (BNP) were determined. Thereafter, they were referred to their local hospital for a pulmonary ventilation/perfusion (V/Q) scintigraphy and echocardiography. Approximately 45% of the V/Q-scans showed perfusion defects and 27 % of echocardiographies showed signs of pulmonary hypertension. In total, 24 cases of CTEPH were identified, resulting in a prevalence of 0.4 % (95 % confidence interval 0.2 %–0.6 %). Conclusion: An acute PE is a serious event, associated with decreased survival, multiple comorbidities, frequent dyspnea, and pathological investigational findings. The term CTEPD seems reasonable as it captures that this is a disease of the pulmonary vasculature, and that pharmacological and surgical interventions used for CTEPH may be useful. Regardless, proper follow-up after acute PE is essential for timely identification of patients in need of appropriate investigations and care.