Lisette van Dam

Chapter 11 170 INTRODUCTION In recent years new imaging techniques have been developed for the diagnosis of acute pulmonary embolism (PE). With the introduction of computed tomography pulmonary perfusion (CTPP), functional images of PE can be obtained with the use of perfusion images. 1 Previous studies haves shown that the addition of CTPP to routine computed tomography pulmonary angiography (CTPA), which is the current imaging test of choice for the diagnosis of PE, improves the diagnosis of acute PE and could be of value in initial risk stratification as well. 1,2 Moreover, perfusion imaging may also play a role in the long-term prognosis of acute PE: extensive clot burden and perfusion defects at the moment of a PE diagnosis have been associated with persistent perfusion defects after 6 months of treatment occurring in up to 50% of PE patients despite anticoagulant treatment. 3-6 This poor recanalization of occluded pulmonary arteries may in turn lead to increased dead- space ventilation and/or abnormal cardiopulmonary response to exercise, or in worst case scenario to chronic thromboembolic pulmonary disease (CTEPD) or pulmonary hypertension (CTEPH). 7 Therefore, extensive perfusion defects on the initial CTPA scan at the time of PE diagnosis may correlate with a future diagnosis of CTEPH, CTEPD and/or functional limitations. 6-8 In this study, we aimed to evaluate the predictive value of CTPP-assessed perfusion defects at initial PE diagnosis for persistent symptoms and adverse outcomes at 3-month follow-up. METHODS This was an exploratory study in which we studied a convenience cohort of 100 consecutive adult patients ( ≥ 18 years old) with hemodynamically stable CTPA- confirmed acute PE in whom CTPP was performed as part of routine clinical practice in the Leiden University Medical Center (LUMC) in Leiden, the Netherlands between July 2017 and October 2019. Patients with clinically suspected acute PE were managed according to the YEARS algorithm, including clinical pre-test probability assessment and D-dimer testing. 9 Anticoagulant treatment was started in patients with CTPA-confirmed acute PE. All patients were followed for three months as part of routine clinical practice. The study protocol was approved by the institutional review board of the LUMC, and informed consent requirement was waived due to its observational nature.