Differential effect of anticoagulant treatment on vascular morphology in patients with acute pulmonary embolism

Abstract

Abstract Introduction Chronic thromboembolic pulmonary hypertension (CTEPH) is described as one of the most severe consequence of acute pulmonary embolism (APE). When signs of chronic PE are present on the CT pulmonary angiogram (CTPA) used to diagnose APE, the question arises whether there is underlying CTEPH. The relevance of chronic lesions, as well as the effect of anticoagulant treatment on their development is currently unknown. Purpose To investigate the effect of anticoagulant treatment on CTPA derived vascular morphological abnormalities in patients with APE. Methods We performed a case-cohort study. As cases, we selected CTEPH patients who had a prior history of a first APE episode. As cohort, we selected patients who had a follow-up CTPA performed 6 months after first episode APE in the context of a clinical trial (den Exter 2015). A baseline (i.e. at moment of APE diagnosis) CTPA and a follow-up CTPA was available for all patients. Experienced chest radiologists morphologically assessed 20 segmental pulmonary arteries per patient as “normal” or “affected” (as defined by a total occlusion by thrombus, central thrombus, mural thrombus, web or tapered pulmonary artery). Pulmonary segmental vessels of the entire cohort were merged for the analysis. All patients were treated adequately with anticoagulant treatment (vitamin K antagonists, direct oral anticoagulation or low molecular weight heparin) in the period between baseline and follow-up CTPA according to current guidelines. Results A total of 30 cases and 116 controls were included. Mean time between baseline and follow-up CTPA was 193 (62) days. At baseline CTPA, 1647 (56%) of the 2920 pulmonary segmental vessels were scored as affected. Almost all central thrombi resolved after oral anticoagulant treatment (1103/1191=93%). Webs (n=85) and tapered pulmonary arteries (n=57) did not change in morphology at follow-up (Figure 1). Most vessels containing a total occlusion by a thrombus at baseline resolved completely (156/280=56%), changed to a tapered pulmonary artery (26%) or became a web (7%). Mural thrombi either remained unchanged (16/34=47%), resolved completely (29%) or became a web (24%). Conclusion After anticoagulant treatment for APE almost all central thrombi completely resolved, whereas mural thrombi or total occlusions by thrombi either resolved or transformed to a web or tapered pulmonary artery. Interestingly, none of the webs and tapered pulmonary arteries resolved after anticoagulant treatment. Therefore, webs and tapered pulmonary arteries at the moment of APE diagnosis indicate a chronic PE state. Figure 1. Web at baseline and follow-up Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Research grant from Actelion Pharmaceuticals