@ERSpublicationsHaemodynamic status has the strongest prognostic implications for short-term mortality in patients with PE http://ow.ly/VEARC Pulmonary embolism (PE) remains one of the leading causes of cardiovascular morbidity and mortality [1]. Acute PE has a spectrum of clinical syndromes and varying clinical outcomes [2,3]. Estimation of patient prognosis helps to prioritise appropriate management strategies. Risk stratification of patients with PE may identify patients at high risk of early PE-related death who may benefit from escalated surveillance or therapy [4,5]. Alternatively, clinicians may consider patients deemed at low risk for early complications (i.e. all-cause mortality, recurrent venous thromboembolism (VTE), and major bleeding) as candidates for partial or complete outpatient PE treatment [6]. According to the recent European Society of Cardiology (ESC) guidelines [7], risk assessment of patients diagnosed with PE should rely on the sequential application of a validated clinical score (i.e. pulmonary embolism severity index (PESI) or simplified PESI (sPESI)), imaging testing assessing right ventricle (RV) function (i.e. echocardiography or computed tomographic pulmonary angiography), and cardiac biomarkers (i.e. cardiac troponins). Though the guidelines state that patients who have acute PE associated with right heart thrombi (RHT) have a potentially life-threatening condition, the authors did not formally incorporate the presence or absence of RHT into their PE prognostication algorithm.RHT typically represent mobilised deep vein thromboses that have become lodged temporarily in the right atrium or RV [8,9]. Though the increased use of two-dimensional echocardiography for risk stratification of PE patients has led to increased detection of RHT, the incidence of RHT remains unknown. In patients with acute PE, RHT pose an unclear risk of mortality [10]. Furthermore, the lack of prospective randomised trials comparing anticoagulant, thrombolytic, catheter-based, and surgical therapies leaves us without guidance regarding optimal management of RHT.In this issue of the European Respiratory Journal, KOĆ et al.[11] report the results of an intriguing study aimed at determining the prognostic significance of RHT and their potential influence on treatment selection. The authors used data from a prospective, multicentre, international Right Heart Thrombi European Registry (RiHTER) in order to assess the independent association between RHT characteristics (i.e. size and mobility) and 30-day all-cause mortality. Furthermore, the study compared the outcomes of patients diagnosed with RHT with a subset of patients from a different database who did not have RHT but were otherwise matched according to relevant clinical factors (e.g. age, sex, right to left ventricular diameter ratio, and heart rate). The clinical prognostic scores (i.e. sPESI [12] and shock index [13]) of the patients predicted mortality, while the RHT characteristics did not. However, patients with RV dysfunction and RHT had an increased m...