Objective Assessment of Pulmonary Embolism Can be Deferred Without Increased Risk

Introduction Pulmonary Embolism (PE), the most serious complication of Deep Vein Thrombosis (DVT), is a relatively common and potentially fatal disease. Its diagnosis usually requires multiple approaches based on diagnostic imaging such as ventilation/perfusion lung scanning (V/Q) or Computed Tomography (CT). However, the performance of such imaging cannot immediately be performed in case of night or week-end referral; in this situation, attending physicians have to decide whether to treat incompletely assessed patients or to hospitalise them until confirmatory tests can be carried out. In lack of guidelines, empirical protective anticoagulation with Low Molecular Weight Heparins (LMWH), drugs showing a more favourable pharmacodynamic profile in comparison to UnFractionated Heparins (UFH), is usually given to patients. However, no clear-cut information is available about the need of such anticoagulation, its dosage and duration, or the time over which deferral of diagnostic procedures can be considered as safe. It seems more appropriate and safer, though, a management based on a preliminary evaluation of the actual risk of thrombosis.

We have recently demonstrated that in patients clinically suspected of venous thromboembolism, Pre-test Clinical Probability (PCP), D-dimer and the use of LMWH can be safely used for delaying diagnostic tests for up 72 hours (Siragusa S et al. Arch Intern Med 2004;164:2477). Our paper was mainly focused to patients suspected of Deep Vein Thrombosis (about 80% of the patients' cohort) which are considered a category at lower risk for complications than PE patients.

Critically, data are lacking to guide the management of patients clinically suspected of having PE who cannot undergo immediate diagnostic imaging.

We plan to perform a prospective clinical trial aimed at evaluating whether data derived from PCP and D-dimer testing, together with the use of LMWHs, permit safe management of patients with suspected PE when objective assessment is not available.

Materials and Methods Patient Population Out-patients presenting with suspected acute PE, when diagnostic imaging were not immediately available (during nights or week-ends), will be considered eligible for the study. The study will be conducted in three Institutions (University Hospital AOUP "Paolo Giaccone" of Palermo, IRCCS Policlinico S. Matteo, Italy and IRCCS Ospedale Maggiore di Milano, Italy) with the same protocol. Exclusion criteria included the following: 1) life-threatening conditions, or serious co-morbidities that required immediate hospitalisation ; 2) relapse of a previously documented PE episode; 3) current use of oral anticoagulant therapy; 4) history of bleeding or any other contraindication to heparin; 5) age younger than 18 years; 6) life expectancy of less than 3 months; 7) refusal to give informed consent.