A Fast Track Strategy for Managing Suspected Pulmonary Embolism (PE) in Outpatients.

Background: Several strategies for managing patients with suspected PE have been validated. However, most of these strategies are complicated, involving multiple rounds of tests, and are thus, time consuming, costly and difficult to apply in clinical practice. Aiming to introduce a simple, fast and cost-effective strategy, we adopted a new diagnostic approach combining clinical probability assessment, D-Dimer and multi-slice spiral CT (MSSCT) scanning.

Aims: The aim of this study was to assess the safety and efficacy of this management strategy by a prospective outcome study with 3-month follow-up.

Methods: 495 consecutive patients referred to the Emergency Department at Østfold Hospital, Fredrikstad, Norway, for suspected PE, between Feb 2002 and Dec 2003, were considered for inclusion. 63 (12.7%) patients were excluded and the final cohort consisted of 432 patients. Patients were managed by serial non-invasive testing starting with D-Dimer test. Normal plasma D-Dimer (Liatest, latex agglutination assay, Stago-France, cut-off <0.4 mg/L) was deemed to rule out PE in patients with low-intermediate clinical probability (CP). CP for PE was assessed according to the categories proposed by Hyers. Patients with normal D-Dimer, but with high CP, and patients with elevated D-Dimer proceeded to MSSCT scan. A 4-row detector spiral CT scan was used in the study (scans were done with 2.5 mm collimation, pitch of 1.25). If MSSCT diagnosis was inconclusive, bilateral compression ultrasonography was recommended followed by a perfusion scan and eventually pulmonary angiography if further verification was necessary. Patients with verified PE received anticoagulation according to the hospitals guidelines. The entire cohort were followed-up for 3 months.

Results: Normal D-Dimer and low-intermediate CP ruled out PE in 100 patients (23.1%). Twenty patients had normal D-Dimer but high CP and proceeded to MSSCT. All proved negative for PE. A total of 332 patients underwent MSSCT examination. PE was diagnosed in 95 patients (22%) and was ruled out by negative MSSCT in 221 patients.

In 16 patients (4.8%), MSSCT was inconclusive due to suboptimal contrast filling (n=7), artefacts (n=2), or uncertain peripheral emboli (n=7). In ten, interpretation was inconclusive but decision to anticoagulate was made by the attending physician. Compression ultrasonography was performed in three of those; two had positive findings for DVT. In the remaining six, anticoagulation was withheld. Five had undergone further examination with ultrasound; none had DVT. Pulmonary angiography was carried out in one and perfusion lung scan in another patient; both examinations were negative.

The diagnostic algorithm yielded a definite diagnosis in 96.3% of the patients. Follow-up was successfully completed in 321 (98.1%) of the patients in whom anticoagulation was withheld. Five of 321 patients (1.5%) in whom the diagnostic algorithm ruled out PE died during the follow-up period. The cause of death was adjudicated as not related to PE in three and possibly related to PE in two. No patient developed venous thromboembolism during the 3 month follow-up period, resulting in a 3-month thromboembolic rate of 0%, 95%CI (0–1.1%).

Conclusions: Our results compare favorably to the results reported in previous outcome studies, and confirm the safety and efficacy of this management strategy combining D-Dimer as a first step test followed by MSSCT as a single imaging test in patients with elevated D-Dimer.