Chest
Volume 129, Issue 1, January 2006, Pages 192-197
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Special Features
Resolution of Thromboemboli in Patients With Acute Pulmonary Embolism: A Systematic Review

https://doi.org/10.1378/chest.129.1.192Get rights and content

Study objectives

Much attention has been paid in recent years to optimizing the diagnosis of acute pulmonary embolism (PE). However, little is known about the changes in clot burden that occur at the level of the pulmonary arteries after documented PE. It is often problematic to distinguish between a new or residual defect on lung scintigraphy or helical CT. This may lead to falsely labeling patients with residual PE as having recurrent PE and consequent unnecessary treatment changes.

Design

We performed a systematic analysis of studies of imaging tests (radionuclide and CT) evaluating resolution rate of PE with independent assessment of predefined methodologic criteria by two investigators.

Results

We identified 29 clinical studies. Of these, 25 studies were excluded and 4 studies were included in our review. Because studies differed largely in patient selection, duration of anticoagulation, and timing of follow-up, the studies were not pooled but briefly described. The percentage of patients with residual pulmonary thrombi was 87% at 8 days after diagnosis, 68% after 6 weeks, 65% after 3 months, 57% after 6 months, and 52% after 11 months.

Discussion

This review shows that complete resolution of PE is not routinely achieved between 8 days and 11 months after diagnosis. More than 50% of patients with PE still have defects 6 months after diagnosis, after which resolution of thrombi appears to reach a plateau phase. Physicians should be aware of the high percentage of incomplete resolution of pulmonary emboli. Routine re-imaging after cessation of anticoagulant therapy in patients with PE to obtain a new baseline could be considered.

Section snippets

Search Strategy

We used electronic search strategies to identify relevant studies. The following electronic databases were searched: PubMed (1966 to November 2004), EMBASE (1980 to November 2004), Cochrane, the Library Issue 1, 2005, and Web of Science using the following search terms: residual thrombosis or incomplete recovery or incomplete resolution or (resolving AND [clots OR clot]) or ([normalization OR normalization] AND [pulmonary arteries OR pulmonary artery]) or ([(thrombi AND regression) or thrombus

Results

We identified 29 clinical studies. Of these, 25 studies were excluded for the following reasons: (1) retrospective design789101112131415; (2) nonconsecutive patients7101112131617181920212223242526272829; (3) lack of objective verification of the diagnosis1017182130; (4) asymptomatic patients25; (5) treatment with inferior vena cava ligation or femoral ligation, embolectomy, or no treatment in some patients789101116181920212324252931; (6) anticoagulant therapy for < 6 weeks10182324; and (7) no

Studies Using V/Q Scintigraphy at Follow-up

Hvid-Jacobsen et al32 re-examined 30 consecutive patients 6 months after diagnosis of PE. All patients were available for follow-up. All underwent repeat V/Q scans and chest radiographs, and all had been treated for 3 months. Six months after diagnosis, 13 patients (43%) had normalized scan findings, 9 patients (30%) had minor defects, 6 patients (20%) had persistent defects, and 2 patients had new defects. None of the patients had symptoms of recurrent PE. In this early study,32 the authors

Studies Using Helical CT at Follow-up

Remy-Jardin et al34 were among the first to use helical CT as a follow-up test to evaluate the resolution of acute PE. Of 111 eligible patients referred to an ICU with massive acute PE, 49 patients did not undergo follow-up evaluation for the following reasons: the patient died during follow-up (22 patients), the patient had a history of (extra-)thoracic malignancy and a poor clinical status (10 patients), the patient was > 85 years old (7 patients), the patient had a history of allergic

Discussion

This review shows that complete resolution of pulmonary thromboembolism is not routinely achieved between 8 days and 11 months after acute PE. Overall, > 50% of patients with PE have persistent defects at their follow-up scan 6 months after diagnosis (Fig 1). Afterward, resolution of thrombi seems to reach a plateau phase, since complete resolution is found in 43% of patients after 6 months and in nearly the same percentage of patients (48%) after 11 months. Of interest is the wide variation in

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