A Study to Evaluate the Safety of Withholding Anticoagulation in Patients With Subsegmental PE Who Have a Negative Serial Bilateral Lower Extremity Ultrasound

Ottawa Hospital Research Institute292 enrolled

Overview

Blood clots in lung arteries (pulmonary embolism) are usually detected using a radiological test called computed tomography (CT scan). As technology advances, the CT scans are able to detect smaller and smaller blood clots. Over time, the frequency of blood clots in the pulmonary arteries has increased significantly (CT scan are now detecting very small blood clots that the investigators could not see before). As a result, more and more people are on blood thinners to treat these small blood clots but their true clinical significance is unknown. The management of blood thinners is costly and also utilizes scarce healthcare resources. These blood thinners need to be monitored with frequent blood work. Furthermore, every year, approximately 3 percent of patients on blood thinners will have a major bleeding event requiring medical attention. The investigators don't think that treating these small blood clots in the pulmonary arteries detected on CT scan is worth the risk of bleeding from the blood thinners. The main goal of this study is to find out if it is safe to not treat very small blood clots in the pulmonary arteries. The investigators plan to follow 300 patients with small blood clots in their lungs for 90 days. These patients will not be treated with blood thinners but will be followed closely with other non-invasive tests to avoid progression or recurrence of blood clots.

Study Type

OBSERVATIONAL

Enrollment

292

Conditions

Subsegmental (Single or Multiple) Pulmonary Embolism

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Age greater or equal to 18 years old. 2. Patients with newly diagnosed isolated SSPE\* (any number). * Isolated SSPE is defined as CTPA demonstrating an intraluminal filling defect in a subsegmental artery with no filling defects visualized at more proximal pulmonary artery levels. Exclusion Criteria: 1. Proximal lower extremity (popliteal vein or above) or upper extremity (subclavian vein or above) DVT. 2. Need for long term oral anticoagulant therapy for reasons other than VTE. 3. SSPE diagnosed in a hospitalized patient (\> 48 hours after hospital admission). 4. Requiring oxygen therapy to maintain an O2 saturation over 92% 5. Previous history of DVT (proximal or distal) of upper or lower extremities, PE, or unusual site thrombosis (e.g. splanchnic or cerebral vein thrombosis). 6. Geographically inaccessible for follow-up 7. Active Malignancy (defined as other than basal-cell or squamous cell carcinoma of the skin; cancer within the past 6 months; any treatment for cancer in the past 6 months; or recurrent or metastatic cancer) 8. Pregnancy 9. Have received more than 48 hours of therapeutic anticoagulation. * Prophylactic dose allowed if required for separate indication and acceptable by the investigator. 10. Unable/refuse to sign informed consent 11. Asymptomatic SSPE (e.g. SSPE is an incidental finding on a CT scan conducted for reasons other than suspected PE)

Locations (9)

Capital District Health Authority

Halifax, Nova Scotia, Canada

Hamilton General Hospital

Hamilton, Ontario, Canada

London Health Sciences Centre

London, Ontario, Canada

Ottawa Hospital

Ottawa, Ontario, Canada

Toronto General Hospital

Toronto, Ontario, Canada

Sir Mortimer B. Davis Jewish General Hospital

Montreal, Quebec, Canada

St. Mary's Hospital Centre

Montreal, Quebec, Canada

Centre Hospitalier Universitaire de Brest

Brest, France

Geneva Hospital

Geneva, Switzerland

Outcomes

Primary Outcomes

Recurrent VTE

Recurrent VTE will be diagnosed according to previously published criteria: 1)Lower extremity US revealing non-compressibility at the trifurcation of the popliteal vein or above; OR 2) Venography demonstrating a constant intraluminal filling defect above the trifurcation of the popliteal vein; OR 3) Pulmonary angiography demonstrating a new constant intraluminal filling defect or a cut off of a vessel; OR 4) Ventilation/perfusion scanning with a high probability of PE; OR 5) CTPA demonstrating new intraluminal filling defect in a subsegmental or greater sized pulmonary artery; OR 6) PE discovered at autopsy.

Time frame: 90 day follow-up

Secondary Outcomes

Interobserver agreement for SSPE diagnosis on CTPA (local Vs. central interpretation)

Time frame: 90 day follow-up

Death due to PE

Definition of death due to PE Certain: hypotension, hypoxia, cardiac arrest with no other explanation other than PE and autopsy or radiographic confirmation Highly probable: criteria for certain but another disease could have caused the death Probable: other cause suspected based on clinical evidence but 100% certainty not available Unlikely: all other cases

Time frame: 90 day follow-up

Death probably due to PE

Certain: hypotension, hypoxia, cardiac arrest with no other explanation other than PE and autopsy or radiographic confirmation Highly probable: criteria for certain but another disease could have caused the death Probable: other cause suspected based on clinical evidence but 100% certainty not available Unlikely: all other cases

Time frame: 90 day follow-up

Major bleeding

Major bleeding will be defined according to previously published criteria (51): 1. Fatal bleeding; OR 2. Symptomatic bleeding in a critical area or organ, such as intracranial, intraspinal, intraocular, retroperitoneal, intraarticular or pericardial, or intramuscular with compartment syndrome; OR 3. Bleeding causing a fall in hemoglobin level of 20 g/L (1.24 mmol/L) or more, or leading to transfusion of two or more units of whole blood or red cells

Time frame: 90 day follow-up

Minor bleeding

Minor bleeding will be defined as any bleeding not meeting the requirements of a major bleeding event.

Time frame: 90 day follow-up