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
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.