Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
Because I had bilateral PEs and because they could never find the source of the original clot, it was SUGGESTED by my doctor and the hematologist he consulted with that I stay on for life. He said he would support me either way as many people in my position don't stay on yet never clot again - it would just be a bit safer if I stayed on.
That being said, I believe hetero means 8-12x more likely to clot, where home is 80x more likely. I am guessing they will want you on for life.
You might check out Clot Connect, which has the following article on how long to remain on anticoagulation treatment:
http://patientblog.clotconnect.org/2011/03/30/dvt-and-pe-how-long-to-treat-with-%E2%80%9Cblood-thinners%E2%80%9D/
Also, I will say that being on lifelong coumadin (or any other thinner) isn't as bad as it could be. I became a "lifer" at age 35 and I've been doing fine. I will suggest, if you stay on coumadin, to look into getting your own home tester for your INR. Makes life (and travel, especially) a lot more manageable.