Hi. I had unprovoked pulmonary embolisms 3 years ago, and was put on a recently NICE approved anticoagulant Rivaroxaban . Much better than warfarin or aspirin I was told. But now that Ive been diagnosed with ET/MF. ( which I think I likely had at the the time, bur no none looked for it) Ive noticed that people only mention being on aspirin. Is fhere any reason for that, apart from the fact that aspirin is a lot cheaper?