My permanent IVC filter was placed the day of my PE event, and my target INR was still 2.0-3.0. Eventually that was raised to 2.5-3.5 but that had nothing to do with the filter.

Ditto. I'm targeted at 2-3 with my filter.

The filter isn't fail-safe, small clots can still get by or the whole device can become clogged. INR at 2-3 keeps clots from forming to begin with so the filter doesn't have to do it's job. But in some folks who can't be on coumadin then IVC is an alternative. I had mine removed back in December (it had been in for 6 months).

I might mention that though it's possible for the things to happen that petvs mentioned, it's not common. In fact, I was only allowed by my doctors to come off coumadin because I have the filter in.

This is one topic where it seems there's really a divide in standards and protocol,no?

I was given a permanent filter because the intent was that I would NOT be on warfarin for life, only for 6 months. However, since I had a second DVT after going off warfarin, I have the benefit of a filter and warfarin for life. I have an aunt who had a permanent filter inserted before a major surgery, since she had a long history of superficial clots (not a DVT) and was a high risk of clotting due weight. She does not take warfarin.

You read and hear so much stuff-- permanent filters should only be used when on warfarin, a permanent filter can be used if not on warfarin, don't get a filter at all, only get temporary filter.

I think so much of it is a judgement call and which side of the arguement your doc falls. I think the size of the clots in my lungs played a part in my doc's decision to insert a filter, a sort of just in case thing. I was comfortable with having a filter regardless if I was on warfarin or not. The potential benefit outweighs any possible risk, to me.

The biggest follow-up study to date involved 400 patients split between a filter group and a no-filter group. Overall the filter group had a higher recurrence of DVT but a lower incidence of PE. These were patients of somewhat older age than was the case in some other studies. Overall mortality was essentially the same between the two after an eight-year followup, with PE being the cause of death for less than 2% of study patients.
A medical advisor may say to stay on warfarin because of any possible higher risk of recurrent DVT, or may incline toward going off with any additional proection from PE, or may make a different determination for their own reasons.
http://www.circ.ahajournals.org/cgi/content/full/112/3/416
While on the warfarin in the first year post-PE I was kept at 2-3 as would have been typical. I am still maintained there indefinitely as a chronic patient, and with the IVC in situ.

That study is why I pushed to have my filter removed. There are several other studies from 2004, 2005 and 2007 that suggest similar, not a huge long term benefit (mortality) for both anti-coagulation therapy and the filter vs anti-coag therapy alone, but some suggetion that long term filter use may end up being a factor in re-clotting for DVT patients or issues of clotting at the site of the filter. This area really needs some additional study as RMB suggested but I didn't feel like being the guinea pig. -P