Lovenox Pkg Insert Updated Dec 2003

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I had a request for the latest info on Lovenox with Heart valves

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Mechanical Prosthetic Heart Valves: The use of Lovenox Injection has not been adequately studied for thromboprophylaxis in patients with mechanical prosthetic heart valves and has not been adequately studied for long-term use in this patient population. Isolated cases of prosthetic heart valve thrombosis have been reported in patients with mechanical prosthetic heart valves who have received enoxaparin for thromboprophylaxis. Some of these cases were pregnant women in whom thrombosis led to maternal and fetal deaths. Insufficient data, the underlying disease and the possibility of inadequate anticoagulation complicate the evaluation of these cases. Pregnant women with mechanical prosthetic heart valves may be at higher risk for thromboembolism.

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I also found this new study
Am J Cardiol. 2004 Jan 15;93(2):247-50.


Comparison of efficacy, safety, and cost of low-molecular-weight heparin with continuous-infusion unfractionated heparin for initiation of anticoagulation after mechanical prosthetic valve implantation.

Fanikos J, Tsilimingras K, Kucher N, Rosen AB, Hieblinger MD, Goldhaber SZ.

Cardiovascular Division, the Department of Pharmacy, and Center for Clinical Excellence, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.

We compared the efficacy, safety, and impact on postoperative hospital length of stay and inpatient hospital costs of low-molecular-weight heparin with that of unfractionated heparin as a "bridge" to achieving therapeutic levels of anticoagulation with warfarin in patients with newly implanted prosthetic heart valves. The patients who received low-molecular-weight heparin had a shorter length of stay and decreased postoperative costs compared with the control subjects receiving unfractionated heparin.

and this
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Am Heart J. 2004 Jan;147(1):3-15.


Periprocedural thromboprophylaxis in patients receiving chronic anticoagulation therapy.

Jafri SM.

Department of Cardiology, Henry Ford Hospital, Detroit, Mich 48202, USA. [email protected]

Patients receiving chronic anticoagulation therapy pose a clinical challenge when therapy needs to be interrupted for surgical or invasive procedures. Maintaining anticoagulation places them at risk for serious bleeding complications, whereas discontinuing anticoagulation puts them at risk of thromboembolic complications. Most patients can undergo dental procedures, cataract surgery, and diagnostic endoscopy without discontinuing anticoagulation. The main patient groups that may require a periprocedural alternative to oral anticoagulation (periprocedural thromboprophylaxis or bridging) include patients with prosthetic heart valves, atrial fibrillation, and hypercoagulable states and patients with chronic venous thrombosis who are undergoing surgery. Currently, there is little consensus on the appropriate perioperative treatment of patients on long-term warfarin therapy. There are an increasing number of studies that evaluate the benefits of periprocedural bridging with low-molecular-weight heparin (LMWH) in place of unfractionated heparin (UFH). An advantage of LMWH over UFH is that perioperative conversion from warfarin therapy with LMWH can be carried out in the outpatient setting, which is more convenient for patients and is cost effective. As with the use of UFH, there are reports of maternal thromboembolic complications with LMWHs in pregnant women with mechanical heart valves. This review brings together the available data on periprocedural bridging to assess the available options for patients on long-term warfarin therapy who are undergoing surgical procedures. It provides a rationale for using LMWHs while individualizing the risks versus benefits in a given patient population.

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I also just checked the US FDA approved prescribing information for heparin. There is not one word about using it with mechanical heart valves. Heparin was on the market before mechanical heart valves were developed. The idea that you are safer going into the hospital and getting a heparin drip is nothing more than a legend. There is considerably more good research showing that Lovenox is effective in preventing clots with mechanical heart valves than there is for a heparin drip.

I'm willing for everyone to challenge me on this by finding research done since 2000 or finding anywhere in the package insert that unfractionated heparin (IV drip) is approved or superior for use with mechanical heart valves.

I'll buy you a drink at the next reunion if you can prove me wrong.
 
Thanks for the info, Al. I sure won't be challenging your findings!
 
Al, Thanks! Good work. I've been looking into this by asking various docs how they would handle this or that situation. I found no consistent answers. Its still all up in the air. I'm glad I havn't had any "events" since surgery. But this is another reason to go tissue valve in my view.
 
Al writes:
>>>
I'm willing for everyone to challenge me on this by finding research done since 2000 or finding anywhere in the package insert that unfractionated heparin (IV drip) is approved or superior for use with mechanical heart valves.
>>>>

I had a question, knowing this will probably be an incredibly dumb question, but reading about this heparin drip issue makes me wonder if warfarin use has ever been proven to be effective in preventing blood clots from mechanical heart valves? I can't imagine they would do a study and compare one group on warfarin with another group without warfarin since no one would want to be in group 2. But just wondering if there is overwhelming proof that warfarin works for metal heart valves?
 
Hi Jim,

Yet another spin. Good question. I am sure Al does have your answer:)

Do recall reading something about the "early days" of valve replacement. They felt the aspirin therapy would be sufficent anticoagulation. It's a scary thought....but maybe some of us have just been plain lucky.
 
It's scary when our own Dr. Marty can't get any consistency in answers to his questions of fellow doctors when using the subject of Al's post. And Jim, good question!!

Yep, you're right Marty -- it's another reason to go tissue valve in my view too. In fact, I've got a whole barrel of reasons to go tissue. It still pisses me off that I wasn't even given a choice -- ER on Sunday, mechanical valve on Thursday and I wasn't in that bad of shape.

Regarding Coumadin -- I was told I would have to take a "pill" the rest of my life. "PILL?" you say, I say rat poison! At my post surgery visit with the surgeon, I asked him what would happen to me if I quit taking the Coumadin and he said I'd be dead in six months. I guess that's when I finally 'gottit' how serious this 'ball and chain' is going to be for the rest of my life. I hated Coumadin then and almost 5 years later, I hate it even more! Whew, that felt good...
 
To my knowledge there were no "controlled" evidence based studies on the efficacy of warfarin in controlling valve clots . However the pioneer heart surgeons got permission from the patients to do post mortem examinations and that is how they
accumulated anecdotal evidence of clots and valve malfunctions.
Warfarin seemed to reduce the number of clotting events so we have been using it ever since. We owe a lot to those heroic early patients and to the conpanies like St.Jude, Medtronic etc. that work to make better valves.
 
Janie, think positive. If you get bit by a rat, it will probably die.
 
I've always wondered about mosquitoes ... do their babies have unusual looking faces?

Like Marty said there are no studies. However, the FDA has examined the evidence and allowed the warfarin package inserts to say that it is indicated for use with mechanical heart valves.

Janie, do you want me to make a shirt that says, "I hate taking rat poison"?
 
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