Blood Clots: When should you stop anticoagulation?

In this video from MedCram, Dr. Seheult discusses when anticoagulation for a blood clot should be stopped.

In the United States, almost a million people every year are diagnosed with a blood clot (venous thromboembolism). Almost all of them get put on some type of anticoagulation. The question is how long should they be on that treatment? Blood clots block the transportation of blood and as a result there is tissue downstream that isn’t getting enough blood and tissue upstream that is getting engorged with blood.  The body has a blood-clotting cascade that involves multiple factors and is too detailed to discuss here, but there are a number of things that can go wrong leading someone to be prone to clotting (hypercoagulable) or even cause bleeding. 

What are risk factors for blood clots?

Risk factors for clotting include obesity, pregnancy, oral contraceptives, sitting for prolonged periods, smoking, injury or surgery, age especially over the age of 60, family history of blood clots, hematologic disorders, chronic inflammatory disease, cancer, and atrial fibrillation. 

There’s even medications that can contribute to clotting including clotting factors, cortisone and ACTH, gonadotropins and drugs related for assisted pregnancy, chemotherapy drugs, valproic acid, furosemide, gold and even heparin which is a blood thinner but can cause clots in some people. One of the vaccines used in COVID-19 initially, the Johnson & Johnson vaccine, caused some people to have blood clots in their brains and eventually the vaccine was pulled off the market. 

Difference between provoked vs unprovoked blood clots?

When you look at the risk factors there are two different types of blood clots–ones that are provoked and ones that are unprovoked. To understand how long someone needs to be on anticoagulation it really depends if the cause or risk for the original clot has been removed. So an example of a provoked blood clot could be related to a pregnancy and this risk will eventually go away so this is a provoked cause. However, in contrast, age can’t be changed or removed.  This would be an unprovoked cause.  This will determine how long someone will need to be on their anticoagulation. 

Studies on anticoagulation treatments

This study was a retrospective study and it used patients who were started on rivaroxaban within 7 days of their first unprovoked blood clot and received three months continuous treatment. Patients who were treated beyond the 3 months formed the continued cohort and the remainder formed the discontinued cohort. The study found that continued rivaroxaban treatment beyond an initial 3 or 6 month treatment significantly lowered the risk of recurrent clots without a significant increase of major bleeding compared to treatment discontinued at 3 or 6 months. This means that for an unprovoked blood clot, and we don’t know what caused it, then this study implies that patient’s do better with longer time periods of anticoagulation. 

This discussion needs to be done with the treating physician to get the best treatment for an individual. 

 

LINKS / REFERENCES:

Clinical outcomes of prolonged anticoagulation with rivaroxaban after unprovoked venous thromboembolism (RPTH) | https://www.rpthjournal.org/article/S…

 

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