Anticoagulation and Pulmonary Arterial Hypertension

A common questions that comes up in caring for patients with PAH is whether they should be prescribed blood thinners such as warfarin or Coumadin. The answer to this question is a bit complicated.

Why is Anticoagluation Considered for PAH Patients?

For more than 30 years, we have believed that blood clots that form inside the small blood vessels of the lungs contribute to the progression of PAH. This is different from patients with Chronic Thromboembolic Pulmonary Hypertension (CTEPH) where the blood clots are the primary problem.

In contrast to the newer therapies that have been approved in the past 15 yeas, there are no high quality research studies looking at warfarin. The majority of the data evaluating the role of warfarin comes from retrospective studies (these are studies looking backwards at the charts of patients that were treated in the past and then trying to determine if warfarin was helpful).

PAH patientOn balance, the available data supports the use of warfarin in PAH patients with a risk of clotting. The intensity of anticoagulation is generally less intense for PH patients than for other indications. The strength of the recommendation is highest in patients with idiopathic PAH. Our practice is as summarized below.  The left column lists the type or cause of the PH, the middle column addresses if anticoagulation should be used and if so what the goal INR (the measure of how thin the blood is—a higher number equates to thinner blood) should be, and the right column are important comments.


 Type/Cause of PH
Anticoagulation Comments
Idiopathic Yes: INR 1.8-2.5 In the absence of increased bleeding risk
Familial (Not HHT) Yes: INR 1.8-2.5 In the absence of increased bleeding risk
Familial (HHT) NO High risk of bleeding
Diet Pill/Stimulant associated Yes: INR 1.8-2.5 In the absence of increased bleeding risk
Lupus/Mixed Connective Yes: INR 1.8-2.5 In the absence of increased bleeding risk
Scleroderma Variable High risk of bleeding from stomach
Cirrhosis/Porto-pulmonary No High risk of bleeding
HIV Variable Depends on other medications and problems
Congenital heart disease Variable Increased risk of bleeding if cyanotic (low oxygen levels)

It must be emphasized that each patient is evaluated on an individual basis. Non-PAH factors are always taken into account. Patients with other indications for anticoagulation such as prior blood clots in the legs or lungs, or atrial fibrillation are generally given warfarin at slightly higher target INR.

Patients taking warfarin must be aware of foods and medicines that interact with warfarin. In general we advise patients to eat a diet that has a consistent amount of vitamin K (fresh fruits and vegetables are rich in vitamin K, especially green colored vegetables). If you are taking warfarin, you should always ask your doctor if you need to make a dosage adjustment whenever you start a new medicine (this is especially true for antibiotics).

Are There Any Alternatives To Warfarin or Coumadin?

The FDA approved several newer blood thinners in the past few years. These include Pradaxa, Xarelto, Eloquis. These newer agents do not require monitoring of the blood levels. However, they are more difficult to reverse or turn off if there is a bleeding problem. At present these newer medications are not approved and difficult to obtain for PAH in the absence of atrial fibrillation or blood clots.

Should PAH Patients Be On Blood Thinners?

So, should you be on blood thinners? This is a complex question that requires you and your doctor to discuss the pros and cons. The advantage is that there is a strong suggestion of mortality benefit (that means that you live longer) in patients with idiopathic PAH and probably diet pill and stimulant associated PAH. The disadvantage is that there is a risk of bleeding while on blood thinners. This risk is low but not zero. Serious bleeding has been reported to occur in between 1-3% of patients per year. Targeting a slightly lower intensity of blood thinning may minimize this risk.

Common Questions From Patients On Blood Thinners?Looking for a PH specialists

Is sexual intercourse safe while on blood thinners? Yes

Will my menses (period) be heavier? Yes. In some patients we skip a few days of warfarin just before menses begins to prevent excessive bleeding.

Can I down hill ski while on warfarin? We recommend wearing a helmet and skiing cautiously.

Can I ride my bicycle while on warfarin? Yes, but always wear a helmet.

What happens if I cut myself? You will bleed more than usual. Most minor cuts will stop bleeding by holding pressure and elevating. If the bleeding continues you should go to the emergency department.

Can I shave with a razor blade while on warfarin? Yes, but if you nick yourself frequently you will have to hold pressure for quite a while. Many people prefer to use an electric razor to prevent this problem.

Can I take aspirin or ibuprofen or naproxen while on warfarain? No. use Tylenol/acetaminophen.


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