PREVENTING CLOTS WITH MEDICATION (ANTI-PLATELETS AND ANTICOAGULANTS)
Drugs such as blood thinners are given to patients to prevent blood clot formation or to treat an existing blood clot. Examples include
Overview of Side Effects
Antiplatelets can increase your risk of bleeding. Even though aspirin can be purchased over the counter, it is important that you do not take more than the dose prescribed by your doctor. Report any of the symptoms stated below to your healthcare provider.
Anticoagulants increase risk of bleeding. If you are prescribed warfarin, there is a monthly blood test that is necessary to monitor and achieve optimal dosing. Read our patient’s guide to taking warfarin.
Important Precautions when taking anti-clotting medications
The INR is the International Normalised Ratio, a measure of how fast blood clots and this evaluates the effectiveness of warfarin in thinning your blood.
Your INR will be measured usually by pricking your finger to obtain a small droplet of blood which is put onto a special strip which can be analysed by a hand-held point-of-care device.
To help Warfarin work effectively, it is important to keep your vitamin K intake as consistent as possible. Sudden increases in vitamin K intake may decrease the effect of Warfarin. On
the other hand, greatly lowering your vitamin K intake could increase the effect of Warfarin.
To keep INR / PT stable and within the recommended range, it is important to:
To help make it easier to keep your intake of vitamin K consistent:
In other words,
Green leafy vegetables are among the best food sources of vitamin K. The average intake of vitamin K for most adults in the U.S. is 70 to 80 micrograms (mcg) per day. The Daily Value for vitamin K, an estimate of daily need, is 80 micrograms. The Percent Daily Values (%DV), listed on the tables below, help consumers determine if a food contains a little or a lot of a specific nutrient.
As indicated below, it is important to limit intake of foods that provide more that 60% of the Daily Value for vitamin K to help keep INR / PT in the desired range.
Foods high in Vitamin K (more than or equal to 200% DV)
Eat no more than 1 serving per day
Food Serving size % Daily Value
Kale, fresh, boiled 1/2 cup 660
Spinach, fresh, boiled 1/2 cup 560
Turnip greens, frozen, boiled 1/2 cup 530
Collards, fresh, boiled 1/2 cup 520
Swiss chard, fresh, boiled 1/2 cup 360
Parsley, raw 1/4 cup 300
Mustard greens, fresh, boiled 1/2 cup 260
Foods moderately high in Vitamin K (60 to 199% DV)
Eat no more than 3 servings per day
Food Serving size % Daily Value
Brussels sprouts, frozen, boiled 1/2 cup 190
Spinach, raw 1 cup 180
Turnip greens, raw, chopped 1 cup 170
Green leaf lettuce, shredded 1 cup 125
Broccoli, raw, chopped 1 cup 110
Endive lettuce, raw 1 cup 70
Romaine lettuce, raw 1 cup 70
Iceberg lettuce, red cabbage, asparagus, and soybean oil are often reported as being high in vitamin K. They contain much smaller amounts than foods listed in the tables above. These, and other foods and beverages not listed in the tables above (including coffee and tea), may be consumed as desired. Food Values are from the U.S. Department of Agriculture, Agricultural Research Service. 2003. USDA National Nutrient Database for Standard Reference, Release 16. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp
Alcohol intake greater than 3 drinks daily can increase the effect of Warfarin. However, some medical doctors advise those taking Warfarin to avoid all alcoholic beverages. Check with your doctor about this issue.
One drink = 5 ounces wine
12 ounces beer
1 1/2 ounces liquor
DIETARY SUPPLEMENTS AND HERBAL MEDICATIONS
Many dietary supplements can alter the INR/ PT. Dietary supplements known to affect the INR/PT include: arnica, bilberry, butchers broom, cat’s claw, dong quai, feverfew, forskolin, garlic, ginger, ginkgo, horse chestnut, insositol hexaphosphate, licorice, melilot (sweet clover) pau d’arco, red clover, St. John’s wort, sweet woodruff, turmeric, willow bark, and wheat grass.
Much is unknown about dietary supplements. The safest policy is for individuals on Warfarin to avoid all dietary supplements unless their physicians approve. This includes any vitamin/mineral supplements that list vitamin K on the label. If they are taken regularly on a daily basis, they pose less of a problem than if taken off and on.
VITAMIN E SUPPLEMENTS
Evidence suggests that vitamin E has blood-thinning effects. Vitamin E intakes above 1,000 International Units (IU) per day may increase the risk of excess bleeding. Research suggests that doses up to 800 IU may be safe for individuals on Coumadin®, but the evidence is not conclusive. It is best for those taking Warfarin to ask their physicians about taking Vitamin E supplements.
Some antibiotics can either lower vitamin K levels in the body or interfere with the activity of Warfarin. Check with your physician or pharmacist about whether you will need to adjust your vitamin K intake or Warfarin dose when you take antibiotics.
What are three important things to remember about Warfarin and vitamin K?
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HAS-BLED- Bleeding risk scoring system
H -Hypertension (uncontrolled)
Is your blood pressure more than 160 mmHg?
A – Abnormal kidney and/or function
Do you have serious kidney problems such as renal failure, are you on dialysis, or have you had a kidney transplant?
Do you have abnormal liver function?
S – Stroke
Have you ever suffered a stroke (even a mini-stroke)?
B – Bleeding
Have you ever suffered any serious bleeding?
L – Labile INRs
Are you on warfarin? (If your answer is no, then score 0). If you are on warfarin is your INR within the range of 2.0 to 3.0 most of the time? (If no, score 1)
E – Elderly
Are you aged 65 or more?
D – Other prescription drugs and alcohol
Do you take aspirin or pain-killers regularly together with a blood-thinning medicine?
Do you drink more than the recommended daily amount of alcohol?
Total maximum score possible
Your doctor will not prescribe a blood-thinning medicine if the risk of bleeding with such treatment outweighs the benefit of reducing your stroke risk.
Your blood-thinning medication may change over time as your risk of stroke changes, for example, as you get older, or if you are at risk of major bleeding by continuing to take a blood-thinning medication. Your doctor will discuss any changes that may need to be made to your medication as necessary.
There are also some situations when your doctor may alter the blood-thinning medication you take, for example, after a heart attack and/or when you have a stent fitted to open up a blocked artery in your heart. Your doctor will discuss any changes that may need to be made to your medication as necessary.
If you and your doctor decide that you would like to try to restore your heart rhythm from atrial fibrillation to the heart’s normal rhythm (known as “sinus rhythm”) then your doctor may suggest a controlled electric shock to the heart (known as ” electrical cardioversion”) or a specialist procedure known as “catheter ablation“. If you decide to have a cardioversion or an ablation procedure, you will need to take an anticoagulant drug for a period of time before and after the procedure to reduce the risk of a blood clot forming as a result of the procedure.
Surgery for atrial fibrillation may also be an option for some patients, with a procedure called surgical ablation or a Maze procedure. These procedures are usually only done in patients who are have heart surgery for another reason (for example, if you are having a heart valve replaced).
WHAT ARE NEWER ORAL ANTICOAGULANTS?
Yes, there are currently 3 alternative blood-thinning medicines available for people with atrial fibrillation which can help to reduce the risk of stroke by thinning your blood.
These new medications have all been successfully tested on thousands of patients with atrial fibrillation and are effective and safe medications which can be used to prevent strokes.
The limitations of warfarin (interactions with food, other drugs and alcohol, and the regular blood tests to monitor the INR) have led to development of these new medications, with the aim to make them more convenient for patients to take than warfarin and at least as effective and safe.
These medications work by blocking the main clotting factors (factors in the blood which help it to clot), factor IIa (which is also called thrombin) (dabigatran) and factor Xa (rivaroxaban and apixaban). These new blood-thinning medicines block the clotting factor itself, not the vitamin K. This means that they work differently to vitamin K antagonists (for example warfarin and acenocouramol) and there are no restrictions on food if you are taking one of the new blood-thinning medicines. In addition, the way the body responds to these new medications is much more stable than with warfarin, so you do not need regular blood tests to measure the effectiveness of these new blood-thinning medicines, as you do with vitamin K antagonists such as warfarin and acenocoumarol.
All 3 medications, dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis) are taken as a pill/tablet. Dabigatran (Pradaxa) and apixaban (Eliquis) are taken twice daily and rivaroxaban (Xarelto) is taken once daily. Unlike warfarin, these new blood-thinning medications do not require regular blood testing.
It is extremely important that you remember to take these new blood-thinning medicines as prescribed (once or twice daily depending on which medication you are prescribed) by your doctor to make sure that you get the protection against stroke that these drugs can offer. If you miss a dose you may be at increased risk of stroke.
DOES EVERY PATIENT NEED TO CHANGE FROM WARFARIN TO ONE OF THE NEW BLOOD-THINNING MEDICATIONS?
Not necessarily. For many patients warfarin gives similar protection against stroke compared to the new drugs but the risk of serious bleeding in the brain (known as intracranial haemorrhage) is much less with the new drugs. However, the new blood-thinning medicines are not suitable for every patient with atrial fibrillation, particularly those with severe kidney or liver problems. Many patients are very happy and confident about taking warfarin and don’t mind the regular blood test checks. Recommendations on blood-thinning medications and their availability may vary from country to country. If you would like to discuss which blood-thinning medicine is most suitable for you, please seek advice from your doctor (hospital doctor or general practitioner).