The heart disease drug heparin, what are the side effects?

Heparin is a heart disease medication to prevent possible complications that can be fatal, such as heart attacks and blood clots. Heparin is also commonly used for the prevention of blood clots or postoperative thrombosis. However, like other medicines, heparin can cause side effects. One of the side effects of heparin to watch out for is thrombocytopenia.

Before delving deeper into the side effects of this one heart disease drug, it's good to know how heparin works first.

How heparin works for heart disease drugs

Blood clots in the arteries leading to the heart can cause acute coronary syndromes, such as unstable angina (feeling of tightness in the chest) or heart attack. To prevent and / or treat this, blood thinners (anticoagulants) such as heparin are needed.

Heparin works to prevent blood clots by activating antithrombin III to block the action of thrombin and fibrin, two factors needed to clot blood. By inhibiting the activation of thrombin and fibrin, heparin thwarts the blood clotting process.

What are the side effects of heparin?

The heart disease drug heparin has several side effects that you should be aware of. Some of them are:

Bleeding: Heparin works to thin the blood, as a result, the body will be more prone to bleeding. If this happens continuously, the dose of heparin must be stopped immediately and an antidote is given, namely protamine sulfate.
May trigger allergic reactions and anaphylactic shock
Osteoporosis: occurs in 30% of patients on long-term heparin doses. Heparin can speed up the process of bone loss.
Increase liver transaminase enzymes
Thrombocytopenia (Heparin - induced thrombocytopenia /HIT)

Why does heparin cause thrombocytopenia?

Thrombocytopenia is a unique side effect of the heart disease drug heparin. Thrombocytopenia occurs due to an insufficient number of platelets or platelets, blood cells that play an important role in the blood clotting process. Generally, a decrease in the number of platelets will increase the risk of bleeding. That's why common symptoms of thrombocytopenia include easy nosebleeds and bruising, slow healing wounds, and heavy menstrual bleeding.

However, when thrombocytopenia is specifically triggered by the use of heparin, aka HIT, the risk of thrombosis or blockage of blood vessels is greater than bleeding. In fact, the decrease in platelets in HIT rarely reaches 20,000 / ul. This is due to the fact that HIT occurs due to the presence of antibodies against the Heparin-PF4 complex.

In the body, heparin will bind to Platelet Specific Protein Factor 4 (PF4). This complex will be recognized by antibodies. Then after binding to the Heparin-PF4 complex, the antibody will bind to the receptor on the platelets, causing platelet activation. This activation of platelets will result in the formation of blockage of blood vessels. Simply put, heparin, which is supposed to work to inhibit blood clotting, in some people the opposite: triggers platelet activation so that blood clots and clogs blood vessels.

How common is heparin-induced thrombocytopenia?

In people taking heparin for the first time, HIT can occur 5-14 days after dosing is started. In patients who have used this medication for heart disease before, heparin side effects may appear earlier (less than 5 days after starting therapy). Symptoms of HIT can appear late in some people, approximately 3 weeks after the dose is stopped.

Some sources say HIT is more prevalent in patients taking postoperative heparin and women with heart disease who are prescribed this drug.

Is thrombocytopenia due to heparin side effects dangerous?

HIT is a dangerous medical condition if it is not detected. According to Medscape, 6-10% of HIT patients die. For that, we need to recognize "4T" in patients who are taking heparin:

Thrombocytopenia (decreased body platelet count)
Timing from a decrease in the platelet count
Thrombosis (blockage)
There are no other causes of thrombocytopenia.

How do doctors diagnose HIT?

HIT can be detected by finding a decrease in platelets to <100,000 / ul or a decrease of> 50% of platelet values before therapy. About 50% of HIT patients experience blockage of blood vessels (Heparin induced thrombocytopenia and thrombosis - HITT). To diagnose thrombosis, an examination can be done doppler.

If the doctor detects signs of HIT, the doctor will do the following:

Immediately discontinue the heparin dose
Replace heparin with another anticoagulant. Here, anticoagulants should still be given given the high risk of blockage in HIT, and given up to + 1 month after the platelet levels returned to normal. Warfarin should only be given after the platelet count has returned to baseline.
No platelet or platelet transfusions should be given.
Evaluate blockage (thrombosis) with doppler or other checks.

Some literature recommends additional testing for HIT namely by Enzyme Linked Assay (ELISA) to detect antibodies to the heparin-PF4 complex; and serotonin release assay to see platelet activation. Serotonin linked assay more accurate in detecting HIT, but it is still difficult to find a health center that has this examination in Indonesia. The risk of thrombosis can be seen by the level of circulating antibodies.

Not everyone should be prescribed heparin for heart disease medications

Given the unique risk of heparin side effects, this heart disease drug should not be given to patients with a previous history of heparin drug allergy, bleeding disorders / disorders, alcoholism, or in patients with a history of brain, eye, and spinal cord surgery.