Walking a fine line: How managing blood clots might change heart attack prevention

Thromboembol in blood vessel. Clot formation, 3D illustration.
Most heart attacks are caused by blood clots. Anti-clotting drug therapy can help decrease the risk under the care of your doctor.

Among the many buzzworthy discussions I’m hearing this week at the 2017 European Society of Cardiology conference in Barcelona, Spain, is talk surrounding an important new study that was released at the conference and simultaneously published in The New England Journal of Medicine: the Cardiovascular Outcomes for People Using Anticoagulation Strategies, also known as the COMPASS trial.

Findings from the COMPASS trial might transform how we personalize therapies to prevent heart attacks in high-risk patients. We know that blood clots (thromboses), cause most heart attacks. A blood clot is formed when cholesterol builds up within the wall of the coronary artery and then comes in contact with blood, triggering a clot and clogging the artery and thereby compromising blood flow to the heart. The result is a heart attack, or myocardial infarction.

Research has shown that clot-suppressing (antithrombotic) drugs, including aspirin, increase the risk of bleeding while at the same time reducing the risk of heart attack, especially in those who have already had one and consequently are at increased risk for another. The COMPASS trial marks a significant advance in the longstanding effort to find the optimal balance of decreasing blood clots without thinning the blood too much.

Risks and benefits of clot-preventing medications

Antithrombotic drugs sometimes cause bleeding in the intestine, which over time can lead to anemia (low iron) or low blood counts. More serious is when bleeding develops in the brain, which can lead to a stroke.

Though the risk of brain or intestinal bleeding is present, the benefits of antithrombotic medication are greater than the risks in many patients at risk for heart attacks. Some high-risk heart disease patients also have risk factors for bleeding that affect the risk/benefit equation. Decreasing the formation of blood clots is vital in preventing heart attack, but we must do so without significantly increasing the risk of excessive bleeding. This risk varies from person to person, so a therapy that is effective and safe for one individual might be too risky for another.

The COMPASS trial examined different types of antithrombotic drugs and combinations of drugs, including low-dose aspirin and low-dose rivaroxaban (XARELTO), a drug that blocks a clotting component in blood cells called factor Xa. These types of drugs are called direct Xa inhibitors, and they work by interfering with and decreasing blood clot formation.

COMPASS trial researchers found that taking low-dose aspirin in combination with low-dose rivaroxaban lowered the risk of heart attack, cardiovascular death, and stroke by 24 percent as compared to taking aspirin alone in participants with stable atherosclerotic vascular disease (hardening of the arteries). However, the rate of major bleeding was 70 percent higher in the drug combination group as compared to participants who took aspirin only.

Even considering the increased risk of bleeding, the benefit of reduced heart events is incredibly important. In fact, this trial was stopped early due to unequivocally positive patient outcomes, which further proves the efficacy of the combined anti-clotting treatment.

When will patients benefit from these data?

The next step in taking the data from this trial into the clinical setting is to do further testing and analysis. One long-term goal is to determine which combination of drugs is most effective for particular populations. For example, individuals with additional risk factors for heart attack, such as a history of smoking or having had a previous heart attack, might require a different dosage or drug combination than a person who has a family history of heart attack but no other personal risk factors.

As further, more focused testing is conducted, we’ll learn more about combination anti-clot medications and how we can personalize them based on a patient’s individual cardiovascular health history and heart attack risk. In the meantime, continue to work with your doctor to find the safest, most effective drug combination to help protect yourself from a heart attack.

To talk with a preventive cardiologist about managing your heart attack risk, request an appointment online or call 214-645-8300.

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