blood thinner

A large clinical trial funded by Astra-Zeneca compared the safety between two blood thinners – clopidogrel and ticagrelor.

Heart attacks are the second leading cause of death in Canada. The development and trapping of blood clots in vessels that supply the heart with blood can cause heart attacks. In many cases, these clots can originate from a distant organ, travel in the bloodstream, and then get lodged in blood vessels supplying our heart.

When these clots lodge in blood vessels, the cardiologist attempt to widen the gap of the blocked vessel and restore blood flow through a procedure called percutaneous coronary intervention (PCI). However, under certain clinical scenarios, this procedure can carry great risks and it is not advisable to conduct this procedure.

Blood thinners aim to dissolve blood clots in vessels

Also, the round-the-clock availability of professionals who can carry out this procedure in an emergency is problematic in parts of the globe. In such cases, clinicians often prescribe blood thinners as pharmaceutical agents to dissolve undesirable blood clots. For these reasons, many pharmaceutical companies are now focusing on developing newer and more potent blood thinners.

Blood thinners are naturally-occurring or man-made substances that can prevent, slow down, or block the formation of blood clots. However, because blood clotting is an essential function, such blood thinner carries a risk of causing inadvertent bleeding in patients upon accidents (e.g. bruising). It is therefore very important to assess the safety and efficacy of such drugs.

Comparing the safety of two blood thinners: ticagrelor and clopidogrel

A recent clinical trial funded by Astra-Zeneca compared two blood thinners – ticagrelor and clopidogrel. Ticagrelor prevents platelet aggregation, which is one of the first critical steps that initiates a blood clotting reaction. The results of this trial were presented at American College of Cardiology’s 68th Annual Scientific Session March 16-18, 2019, in New Orleans, United States. The results of the study were also published in the Journal of the American College of Cardiology. 

A previous trial had shown the superiority of ticagrelor over clopidogrel. The goal of this trial was to compare the safety of ticagrelor and clopidogrel. The trial was coordinated by Research Institute – Heart Hospital (HCor) – São Paulo, Brazil. The trial enrolled over 3800 patients treated in more than 180 medical centers across in 10 countries on five continents. Many subjects were lower-income countries – where instant availability of percutaneous coronary intervention (PCI) is limited. The patients were randomly assigned to take either clopidogrel and ticagrelor.

Ticagrelor may be safer than clopidogrel

The researchers calculated a score that measures the combined rate of death from vascular complications, heart attack, stroke, and other such events 12 months after the treatment. The results showed that ticagrelor was safer in comparison to clopidogrel. The rate of such events was calculated to be 8% for ticagrelor and 9.1% for those on clopidogrel. The 1% difference in the rate of death from vascular complications suggested that clopidogrel has a similar safety profile when compared to ticagrelor.

The researchers also computed the rate of major bleeding events for both patient subsets. The rate of a major bleeding event was very similar for the two drugs differing by one 1%. The encouraging results from this trial suggest that there may be alternative and safe options that can be developed for managing heart attacks caused due to blood clots.

Written by Vinayak Khattar, Ph.D., M.B.A.

Reference: Berwanger, O., Lopes, R. D., Moia, D. D. F., Fonseca, F. A., Jiang, L., Goodman, S. G., . . . Nicolau, J. C. (2019). Ticagrelor versus Clopidogrel in Patients with STEMI Treated with Fibrinolytic Therapy: TREAT Trial. J Am Coll Cardiol. doi:10.1016/j.jacc.2019.03.011

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