Clinical Trial of Stroke Treatments

Findings on Antiplatelet Therapy

A clinical trial investigating stroke treatments revealed that administering three antiplatelet therapy drugs offers no advantage over the use of two and is linked to an increased risk of bleeding. Previous large-scale clinical trials established that initiating treatment with two antiplatelet therapy drugs following a stroke, rather than one, significantly decreases the likelihood of experiencing a second stroke. To explore whether three drugs might be more effective than two, a multinational team of researchers from the UK, New Zealand, Denmark, and Georgia conducted this clinical trial, with results published in The Lancet.

Understanding Stroke

A stroke occurs when blood flow to the brain is interrupted, depriving brain cells of essential nutrients and leading to potential damage. In the case of ischaemic stroke, this disruption happens due to a blockage or clot in a blood vessel. Additionally, some individuals may experience a mini-stroke, where a small clot temporarily obstructs the artery.

Clot Formation

Clots form when blood components known as platelets aggregate. While this mechanism is crucial for stopping bleeding, it can be harmful in stroke situations. The risk of a secondary stroke is highest immediately following the first one, prompting the use of antiplatelet therapy in stroke patients, with aspirin being a commonly recognized antiplatelet drug.

Design of the Clinical Trial

The researchers structured the clinical trial to ensure high-quality evidence. This involved a significant number of participants from various hospitals and employing randomization for treatment assignment, akin to a coin flip, to eliminate bias. A total of 3,096 patients who had experienced either an ischaemic stroke or mini-stroke within the last 48 hours were enrolled. These patients received either one, two, or three antiplatelet therapy drugs, and were monitored for 90 days.

Outcomes and Early Termination

During the study, researchers tracked recurrent strokes, stroke severity, bleeding events, and quality of life. However, midway through the study, after 76% of the targeted patient enrollment was achieved, an independent safety monitoring board halted the trial. The board noted that patients receiving three antiplatelet therapy drugs experienced more bleeding, including severe cases, with no significant benefits observed in stroke recurrence compared to those receiving two drugs. Furthermore, there were no notable differences in mortality or quality of life among the groups.

Recommendations Against Three Drug Therapy

The research team advises against prescribing three antiplatelet therapy drugs following a stroke. They noted that the increased bleeding risk may have been influenced by a separate medication administered to some patients that dissolves clots. The combination of this clot-dissolving drug with antiplatelet therapy might elevate the risk of severe bleeding. However, the researchers assert that the clot-dissolving medication should have been eliminated from the body before antiplatelet therapy initiation.

In conclusion, the researchers recommend continuing adherence to existing guidelines, which advocate for the use of one or two antiplatelet therapy drugs after an ischaemic stroke or mini-stroke.

References

(1) Bath P, Woodhouse L, Appleton J, et al. Antiplatelet therapy with aspirin, clopidogrel, and dipyridamole versus clopidogrel alone or aspirin and dipyridamole in patients with acute cerebral ischaemia (TARDIS): a randomised, open-label, phase 3 superiority trial. Lancet. 2017. doi:10.1016/S0140-6736(17)32849-0.
(2) Heart and Stroke Foundation. What is stroke? http://www.heartandstroke.ca/stroke/what-is-stroke. Last accessed May 18, 2018.