Aspirin surgery on neck arteries can prevent complications

Popping an aspirin the night before you are due to have surgery on neck arteries could help prevent a dangerous complication, a team of researchers at the University of Leicester has discovered.

The medical team found that taking an antiplatelet drug, clopidogrel, and aspirin the night before surgery to unclog neck arteries had enormous benefits. The work was funded by The Stroke Association and the UHL NHS Trust.

The findings, reported in Circulation: Journal of the American Heart Association, describes how carotid endarterectomy surgery removes the plaque that narrows neck arteries and increases the risk of stroke. While the surgery reduces the risk of stroke long term, it's associated with a small risk of stroke during and soon after the procedure. Stroke after the surgery happens because tiny clots called microemboli break off the surface of the cleaned artery.

"Worldwide, about 6 percent of patients will either die or have a stroke around the time of carotid endarterectomy," said study senior author Ross Naylor, honorary Professor of Surgery in the Department of Cardiovascular Sciences at the University of Leicester. "This is the first study that has ever shown that we might be able to prevent strokes caused by post-operative thrombosis by administering a tablet preoperatively."

Aspirin is traditionally given to all patients during carotid endarterectomy to prevent excess clotting, but some patients continue to clot. Researchers investigated why some patients appeared to be at higher risk of forming these blood clots.

They found that in high-risk patients, blood platelets, which initiate clotting, were highly sensitive to a chemical called adenosine diphosphate (ADP). The researchers found that aspirin was blocking one clot-activating path in the platelet, but not affecting the ADP pathway. The researchers thought that the antiplatelet drug clopidogrel, an ADP-inhibitor, might reduce the number of emboli going to the brain.

One 75-milligram (mg) tablet of clopidogrel reduced the overall platelet response to ADP by 8.8 percent, which resulted in a 10-fold reduction in the number of patients having more than 20 microemboli within three hours of surgery. Just as important, the one dose of clopidogrel - while enough to stop or slow clotting - did not cause excessive bleeding, which can also be dangerous in these patients.
"It is now possible to prevent a complication that was previously considered unpredictable and unpreventable," Naylor said. "It is important to stress, however, that this is a small study and was not powered to evaluate the clinical effect of clopidogrel in preventing strokes."

The study included 100 carotid endarterectomy patients who were already taking aspirin. Researchers gave 75mg of clopidogrel to 46 patients the night before surgery and a placebo to 54 others.

The researchers monitored patients with a transcranial Doppler (an ultrasound machine that can focus on the main blood vessel of the brain and detect microemboli) and angioscopy (checking the inside of the artery with a tiny camera before finishing the operation). Angioscopy enables surgeons to identify technical problems before blood flow is restored to the brain.

"The technique has nearly eradicated strokes occurring during the operation," Naylor said. "This study, however, is focused on preventing strokes that occur after the patient has woken up from anesthesia." 

The surgical team was led by Professor Ross Naylor and the project was run in association with Professor Alison Goodall (Professor of Thrombosis & Haemostasis) and Mr Paul Hayes (Clinical Lecturer in Surgery). The research was carried out by Mr David Payne, a Clinical Research Fellow, with assistance from Mr Chris Jones, a research working in Professor Goodall's laboratory. All staff are part of the Department of Cardiovascular Sciences at the University of Leicester.