ATACAS Trial
The ATACAS (Aspirin and Tranexamic Acid in Coronary Artery Surgery) study was established to answer a clinically important question: Should aspirin or tranexamic acid, or both, be used in people having heart bypass surgery? The trial is funded by a project grant from the NHMRC.
The trial commenced in May 2006, with the first patient being randomised at the Alfred Hospital, Melbourne. There are currently five centres (Monash Medical Centre, Geelong Hospital, Austin Hospital, St Vincent's Hospital and the Alfred Hospital) actively recruiting patients, with a further six sites awaiting ethics approval (Flinders Medical Centre, Royal Perth Hospital, Royal Adelaide Hospital, Escorts Heart Hospital India, Singapore General & Queen Elizabeth Hospital Hong Kong.) To date there have been 173 patients recruited to the trial.
In January 2007 the New England Journal of Medicine published the results of an observational study by Mangano et al. The study includ ed 4374 patients undergoing cardiac surgery and suggested that aprotinin, an antifibrinolytic drug, was associated with serious thrombotic complications. They concluded that there is a definite need for randomised controlled studies to answer the clinically relevant question: Are there safer and cheaper treatment alternatives to aprotinin?
Patients treated with aspirin (which is common in those needing heart surgery) have increased bleeding during and after surgery. Thus it is routine practice in most cardiac surgical centres around the world for aspirin to be stopped about one week before surgery.
However, a study published in the New England Journal of Medicine in 2002 found that patients who received aspirin early after their heart surgery had a lower death rate, as well as less heart attacks, stroke, and kidney failure. The authors believed that these beneficial effects could have occurred because aspirin prevents thrombosis (blood clots) in the blood vessels supplying the heart, brain and kidneys. Could it be that, although aspirin may cause more bleeding, there is a net benefit because of less thrombosis?
Another drug, tranexamic acid, is sometimes used to reduce bleeding after heart surgery. It works by blocking the clot breakdown that occurs early after heart surgery. This reduces bleeding, and the need for a blood transfusion. Importantly, there is some published information to suggest it is particularly effective in patients on aspirin. But we do not know whether or not tranexamic acid increases the risk of thrombosis (heart attack, stroke).
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