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Professor Graham Hillis

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Professor Graham Hillis

The aspirin in mechanical heart valves pilot trial

Professor Graham Hillis, University of Western Australia

2018 Vanguard Grant

Years funded: 2019-2022

Valvular heart disease remains a major cause of morbidity and mortality worldwide and in Australia, where it is particularly prevalent in indigenous Australians. Surgical valve replacement is the only option for many patients and in younger patients it is recommended that a metal (mechanical) heart valve is used. This is an effective treatment and the outcomes from surgery are excellent. However, metal valves are associated with a high risk of blood clots forming in the heart, leading to major complications such as stroke. To prevent this these patients must take lifelong blood thinning medication (warfarin). There is some evidence that patients with metal valves who also take regular low dose aspirin have less problems with blood clots and may even live longer than those who take warfarin alone.

However, this evidence has limitations. It is from small studies performed years ago, when metal valves were less well designed and blood clots were more common. In addition, the studies included patients who might have benefited from aspirin for other reasons. There are also risks associated with combining aspirin with warfarin, mainly a higher chance of bleeding. The lack of clear evidence means that in the USA it is recommended that all patients with a metal heart valve take both warfarin and aspirin, whereas in Europe (and likely Australia) this combination is usually only used in patients who are a highest risk. This may be correct - but it may be that we are depriving most patients with metal heart valves of a simple, inexpensive, treatment that would reduce their risk of stroke and premature death.

The only way to clarify the best treatment is a well designed clinical trial. This application seeks funding for the initial phases of such a trial. This will assess how doctors in Australia usually treat patients with a metal heart valve, involve patients in designing the study and begin the trial in 3 centres in Perth, where we will recruit 50 patients.

Last updated12 July 2021