Research Summaries



Introducing research papers published in high-impact medical journals by members of the Stroke group at the Melbourne Brain Centre.


Dr Bruce Campbell


Stroke is the leading cause of disability in adults and the second leading cause of death worldwide with 80% caused by a clot blocking a blood vessel that supplies the brain.  Clot-dissolving treatment to restore blood flow reduces disability but has limited effectiveness in patients with blockage of large blood vessels.

The EXTEND-IA trial tested whether a patient’s recovery from stroke is improved by conducting a minimally invasive procedure called “thrombectomy” (basically, pulling a clot out of a vessel), after also giving the patient a clot-dissolving medication e.g. tPA. 


The thrombectomy was performed via an angiogram, which involved inserting a small tube into an artery in the groin and feeding it up into the brain to capture the clot and remove it.  Half the patients had the thrombectomy after standard clot-dissolving treatment and the other half had clot dissolving medication alone. EXTEND-IA was conducted across 14 centres in Australia and New Zealand.   Previously, 3 trials of thrombectomy published in 2013 did not show benefit. However, these studies were limited by less effective devices, delays in performing the treatment and a lack of advanced brain imaging to identify patients most likely to benefit from thrombectomy.


In the trial, thrombectomy more than doubled the rate of successfully opening the blocked artery and also worked faster than the clot-dissolving medicine.  The rate of early improvement of stroke symptoms was also more than doubled, with 71% of thrombectomy patients independent at 3 months compared to 40% of patients who received tPA only.  There were no differences in the rate of death or major bleeding between treatment groups and no safety concerns with the thrombectomy procedure. 


As a result of this clinical trial, thrombectomy has now become the standard treatment for patients with stroke caused by a large artery blockage at the hospitals that participated in EXTEND-IA and in other centres around the world. In Australia, there are still a limited number of centres that are able to provide thrombectomy and limited specialist doctors trained to perform the procedure. Currently many patients have to be transferred between hospitals and rural patients rarely have access within a suitable timeframe. Thus, we are now working to re-design the system of care so that we can give patients rapid access to this treatment.


A/Prof Atte Meretoja


The major treatment for stroke is thrombolysis, which is the use of a pharmacological agent to break down the offending blood clot. A common clot dissolving agent is “tissue plasminogen activator” or tPA. The length of time between when a person has a stroke and when they receive tPA is a critical factor influencing their health outcomes. However, no studies had previously investigated the long-term effects of reductions in treatment delays - even small reductions. Could these small changes have a significant impact?


Our MBC Stroke researchers looked at 2258 people who had received thrombolytic treatment following stroke at Australian and Finnish centres between 1998 and 2011. Our findings showed that reducing the time to treatment by as little as a few minutes had significant benefits for the individual, resulting in extra days, weeks and even months of disability-free life. This highlights the importance and advantages of providing rapid thrombolytic treatment in the event of a stroke. Thus, it is crucial to promote the need for better community recognition of stroke symptoms and to develop improved technologies, such as mobile CT scanners, to assist in reducing treatment delays.




A/Prof Meretoja was interviewed by ABC News 24 to discuss this study in more detail.