Dawn Trial

January 21, 2018


Extending the treatment window for patients who have had an ischemic stroke from 6 hours to 24 hours significantly reduces disability and improves outcomes.

Those are the findings of a landmark clinical stroke trial that was recently published in the New England Journal of Medicine. The results validate protocols that have been used by Memorial Healthcare System’s (MHS) two Comprehensive Stroke Centers since 2014.

Several large scale studies published in the New England Journal of Medicine in 2015 ushered in a whole new era for stroke treatment with stentriever devices to remove blood clots in the brain. This type of therapy is called mechanical thrombectomy and it is now the standard of care in stroke patients with blockage of one of the major arteries supplying flow to the brain, also known as large vessel occlusion (LVO), who arrive at the hospital within the first 6 hours of symptom onset. Unfortunately, a significant number of stroke victims do not get to the hospital in time for these life-saving therapies.

In 2016, the DAWN trial took place among 50 sites worldwide to examine outcomes for patients presenting with stroke due to a large vessel blockage. The study utilized advanced imaging technology known as RAPID CT Perfusion (CTP) to assess regions of the brain deprived of blood flow in patients with LVO. The imaging technology has been shown to be useful in identifying patients who may benefit from aggressive treatment despite presenting in the later time windows after stroke onset.

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Datasource: Dawn Trial


Because of the innovative stroke protocols in place at Memorial Regional Hospital combined with its high stroke volume and efficient work flow, the hospital was chosen as one of only two stroke centers in south Florida to participate in the study.

Research shows that 20-30% of stroke patients arrive to the hospital well beyond 6 hours from symptom onset. These patients are classified as late presenting strokes. Also included in this population are patients who experience symptoms during sleep and have no knowledge as to the time of stroke symptom onset. Such patients have had limited treatment options available to them based on current American Stroke Association (ASA) guidelines and, as a result, suffer from long-term disability and poor quality of life.

However, that has not been the case for patients who present at Memorial Healthcare System’s Comprehensive Stroke Centers at Memorial Regional Hospital in Hollywood and Memorial Hospital West in Pembroke Pines.

Based on advanced imaging selection protocols, NeuroInterventional Surgeons at the healthcare system have been treating stroke patients who present themselves with symptoms well beyond traditional time windows and consistently demonstrate good outcomes. 

“For the folks in our community, the implications of the findings are significant because we know that large number of patients tend to present as wake up strokes or we simply do not know the time of symptom onset, said Brijesh P. Mehta, MD, a NeuroInterventional Surgeon and the Director of Stroke and Neurocritical Care at Memorial Healthcare System.

“As home to two Comprehensive Stroke Centers that perform among the highest volume of endovascular stroke procedures in the country, Memorial is proud to have designed stroke systems of care which ensure every patient will be considered for the most advanced endovascular treatments in the catheterization lab.”