The DAWN Trial: An Update on Thrombectomy for Stroke


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Nurses Edition Commentary

Kathy Garvin, RN and Lisa Chavez, RN

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Kevin G. -

the written summary says: " We need to be smart regarding administration of tPA as well.
Giving alteplase to patients later on in their disease course has
increased risk. We know that giving it earlier decreases the risk
of bleed." what it should it should say is "... decreases the risk of bleed compared to giving it later."

this is what you mean, but of course the risk of bleed is increased by a lesser amount, not decreased.

Evie M. -

Kevin, that was indeed implied as part of the context, but thanks for adding clarification.

Mark M. -

It is important to emphasize what little applicability the DAWN trial has for most ERs in the US. It took almost 3 years from 26 very large centers (doing more than 40 thrombectomies annually) across 3 countries to find 207 patients whose NIHSS >10 with very strict criteria found on CT perfusion requiring specialized software.

The only way the DAWN trial has any applicability is if a lot of EDs are not just guilty of "indication creep" but rather choose to "blindly run" their programs without following many of the very specific conditions required in the DAWN trial.

Evie M. -

You make a good point in that the indication for thrombectomy is specific, and will not be applicable to many of our patients with stroke. However, we will not find those patients if we are not screening patients with stroke. Opening up the time window for stroke evaluation makes it possible that these patients will be found and treated. Let's not confuse "indication creep" with proper application of stroke assessment tools. The prehospital providers and emergency physicians are the front line for finding these patients - if we are not opening the time window, patients who may have qualified will lose the opportunity for thrombectomy. Indication creep is a function of performing the intervention on an inappropriate patient - has less to do with the assessment and evaluation of the stroke patient.

Mike J., M.D. -

Couple things,

At this point we have no useful tools other than CTA to determine LVO stroke. The literature is rife with scoring tools, but none have adequate sensitivity/specificity to find these strokes. At my shop, we go immediately to CT/CTA from EMS for patients with a positive Cincinnati stroke scale, within the appropriate time frame, (for us this is <6hrs for Anterior Circ <12 for posterior). We have not moved to CT perfusion as of yet. Your statement that CTA/CTP for all may be applicable in larger centers with rapid access to neurointervention. In rural areas it may be that it is MORE Important to do CTA/CTP sooner, to facilitate transfer to a neurointerventional facility. In my world this can take 5-6 hours and thus, earlier dx=earlier tx.

Ian L. -

There are possible advances in the efficacy and safety of Thrombolytics in large vessel occlusion with the Extend IT trial published from Australia finding Tenecteplase IV superior to Ateleplase in a trial of 200 plus patients with middle cerebral artery and other large artery strokes .
With research better Thrombolytics safer and efficacious ought be discovered that with better endovascular therapy ought improve treatment of stroke .
For TIA large artery occlusion can be sought and maximal medical dietary (vegan low salt) graded exercise and stress reduction therapy offered .

Katherine B. -

I am writing for a clarification.

Does this new study indicate we should not give tpa if the patient is a potential transfer for endovascular approach?

My particular hospital has a goal of tpa in 270 minutes and this is often a narrow window to obtain.

Also, there are hurdles to achieving a timely cta at my hospital. Should I only call about an evaluation for endovascular treatment if i have both the ct and cta?

Thank you for the clarification.

Anand S. -

Great questions
In the majority of studies, systemic tPA given to all eligible patients meaning if they presented < 4.5 hours after onset, they got lytics AND neurointerventional therapy. In the studies looking at longer time to therapy (DAMN, DEFUSE 3), if patients presented > 4.5, they were either treated with neurointerventional or standard treatment alone.
While I'm not much of a fan of tPA in stroke overall, current guidelines support using it in patients presenting at < 4.5 hours and then considering further treatment (ie endovascular/neurointerventional).
If CTA is difficult to obtain, you should probably be prepared to transfer patients with suspected LVO (large vessel occlusion) prior to obtaining CTA. From a resource standpoint, this means that it's important to be able to delineate clinically who could have an LVO. We don't have ideal ways to do this. Most of these studies looked at NIHSS > 6 as a trigger to consider LVO though there are other approaches being investigated.
Bottom line, if you are not a stroke center and you have a patient in whom you suspect LVO, you should be transferring to a stroke center.
Of course, I say all this understanding that this will lead to increased transfers and resource utilization with small gains as the group of patients for endovascular therapy is small.

Katherine B. -

Thank you!

Ian L. -

Intensive LifeSyle Changes for Reversal of Coronary Heart Disease : a paper authored by Dean Ornish et al in JAMA 1998; 280:2001-2007 :
Objectives :To determine feasibility of patients to sustain intensive lifestyle changes for a total of 5 years (without lipid lowering drugs ) on coronary heart disease .
They had twenty patients in an intensive group and twenty in a usual care for the early 1990s standards of care .
Angiograms to measure Stenosis at baseline one year and 5 years .
Conclusion : " More regression of coronary atherosclerosis occurred after 5 years than one year in the experimental group with 10% fat Vegetarian diet moderate aerobic exercise stress management training smoking cessarption and group psycholosocial support reduction training
Also half the cardiovascular events in the high intensity healthy lifestyle experimental group than usual care .
So in high risk for ischaemic stroke patients a repeat trial with the low salt plant based diet graded exercise stress reduction psychosocial support plus maximal medical therapy with measurement by MRA angiogram for Large vessel stenosis Monitor of atrial fibrillation events and carotid artery narrowing and Adverse Cerebrovascular Events for High Risk patients from aged 60 for one to five years ought add gravity to recommendations to impact motivation and guideline recommendation .

Jonathan G. -

question for Dr Evie,

Can you give us an example of how/when you fit CT Perfusion into the imaging algorithm?


Evie M. -

Great question, and it comes up a lot. Briefly, here's how I think about it:
Pt comes in as stroke alert - exam and get noncon CT.
If there's a bleed - do what you need to do and admit (reverse anticoag and lower BP prn)
If no bleed - consider tPA within the guidelines
also ask yourself: is the exam consistent with large vessel occlusion (LVO)?
If so - get a CTA and CTP if you have the capability and are in the time window (this will give you information re: penumbra tissue that's at risk vs core tissue that's already dead and not salvageable. if large penumbra and small core = great candidate for thrombectomy if within the window, which now is 24 hours depending on the case. if large core and small penumbra = poor candidate because of higher risk for reperfusion hemorrhage)
If not - call neurology and your interventionalist to discuss whether they would consider thrombectomy and proceed from there with agreed upon imaging.

Now I can hear some people screaming because if not LVO, then considering thrombectomy is outside the indication! Yes it is, but if your patient has a basilar artery occlusion, you are only going to help and can't make the outcome any worse. Think about that - its worth a discussion.

Swami and Salim have put together a more detailed graphic of this and explanation with references at REBELEM:

Jonathan G. -

Thanks so much Dr Marcolini!

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