Severe strokes, and promising thrombectomies

A major meta-analysis confirms the advantages of catheter intervention for more severe and moderate strokes. This therapeutic option must also be made available in rural regions.

October 29th is the World Stroke Day

Just in time for World Stroke Day on 29 October, a major meta-analysis now confirms the advantages of catheter intervention for more severe and moderate strokes. However, this therapeutic option must also be made available to patients from rural regions.

Most strokes are caused by blood clots, in which an artery suddenly becomes blocked and no more blood reaches the brain. Permanent damage can be prevented if the thrombus is dissolved or removed as quickly as possible - either by drug therapy (lysis treatment) or by a vascular catheter or endovascular surgery.

The most common cause of a stroke: a sudden stop in blood flow or reduced blood flow because a brain artery is blocked by a blood clot (thrombus). This leads to a lack of oxygen in the brain tissue and, depending on the area of the brain affected, to the corresponding stroke symptoms. As permanent damage occurs after just 4.5 hours, the blood flow must be restored as quickly as possible. Either through a drug-based thrombus dissolution (intravenous thrombolysis/short: lysis treatment) or in specialized centers through a vascular catheter or endovascular intervention (interventional thrombectomy).

Endovascular therapy for acute ischaemic stroke has an evidence level of 1. But does the therapy also have advantages for all patients? Even in those with only mild symptoms (National Institutes of Health Stroke Scale or NIHSS score <6) and those with severe symptoms (Alberta stroke program early CT or ASPECT score <6)? What are the results of the therapy if the treatment is not carried out in a "study setting" but in everyday clinical practice?

Meta-analysis looks at trials from ten years

In the meta-analysis that has just been published, 15 randomized controlled trials (RCTs, number of patients n=3,694), and 37 observational studies (n=9,090) were evaluated between 2009 and 2019, comparing the two therapeutic principles. Three groups were divided up based on the imaging data of patients at the time of hospital admission:

The modified Rankin scale (mRS) degree of disability: score 0-6, where 0=no symptoms and 6=death) was used to measure the outcome, 90-day mortality, and the rate of symptomatic cerebral hemorrhages in the first 24 hours after treatment.

Is thrombectomy better than lysis treatment?

In the randomized trials, thrombectomy was superior to lysis treatment (p <0.001 for a lower disability score; p=0.033 for mortality). In the "real life" settings of the observational studies, however, not all patients benefited equally from the intervention. Thrombectomy was associated with a lower degree of disability (better mRS values; frequent score 0-2) and lower mortality in patients with moderate strokes. However, these patients had more cerebral hemorrhages after the procedure.

In patients with severe cerebral infarctions, the invasive procedure was associated with less disability and lower mortality, and there was no difference in cerebral hemorrhage, so these patients benefited most from the treatment. Patients with mild strokes, on the other hand, had no advantage in terms of the degree of disability caused by thrombectomy, and the procedure was associated with higher mortality and cerebral hemorrhage rates in this group.

It depends on the severity of the stroke

Endovascular thrombectomy would therefore be the procedure of choice for patients with severe and moderate strokes. In contrast to the current guidelines, however, the meta-analysis data do not support the use of this procedure in patients with mild strokes (MSG; NIHSS score <6). According to the DGN (the German Society of Neurology), treatment should take into account not only the severity of the stroke but also factors such as the potential risk of anesthesia in older people.

However, the study also showed the need to improve care structures and create networks to enable people in rural areas to have access to mechanical thrombectomy in an experienced center.  While lysis treatment only has a treatment window of 4.5 hours, people with severe symptoms benefit from thrombectomy even later.

Zhao Z, Zhang J, Jiang X et al. Is Endovascular Treatment Still Good for Ischemic Stroke in Real World?: A Meta-Analysis of Randomized Control Trial and Observational Study in the Last Decade Stroke 2020 Sep 14 Online ahead of print. DOI: 10.1161/STROKEAHA.120.029742