East Asians may be at more risk of post-stroke complications due to a rare genetic disorder, a new study suggests.
Researchers found that patients of East Asian descent who underwent endovascular therapy to mechanically remove a clot in their large brain artery were more likely to have a rare genetic variant causing the vessel reclog shortly after or during the procedure.
The director of neurology at the National Cerebral and Cardiovascular Centre in Osaka, Masafumi Ihara, who led the study, said: “In the field of acute stroke, genetic testing has not been considered important.
“However, since our study found that a specific genetic variant substantially affects the outcome of endovascular therapy, physicians involved in acute stroke medicine, especially in East Asian countries and in western countries where many East Asian descendants are living, need to know these findings.”
When blood clots block a large artery which supplies blood to the brain, a severe stroke which has the potential to cause serious disability may occur.
The American Heart Association/American Stroke Association reports that clot-caused strokes account for 87 per cent for all strokes in the US.
The rare genetic variant studied, known as RNF213 p.R4810K is present in 1 in 50 individuals of East Asian descent and in 80 per cent – 90 per cent of those with the genetic disorder moyamoya disease.
Moyamoya is a rare, progressive disorder caused by blocked arteries at the base of the brain that can result in a stroke.
It is a disease is diagnosed by conventional brain angiography or magnetic resonance angiography (MRA) and symptoms are varied and stroke-related.
However, many people that have moyamoya disease may not know they have it until they have a stroke.
Bypass surgery is also a treatment option to increase cerebral blood flow, in addition to endovascular therapy.
Antiplatelets are used to subdue clot formation in constricted or narrowed arteries.
The researching team analysed the outcomes of 277 East Asian patients (53.8 per cent male, average age of 76) who had undergone endovascular therapy for an ischemic stroke at the National Cerebal and Cardiovascular Centre in Osaka, between 2011 and 2021.
All of the patients in the study sample had an acute anterior-circulation large vessel occlusion, a stroke where a clot blocks one of the large arteries responsible for supplying blood to the forebrain.
Numerous types of endovascular procedures are available to restore blood flow to the artery, including removing the blood clots through a stent retriever or suction device and opening the clogged vessel by inflating a balloon in the area and installing a stent to hold the blood vessel open.
The medical team determined the procedure that was performed and it was unrelated to whether or not the patient had the genetic variant.
Researchers compared 10 of the patients that were found to be carrying the RNF213 p.R4810K variant to 267 patients without the variant on several short-term outcome measures.
The results were adjusted for the age of the patients.
Those with the genetic variant and those without, at first are likely to have the same success with reestablishing blood flow to at least half of the brain tissue hat had been deprived of blood during the stroke.
Outcomes from the study included:
- Those with the genetic variant were far more likely (70 per cent) than non-carriers (5.6 per cent) to have the treated artery become re-blocked before the procedure was complete, known as instant reocclusion.
- Those with the genetic variant were also far more likely (60 per cent) than non-carriers (0.4 per cent) to have the treated artery become re-blocked within two weeks of an initially successful endovascular procedure, known as early reocclusion.
Ihara said: “We did not imagine this genotype would affect the outcome of endovascular therapy so substantially.”
“Information on the genotype will be useful for people who receive endovascular therapy (hopefully before the procedure) because individuals who are of East Asian descent and have the genetic variant need to be more strictly monitored than usual for reocclusion during and after endovascular treatment.”
The same sample size of patients that were discovered to have the genetic variant was unfortunately too small to determine which clot removal devices or medicines would be best at preventing reocclusion.
To help determine which methods would be best for preventing reocculsion, the research team are initiating a larger, multi-site study.
