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PHOENIX -- Transradial access for endovascular thrombectomy was noninferior to standard transfemoral access, a single-center randomized trial showed.

The rate of recanalization success was 87.9% (51 of 58) with transfemoral access and 96.6% (56 of 58) with transradial access, with an adjusted risk difference of 3.3% and a lower bound of -5.0% that fell within the noninferiority margin of -13.2%.

The secondary endpoint of final complete or near complete recanalization was similar between groups as well, Manuel Requena, MD, PhD, of Hospital Universitari Vall d'Hebron in Barcelona, reported at the American Stroke Association's International Stroke Conference. The findings were simultaneously published in .

However, the radial approach took longer -- a median 11 minutes longer from angio suite arrival to first pass (P<0.001) and 17.5 minutes longer from angio suite arrival to recanalization (P<0.05).

Greater safety, early ambulation, and reduced hospital costs drove adoption of transradial access in interventional cardiology for coronary procedures, and there's been growth in use for acute ischemic stroke treatment with mechanical thrombectomy as well. Retrospective case series have had disparate findings with regard to transradial access for endovascular stroke treatment.

"We have followed cardiologists in a lot of things in our field," Requena said at the session. "With more than 10,000 patients, they have seen that it is more safe for patients."

His trial, with just 116 patients, was underpowered for safety and disability outcome comparisons. And the advantages of transradial access (TRA) in percutaneous coronary interventions might not necessarily translate to endovascular stroke care because of the larger catheter systems and greater use of closure devices for transfemoral access (TFA) as well as the lower rate of antiplatelet and heparin use during mechanical thrombectomy.

Also, time is more critical for the brain than for the heart, Requena acknowledged. "In our field it is more important, these short delays." Given the similar rate of severe complications, those delays "may favor TFA as default first approach," his group wrote.

Reasons for the delays, the researchers pointed out, included greater experience by neurointerventionalists with TFA and use of ultrasound guidance for radial puncture and administration of verapamil before placing the 6F long sheath, "requiring more preparation time."

Requena noted that even the most experienced of the TRA neurointerventionalists at his high-volume comprehensive stroke center, doing at least 300 mechanical thrombectomy procedures per year, would fall in the lowest quartile for experience according to cardiology standards.

As far as anatomy, just 20% of the unselected patient population had aortic arch type 2 or 4, which is the group supposed to benefit by radial access.

Nevertheless, Requena concluded: "In my experience in my center, I think transradial is the future."

Neurointerventional practice can overcome the hurdles, his group suggested: "Simplifying TRA with some changes such as skipping the micropuncture set or guiding the puncture using anatomical reference instead of ultrasound may reduce the gap between TRA and TFA. Extending the use of TRA in elective cases (diagnostic angiography, aneurysm embolization, carotid artery stenting, etc.) would be a first step to increase experience before establishing it as first-line approach for a time-dependent pathology."

Other potential advances could be using clinical and radiological characteristics to select patients who might stand to benefit more from TRA as the first approach. "In the future, automated analysis of the aortic arch or artificial intelligence-guided decisions supported by clinical and radiological data might minimize the time from puncture to recanalization and access conversion rate," the researchers wrote.

Their single-center trial, dubbed SFERA, included 116 patients with moderate-to-severe acute ischemic stroke (National Institute of Health Stroke Scale ≥10) due to a large vessel occlusion of the anterior and vertebrobasilar circulation, either confirmed on the initial angiogram or highly suspected for cases that went directly to angiography without CT angiography before arterial puncture.

Patients were enrolled after ultrasound confirmation of femoral artery patency and a minimal radial artery diameter of 2.5 mm.

Patients were randomized open-label to TFA or TRA endovascular treatment performed by six certified neurointerventionalists with more than 2 years of experience in TRA procedures.

The protocol for transfemoral access called for use of closure devices (mostly Perclose ProGlide) and compression bandages for femoral access hemostasis at the end of the procedure. Radial access hemostasis comprised use of a compression band with kaolin (QuikClot).

Final reperfusion status and outcomes were assessed by internal core lab interventionalists blinded to treatment assignment. Successful reperfusion after mechanical thrombectomy was defined as expanded Treatment in Cerebral Ischemia (eTICI) scores of 2b or better.

Mechanical thrombectomies were mainly performed under conscious sedation (84.5%). Nearly all procedures (93%) used combined stent retriever and distal access catheter aspiration as the first-line approach.

Access conversion occurred in seven of the transradial cases (12.1%) and five of the transfemoral cases (8.6%), which was not a significant difference. After excluding access conversion, TRA remained noninferior to TFA.

Severe vascular access complications occurred at the same 1.7% rate, with one complication in each group: a death after a severe retroperitoneal hemorrhage due to a femoral pseudoaneurysm in the TFA group and radial artery occlusion with hand ischemia that resolved after surgery in the TRA group. Mild access complications occurred in 10.3% of TRA and 1.7% of TFA patients.

The researchers cautioned that their single-center trial design means that the results "may be strongly influenced by internal protocols and the results may differ in centers where radial is more or less expanded."

"Future multicenter randomized clinical trials powered to explore safety variables and 90-days functional outcomes are warranted," Requena noted.

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