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Lengthy endovascular thrombectomy was associated with less benefit and more risk, a large retrospective study found.

Likelihood of good functional outcomes with a modified Rankin Scale (mRS) score of 0 to 2 took a 40% dive beyond 30 minutes of procedural time then plateaued at 60 minutes with an estimated 70% risk of adverse outcomes.

Functional independence rates were 45% for those treated in less than 30 minutes, 33% with procedures 30 to 60 minutes long, and 27% when procedures took more than 60 minutes (98 on average), reported Alejandro Spiotta, MD, of Medical University of South Carolina in Charleston, and colleagues in the .

Complication risk doubled after 50 minutes overall, while symptomatic intracerebral hemorrhage (sICH) risk doubled every 26 minutes. Mortality risk was significantly higher for the over 60 minute group than in those treated in 30 to 60 minutes (90 day, 22% vs 39%).

Each additional attempt at recanalization attempt had a linear impact on outcome, but 67% of recanalization success occurred within the first three attempts.

"In patients with procedure time <30 min or 30 to 60 min, fewer attempts but not shorter procedure time were an independent predictor of good outcome, which indicates that in addition to fast recanalization, the use of few recanalization steps was an independent predictor of outcomes," the researchers noted, whereas each minute mattered in the extended duration group.

Previous research has indicated that when it comes to mechanical thrombectomy, procedure time has a significant effect on patient outcomes. Procedures that lasted longer were associated with increased cost, worse outcomes, and increased incidence of complications, the investigators noted.

The new findings underscore the importance of timely recanalization and suggest there's a point at which continuing to manipulate the intracranial artery may not be helpful for the patient, noted Nestor Gonzalez, MD, of Cedars-Sinai Medical Center in Los Angeles, in .

Based on these findings, "it seems reasonable to conclude that at 60 minutes, one should consider the futility of continuing the procedure. It is also apparent that the number of thrombectomy attempts is negatively associated with good outcomes. However, in terms of defining the futility of additional attempts, it is less clear that 3 attempts should be the limit," Gonzalez continued.

"Time is brain, and time has always been brain. Whether it's stent thrombolysis or thrombectomy, the longer we take to recanalize the patients, the worse their outcomes are going to be," said Patrick Lyden, MD, also of Cedars-Sinai, who was not involved in the study.

Spiotta's group evaluated 1,357 participants (51% female, mean age 67) at seven U.S. medical centers. Of the patients, 12% showed signs of posterior circulation stroke and 46% of cases received IV tissue-type plasminogen activator.

Using a prospectively-maintained database that consisted of clinical and technical outcomes and baseline variables, the researchers evaluated patients that underwent endovascular thrombectomy with direct aspiration as first pass technique or a stent retriever.

"It's a retrospective study. They collected their experience retrospectively and combined it together, so there's always a chance of case ascertain bias or other bias in the collection of the cases. Another limitation is the fact that these are quality, busy centers, and the results might even worse if less experienced centers were included. It's a little bit like getting the cream of the crop and analyzing their data," said Lyden.

"Future studies should gather data on the relationship between specific thrombectomy devices and techniques and the success of recanalization procedures for patients with AIS," the study authors concluded.