When Is It Time to Abandon Thrombectomy for Acute Stroke? New Clues

When endovascular thrombectomy procedures for acute ischemic strokes caused by large-vessel occlusions take too long or require more than three passes to get the clot out, outcomes worsen and complications rise, new data suggest.

As procedure time increased, the likelihood of having a good functional outcome at 90 days declined, with a big drop-off after 30 minutes. There was about a 70% chance of having a poor outcome if the procedure lasted more than 60 minutes, according to researchers led by Ali Alawieh, PhD (Medical University of South Carolina, Charleston).

Moreover, needing more than three passes to remove the clot was also associated with a reduced likelihood of having a good functional outcome, they report in a study published online ahead of the March 5, 2019, issue of the Journal of the American College of Cardiology.

“Exceeding 60 minutes or three attempts should trigger careful assessment of futility and risks of continuing the procedure,” they say.

The findings are consistent with prior studies showing that longer procedure times for stroke thrombectomy are associated with lower rates of functional independence, more complications, and higher cost, but the decision to give up on a procedure that is dragging on remains a difficult one.

Alawieh et al delved into the issue by examining data on 1,359 patients (mean age 67 years; 51% women) who underwent endovascular thrombectomy with either a stent retriever or aspiration as a first-pass technique between June 2013 and February 2018 at seven comprehensive stroke centers in the United States. Intravenous thrombolysis was used in 46% of cases.

The likelihood of a good functional outcome—defined as a modified Rankin Scale (mRS) score of 0 to 2—fell as procedure time increased, with a 40% drop-off after 30 minutes. The curve leveled off after about 60 minutes.

Longer procedures were also tied to exponentially rising risks of symptomatic intracerebral hemorrhage (sICH) and complications, with risks doubling for every 26 and 50 minutes, respectively, of procedure time.

In contrast, there was a more linear relationship between the number of recanalization attempts and functional outcomes, with a greater number of attempts associated with a lower likelihood of good results.

The researchers then divided patients into three groups according to procedure time: less than 30 minutes (rapid), 30 to 60 minutes (intermediate), and more than 60 minutes (extended). The rate of good functional outcome at 90 days was highest in the rapid group (45%), followed by the intermediate group (33%) and the extended group (27%). Mortality rates trended in the opposite direction, from 17% in the rapid group to 22% and 39% in the intermediate and extended groups.

Likewise, patients who underwent rapid procedures had the lowest rate of sICH and parenchymal hemorrhage type 2 (2.3%); that figure was 6.0% in the other two groups.

On multivariate adjustment, recanalization within 30 minutes was independently associated with a greater likelihood of good functional outcomes (OR 1.55; 95% CI 1.14-2.09) and a lower likelihood of sICH or parenchymal hemorrhage type 2 (OR 0.47; 95% CI 0.24-0.93).

The researchers found that in addition to procedure time, the number of attempts was important as well. When the intermediate and extended groups were combined, successful recanalization and good functional outcomes were associated with fewer attempts (P < 0.01).

“Each thrombectomy pass represents an independent interaction with the vessel with a finite complication rate, so that multiple attempts begin to cumulatively add to the risk profile,” the authors write.

Because use of a direct aspiration at first pass technique (ADAPT) was associated with a shorter procedure time compared with use of a stent retriever as the frontline approach (35 vs 59 minutes; P < 0.001), the investigators looked into differences between the two procedures in more detail. In addition to longer procedure times, the stent retriever group had lower rates of complete recanalization and a numerically higher mortality rate, although the latter difference was not significant on multivariate analysis. Functional outcomes at 90 days were similar with both approaches.

“This again highlights the idea that the time to gain access to the occlusion may not be as critical as the amount of time spent attempting recanalization once access is achieved,” the authors explain. “Performance of aspiration-based thrombectomy is associated with faster intracranial access times than stent retriever thrombectomy, which could explain why the aspiration cohort was more sensitive to procedure times < 30 min.”

Need to Better Identify Difficult-to-Treat Patients

Commenting for TCTMD, Albert Yoo, MD (Texas Stroke Institute, Plano), said the findings in terms of the relationships between poorer functional results and longer procedures and more attempts align with his personal experience. “If [the vessel] doesn’t open in the first three passes, you typically start getting pessimistic about the chances of, one, the vessel opening, and two, the patient having a good outcome,” he said.

Yoo added that the major point to take away from this study is not that performing faster procedures is better—interventionalists are already moving as quickly as possible in the setting of acute stroke—but that there is a need to better address the types of patients who require lengthy procedures involving multiple recanalization attempts.

“We need to figure out how to predict who these patients are that require these greater-than-60-minute procedure times, because people are moving quickly no matter what and there is a reason why it’s taking longer to treat these patients,” he said. “Likely, these patients are sicker, they have vascular tortuosity and other factors potentially clot-related that may make it difficult to open these vessels.”

Although successful thrombectomy often happens in one pass, Yoo said, a “substantial minority” of cases—maybe 25%—present challenges resulting in extended procedures and multiple attempts.

“I think that more research needs to go into predicting who these patients are and, more importantly, what types of maneuvers, potentially new devices, would better target these sorts of refractory clots,” he said.

As for the comparisons between stent retrievers and aspiration, Yoo said the field should defer to higher-level evidence from randomized controlled trials because this study involved a small number of centers, one of which is “very proficient” in aspiration and coined the term ADAPT. “Taking from this study that one approach is superior to another I think is a reach scientifically,” he said.