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The stricter criteria for stroke thrombectomy presenting more than 6 hours after onset might not be warranted, according to a pooled trial analysis that found no different outcomes before and after that threshold with broader criteria.

Thrombectomy increased the odds of better functional outcomes, reflected in a shift in modified Rankin Scale scores, 2.54-fold compared with medical therapy alone in the adjusted model (P<0.0001).

That impact was just as good as the 2.49 odds ratio found in the of trials treating strokes before 6 hours, Tudor Jovin, MD, of Cooper University Healthcare in Camden, New Jersey, reported at the virtual International Stroke Conference.

Notably, in subgroup analysis, the treatment effect was even stronger among patients treated in the 12- to 24-hour window than in the 6- to 12-hour window.

"Why 6 hours? This cutoff point is somewhat arbitrarily chosen, but it is highly consequential," Jovin said. "Virtually all guidelines recommend different approaches to patients whether they present within 6 hours or beyond 6 hours. The beyond 6 hour selection is more restrictive, comes with more strings attached."

That was based on the stringent enrollment criteria of the two large trials, DAWN and DEFUSE, that helped push guidelines to expand the thrombectomy threshold to within 24 hours of onset.

However, for safety, the results were again similar in Jovin's pooled analysis:

• Symptomatic intracerebral hemorrhage was not significantly greater with thrombectomy after 6 hours last known well than with medical treatment alone (5.3% vs 3.3%, OR 1.74, P=0.2313), the same as in HERMES (4.4% vs 4.3%, OR 1.07, P=0.81)

• Mortality at 90 days was nonsignificantly lower with thrombectomy in that later window than medical therapy alone (16.5% vs 19.3%, OR 0.96, P=0.8774), the same as in HERMES with the earlier window (15.3% vs 18.9%, OR 0.73, P=0.16).

It would take treating only three patients to improve the functional outcomes of one, Jovin noted at the late-breaking trial session.

"We are in the dawn of the era of moving toward selection of patients-based physiological data rather than on time," Jovin said, expressing hope that his analysis would push in that direction.

Session moderator and conference chair Louise McCullough, MD, PhD, of the University of Texas Health Science Center at Houston, agreed: "More patients getting treated is always our goal."

The AURORA collaboration pooled individual patient data from those two large trials, and , along with four small trials: , RESILIENT, POSITIVE, and . The latter four were much smaller but all randomized patients to best medical therapy alone or with thrombectomy, whether stent retriever use only or mixed together with aspiration catheters.

The time window ranged from 6 to 24 hours in DAWN, 6 to 16 hours in DEFUSE, 6 to 12 in ESCAPE and POSITIVE, and 6 to 8 in RESILIENT and REVASCAT. Median time from stroke onset to randomization was about 10.5 hours, to puncture was 11 hours, and to reperfusion was about 12 hours.

All the trials required a proven proximal occlusion. The minimum NIH Stroke Scale score ranged from 6 to 10 (median ended up at 16), and imaging criteria varied.

Subgroup analyses favored intervention across age, sex, occlusion location, mode of presentation (witnessed or wake-up stroke), and when comparing the two largest trials against all others.