Muhammad Zeeshan Memon, MD
Recently, two trials demonstrated that the benefit of endovascular thrombectomy extended beyond 6 hours to up to 24 hours after last seen well in selected patients. The DEFUSE 3 trial (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke 3) was a randomized study comparing medical therapy to endovascular treatment plus medical therapy 6 to 16 hours after last known well, and DAWN (DWI or CTP Assessment With Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention With Trevo) was a multicenter, prospective, randomized trial comparing medical treatment with Trevo stent retriever. Before these trials, there is very limited about effectiveness of thrombectomy beyond 6 hours.
The DEFUSE 3 investigators are now reporting the angiographic outcomes of patients who underwent endovascular treatment in the trial. Data collected from the DEFUSE 3 study also offer an opportunity to correlate angiographic data with baseline and follow-up non-invasive imaging and devices used to achieve recanalization. They reported that successful reperfusion [TICI 2B-3] was achieved in 70 of 92 patients (76%). Not surprisingly, TICI 2B-3 reperfusion showed a more favorable distribution of Rankin scores [0-2] compared with TICI 0-2A; odds ratio, 2.77; 95% confidence interval, 1.17–6.56; P=0.019. TICI 2B-3 was independent of the device used, the site of occlusion (internal carotid artery or M1) or adjunctive use of carotid angioplasty and stenting. In addition, significantly less infarct growth at 24 hours was seen in TICI 3 patients compared with TICI 0-2A (P=0.0015) and TICI 2B (P=0.0002) patients.
The 76% rate of successful recanalization reported in DEFUSE 3 is similar to DAWN (84%) and to the HERMES (Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials) meta-analysis of earlier time window trials (71%). These results suggest the ability to reperfuse large arteries with current devices is not adversely affected by treatment in an extended time window. However, DEFUSE 3 patients had a good collateral status with relatively small cores, which is a major factor that influences the ability to reperfuse large artery occlusions beyond 6 hours .Nevertheless, the results of this report are reassuring that recanalization rates in an extended time window are similar to earlier time window studies and lead to a higher rate of good functional outcome at 90 days in appropriately selected patients.