Motivation: I made many resolutions this new year – one of them was to restart this blog. Many competing interests made me delinquent, but I am resolved to continue learning! For the first article of this year, we will turn to a long-standing issue in stroke neurology. Does intra-arterial therapy for stroke improve outcomes? Two years ago, I had thought about interventional neurology as a career but was dissuaded by the negative trials. Is intravenous tPA going away in 2015?
Paper: Berkhemer OA, Fransen PSS, Beumer D, et al. "A Randomized Trial of Intraarterial Treatment for Acute Ischemic Stroke." NEJM (2015); 372(1): 11-20.
Methods: A randomized, multi-center, open label but endpoint blinded trial in Netherlands in which adults admitted within 6 hours of stroke onset with imaging evidence of anterior arterial circulation occlusion were randomized to usual care (including IV tPA) or usual care plus intraarterial therapy (which consisted of mechanical thrombectomy and/or intraarterial thrombolysis). The primary outcome was modified Rankin scale at 90 days (0-6 with 2 or less indicating functional independence).
Results:
Cohort: 500 subjects (233 in intervention arm and 267 in control group) were randomized with mean age of 65 years (range 23 to 96) and 58% males. Median NIH stroke scale was 17 in intervention group and 18 in control. Around 80% in both groups had prestroke modified Rankin scale of 0. IV tPA was used in 87% and 91% of subjects in intervention and control group respectively. Most common imaging finding was M1 segment MCA artery occlusion. Median time from stroke onset to randomization was 204 and 196 minutes respectively in intervention and control groups. In the intervention group, time from stroke onset to groin puncture was 260 minutes.
Clinical Outcome: At 90 days, the median mRS was 3 in intervention group and 4 in control (unadjusted odds ratio of 1.66, 95% CI of 1.21-2.28). Adjusting for variables such as time from stroke to randomization, diabetes, atrial fibrillation, etc., the adjusted odds ration is 1.67 (95% CI: 1.21-2.30). When examining for independence (mRS of 0-2), 32.6% in intervention arm vs 19.1% in control group had mRS of 0-2 at 90 days (OR of 2.16, 95% CI 1.39 to 3.38).
Radiological Outcome: No intracranial occlusion was present in 75.4% in intervention group and 32.9% in control group. Final infarct volume was 49 mL in intervention group and 79 mL in control group.
Adverse Effects: No overall difference in serious adverse effects. However, embolization into new territory occurred in 8.6% of interventions, new dissection from manipulation in 1.7%, and vessel perforation in 0.9%.
Discussion:The trial shows that addition of intraarterial therapy to conventional IV tPA may have clinical benefit. This trial is in contrast to prior ones which did not show a benefit. Two reasons (among many) are that for part of the trial, the procedure was only offered within the context of the trial resulting in inclusion of many patients. In the US, many who are likely to benefit get the procedure anyway and are not included. Secondly, all the patients in this trial unlike previous ones had known arterial occlusion by imaging prior to randomization. While the results are encouraging, this new trial could also be the one lucky one showing benefit among many failed trials. Another major deficit was that the patients were not blinded and may have been biased while reporting! We will likely need follow-up corroborative trials elsewhere prior to accepting this therapy.
Paper: Berkhemer OA, Fransen PSS, Beumer D, et al. "A Randomized Trial of Intraarterial Treatment for Acute Ischemic Stroke." NEJM (2015); 372(1): 11-20.
Methods: A randomized, multi-center, open label but endpoint blinded trial in Netherlands in which adults admitted within 6 hours of stroke onset with imaging evidence of anterior arterial circulation occlusion were randomized to usual care (including IV tPA) or usual care plus intraarterial therapy (which consisted of mechanical thrombectomy and/or intraarterial thrombolysis). The primary outcome was modified Rankin scale at 90 days (0-6 with 2 or less indicating functional independence).
Results:
Cohort: 500 subjects (233 in intervention arm and 267 in control group) were randomized with mean age of 65 years (range 23 to 96) and 58% males. Median NIH stroke scale was 17 in intervention group and 18 in control. Around 80% in both groups had prestroke modified Rankin scale of 0. IV tPA was used in 87% and 91% of subjects in intervention and control group respectively. Most common imaging finding was M1 segment MCA artery occlusion. Median time from stroke onset to randomization was 204 and 196 minutes respectively in intervention and control groups. In the intervention group, time from stroke onset to groin puncture was 260 minutes.
Clinical Outcome: At 90 days, the median mRS was 3 in intervention group and 4 in control (unadjusted odds ratio of 1.66, 95% CI of 1.21-2.28). Adjusting for variables such as time from stroke to randomization, diabetes, atrial fibrillation, etc., the adjusted odds ration is 1.67 (95% CI: 1.21-2.30). When examining for independence (mRS of 0-2), 32.6% in intervention arm vs 19.1% in control group had mRS of 0-2 at 90 days (OR of 2.16, 95% CI 1.39 to 3.38).
Radiological Outcome: No intracranial occlusion was present in 75.4% in intervention group and 32.9% in control group. Final infarct volume was 49 mL in intervention group and 79 mL in control group.
Adverse Effects: No overall difference in serious adverse effects. However, embolization into new territory occurred in 8.6% of interventions, new dissection from manipulation in 1.7%, and vessel perforation in 0.9%.
Discussion:The trial shows that addition of intraarterial therapy to conventional IV tPA may have clinical benefit. This trial is in contrast to prior ones which did not show a benefit. Two reasons (among many) are that for part of the trial, the procedure was only offered within the context of the trial resulting in inclusion of many patients. In the US, many who are likely to benefit get the procedure anyway and are not included. Secondly, all the patients in this trial unlike previous ones had known arterial occlusion by imaging prior to randomization. While the results are encouraging, this new trial could also be the one lucky one showing benefit among many failed trials. Another major deficit was that the patients were not blinded and may have been biased while reporting! We will likely need follow-up corroborative trials elsewhere prior to accepting this therapy.
