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Endovascular interventions for acute ischemic stroke no better than intravenous fibrinolysis

Susan C Fagan, Pharm.D., FCCP, BCPS
Jowdy Professor and Assistant Dean
University of Georgia College of Pharmacy
March, 2013

Disclosure: As an investigator of the NINDS tPA Stroke trial that led to the FDA approval of intravenous tPA for acute ischemic stroke in 1996, I am biased in favor of IV tPA.

Strategies to improve upon the incomplete recanalization rates achieved with intravenous tPA have been in development since even before the FDA approval of tPA for ischemic stroke in 1996. Following in the footsteps of our colleagues in cardiology, endovascular interventions designed to reopen the occluded artery, while reducing or preventing the systemic exposure of the patient to a fibrinolytic, are incredibly seductive. In fact, use of devices approved by the FDA for their ability to reopen an occluded cerebral artery (Merci, Penumbra, etc.) have been used routinely in some institutions and even reimbursed by health insurance policies. In patients eligible for intravenous tPA, by-passing the FDA-approved therapy was sometimes chosen in order to facilitate endovascular intervention.

The only missing piece of data was the impact of the endovascular interventions on patient outcomes. In February, 2013, the results of two important investigations were published comparing the impact of intravenous tPA to endovascular interventions on ischemic stroke outcome at 90 days.1,2

The Synthesis Expansion trial1 randomized 362 ischemic stroke patients to either intravenous tPA or endovascular intervention with either intraarterial tPA or mechanical clot disruption or retrieval or a combination of both. Patients were to be treated within 4.5 hours of symptom onset and the primary outcome was survival without disability (modified Rankin 0 or 1) at 90 days. With 181 patients in each group, the time to randomization was 2:28 vs 2:25 (hr:min) in the endovascular versus IV tPA group, respectively, but the time to treatment was significantly earlier in the IV tPA group (2:45 vs 3:45; p<0.001). At 90 days, the proportion of patients with no disability was 30.4% in the endovascular group and 34.8% in the IV tPA group and this was not significantly different even when adjusted for baseline factors. The incidence of symptomatic intracranial hemorrhage was 6% in each group. The investigators concluded that endovascular interventions, requiring considerable more expense and expertise, are NOT superior to IV tPA. In fact, the trend in the data was toward improved outcome in the patients who received IV tPA and, if borne out, could have been due to the one hour time delay inherent in the institution of the endovascular intervention.

The Interventional Management of Stroke (IMS) III trial2 was published one day later and addressed some of the issues raised in the Synthesis expansion trial regarding time of treatment. In IMS III, all patients received IV tPA within 3 hours of onset of ischemic stroke symptoms and were then randomized to receive additional endovascular intervention or no additional treatment in a 2:1 ratio. The type of endovascular treatment varied with clinicians’ discretion but had to begin within 5 hours symptom onset. The trial was an international, randomized, and open-label trial with a blinded outcome. The primary outcome was independence (modified Rankin of 2 or less) at 90 days. The time from stroke onset to IV tPA initiation was 122.4 vs 121.2 minutes in the endovascular vs tPA groups, respectively. The trial was stopped prematurely for futility when 656 of 900 patients were enrolled. There was no significant difference in the number of patients with modified Rankin scores of 2 or less between endovascular (40.8%) and the IV tPA (38.7%) groups. The rates of symptomatic intracranial hemorrhage were 6.2% and 5.8% with endovascular and IV tPA groups, respectively. The investigators reported higher recanalization rates in the endovascular group and a tendency for earlier recanalization to be associated with better outcome but did conclude that an open artery does not guarantee a better outcome.

Summary

The place of early IV tPA as the only proven acute therapy for treatment of acute ischemic stroke remains secure. There are no data to support the use of endovascular interventions over IV tPA in eligible patients. Routine use of endovascular interventions in the treatment of ischemic stroke patients cannot be recommended. This is another case of a very elegant and seductive treatment in search of an indication.

References:

  1. Ciccone A, Valvassori L, Nichelatti M, Sgoifo A, et al. Endovascular treatment for acute ischemic stroke. N Engl J Med 2013; epub February 6, 2013

  2. Broderick JP, Palesch YY, Demchuk AM, Yeatts SD, et al. Endovascular therapy after intravenous t-PA alone for stroke. N Engl J Med 2013; epub February 7, 2013
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