Experts Disagree Over Endovascular Therapy for Acute Stroke
Speaking in favor of the proposition, Philip M. Meyers, MD, of NewYork-Presbyterian Hospital/Columbia University Medical Center, New York, contended that endovascular stroke therapy remains unproven and that evidence to date does not support its use outside of clinical trials. Moreover, CMS payment for endovascular stroke therapy has funded the development of a large network of centers that are underutilized.
He stressed that “time is brain” and thus timely treatment is critical, noting that in the IMS I and II trials, a patient’s chances of good clinical outcome decreased by 10% for every 30 minutes after symptom onset that they went unreperfused.
Interest in endovascular stroke therapy dates back about 30 years, but in 1998, the PROACT II trial put it on the map by showing superior recanalization and improved outcomes with intra-arterial prourokinase plus heparin vs. heparin alone.
Over the next decade, although trials continued to show good recanalization, the clinical outcomes deteriorated, likely due to treatment of patients with no chance of improvement, Meyers suggested. The tipping point came in 2013 when the New England Journal of Medicine published three randomized trials — IMS-III, MR RESCUE, and SYNTHESIS EXPANDED — showing no significant difference in functional independence with endovascular therapy compared with IV-tissue plasminogen activator (tPA) alone.
According to Meyers, the importance of imaging to determine tissue viability has been recognized by the field, but in the MR RESCUE trial, no difference in outcomes was seen between patients with or without a ‘favorable’ penumbral pattern by CT or MRI. Perfusion imaging has proven to be ineffective, and hopes rest with multimodal imaging, with core infarct volume emerging as a critical element. Furthermore, it appears that infarct volume must be very small for patients to have good clinical outcomes, and some data suggest that those with a larger infarct volume could be harmed by intervention.
Meyers concluded that endovascular stroke treatment remains experimental, and only a small fraction of stroke patients are eligible for it. The bottom line is that time is of the essence, he said, and therapy cannot be delivered fast enough in many cases. This situation could change, however, if an effective neuroprotective agent can be identified.
Potential for benefit
On the opposing side, Tudor G. Jovin, MD, of the University of Pittsburgh Medical Center, Pittsburgh, Pa., contended that use of endovascular therapy is justified in part by the dismal natural history of acute large-vessel stroke. For severe stroke, the chance of a good outcome is about 3% and of survival about 46%, he reported. Although only 5% of those with internal carotid artery occlusions treated with IV-tPA achieve good outcomes, a recent study showed a clear trend toward a benefit of endovascular therapy.
Two types of patients should be considered for this type of therapy, Jovin said. The “low-hanging fruit” patients are those not eligible for IV-tPA, in whom benefit has been directly demonstrated in the randomized PROACT II trial and indirectly shown in the SYNTHESIS EXPANSION trial. But patients eligible for IV-tPA should also be considered, even though endovascular outcomes are still suboptimal.
Importantly, better systems of care, technology and patient selection have been shown to yield improved outcomes compared with those reported in randomized trials thus far, Jovin said. The introduction of stent retrievers marks a revolution in endovascular therapy that is being translated into improved recanalization rates and better outcomes.
Meanwhile, Jovin urged endovascular practitioners to “get their act together” to reduce the time to reperfusion, noting that the time from tPA bolus to groin puncture was 85 minutes in IMS III, with another 85 minutes from therapy initiation to reperfusion.
Currently, the bottom line is that there are no randomized data, he said, although such data will be forthcoming, with some 10 randomized trials underway.
Perhaps unsurprisingly, the session audience, composed mostly of interventional cardiologists, voted overwhelmingly against the proposition.
- Meyers reports receiving consultant fees/honoraria from Codman and Stryker.
- Jovin reports receiving consultant fees/honoraria from Silk Road Medical.