A new approach to stroke treatment initially developed by Dr. Jeffrey Saver's group at the UCLA Stroke Center combines the ability to restore circulation and remove clots using only a single device ... and it's showing significant promise in trials. In a study comparing the Covidien Solitaire FR Revascularization Device with the FDA-approved Merci Retriever, the device successfully and safely treated roughly 60 percent of stroke patients, compared to roughly 30 percent when the Merci Retriever was used.
Such treatment is intended to minimize brain damage due to lack of oxygen and/or glucose in patients presenting with blockage of large intracranial blood vessels - particularly those for whom the use of clot-dissolving drugs is not advisable.
Roughly speaking, there are four main steps in the operation:
1. Poke a hole in the clot with a microcatheter (roughly 2.5 mm/0.1-inch in diameter).
2. Slide the Solitaire device through the microcatheter until it extends on either side of the clot.
3. Slide the microcatheter back so that the Solitaire device expands and traps the clot.
4. Pull the Solitaire device back to the end of the microcatheter, and use suction to remove the clot from the blood vessel.
Various stages in the revascularization and clot removal procedure are shown in the picture gallery.
The Solitaire With the Intention For Thrombectomy (SWIFT) study was designed to compare the results of using the Solitaire on acute stroke patients with the FDA-approved Merci Retriever. The Merci Retriever functions like a corkscrew that snares and removes a clot, but has a tendency to uncoil and lose the clot.
The SWIFT study was ended prematurely because of the remarkable effectiveness of the Solitaire device. One hundred and forty-four patients with acute ischemic stroke who either were not candidates for clot-busting drugs or in whom they had been ineffective were chosen for the study. Patients were a mixed lot, but both treatment groups were very similar. The patients were randomly assigned to be treated with the Solitaire or with the Merci devices.
The results:
- Reestablishment of blood flow occurred in 83% of the Solitaire treatments versus 48.1% of the Merci treatments
- Reestablishment of blood flow without symptoms due to intracranial hemorrhage occurred in 60.7% of the Solitaire treatments versus 24.1% of the Merci group
- Good mental/motor functioning was restored within 90 days in 58.2% of Solitaire patients as compared to 33.3% of Merci patients
The Solitaire group had lower mortality at 3 months: 17.2% versus 38.2% for the Merci treated patients
"Initial treatment with Solitaire rather than Merci is associated with more frequent reperfusion, less symptomatic intracranial hemorrhage, reduced mortality, and increased good neurologic outcomes," says Dr. Saver. More simply put, the Solitaire device does its job more effectively and causes fewer problems while doing it.
The Solitaire is now approved for use in the Interventional Management of Stroke trial study. This is a stage III clinical trial, started in 2006, whose purpose is to examine if a combination of clot-busting drugs and intra-arterial therapy is more effective than clot-busting drugs alone. Among the intra-arterial therapies is the Merci Retriever. Even though over 675 of the 900 patients participating in the trial have already been studied, it has been expanded to include the Solitaire as an intra-arterial treatment for the remainder of the study.
Inclusion in the IMS clinical trial study reflects the enthusiastic response of the neurological medical community for the results of the SWIFT study. Hopefully the FDA will put Solitaire on the fast track as well.
