OK, so I admit PCI for stroke is something I made up, but I think it’s a reasonable analogy. Given that treatment for STEMI moved from tPA to PCI then it’s hardly surprising to see a similar trend in the stroke world.
The idea is to remove (or sometimes lyse intrarterially) the cerebral arterial occlusion using interventional radiology. Whatever you make it’s certainly pretty cool and ambitious technology. There are a number of trials and devices out there for this type of thing, perhaps the most famous being the MERCI device.
Below is a review of two recent studies that compared new devices against the MERCI device.
Nogueira, Raul G, Helmi L Lutsep, Rishi Gupta, Tudor G Jovin, Gregory W Albers, Gary A Walker, David S Liebeskind, Wade S Smith, TREVO 2 Trialists. “Trevo Versus Merci Retrievers for Thrombectomy Revascularisation of Large Vessel Occlusions in Acute Ischaemic Stroke (TREVO 2): a Randomised Trial..” Lancet 380, no. 9849: 1231–1240. doi:10.1016/S0140-6736(12)61299-9.
- big sponsored trial to prove that the TREVO is better than MERCI device. Stryker makes both interestingly…
- both are retrieval devices where the coil goes distal and the clot is withdrawn (there are others called micro aspiration)
- all had to have failed tPA or be ineligible for it. (ALERT – lots of cherry picking can be done here)
- lots of exclusion criteria (excluded 80% of those screened)
- end point was revascualrisation NOT clinical outcome; hardly unsurprising though
- 180 pts
- The TREVO (the new device) did better in both the reperfusion and the clinical outcomes.
- more died in the TREVO group at 90 days (24% v 34%) they somehow neglect to mention this…
Saver, Jeffrey L, Reza Jahan, Elad I Levy, Tudor G Jovin, Blaise Baxter, Raul G Nogueira, Wayne Clark, Ronald Budzik, Osama O Zaidat, SWIFT Trialists. “Solitaire Flow Restoration Device Versus the Merci Retriever in Patients with Acute Ischaemic Stroke (SWIFT): a Randomised, Parallel-Group, Non-Inferiority Trial..” Lancet 380, no. 9849: 1241–1249. doi:10.1016/S0140-6736(12)61384-1.
- a Dublin made device being trialled in the US against the only currently approved device
- similar criteria as the previous trial – either failed tPA or contraindications and within 8 hrs
- primary outcome was recanalisation NOT clinical outcome
- total 120 pts
- excluded 80% assessed
- stopped early for benefit (always a shame…)
- solitaire device was better on everything (even mortality in this tiny trial)
- of note mortality was 44% in the MERCI group and 18% in the Solitaire group. Think about that for a second – in the MERCI group almost half died – that seems a bit off to me – most strokes don’t die in numbers like this – at least not by 90 days. They certainly didn’t die in these rates in the lytic trials.
These are all very selected patients – so this is the best possible picture of the results. This is NOT a treatment that will be available to all your stroke patients. Often it will be limited by anatomy but it’s also only gonna be done in the younger patients with a better chance of outcome. The key will be (as with most things) being able to work out who might actually benefit from this sort of thing.
This may over the next 20 years become like PCI for STEMIs. But i doubt it, for the same reasons I’m dubious about lytics in stroke.
- diagnostically stroke is a much more difficult disease than STEMI
- the brain and its circulation is a lot more complex and tenuous than the heart (we have a circle of willis for a reason - a built in collateral circuit in case of failure of flow.)
For added value I’ve added a demonstration video for all 3 devices below. See if you can spot the differences.