Retrieving Blood Clots
Clot-removing devices provide better outcomes for stroke survivors
Image courtesy Medtronic
Strokes caused by large blood clots in the brain are less likely to result in disability or death if the blockage is removed in the crucial early hours, according to reaffirming new research.
In October, Dutch researchers reached the same conclusion in a trial known as MR CLEAN. Three new studies reported at the American Stroke Association’s International Stroke Conference reinforced those results from the Netherlands.
The trials had been halted early because their results were so positive. Researchers said that clot-grabbing devices used alongside a standard drug that dissolves clots, can greatly improve the outcomes for people having the worst and most disabling strokes.
"This is a watershed moment in the management of acute stroke," said Lee Schwamm, M.D., an American Heart Association volunteer and director of acute stroke services at Massachusetts General Hospital who was not involved in the studies. "Stroke is now a treatable disease in its earliest hours, and we can offer hope and promise to patients that early treatment can lead to dramatic reductions in disability and death."
Each year, more than 690,000 Americans have ischemic strokes. The standard treatment is a clot-dissolving drug called tPA. But it must be given intravenously within 4.5 hours to be effective. For people with large clots it only works about a third of the time.
In the past, there had been disappointing results in clinical trials using less sophisticated clot retrieval devices. But the new studies tested more modern devices such as a retrievable stent, a tiny wire cage attached to a catheter. The catheter is threaded through an artery in the groin until it reaches the blocked artery in the brain. The stent opens and traps the clot, allowing doctors to extract it and reopen the artery nearly every time.
Among the new research is a Canadian study known as ESCAPE that involved 315 stroke patients. Most were given the clot-busting medicine tPA, and about half of them were also treated with a clot removal device.
Three months after their strokes, 53 percent of patients whose treatment included clot removal were functionally independent and able to take care of themselves compared with about 29 percent given tPA alone. The treatment also improved the odds of survival. In the clot-removal group, about 90 percent of patients were still alive after three months compared with 81 percent in the tPA-only group.
Results were similar in a smaller Australian study called EXTEND-IA: 71 percent of stroke patients given both treatments were functionally independent after three months compared with 40 percent of those given tPA alone.
Bruce Campbell, M.D., a neurologist at the Royal Melbourne Hospital, led the Australian study and said clinical guidelines will now change.
"It’s a difference for patients between having paralysis down one side and not being able to talk compared to getting home and back to all their usual activities," Campbell said.
The next step will be to make sure stroke patients are taken to hospitals with specialists who can perform the clotremoving procedure, said Jeffrey Saver, M.D., a director at the UCLA Stroke Center and lead investigator of the SWIFT PRIME study. "We need to change the medical system," he said.
In all three studies, the clot was removed from the blocked artery within six to 12 hours after stroke symptoms started. Researchers used simple imaging to quickly assess whether a stroke patient had a large clot.
Schwamm said the findings give people an even more convincing reason to call 911 as soon as they notice arm weakness, speech difficulty or facial drooping — the telltale signs of a stroke.
"When I first started in neurology, when you had a stroke, you came into the hospital, you got admitted to a room and then we went about trying to figure out why it happened," said Schwamm. "There was really no focus on treating the stroke itself. This is the dawn of a new era."