TCT.15: Stent retriever endovascular therapy improves clinical outcomes versus standard stroke therapy

A meta-analysis of five randomized controlled trials found that performing endovascular therapy with stent retrievers was safe and effective in managing acute ischemic stroke and led to a significant improvement in functional clinical outcomes compared with standard therapy.

There was no difference in the rates of symptomatic intracranial hemorrhage in patients receiving stent retrievers or standard therapy, while there appeared to be a trend towards overall decreased 90-day mortality in the stent retriever group.

Konstantinos Marmagkiolis, MD, of the Heart and Vascular Institute at Citizens Memorial Hospital in Bolivar, Mo., and colleagues published their findings online in the Journal of the American College of Cardiology: Cardiovascular Interventions on Oct. 11.

Results were simultaneously released in an abstract at the Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium in San Francisco.

“This is an important breakthrough in stroke treatment; in fact, the most important breakthrough since the NINDS (National Institute of Neurological Disorders and Stroke) t-PA trial that established the use of IV thrombolysis for ischemic stroke 20 years ago,” the researchers wrote. “It is anticipated to result in major changes in healthcare systems and accelerate the development of centers of excellence, such as comprehensive stroke centers, that will be preferentially able to accept and treat patients with the most severe ischemic strokes. Several current or planned studies may provide high-level evidence for the efficacy of endovascular treatment in different patient populations and subgroups, refinement of retrieving devices and selection criteria that may allow the time window to be extended even further.”

After conducting a literature search of articles published from May 2005 to May 2015 and searching published abstracts from major cardiovascular conferences, the researchers identified the following five randomized controlled trials that compared stent retrievers with conventional therapy to manage acute stroke due to large-vessel occlusion: MR CLEAN, ESCAPE, EXTEND-IA, SWIFT-PRIME and REVASCAT.

The meta-analysis included 634 patients in the stent retriever group and 653 patients in the standard therapy group. The standard therapy included intravenous thrombolysis within 4.5 hours of acute stroke symptoms, which is the most common strategy for prompt recanalization. However, the researchers mentioned that intravenous thrombolysis has a narrow time window, a low recanalization rate in patients with large vessel occlusion and bleeding complications.

The researchers noted that 42.6 percent of patients in the stent retriever group and 26.1 percent of patients in the standard therapy group had functional independence, which they defined as a 90-day modified Rankin Score of 0 to 2.

Further, 4.2 percent of patients in the stent retriever group and 4.3 percent of patients in the standard therapy group had intracranial bleeding, while the overall 90-day mortality was 15.1 percent and 18.7 percent, respectively.

The researchers noted a few study limitations, including a heterogeneity in the neuroimaging criteria for selecting patients, although all five studies required pre-treatment imaging confirmation of large-vessel occlusion. The studies used different time points, as well: three treated patients up to six hours from onset of acute stroke, another treated them up to eight hours and another treated them up to 12 hours. The researchers mentioned future studies should identify patients with salvageable tissue within six to 12 hours from stroke onset. Finally, three of the studies were terminated after an unplanned interim analysis and another study was terminated after the first planned interim analysis.

“Even though the interim conservative analyses demonstrated that equipoise did not longer exist, and the respective data and safety monitoring boards concluded that the studies should be discontinued, it is possible that the early termination is associated with a magnification of the apparent treatment effect,” the researchers wrote.