Ali Saad, MD
Broderick JP, Palesch YY, Demchuk AM, Yeatts SD, Khatri P, Hill MD, et al. Evolution of Practice During the Interventional Management of Stroke III Trial and Implications for Ongoing Trial. Stroke. 2014
One of the criticisms of IMS III was that practice parameters were changing throughout the 7-year course of the trial. The authors address this criticism by comparing various parameters between protocols 1-4 vs protocol 5 (the final protocol).
Patients in the final protocol tended to be older, have baseline CTAs, were less likely to have a premorbid mRS of 0, but were offset by quicker times to reperfusion and being less likely to get IA-tPA as part of the treatment. ultimately this didn’t improve outcome or safety measures. This was likely related to less statistical power and more lenient inclusion criteria for protocol 5 patients. but the authors cite that their efforts did decrease time to intervention and reperfusion as well as recanalization rates.
The final protocol may reflect the current practice parameters at many large academic institutions offering endovascular therapy and parallel the evolution of the field over time. In the post-IMS III era, stent retrievers are more commonly used, older patients are being offered treatment, and time to treatment is going down.
Endovascular intervention for acute ischemic stroke is a rapidly evolving field. in retrospect, IMS-III mirrors that evolution. although the trial did not demonstrate endovascular intervention + IV-tPA to be superior to IV-tPA alone, I firmly believe that it is simply a matter of time. There were several “negative” trials testing the efficacy of IV-tPA before the success of the landmark 1995 NINDS trial. decreasing the time to reperfusion is probably of the utmost importance, but patient selection by clinical and radiographic criteria is also critical. since the NINDS study, subsequent studies have been published showing greater efficacy and less risk when IV-tPA is given earlier to more carefully selected patients. i expect the field of endovascular therapy will follow a similar trajectory. Once a future trial hits the “sweet spot” and reaches statistical significance, it will start to become the standard of care for select patients at which point financial incentives will kick in and dramatically increase workflow efficiency and raise the field’s standards of practice.