LOS ANGELES — Results of a study suggest that patients with stroke may still experience good outcomes when endovascular therapy is administered between 6 and 18 hours of symptom onset.
“Time is still brain. Our findings do not negate that an early successful treatment likely promises the best outcome,” Jenny P. Tsai, MD, CM, FRCPC, study investigator from Stanford University in Palo Alto, Calif., told Neurology Advisor. “What they do suggest is that all is not lost for patients presenting with severe strokes beyond 6 hours from last known well. Rather, they should be evaluated with perfusion imaging as soon as possible, as some may still benefit from endovascular therapy.”
Dr Tsai and researchers from several U.S. institutions conducted the study, which was presented here at the 2016 International Stroke Conference.
Currently, intra-arterial therapy has become the standard-of-care for stroke patients with large vessel occlusions who present within 6 hours of symptom onset, although the efficacy of the treatment at later times remains unknown.
This led Dr Tsai and colleagues to use data from the CT Perfusion (CTP) to Predict Response to Recanalization in Ischemic Stroke Project (CRISP) to examine the relationship between time to treatment and the probability of good outcomes.
“Since 2015, we have [had] evidence that mechanical thrombectomy can treat patients with very large and severe strokes,” Dr Tsai said. “The stroke community continues to use the time the patient was last known well, in conjunction with a non-contrast CT, [to] determine if the patient may benefit from treatment. We wanted to know if CTP may allow us to identify candidates who benefit from the treatment who may otherwise be excluded by the clock.”
The researchers hypothesized that patients who have a profile with a small infarct core and large penumbra on CTP would do well after successful thrombectomy, regardless of the time between stroke onset and treatment.
At baseline, all patients received CTP. Researchers included data from patients with target mismatch who achieved endovascular reperfusion, and established reperfusion status by early magnetic resonance imaging or CTP follow-up, or final thrombolysis in cerebral infarction score of 2b/3 if early follow-up perfusion imaging was unavailable.
A modified Rankin Scale score of 0 to 2 at 90 days served as a good functional outcome. The probability of good outcome as a function of onset-to-reperfusion time was determined via logistic regression, with prespecified adjustment for age and baseline National Institutes of Health Stroke Scale (NIHSS) score.
Overall, 102 patients with target mismatch achieved reperfusion after intra-arterial intervention was performed within 18 hours of symptom onset. Researchers reported a median onset-to-reperfusion time of 6.6 hours (interquartile range, 5.2-9.5).
Univariate analysis results indicated that onset-to-reperfusion time was not associated with good functional outcome (P=.19); however, age and NIHSS score were. Results were similar in multivariate analysis.
Furthermore, the adjusted relative risk per hour of delay was 0.994 (95% confidence interval, 0.97-1.02), and good functional outcome was attained in 71.4% of patients treated within 6 hours and 61.7% of patients treated after 6 hours.
“CTP can reliably identify patients who benefit from treatment even beyond our current treatment time window of 6 hours,” Dr Tsai said. “Moreover, [these findings] suggest that over 50% of these patients may achieve good functional outcome at 3 months after stroke even beyond 8 hours from last known well.”
Dr Tsai did note, however, that the results are limited because they come from an observational analysis.
“We need more data to continue improving the care we deliver to patients affected by these severe strokes,” she said. “This motivation is the basis for on-going clinical trials specifically using CT and [magnetic resonance] perfusion imaging to evaluate the benefit of endovascular therapy in patients presenting beyond 6 hours. They include DAWN, POSITIVE, and the [National Institute of Neurological Disorders and Stroke]-funded DEFUSE 3 study.”
For more coverage of ISC 2016, go here.
Tsai JP, Mlynash M, Christensen S, et al. Abstract 6. Patient Selection Is a Better Predictor of Good Outcome Than Time to Reperfusion In Acute Ischemic Stroke. Presented at: International Stroke Conference; Feb. 16-19, 2016; Los Angeles.