A new device (FAST>ER GSTP; Galaxy CCRO, Corpus Christie, TX) has been developed that may help determine time of stroke onset at the point of care. The device uses lateral flow technology (similar to that of a pregancy test or glucometer) to measure serum levels of the biomarker glutathione-S-transferase pi (GSTP). Serum levels of GSTP correlate with stroke time of onset in people with transient ischemic attacks (TIAs) and mild, moderate, or severe stroke (Turck et al. PLoS ONE. 2012;7(9):e43830). Levels of GSTP rise within the first 15 minutes of stroke onset and continue rising for 4 to 5 hours, reaching a plateau and remaining high for an additional 1 to 3 hours. Approximately 8 hours after stroke onset, serum levels of GSTP begin to decline.
Before development of this device, the assay time for measuring GSTP was 3 hours, making clinical use of this biomarker unfeasible. To use this test, a pinprick lancet in the self-contained device is used to draw a drop of blood; capillary action takes this over a filter that produces a colored line to show whether GSTP is elevated or not. With serial measurements whether GSTP levels are rising, high, or declining could be determined. Although a CT scan will still be required to exclude hemorrhagic stroke, the impact of FAST>ER on door-to-needle time may be significant because it would identify the need for transport to a higher-level stroke center and the need for immediate CT. Preliminary testing has shown clinically relevant limits of detection and a linear response to GSTP concentration. Clinical trials in Europe and the US are planned.
If accuracy, sensitivity, and specificity are proven, the ability for emergency responders to test GSTP levels and estimate time of stroke onset is likely to improve triage, increase the accurate routing of patients to appropriate level stroke centers, provide earlier indications for thrombolysis, and improve outcomes after stroke.
Ian Pike, PhD, chief scientific officer of Galaxy CCRO and first author of a late-breaking abstract on these results at the International Stroke Conference in Los Angeles, CA Feb 19-21, 2020 said, "If clinical trials prove this can be done in a routine manner, it is estimated that the number of people with AIS who could benefit from treatment with thrombolysis may go from 10% to 50% of those experiencing AIS. Galaxy is proud to have developed this device and we are looking forward to potentially confirming the validity of routine that could have a large positive effect on outcomes for people experiencing stroke."
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