Abstract Body: Abstract
Background
Remote ischemic conditioning (RIC) with transient cycles of limb ischemia and reperfusion is a safe and promising neuroprotective therapy in acute ischemic stroke (AIS). The results from recent clinical trials show mixed results on clinical outcomes and may depend on the studied population, timing- and dosage of RIC. In this study, we evaluated the effect of RIC on infarct growth measured from baseline to 24-hour on diffusion-weighted magnetic resonance imaging (MRI) scans using a deep learning (DL) segmentation method.

Methods
In this predefined sub-study of the Remote Ischemic Conditioning in Patients with Acute Stroke Trial (RESIST), we compared the change in brain infarct volumes from the acute MRI (baseline) to the 24-hour MRI, between the RIC and Sham-treated patients. Infarct volumes were automatically segmented using an ensemble DL approach, which was optimized on a previous study population. Mann-Whitney U test was used to assess differences in infarct growth between treatment groups, considering an interquartile range and setting a significance threshold at p < 0.05.

Results
RESIST includes 384 AIS patients, with 346 analyzed; 32 were excluded for only having baseline scans, and six for insufficient segmentation due to incomplete or disrupted MRI scans. No significant differences were found in mean age (P=0.481) or gender ratio (P=0.715) between the Sham (n=184; mean age = 70.79; female/male = 117/67) and RIC (n=162; mean age=69.83; female/male=107/55) groups. For the primary endpoint there was no difference in mean infarct growth (from baseline to 24-hour) between RIC 6.18 mL (SD 31.18) and Sham 5.83 mL (SD 25.26), P=0.824. Supplemental subgroup analysis will be presented at the conference.

Conclusion
Pre-hospital and in-hospital RIC treatment did not result in reduced 24-hour infarct growth in patients with AIS. This is the largest study to date examining the effect of RIC on infarct growth, with subgroup analysis that will be presented at the conference.