Highlights
In the EnTRIPS multicenter randomized clinical trial, remote ischemic postconditioning (RIPC) started within 6 hours after endovascular treatment (EVT) did not significantly improve 90-day functional independence in patients with acute ischemic stroke who achieved successful recanalization.
Functional independence, defined as a modified Rankin Scale score of 0 to 2 at 90 days, occurred in 60.9% of the RIPC group and 57.8% of the control group, with an adjusted risk ratio of 1.07 (95% CI, 0.89-1.30; P=0.46).
RIPC was feasible and appeared safe. RIPC-related adverse events occurred in 7.5% of treated patients, and no major safety signal was reported.
The trial meaningfully informs the neuroprotection field by showing that biologically plausible adjunctive conditioning strategies may still fail to produce measurable clinical benefit in the modern thrombectomy era.
Background
Acute ischemic stroke caused by large-vessel occlusion remains a major source of death and long-term disability worldwide. Over the past decade, EVT has transformed care for appropriately selected patients, particularly those with proximal anterior circulation occlusion and salvageable brain tissue. Yet even after technically successful recanalization, many patients do not regain functional independence. This gap between vessel reopening and clinical recovery has sustained interest in adjunctive neuroprotective strategies.
One of the key pathobiologic targets is ischemia-reperfusion injury. Although restoring blood flow is essential, reperfusion can paradoxically trigger oxidative stress, inflammatory signaling, endothelial dysfunction, blood-brain barrier disruption, microvascular no-reflow, and hemorrhagic transformation. Remote ischemic conditioning, typically produced by intermittent inflation and deflation of a limb blood-pressure cuff, has been proposed as a simple, noninvasive method to activate endogenous protective pathways. Depending on timing, it can be applied before ischemia, during ischemia, or after reperfusion; the latter is termed remote ischemic postconditioning.
Preclinical work and some early clinical studies have suggested neuroprotective potential for remote ischemic conditioning in cerebrovascular disease. Mechanistically, proposed benefits include modulation of inflammatory cascades, reduction in excitotoxic injury, improved endothelial function, and enhancement of collateral and microcirculatory resilience. However, translation to robust clinical outcome improvement has been inconsistent. The modern thrombectomy population introduces additional complexity because EVT patients often receive highly protocolized care, experience varying infarct sizes and collateral profiles, and may already have outcome trajectories strongly influenced by age, baseline stroke severity, time to reperfusion, and procedural factors.
Against this backdrop, the EnTRIPS trial evaluated whether ultra-early RIPC administered after successful EVT could improve outcomes in acute ischemic stroke.
Study Design
Trial overview
EnTRIPS, short for Endovascular Treatment Combined with Remote Ischemic Postconditioning in Patients with Acute Ischemic Stroke, was a multicenter, randomized, controlled, prospective clinical trial with blinded outcome assessment. The study was conducted at 8 hospitals in China between April 12, 2021, and March 26, 2025.
Population
Eligible participants were adults with acute ischemic stroke due to large-vessel occlusion who presented within 24 hours of symptom onset, underwent EVT, and achieved successful recanalization. Randomization occurred within 6 hours after EVT. This is an important design feature because it specifically tested an ultra-early post-reperfusion intervention, when reperfusion injury would be expected to be most biologically relevant.
A total of 270 eligible patients were randomized, with 135 assigned to RIPC plus guideline-based therapy and 135 assigned to guideline-based therapy alone. Trial completion was excellent: 268 of 270 randomized patients (99.3%) completed the study, including 133 in the RIPC group and 135 in the control group. The mean age was 65.5 years (SD, 16.8), and 171 participants (63.8%) were men.
Intervention and comparator
RIPC was administered using pneumatic devices for 7 days. Each session consisted of 5 cycles of bilateral upper-arm cuff inflation to 180 mm Hg for 5 minutes, followed by deflation for 3 minutes. The comparator group received guideline-based therapy alone.
The regimen is notable for both its intensity and duration. Bilateral arm application may produce a larger conditioning stimulus than unilateral treatment, while repeating the intervention across 7 days was likely intended to sustain protective signaling beyond the immediate reperfusion period.
Endpoints
The primary efficacy endpoint was functional independence at 90 days, defined as a modified Rankin Scale score of 0 to 2. This is the standard clinically meaningful endpoint in modern stroke trials, reflecting independent or near-independent daily functioning.
Safety outcomes included the incidence of RIPC-related adverse events within 7 days. Outcome assessor blinding strengthens internal validity, although the intervention itself was not sham-controlled according to the abstract, an issue relevant to interpretation of subjective or care-process-related effects.
Key Findings
Primary efficacy outcome
At 90 days, functional independence was achieved in 81 of 133 patients (60.9%) in the RIPC group and 78 of 135 patients (57.8%) in the control group. The adjusted risk ratio was 1.07, with a 95% confidence interval of 0.89 to 1.30, and the P value was 0.46.
Clinically, this means the trial did not demonstrate a statistically significant benefit of ultra-early RIPC on the main patient-centered outcome. The point estimate numerically favored RIPC, but the confidence interval crossed 1.0 and was compatible with no meaningful benefit. The result also suggests that, if any true effect exists, it is likely modest and smaller than what would be needed to change practice based on this trial alone.
Safety and tolerability
RIPC-related adverse events occurred in 10 of 133 treated patients (7.5%). No intervention-related adverse events occurred in the control group, as expected. The abstract does not describe the nature of these events in detail, but the investigators concluded that ultra-early RIPC was safe in this setting.
This is an important finding for implementation science and future trial design. A bedside, device-based therapy that can be delivered soon after EVT without major safety concerns remains attractive, particularly if biomarkers or enriched subgroups can later identify patients more likely to benefit.
Interpretation of the effect size
The absolute difference in functional independence between groups was 3.1 percentage points. In many stroke trials, even small absolute gains can be clinically meaningful at a population level. However, the current estimate was imprecise and not statistically persuasive. The confidence interval indicates that the true effect could range from a small decrease in benefit to a modest increase, but it does not support a definitive positive conclusion.
The high overall rates of functional independence in both groups also deserve attention. A 57.8% rate in the control group suggests a relatively favorable post-EVT cohort, possibly reflecting successful reperfusion, contemporary stroke systems of care, and patient selection. When baseline outcomes are already strong, demonstrating added benefit from an adjunctive neuroprotective strategy becomes more difficult.
Why Might a Biologically Plausible Therapy Have Failed?
Negative neuroprotection trials are common in stroke, and EnTRIPS fits a familiar pattern: a credible mechanistic hypothesis, a pragmatic and low-risk intervention, but no clear improvement in hard clinical outcomes.
Several explanations are plausible. First, the magnitude of reperfusion injury that remains modifiable after successful EVT may be smaller than expected, especially in patients with good collaterals or limited infarct core. Second, the conditioning stimulus may have been too weak, too nonspecific, or poorly matched to the timing of human ischemia-reperfusion biology, even though it was initiated early. Third, EVT-treated stroke is highly heterogeneous. Patients differ in clot burden, infarct size, collateral status, anesthesia exposure, procedural duration, blood pressure trajectories, and concurrent intravenous thrombolysis. A modest treatment effect could easily be diluted in an unselected population.
Another issue is endpoint sensitivity. Global disability at 90 days is the most relevant clinical outcome, but it integrates many determinants beyond reperfusion injury alone, including rehabilitation intensity, medical complications, prestroke frailty, and social support. RIPC might influence intermediary processes such as edema, infarct growth, microvascular perfusion, or inflammation without generating a detectable shift in the mRS distribution in a trial of this size.
Finally, remote ischemic conditioning has shown mixed results across cardiovascular and neurologic settings. This inconsistency may reflect variability in treatment protocols, patient selection, and biological responsiveness. It also underscores the challenge of translating endogenous protective phenomena observed in experimental models into routine clinical benefit.
Clinical Commentary
For stroke clinicians, the EnTRIPS results do not support routine use of ultra-early RIPC after successful thrombectomy for the purpose of improving 90-day functional recovery. EVT, guideline-based secondary prevention, optimized blood pressure management, dysphagia screening, early mobilization when appropriate, and structured rehabilitation remain the cornerstones of post-reperfusion care.
At the same time, the trial should not be read as the final word on remote ischemic conditioning in stroke. It provides a high-quality test of one specific strategy: postconditioning, initiated within 6 hours after EVT, using a 7-day bilateral upper-arm protocol, in patients with successful recanalization. Different conditioning paradigms, biomarker-guided enrollment, imaging-selected subgroups, or mechanistic endpoints may still be worth studying.
Potentially relevant subgroups include patients with large reperfusion territories, incomplete microvascular reperfusion despite macrovascular recanalization, or imaging evidence of ongoing penumbral injury. Future studies may also benefit from incorporating advanced MRI or perfusion imaging, circulating inflammatory markers, or physiologic metrics that can better detect whether conditioning engages its intended biological targets.
From a methodology standpoint, EnTRIPS has several strengths: randomization, multicenter enrollment, prospective design, blinded outcome assessment, and excellent follow-up completeness. Its main limitations, based on the abstracted information, include modest sample size for detecting small effects, uncertain generalizability beyond Chinese stroke centers, and limited public detail in the abstract about secondary outcomes, subgroup analyses, infarct imaging, and the exact nature of adverse events.
The absence of a sham procedure may be less problematic for a hard endpoint such as 90-day mRS assessed by blinded evaluators, but sham control remains valuable when interventions might influence bedside attention, protocol adherence, or co-interventions. Whether such factors meaningfully affected this study is impossible to determine from the abstract alone.
Implications for Research and Practice
EnTRIPS reinforces an important contemporary lesson in stroke therapeutics: successful reperfusion does not automatically create an easy opportunity for adjunctive neuroprotection. Any additional therapy must either have a substantial biological effect or be directed to precisely selected patients.
Future investigations should focus on three areas. First, mechanistic validation is needed. Trials should confirm whether RIPC measurably alters biomarkers of inflammation, endothelial injury, oxidative stress, or tissue perfusion after EVT. Second, enrichment strategies may improve signal detection. Imaging or physiologic criteria could identify patients most likely to have clinically relevant reperfusion injury. Third, outcome selection should be broadened to include both patient-centered disability scales and mechanistic or imaging endpoints.
There may also be value in combining conditioning approaches with other post-EVT strategies, though any such approach would require careful testing and a clear rationale. The field should remain disciplined: low-cost and low-risk interventions are attractive, but they still require the same evidentiary rigor as pharmacologic therapies.
Conclusion
The EnTRIPS randomized clinical trial found that ultra-early remote ischemic postconditioning after successful EVT in acute ischemic stroke was safe but did not significantly improve 90-day functional independence. The findings argue against immediate adoption of this strategy in routine post-thrombectomy care, while still leaving room for more targeted mechanistic and subgroup-driven research. In the thrombectomy era, the challenge is no longer only reopening the artery, but identifying which post-reperfusion processes remain meaningfully modifiable and in whom.
Funding and Trial Registration
ClinicalTrials.gov identifier: NCT04581759.
The abstract provided does not specify the funding source. Readers should consult the full published article in Stroke for complete funding and disclosure details.
Citation
Cheng Y, Chen W, Chang M, Han X, Yu J, Wei M, Qi Y, Song B, Yao L, Lv H, Jia Y, Zhang X, Zhang G, Qiu Z, Zuo Q, Li G, Zhang Y, Chen C, Ma W, Wang Y, Cheng S, Liu F, Han J, Luo G. Remote Ischemic Postconditioning in Endovascular Thrombectomy for Stroke: The EnTRIPS Randomized Clinical Trial. Stroke. 2026-06-10. PMID: 42267436. URL: https://pubmed.ncbi.nlm.nih.gov/42267436/
Selected References
Goyal M, Menon BK, van Zwam WH, et al. Endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of individual patient data from five randomised trials. Lancet. 2016;387(10029):1723-1731.
Powers WJ, Rabinstein AA, Ackerson T, et al. 2019 update to the 2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke. 2019;50(12):e344-e418.
Turc G, Bhogal P, Fischer U, et al. European Stroke Organisation (ESO) guidelines on mechanical thrombectomy in acute ischemic stroke. Eur Stroke J. 2019;4(1):6-12.
Zhao W, Che R, Shang S, et al. Low-dose tirofiban improves functional outcome in acute ischemic stroke patients treated with endovascular thrombectomy. Stroke. 2017;48(12):3289-3294. This reference is included as an example of adjunctive therapy research in EVT-era stroke, not as evidence for RIPC.
