hermes consortium stroke thrombectomy | endovascular thrombectomy for stroke

Acute ischemic stroke (AIS), a devastating neurological event caused by a sudden interruption of blood flow to the brain, is a leading cause of disability and death worldwide. For decades, the primary treatment for AIS focused on intravenous thrombolysis with recombinant tissue plasminogen activator (rtPA), a medication that dissolves blood clots. While rtPA can be effective in some patients, its effectiveness is limited, particularly in cases of large vessel occlusion (LVO), where a major artery supplying the brain is blocked.

The emergence of endovascular thrombectomy (EVT), a minimally invasive procedure to physically remove the clot from the blocked artery, has revolutionized the treatment of AIS, especially in patients with LVO. The HERMES (Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke trials) consortium, a collaborative effort bringing together data from multiple randomized controlled trials (RCTs), has played a pivotal role in establishing EVT as the standard of care for eligible patients with acute ischemic stroke due to large vessel occlusion.

This article delves into the significance of the HERMES consortium stroke thrombectomy, exploring its impact on patient outcomes, the evidence supporting its efficacy, and its implications for the future of stroke care.

The HERMES Consortium: A Collaborative Force in Stroke Research

The HERMES consortium was formed to pool data from several independent, prospective, randomized controlled trials evaluating the efficacy of EVT in patients with acute ischemic stroke due to LVO. This collaborative approach was crucial because individual trials, while promising, often lacked the statistical power to definitively demonstrate the benefit of EVT, particularly when considering various patient subgroups and clinical scenarios.

By combining data from multiple trials, the HERMES consortium provided a more robust and comprehensive analysis, allowing for a clearer understanding of the true benefits and risks of EVT. The core trials included in the HERMES meta-analysis were:

* MR CLEAN (Multicenter Randomized Clinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands): This landmark trial was one of the first to demonstrate the superiority of EVT plus standard medical care (including rtPA if eligible) compared to standard medical care alone in patients with anterior circulation LVO.

* ESCAPE (Endovascular treatment for Small Core and Proximal Occlusion Ischemic Stroke): ESCAPE further confirmed the benefit of EVT in patients with anterior circulation LVO and a relatively small ischemic core (the area of brain tissue already irreversibly damaged).

* EXTEND-IA (Extending the Time for Thrombolysis in Emergency Neurological Deficits – Intra-Arterial): EXTEND-IA showed that EVT was effective, even when initiated beyond the traditional 6-hour window from stroke onset, particularly in patients with favorable imaging profiles.

* REVASCAT (Randomized trial of Revascularization with Solitaire FR device versus best medical therapy in the treatment of acute stroke due to anterior circulation large vessel occlusion): REVASCAT provided further evidence supporting the efficacy of EVT using stent retrievers (devices that trap and remove the clot).

* SWIFT PRIME (Solitaire With the Intention For Thrombectomy as PRIMary Endovascular treatment for Acute ischemic stroke): SWIFT PRIME demonstrated the superiority of EVT using the Solitaire stent retriever in combination with rtPA compared to rtPA alone.

* THRACE (Trial and Cost Effectiveness Analysis for Mechanical Thrombectomy in Acute Ischemic Stroke): THRACE was a French multicenter trial that also showed the benefit of EVT in patients with acute ischemic stroke.

Key Findings of the HERMES Consortium:

The HERMES consortium's meta-analysis, published in *The Lancet*, provided compelling evidence supporting the efficacy of EVT in patients with acute ischemic stroke due to LVO. The key findings included:

* Improved Functional Outcomes: Patients treated with EVT plus standard medical care had significantly better functional outcomes at 90 days compared to those treated with standard medical care alone. Functional outcome was typically assessed using the modified Rankin Scale (mRS), a scale ranging from 0 (no symptoms) to 6 (death). A shift towards lower mRS scores indicated better functional independence.

* Increased Likelihood of Functional Independence: The HERMES analysis showed that EVT significantly increased the odds of achieving functional independence (mRS score of 0-2) at 90 days.

* Reduced Mortality: While not always statistically significant in individual trials, the HERMES meta-analysis demonstrated a trend towards reduced mortality in patients treated with EVT.

* Benefit Across Subgroups: The benefits of EVT were observed across various patient subgroups, including those with different occlusion sites, baseline stroke severity, and time since stroke onset.

* Importance of Rapid Reperfusion: The HERMES analysis emphasized the critical importance of achieving rapid and complete reperfusion (restoration of blood flow) in the affected brain area. Faster and more complete reperfusion was associated with better functional outcomes.

Clinical Implications and Impact on Stroke Care:

The findings of the HERMES consortium had a profound impact on the management of acute ischemic stroke due to LVO. Based on the robust evidence provided by HERMES, guidelines from major stroke organizations worldwide, including the American Heart Association/American Stroke Association (AHA/ASA) and the European Stroke Organisation (ESO), were updated to recommend EVT as the standard of care for eligible patients.

The implications of the HERMES findings include: