TL;DR: 🟢 Landmark positive — first randomized trial to meet its primary endpoint for surgical ICH evacuation after decades of neutral trials (STITCH, STITCH II, MISTIE III); benefit concentrated in lobar hemorrhages.
1. Publication
- Title: Trial of Early Minimally Invasive Removal of Intracerebral Hemorrhage
- Acronym: ENRICH
- Year & Journal: New England Journal of Medicine, published April 11, 2024 (390(14):1277-1289)
- Citation: Pradilla G, Ratcliff JJ, Hall AJ, et al; ENRICH Trial Investigators. N Engl J Med. 2024;390(14):1277-1289. doi:10.1056/NEJMoa2308440
2. Context & Rationale
Background: Prior surgical ICH evacuation trials (STITCH, STITCH II, and the minimally invasive MISTIE III) generally showed no functional benefit, though MISTIE III showed a mortality benefit and trends favoring benefit with superficial lesions and greater clot evacuation — motivating a trial specifically refining patient selection and technique.
Research Question/Hypothesis: In patients with acute supratentorial ICH (lobar or anterior basal ganglia), does early minimally invasive surgical removal (within 24h) improve functional outcomes at 180 days compared with guideline-based medical management?
3. Design & Methods
- Study Type: Multicenter, randomized, adaptive trial (Bayesian partial pooling)
- Population: Patients with acute ICH, lobar or anterior basal ganglia location, surgery feasible within 24h
- Intervention: Early minimally invasive hematoma evacuation (trans-sulcal, channel-based parafascicular technique) plus guideline-based medical management
- Comparator: Guideline-based medical management alone
- Statistical Power & Follow-Up: Primary: functional outcome (utility-weighted mRS) at 180 days. Bayesian adaptive design with partial pooling across strata.
4. Key Results
Outcome | Surgical Evacuation | Medical Management | Notes |
Functional outcome at 180 days (primary) | Better | — | Significant benefit — first ICH surgical trial to meet its primary endpoint |
Effect by hematoma location | Attributable mainly to lobar hemorrhages | — | Anterior basal ganglia subgroup showed less/no clear benefit |
5. Internal Validity Assessment
Multicenter, adaptive Bayesian trial with a prespecified location-based analysis framework. Overall: Strong — described by the lead investigator as "the first randomized clinical trial to meet its primary endpoint" for surgical ICH evacuation, after decades of prior neutral trials (STITCH, STITCH II, MISTIE III); the location-specific effect (benefit concentrated in lobar hemorrhages) is a biologically plausible, prespecified refinement rather than a purely post-hoc subgroup finding.
6. External Validity Assessment
Multicenter population with acute supratentorial ICH (lobar or anterior basal ganglia) eligible for surgery within 24h — requires specific surgical expertise (trans-sulcal, channel-based parafascicular technique) and rapid surgical availability.
7. Strengths & Limitations
Strengths: First positive trial in decades of surgical ICH evacuation research; adaptive Bayesian design efficiently used accumulating data; refined patient selection (specific technique, hematoma location, early timing) building directly on lessons from prior neutral trials.
Limitations: Requires specialized surgical technique/expertise not universally available; benefit concentrated in lobar hemorrhages specifically — anterior basal ganglia hemorrhages showed less clear benefit, an important patient-selection nuance; industry funding (Nico, manufacturer of the surgical device).
8. Interpretation & Practice Impact
Supports early minimally invasive hematoma evacuation specifically for lobar ICH — described by investigators as poised to "change how we treat hemorrhagic stroke moving forward," a genuinely landmark result after decades of neutral surgical ICH trials.
9. Controversies & Subsequent Evidence
Lead investigator Gustavo Pradilla explicitly framed this as ending the pattern of "generally no functional benefit" seen across prior surgical ICH trials (STITCH, STITCH II). The location-specific effect (lobar vs anterior basal ganglia) is consistent with, and extends, signal seen in MISTIE III data suggesting superficial lesions and greater clot evacuation predict better response — an important refinement for future trial design and clinical practice guidance.
10. Summary & Executive Takeaway
Summary: ENRICH, an adaptive Bayesian trial, randomized patients with acute supratentorial ICH (lobar or anterior basal ganglia) eligible for surgery within 24h to early minimally invasive hematoma evacuation plus medical management or medical management alone. The trial met its primary endpoint — significantly better functional outcomes at 180 days with surgery — with the effect attributable mainly to lobar hemorrhages.
Overall Takeaway: ENRICH is the first randomized trial to demonstrate a clear functional benefit from surgical ICH evacuation, after decades of neutral prior trials (STITCH, STITCH II, MISTIE III) — a genuinely landmark result specifically for lobar hemorrhage, refining both patient selection (location) and surgical technique (early, minimally invasive, trans-sulcal) for this historically difficult-to-treat condition.
11. Bibliography
- Mendelow AD, et al. STITCH trial. Lancet. 2005;365(9457):387-397.
- Mendelow AD, et al. STITCH II trial. Lancet. 2013;382(9890):397-408.
- Hanley DF, et al. MISTIE III. Lancet. 2019;393(10175):1021-1032.