Intracranial haemorrhage without early clinical deterioration after mechanical thrombectomy: rethinking the “asymptomatic” label

INTRODUCTION: ICH is a common complication following endovascular therapy (EVT) for ischaemic stroke. While sICH is known to worsen outcomes, the impact of ICH without early neurological deterioration (END), commonly referred to as "asymptomatic" (aICH), remains controversial. This study aimed to assess imaging patterns of aICH and its effect on clinical outcomes. PATIENTS AND METHODS: This study used data from the prospective, multicentre German Stroke Registry-Endovascular Treatment. Bleedings were assessed on follow-up imaging at 24 hours applying the Heidelberg Bleeding Classification. European Cooperative Acute Stroke Study III (ECASS)-III criteria were used to stratify patients into (1) no ICH, (2) aICH and (3) sICH. The primary outcome was functional independence (mRS ≤ 2) at 3 months. Secondary outcomes included mRS shift and 3-month mortality. RESULTS: Among 4834 patients with EVT (median age 76, 51% female, median NIHSS 14), ICH occurred in 13.2% (aICH: 9.7%, sICH: 3.5%). Haemorrhage patterns differed, with sICH being more often parenchymal (48.2% vs 34.6%), multicompartmental (34.1% vs 20.2%) and involving the ventricular system (18.8% vs 7.6%), while aICH were predominantly haemorrhagic transformation (34.6% vs 21.8%). Functional independence at 90 days was reached by 40.0% (no ICH), 25.4% (aICH; adjusted odds ratio [aOR] 0.43 [0.32-0.58]) and 6.5% (sICH; aOR 0.06 [0.03-0.14]), respectively. aICH was associated with worse overall recovery (mRS shift adjusted common OR 0.51 [0.41-0.63]) and higher 90-day mortality (35.5% vs 24.9%; aOR 1.90 [1.44-2.51]), when compared to no ICH. CONCLUSION: ICH after EVT was associated with worse functional recovery and higher mortality, even in the absence of END. Given these results, the term "asymptomatic ICH" warrants reconsideration.