Introduction Early treatment with intravenous thrombolysis (IVT) < 4.5 hours from symptom onset increases the proportion of patients who survive with a favourable outcome after an acute ischemic stroke (AIS). Intracerebral haemorrhage (ICH) is the feared risk of systemic thrombolysis and may be secondary to haemorrhagic transformation, bleeding into an ischaemic area following reperfusion or cerebral microbleeds (CMBs).

Aim of Study The primary aim is to examine the association between IVT in patients with AIS and post IVT ICH. The secondary aim is to evaluate CMBs as an independent risk factor for post IVT ICH.

Methods A 5-year retrospective analysis of all patients treated with IVT for AIS in our institution was performed. Gradient Echo MRI sequences were used to evaluate the presence, number, and location of CMBs. Statistical models were used to determine the relationship between CMBs and haemorrhagic transformation.

Results Of 434 patients (average age 65 years, 54% women, mean NIHSS score 9), the incidence post IVT intra or extra axial bleeding was 9.9%. Of those, 79.5% had ICH, 18.2% had SAH and 2.3% had SDH. Of patients with ICH, 30 (85.7%) patients had haemorrhagic transformation (HT). Old age, extensive small vessel disease, chronic infarcts and early cortical swelling were predisposing factors in these cases. 5 patients (14.3%) had >10 CMB consistent with probable CAA.

Conclusion The rate of post IVT ICH is approximately 1 in 10 in our cohort. Reliable risk assessment for probable CAA requires pre-existing MRI head prior to IVT treatment. This is a practical limitation of current practice.

Disclosure of Interest no.