Background and Purpose— During intra-arterial revascularization, either guide catheter injections of contrast in the neck or microcatheter contrast injections (MCIs) at or beyond the site of an occlusion, can be used to visualize intracranial vasculature. Neurointerventionalists vary widely in their use of MCIs for a given circumstance. We tested the hypothesis that MCIs are a risk factor for intracranial hemorrhage (ICH) in the Interventional Management of Stroke (IMS) I and II trials of combined intravenous/IA recombinant tissue plasminogen activator therapy.

Methods— All arteriograms with M1, M2, and ICA terminus occlusions were reanalyzed (n=98). The number of MCIs within or distal to the target occlusion was assigned. Postprocedure CTs were reviewed for contrast extravasation and ICH. Contrast extravasation was defined as a hyperdensity suggestive of contrast (Hounsfield unit >90) seen at 24 hours or present before 24 hours and persisting or replaced by ICH at 24 hours.

Results— In this IMS subset, the rate of any ICH was 58% (57 of 98). More MCIs were seen in the ICH group (median=2 versus 1; P=0.04). Increased MCIs were associated with higher ICH rates (P=0.03). MCIs remained associated with ICH in multivariable analysis (P=0.01) as did baseline CT edema/mass effect, atrial fibrillation, time to intravenous recombinant tissue plasminogen activator initiation, and Thrombolysis in Cerebral Infarction reperfusion score. MCIs were also associated with contrast extravasation in unadjusted and adjusted analyses.

Conclusions— MCIs may risk ICH in the setting of combined intravenous/intra-arterial recombinant tissue plasminogen activator therapy, possibly due to contrast toxicity or pressure transmission by injections. MCIs should be minimized whenever possible. These findings will be tested prospectively in the IMS III trial.