Does intravenous rtPA benefit patients in the absence of CT angiographically visible intracranial occlusion?

Abstract

Background : In patients with acute stroke receiving intravenous tissue plasminogen activator (tPA), we postulated that the presence of intracranial occlusion on CT angiography (CTA) modifies the benefit of thrombolysis. Materials and Methods : Using a retrospective cohort design, we identified patients with acute ischemic stroke in our CTA database between May 2002 and August 2007. All the patients had a CTA within 12 h of onset, a premorbid modified Rankin scale (mRS) #1, and a baseline National Institute of Health Stroke Scale score(NIHSS)f $6. The primary outcome was early effectiveness of tPA defined as an NIHSS score of #2 at 24 h or a 4-point NIHSS improvement at 24 h. Secondary outcome included mRS #1 at 90 days. The relationship between intracranial occlusion on CTA and benefit of tPA was assessed using a test for interaction. Results : A total of 287 patients met the criteria [occlusion present N =168; (98 with tPA; 70 without tPA) and occlusion absent N = 119; (52 with tPA; 67 without tPA)]. Those with intracranial occlusion were likely to have more severe strokes (NIHSS $15; P < 0.001) and abnormal brain imaging (ASPECTS #7; P < 0.001). For outcome of 4-point NIHSS score improvement at 24 h, benefit from tPA was observed only among patients with a visible occlusion (absolute difference in favor of tPA: 20.4% vs. 0.7%; P = 0.06). Conclusion : In patients with acute ischemic stroke, thrombolysis produced a better early clinical response among patients with intracranial occlusion, which needs to be confirmed in stroke thrombolysis trials.