Influence of antiplatelet pre-treatment on the risk of intracranial haemorrhage in acute ischaemic stroke after intravenous thrombolysis

Background: Pre-treatment with antiplatelet agents (AP) is present amongst 30% of acute stroke patients. Previous studies have shown conflicting results on the effect of these drugs regarding haemorrhagic transformation after thrombolytic therapy. The hypothesis that pre-treatment with AP may increase the risk of cerebral haemorrhage (ICH) after intravenous tissue plasminogen activator (tPA) was assessed. Methods: Retrospective study of consecutive prospectively registered patients with acute ischaemic stroke treated with iv tPA (n = 235) in the last 5 years. Baseline characteristics and prior AP therapy were registered on admission. Computed tomography (CT) scan was performed on admission and 24-36 h after tPA. ICH was classified according to the ECASS II criteria into haemorrhagic infarction and parenchymal haematoma (PH). Symptomatic intracerebral haemorrhage (SICH) was defined as a worsening of >= 4 points in the NIHSS score during the first 36 h in any haemorrhage subtype. Results: Seventy-two (30.6%) patients were pre-treated with AP (55 aspirin, 14 clopidogrel, 2 aspirin + clopidogrel, 1 triflusal). PH was observed in 33 (14.1%) patients (PH1 13, PH2 12, PHr 8) of whom 16 were symptomatic. Male gender (78.8% vs. 21.2%, P = 0.036), prior AP therapy (54.5% vs. 26.9%, P = 0.001), stroke severity (median NIHSS, 17 vs. 12, P = 0.005) and early CT signs of infarction (12.5% vs. 2.1%, P = 0.004) were associated with PH. The adjusted odds ratios of PH for patients pre-treated with AP therapy was 3.5 (1.5-7.8, P = 0.002) and for SICH 1.9 (0.6-5.9, P = 0.2). Conclusions: Pre-treatment with AP is associated with an increased risk of PH after intravenous thrombolysis in patients with acute ischaemic stroke.