You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Low molecular-weight heparin versus aspirin in patients with acute ischaemic stroke and atrial fibrillation : a double-blind randomised study . HAEST Study Group . Heparin in Acute Embolic Stroke Trial . BACKGROUND Patients with acute ischaemic stroke and atrial fibrillation have an increased risk of early stroke recurrence , and anticoagulant treatment with heparins has been widely advocated , despite missing data on the balance of risk and benefit . METHODS Heparin in Acute Embolic Stroke Trial ( HAEST ) was a multicentre , randomised , double-blind , and double-dummy trial on the effect of low-molecular-weight heparin ( LMWH , dalteparin 100 IU/kg subcutaneously twice a day ) or aspirin ( 160 mg every day ) for the treatment of 449 patients with acute ischaemic stroke and atrial fibrillation . The primary aim was to test whether treatment with LMWH , started within 30 h of stroke onset , is superior to aspirin for the prevention of recurrent stroke during the first 14 days . FINDINGS The frequency of recurrent ischaemic stroke during the first 14 days was 19/244 ( 8.5 % ) in dalteparin-allocated patients versus 17/225 ( 7.5 % ) in aspirin-allocated patients ( odds ratio=1.13 , 95 % CI 0.57-2.24 ) . The secondary events during the first 14 days also revealed no benefit of dalteparin compared with aspirin : symptomatic cerebral haemorrhage 6/224 versus 4/225 ; symptomatic and asymptomatic cerebral haemorrhage 26/224 versus 32/225 ; progression of symptoms within the first 48 hours 24/224 versus 17/225 ; and death 21/224 versus 16/225 . There were no significant differences in functional outcome or death at 14 days or 3 months . INTERPRETATION The present data do not provide any evidence that LMWH is superior to aspirin for the treatment of acute ischaemic stroke in patients with atrial fibrillation . However , the study could not exclude the possibility of smaller , but still worthwhile , effects of either of the trial drugs .
{"Intervention": ["aspirin :", "Heparin", "heparins", "dalteparin", "Low molecular-weight heparin", "aspirin", "low-molecular-weight heparin ( LMWH", "LMWH"], "Outcome": ["frequency of recurrent ischaemic stroke", "early stroke recurrence", "progression of symptoms within the first 48 hours", "functional outcome or death", "symptomatic cerebral haemorrhage", "recurrent stroke", "symptomatic and asymptomatic cerebral haemorrhage"], "Participant": ["449", "acute ischaemic stroke", "atrial fibrillation", "acute ischaemic stroke and atrial fibrillation"]}