History of cerebrovascular accident (CVA) within months prior to randomization or that is not stable History of cerebrovascular accident (CVA) within months prior to randomization or that is not stable Cerebral vascular accident (CVA) or transitory ischemic attack (TIA) in the year before enrollment, or presence of residual symptoms from CVA that happened more than a year before History of a venous thromboembolic event, cerebrovascular accident (CVA), hepatic impairment, or heart failure Prior cerebrovascular accident (CVA) with persistent neurological deficit History of cerebral vascular accident (CVA), myocardial infarction or unstable angina within the previous six months before starting therapy Severe cerebrovascular disease (multiple CVA or CVA within months) Seizure or cerebrovascular accident (CVA) in the last year Patients who had, within the past months, a cardiovascular accident (CVA) or at risk for arterial thrombus such as severe peripheral vascular disease (PVD) and carotid artery disease (CAD) History of cerebro-vascular accident within months of enrollment Patient must have no history of cerebrovascular accident (CVA) within months of randomization No CVA neutralising antibody (? :) History of cerebral vascular accident or stroke within the previous years History of stroke, cerebral vascular accident (CVA) or transient ischemic attack within months prior to registration Cerebral Vascular Accident (CVA) within months prior to consent. History of stroke, cerebral vascular accident (CVA) or transient ischemic attack within months Severe cerebrovascular disease (multiple CVA or CVA within months) Prior cerebrovascular accident (CVA) with persistent neurological deficit History of stroke, cerebral vascular accident (CVA) or transient ischemic attack within months History of cerebral vascular accident (CVA) within months Substantial central nervous system (CNS) disease including\r\n* History of CNS bleeding\r\n* Mass lesions in the brain\r\n* Uncontrolled seizure disorder\r\n* Recent history of cerebrovascular accident (CVA) (e.g. within the past months) History of a stroke or cerebrovascular accident (CVA) within months Severe cerebrovascular disease (multiple cerebrovascular accidents [CVAs] or CVA within months) History of cerebrovascular accident (CVA) within months prior to registration or that is not stable. History of cerebral vascular accident (CVA) within months prior to registration History of CVA within six months Cerebral vascular accident Severe cerebrovascular disease (multiple CVA or CVA within months) History of cerebral vascular accident (CVA) or other central nervous system disorder resulting in residual weakness or paresis of extremity contralateral to the site of disease Cerebrovascular accident (CVA) or stroke within the past months Severe cerebrovascular disease (multiple CVA or CVA within months)