Patients with atrial fibrillation (AF) and ischemic stroke are at high risk for stroke recurrence. Early anticoagulation may reduce the risk of recurrent events but is usually avoided due to the risk of hemorrhagic transformation (HT). Current guidelines are based on empiric expert opinion. The assumed risk of HT is based on historical data from an older generation of anticoagulants. The direct oral anticoagulants (DOACs) have demonstrated lower risk of intracranial hemorrhage compared to older anticoagulants. However, the optimal timing of DOAC initiation after AF-related ischemic stroke has remained an area of clinical equipoise, as the pivotal phase III trials did not include patients in the early period after ischemic stroke. Multiple prospective studies and a few smaller randomized controlled trials evaluating the safety and efficacy of early versus delayed DOAC initiation have been completed. These studies have reported promising results of early DOAC initiation after acute ischemic stroke. However, a standardized documentation of HT rates on follow-up imaging with objective assessment criteria is missing from most of these studies. Larger randomized trials of early versus delayed DOAC are ongoing. A literature review was performed using keywords and Medical Subject Headings in MEDLINE/PubMed and Google Scholar databases. For each relevant paper, the bibliography was scrutinized for other relevant articles and journals. In this article, we review the risk of recurrent ischemic stroke and HT in patients with AF, pathophysiology, classification, predictors, natural history, and outcomes of HT and discuss the studies of early anticoagulation after AF-related ischemic stroke.

Guidelines are lacking for management of acute ischemic stroke and stroke prevention in patients with immune thrombocytopenia (ITP). Our aim is to highlight the dilemma inherent in managing patients with both significant bleeding and thrombotic risk factors. In this review, we present two patients with history of ITP who presented with acute ischemic stroke and received tissue plasminogen activator (tPA) and endovascular thrombectomy (EVT), a rare management strategy in this patient population. In addition, we identified 27 case reports of ischemic stroke in patients with ITP; none of them received tPA or EVT. Furthermore, there are 92 patients with significant thrombocytopenia with no available data regarding the cause of thrombocytopenia, who were acutely treated with tPA or EVT. Conclusive evidence cannot be determined based on these limited number of cases. Future multicenter prospective cohort studies in patients with ITP are needed to provide better evidence-based treatment plans. At present, treatment of acute ischemic stroke in patients with ITP requires close collaboration between hematology and vascular neurology experts to find a balance between the benefit and risk of hemorrhagic complications.

Patients with mechanical heart valves are at high thrombotic risk and require warfarin. Among those developing intracranial hemorrhage, limited data are available to guide clinicians with antithrombotic reinitiation. This 13-patient case series of warfarin-associated intracranial hemorrhages found the time to reinitiate antithrombotic therapy (17 days, interquartile range 21.5 days), and changes to international normalized ratio targets were variable and neither correlated with the type, location, or etiology of bleed, nor the valve and associated thromboembolic risk. The initial presentation significantly impacted prognosis, and diligent assessment and follow-up may support positive long-term outcomes.

Symptomatic extracranial internal carotid artery stenosis poses a high short-time risk of ischemic cerebral stroke, as high as 20% to 30% in the first three months. Timely performed carotid endarterectomy (CEA) has been shown to be highly effective in reducing this risk although, in recent years, there has been great interest in replacing this procedure with less invasive carotid angioplasty and stenting (CAS). In this update we review recent studies and provide recommendations regarding the indications, methods and timing of surgical intervention as well as the anaesthetic management of CEA, and we report on recently published randomized controlled trials comparing CEA to CAS. We also provide recommendations regarding the sometime neglected but important medical management of patients undergoing carotid intervention, including antithrombotic and antihypertension therapy, lipid lowering agents, assistance with smoking cessation, and diabetes control.

Chronic cerebrovascular disease and large ischemic stroke are both associated with cognitive impairment. Much less is known about the acute cognitive sequelae of transient ischemic attack (TIA). Although often overlooked, there is increasing evidence that cognitive impairment does occur following TIA. In some patients, cognitive changes persist after resolution of focal neurological deficits, but the temporal profile of these symptoms is unknown. In addition, clinical and imaging correlates of cognitive impairment after TIA have not been systematically studied. This under-studied and recognized problem has significant implications for TIA patient management. In this review, we summarize the evidence currently available and identify future research priorities.

A 4Mb magnetoresistive random access memory (MRAM) with a novel magnetic free layer and toggle switching mode is presented. The new free layer uses a balanced synthetic-antiferromagnet trilayer structure and a novel write pulse sequence to provide robust switching performance with immunity from ½-select disturbs. This new mode greatly improves the switching performance of the MRAM as compared to conventional MRAM. The intrinsic reliability of the magnetoresistive tunnel junction (MTJ) and the metal interconnect system of MRAM are two other areas of great interest due to the new materials involved. Time dependent dielectric breakdown (TDDB) and resistance drift were the two main failure mechanisms identified for intrinsic memory bit reliability. Results indicated that a lifetime over 10 years is achievable under the operating conditions. Finally data retention is demonstrated over times that are orders of magnitude longer than 10 years.

A 4Mb magnetoresistive random access memory (MRAM) with a novel magnetic free layer and toggle switching mode is presented. The new free layer uses a balanced synthetic-antiferromagnet trilayer structure and a novel write pulse sequence to provide robust switching performance with immunity from ½-select disturbs. This new mode greatly improves the switching performance of the MRAM as compared to conventional MRAM. The intrinsic reliability of the magnetoresistive tunnel junction (MTJ) and the metal interconnect system of MRAM are two other areas of great interest due to the new materials involved. Time dependent dielectric breakdown (TDDB) and resistance drift were the two main failure mechanisms identified for intrinsic memory bit reliability. Results indicated that a lifetime over 10 years is achievable under the operating conditions. Finally data retention is demonstrated over times that are orders of magnitude longer than 10 years.

A carbon composite bipolar plate for PEM fuel cells has been developed that has high electrical conductivity, high strength, light weight, is impermeable, and has the potential for being produced at low cost. The plate is produced by slurry molding short carbon fibers into preform structures, molding features into the green body, and using chemical vapor infiltration to strengthen the material, give it high conductivity, and densify the surface to make it impermeable. Current efforts have focused on optimizing the fabrication process and characterizing prototypical components.