Thrombotic thrombocytopenic purpura associated with clopidogrel

Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated guideline is to provide comprehensive and timely evidence-based recommendations on the prevention of future stroke among survivors of ischemic stroke or transient ischemic attack. The guideline is addressed to all clinicians who manage secondary prevention for these patients. Evidence-based recommendations are provided for control of risk factors, intervention for vascular obstruction, antithrombotic therapy for cardioembolism, and antiplatelet therapy for noncardioembolic stroke. Recommendations are also provided for the prevention of recurrent stroke in a variety of specific circumstances, including aortic arch atherosclerosis, arterial dissection, patent foramen ovale, hyperhomocysteinemia, hypercoagulable states, antiphospholipid antibody syndrome, sickle cell disease, cerebral venous sinus thrombosis, and pregnancy. Special sections address use of antithrombotic and anticoagulation therapy after an intracranial hemorrhage and implementation of guidelines.

Acute serious thrombocytopenia associated with intracoronary tirofiban use for primary angioplasty

Tirofiban, a specific glycoprotein IIb/IIIa inhibitor, may cause extensive thrombocytopenia with an incidence of 0.2% to 0.5%. We report the case of a 50-year-old man who developed thrombocytopenia after tirofiban use (both intracoronary and peripheral) over hours and the successful management of this complication after primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction.

Cisplatin: process and future

One of the most important anticancer agents is cisplatin (CDDP). Numerous studies with a CDDP-based combination have been reported over the last 30 years. The use of CDDP in the 1980s and 1990s showed responses in advanced stage non-small-cell lung cancer (NSCLC). Over the years it was found that the side effects of this agent (particularly nephrotoxicity) were a common problem. Agents such as carboplatin, taxanes, gemcitabine, irinotecan and pemetrexed proved to be effective in NSCLC with reduced or no nephrotoxicity. The administration of these newer agents improved several side effects, but without improving efficacy. When prophylactic (adjuvant) treatment for NSCLC was introduced, CDDP was the agent selected, which indicated the value of the drug. Recently, a novel formulation of CDDP, liposomal cisplatin, which has shown very low toxicity, no nephrotoxicity and equal effectiveness was produced; its importance is its higher effectiveness than standard CDDP in lung adenocarcinoma.

Results from the first decade of research conducted by the Research on Adverse Drug Events and Reports (RADAR) project

INTRODUCTION

In 1998, a multidisciplinary team of investigators initiated the Research on Adverse Drug events And Reports (RADAR) project, a post-marketing surveillance effort that systematically investigates and disseminates information describing serious and previously unrecognized serious adverse drug and device reactions (sADRs).

OBJECTIVE

Herein, we describe the findings, dissemination efforts, and lessons learned from the first decade of the RADAR project.

METHODS

After identifying serious and unexpected clinical events suitable for further investigation, RADAR collaborators derived case information from physician queries, published and unpublished clinical trials, case reports, US FDA databases and manufacturer sales figures.

STUDY SELECTION

All major RADAR publications from 1998 to the present are included in this analysis.

DATA EXTRACTION

For each RADAR publication, data were abstracted on data source, correlative basic science findings, dissemination and resultant safety information.

RESULTS

RADAR investigators reported 43 serious ADRs. Data sources included case reports (17 sADRs), registries (5 sADRs), referral centers (8 sADRs) and clinical trial reports (13 sADRs). Correlative basic science findings were reported for ten sADRs. Thirty-seven sADRS were described as published case reports (5 sADRs) or published case-series (32 sADRs). Related safety information was disseminated as warnings or boxed warnings in the package insert (17 sADRs) and/or 'Dear Healthcare Professional' letters (14 sADRs).

CONCLUSION

An independent National Institutes of Health-funded post-marketing surveillance programme can supplement existing regulatory and pharmaceutical manufacturer-supported drug safety initiatives.

Thrombocytopenia in critically ill patients receiving thromboprophylaxis: frequency, risk factors, and outcomes

BACKGROUND

Thrombocytopenia is the most common hemostatic disorder in critically ill patients. The objective of this study was to describe the incidence, risk factors, and outcomes of thrombocytopenia in patients admitted to medical-surgical ICUs.

METHODS

Three thousand seven hundred forty-six patients in 67 centers were enrolled in a randomized trial in which unfractionated heparin was compared with low-molecular-weight heparin (LMWH) for thromboprophylaxis. Patients who had baseline platelet counts < 75 × 10(9)/L or severe coagulopathy at screening were excluded. We analyzed the risk of developing mild (100-149 × 10(9)/L), moderate (50-99 × 10(9)/L), and severe (< 50 × 109/L) thrombocytopenia during an ICU stay. We also assessed independent and time-varying predictors of thrombocytopenia and the effect of thrombocytopenia on major bleeding, transfusions, and death.

RESULTS

The incidences of mild, moderate, and severe thrombocytopenia were 15.3%, 5.1%, and 1.6%, respectively. The predictors of each category of thrombocytopenia were APACHE (Acute Physiology and Chronic Health Evaluation) II score, use of inotropes or vasopressors, and renal replacement therapy. The risk of moderate thrombocytopenia was lower in patients who received LMWH thromboprophylaxis but higher in surgical patients and in patients who had liver disease. Each category of thrombocytopenia was associated with subsequent bleeding and transfusions. Moderate and severe thrombocytopenia were associated with increased ICU and hospital mortality.

CONCLUSION

A high severity of illness, prior surgery, use of inotropes or vasopressors, renal replacement therapy, and liver dysfunction are associated with a higher risk of thrombocytopenia developing in the ICU, whereas LMWH thromboprophylaxis is associated with a lower risk. Patients who develop thrombocytopenia in the ICU are more likely to bleed, receive transfusions, and die.

Commonly used drugs in hematologic disorders

The drugs used to treat hematologic disorders constitute an extraordinary array of agents and include therapy for anemias, bleeding diatheses, thromboembolism and hematologic malignancies. Within many of these categories, hematologic therapies represent molecular understanding of the disease pathophysiology and a treatment targeted precisely at the known aberration. In this chapter we discuss these treatments, with greater emphasis on the most commonly used agents and the latest advances in the specific field. The chapter includes discussion on old (cyclooxygenase inhibitors) and new antiplatelet agents (ADP receptor P2Y12 inhibitors), newly described oral thrombin inhibitors such as dabigatran, treatment targeted at the bcr-abl tyrosine kinase in chronic myeloid leukemia and demethylating agents in myelodysplasia. The discussion is also oriented towards neurologic implications, both therapeutic and toxic, for each therapy or therapeutic group.

Acquired pure red cell aplasia due to treatment with clopidogrel: first case report

A 62-year-old woman with hypertension, type 2 diabetes mellitus, hyperlipemia and coronary heart disease started taking clopidogrel, with no addition of any other new drugs. However, with the addition of the drug, the patient was diagnosed as having acquired pure red cell aplasia (PRCA), and no any other inducing factors were detected from the patient. Furthermore, with the withdrawal of clopidogrel from the treatment, the patient recovered from the PRCA and did not recur. Therefore, we report PRCA as a rare side effect of clopidogrel for the first time.

Low ADAMTS-13 in plavix induced thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenia purpura (TTP) was first described in 1924 as a "pathologic alteration of the microvasculature, with detachment or swelling of the endothelium, amorphous material in the sub-endothelial space, and luminal platelet aggregation leading to compromise of the microcirculation". Ticlopidine induced TTP has been highly associated with autoimmune induced reduction in ADAMTS-13 activity. These findings, to a lesser extent, have also been found in clopidogrel induced TTP. We report a case of clopidogrel associated TTP in a patient that presented with acute stroke, renal failure, and non-ST elevation myocardial infarction.

Bisphosphonates and nonhealing femoral fractures: analysis of the FDA Adverse Event Reporting System (FAERS) and international safety efforts: a systematic review from the Research on Adverse Drug Events And Reports (RADAR) project

BACKGROUND

In the United States, hip fracture rates have declined by 30% coincident with bisphosphonate use. However, bisphosphonates are associated with sporadic cases of atypical femoral fracture. Atypical femoral fractures are usually atraumatic, may be bilateral, are occasionally preceded by prodromal thigh pain, and may have delayed fracture-healing. This study assessed the occurrence of bisphosphonate-associated nonhealing femoral fractures through a review of data from the U.S. FDA (Food and Drug Administration) Adverse Event Reporting System (FAERS) (1996 to 2011), published case reports, and international safety efforts.

METHODS

We analyzed the FAERS database with use of the proportional reporting ratio (PRR) and empiric Bayesian geometric mean (EBGM) techniques to assess whether a safety signal existed. Additionally, we conducted a systematic literature review (1990 to February 2012).

RESULTS

The analysis of the FAERS database indicated a PRR of 4.51 (95% confidence interval [CI], 3.44 to 5.92) for bisphosphonate use and nonhealing femoral fractures. Most cases (n = 317) were attributed to use of alendronate (PRR = 3.32; 95% CI, 2.71 to 4.17). In 2008, international safety agencies issued warnings and required label changes. In 2010, the FDA issued a safety notification, and the American Society for Bone and Mineral Research (ASBMR) issued recommendations about bisphosphonate-associated atypical femoral fractures.

CONCLUSIONS

Nonhealing femoral fractures are unusual adverse drug reactions associated with bisphosphonate use, as up to 26% of published cases of atypical femoral fractures exhibited delayed healing or nonhealing.

Paradoxical thrombosis, part 2: anticoagulant and antiplatelet therapy

Arterial thrombosis is the leading causes of morbidity and mortality worldwide, whereas venous thrombosis is the most common preventable cause of hospital death. In either case, venous and arterial thrombosis should be considered autonomous entities, with only minor overlaps in terms of risk factors, predisposing conditions and pathogenesis. Besides the widespread perception of embolization originating from low-pressure venous system and triggering ischemic stroke or peripheral arterial occlusion, "paradoxical" thrombosis might also develop or occur within clinical or biological circumstances where the blood should be less predisposed to clot, and wherein this risk is mostly unpredictable or overlooked. In this article we review epidemiological evidence and potential pathogenetic mechanisms of paradoxical thrombosis developing during antithrombotic therapy with vitamin K antagonists and heparin (i.e. heparin-induced thrombocytopenia), or antiplatelet agents such as aspirin, glycoprotein IIb/IIIa inhibitors or clopidogrel, and mostly attributable to direct effect of the agent.

Tirofiban-induced acute profound thrombocytopenia after primary angioplasty

Glycoprotein IIb/IIIa inhibitors are used in the acute coronary syndromes and percutaneous coronary intervention as antiplatelet agents. However, these agents induce thrombocytopenia in approximately 1% to 5% of patients, and may lead to bleeding complications. Abciximab is associated with higher incidence of thrombocytopenia than eptifibatide and tirofiban. We describe a case of acute profound thrombocytopenia due to on tirofiban treatment in a patient who underwent primary angioplasty.

Ticlopidine-, clopidogrel-, and prasugrel-associated thrombotic thrombocytopenic purpura: a 20-year review from the Southern Network on Adverse Reactions (SONAR)

Thienopyridine-derivatives (ticlopidine, clopidogrel, and prasugrel) are the primary antiplatelet agents. Thrombotic thrombocytopenic purpura (TTP) is a rare drug-associated syndrome, with the thienopyridines being the most common drugs implicated in this syndrome. We reviewed 20 years of information on clinical, epidemiologic, and laboratory findings for thienopyridine-associated TTP. Four, 11, and 11 cases of thienopyridine-associated TTP were reported in the first year of marketing of ticlopidine (1989), clopidogrel (1998), and prasugrel (2010), respectively. As of 2011, the FDA received reports of 97 ticlopidine-, 197 clopidogrel-, and 14 prasugrel-associated TTP cases. Severe deficiency of ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) was present in 80% and antibodies to 100% of these TTP patients on ticlopidine, 0% of the patients with clopidogrel-associated TTP (p < 0.05), and an unknown percentage of patients with prasugrel-associated TTP. TTP is associated with use of each of the three thienopyridines, although the mechanistic pathways may differ.

Recurrent thrombotic thrombocytopenic purpura-like syndrome as a paraneoplastic phenomenon in malignant peritoneal mesothelioma: a case report and review of the literature

We report the case of an African American male with no significant past medical history presenting with recurrent, rapidly relapsing episodes of thrombotic thrombocytopenic purpura (TTP) despite aggressive treatment with several lines of treatment. Incidentally, these episodes were associated with severe abdominal pain which eventually developed into acute abdomen and prompted exploratory laparotomy, revealing diffuse carcinomatosis with a tumor located on the left pelvis that was encasing the distal sigmoid colon. Pathology made a final diagnosis of peritoneal mesothelioma. TTP-like syndrome (TTP-LS) has been described as a paraneoplastic phenomenon in several malignancies but never before in the setting of malignant mesothelioma. Paraneoplastic TTP-like syndrome has historically been associated with a dismal prognosis and particular clinical and laboratory abnormalities described in this paper. It is of utmost importance to make a prompt determination whether TTP is idiopathic or secondary to an underlying condition because of significant differences in their prognosis, treatment, and response. This paper also reviews the current literature regarding this challenging condition.

Ten patient stories illustrating the extraordinarily diverse clinical features of patients with thrombotic thrombocytopenic purpura and severe ADAMTS13 deficiency

Patients with thrombotic thrombocytopenic purpura (TTP) and severe ADAMTS13 deficiency are often considered to have typical clinical features. However, our experience is that there is extraordinary diversity of the presenting features and the clinical courses of these patients. This diversity is illustrated by descriptions of 10 patients. The patients illustrate that ADAMTS13 activity may be normal initially but severely deficient in subsequent episodes. Patients with established diagnoses of systemic infection as the cause of their clinical features may have undetectable ADAMTS13 activity. Patients may have a prolonged prodrome of mild symptoms with only microangiopathic hemolytic anemia and thrombocytopenia or they may have the sudden onset of critical illness with multiple organ involvement. Patients may die rapidly or recover rapidly; they may require minimal treatment or extensive and prolonged treatment. Patients may have acute and severe neurologic abnormalities before microangiopathic hemolytic anemia and thrombocytopenia occur. Patients may have concurrent TTP and systemic lupus erythematosus. Patients may have hereditary ADAMTS13 deficiency as the etiology of their TTP rather than acquired autoimmune ADAMTS13 deficiency. These patients' stories illustrate the clinical spectrum of TTP with ADAMTS13 deficiency and emphasize the difficulties of clinical diagnosis.

Antiplatelet therapy in acute coronary syndromes: current agents and impact on patient outcomes

Platelets play a central role in atherothrombosis and subsequent development of acute coronary syndromes (ACS). The understanding of this process has driven a large body of evidence demonstrating the mortality and morbidity benefits of antiplatelet agents in the ACS population. As expected, however, these agents come with an intrinsically increased risk of bleeding which underlies the vast majority of their complications and adverse effects. In today’s setting of compounding comorbidities and broadening indications, finding the balance between thrombosis prevention and bleeding risk remains the challenge for all clinicians considering these medications. This article reviews the current main antiplatelet agents that are available for clinical use and outlines their impact on ACS outcome. We also outline factors which affect the response to these agents and discuss strategies to optimize clinical outcomes.

Efficacy and safety of clopidogrel in children with diarrhea associated hemolytic uremic syndrome

INTRODUCTION

Hemolytic uremic syndrome is a thrombotic microangiopathy. Clopidogrel, a recently developed platelet aggregation inhibitor, has not been previously reported as a treatment for this illness. Our study's objective was to explore the efficacy and safety of clopidogrel in children with diarrhea associated hemolytic uremic syndrome.

MATERIALS AND METHODS

We performed a retrospective chart review of all children (≤ 18 years) hospitalized with diarrhea associated hemolytic uremic syndrome. Outcomes in clopidogrel treated children were described. In subgroup analysis, outcomes were compared to those untreated with platelet aggregation inhibitors.

RESULTS

Of 72 children with diarrhea associated hemolytic uremic syndrome, 88% were treated with platelet aggregation inhibitors (clopidogrel 56%, sulfinpyrazone 19%, dipyridamole 13%). The median age of clopidogrel treated children was 5 years; 40% were male. Initial median hemoglobin, platelet count, and serum creatinine were 10.1g/dL, 53 × 10(3)/μL, and 2.3mg/dL respectively. Clopidogrel (median dose 1mg/kg/d) was given for a median of 4 days (range 1-15). Other therapies included erythropoietin (98%), red blood cell transfusions (80%), diuretics (58%), anti-hypertensive agents (45%), and dialysis (33%). The median hospital length of stay was 9 days (range 3-26). Three children had bleeding complications (epistaxis/hematemesis). The risk of chronic kidney disease was 5% and death 2.5%. In subgroup analysis, median duration of dialysis was 11 days in thirteen clopidogrel treated children compared to 21 days in five untreated patients (P=0.04).

CONCLUSIONS

Children with diarrhea associated hemolytic uremic syndrome treated with clopidogrel have outcomes comparable to untreated patients. Bleeding complications may occur.

Antiplatelet drugs: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

The article describes the mechanisms of action, pharmacokinetics, and pharmacodynamics of aspirin, dipyridamole, cilostazol, the thienopyridines, and the glycoprotein IIb/IIIa antagonists. The relationships among dose, efficacy, and safety are discussed along with a mechanistic overview of results of randomized clinical trials. The article does not provide specific management recommendations but highlights important practical aspects of antiplatelet therapy, including optimal dosing, the variable balance between benefits and risks when antiplatelet therapies are used alone or in combination with other antiplatelet drugs in different clinical settings, and the implications of persistently high platelet reactivity despite such treatment.

A patient with acquired hemophilia A induced by clopidogrel

Acquired hemophilia A (AHA) is a rare bleeding disorder caused by autoantibodies against factor VIII (FVIII). Treatment with clopidogrel is a cause of AHA, but its clinical course is unknown. Recently, we treated a 65-year-old man who was hospitalized for cerebellar infarction and had a prolonged activated partial thromboplastin time (aPTT) with soft tissue oozing after 3 weeks of clopidogrel use. We terminated clopidogrel administration and transfused the patient with fresh frozen plasma. However, the aPTT increased up to 98.8 seconds, and the FVIII and FVIII inhibitor levels were <1% and 5.4 Bethesda units/mL, respectively. Clopidogrel-associated AHA was considered, and we began steroid treatment. Two months later, FVIII, FVIII inhibitor, and aPTT values were normalized. No further bleeding or aPTT prolongation has been reported during the 2-year follow-up period. AHA should be considered in patients taking clopidogrel and experiencing bleeding, unless the platelet count and coagulation screen are normal.

Anaemia in pregnancy

Anaemia in pregnancy, defined as a haemoglobin concentration (Hb) < 110 g/L, affects more than 56 million women globally, two thirds of them being from Asia. Multiple factors lead to anaemia in pregnancy, nutritional iron deficiency anaemia (IDA) being the commonest. Underlying inflammatory conditions, physiological haemodilution and several factors affecting Hb and iron status in pregnancy lead to difficulties in establishing a definitive diagnosis. IDA is associated with increased maternal and perinatal morbidity and mortality, and long-term adverse effects in the new born. Strategies to prevent anaemia in pregnancy and its adverse effects include treatment of underlying conditions, iron and folate supplementation given weekly for all menstruating women including adolescents and daily for women during pregnancy and the post partum period, and delayed clamping of the umbilical cord at delivery. Oral iron is preferable to intravenous therapy for treatment of IDA. B12 and folate deficiencies in pregnancy are rare and may be due to inadequate dietary intake with the latter being more common. These vitamins play an important role in embryo genesis and hence any relative deficiencies may result in congenital abnormalities. Finding the underlying cause are crucial to the management of these deficiencies. Haemolytic anaemias rare also rare in pregnancy, but may have life-threatening complications if the diagnosis is not made in good time and acted upon appropriately.

Clopidogrel (plavix)

Clopidogrel is an inhibitor of platelet aggregation, indicated for the prevention of ischemic stroke and in-stent thrombosis. However, it has a number of drawbacks, including an increased risk of hemorrhage; a clinical effect that is slow in onset and irreversible; a genetically determined variability in its clinical potency; and interactions with other commonly administered drugs.

Managing adverse effects and drug-drug interactions of antiplatelet agents

Antiplatelet therapies have reduced the frequency of adverse events associated with plaque rupture in several clinical situations. These therapies include established antiplatelet agents (such as aspirin, clopidogrel, or glycoprotein IIb/IIIa inhibitors) as well as new agents (such as prasugrel and ticagrelor). In this Review, we address the most important adverse events of antiplatelet therapy, including hemorrhage, hematologic reactions, and dyspnea. We discuss strategies to reduce the incidence of complications and outline potential methods to manage adverse reactions. Interactions between antiplatelet agents and other drugs--such as proton-pump inhibitors, calcium-channel blockers, statins, warfarin, or NSAIDs--are also addressed, as well as specific issues relating to the use of antiplatelet therapies in elderly patients.

Use of antiplatelet inhibitors in peripheral vascular interventions

In the past decade, a tremendous amount of information has been gathered about platelet function and its impact on percutaneous vascular interventions. Strategies for prevention of platelet aggregation have moved beyond aspirin administration. Powerful oral antiplatelet agents such as ticlopidine (Ticlid) and clopidogrel (Plavix) have been developed to prevent platelet aggregation and thrombosis. The discovery of the glycoprotein IIb/IIIa receptor, which is responsible for platelet aggregation, has led to the development of receptor antagonists. These drugs include abciximab (ReoPro), eptifibatide (Integrilin), and tirofiban (Aggrastat). Several large studies have demonstrated that these drugs can improve outcomes in coronary interventions. Because most of the data regarding antiplatelet agents in percutaneous interventions comes from studies of coronary interventions, knowledge of these studies is necessary before using the antiplatelet drugs in peripheral vascular interventions. This article reviews the use of these agents in percutaneous coronary artery interventions and discusses their potential use in peripheral interventions.

The PPAR-Platelet Connection: Modulators of Inflammation and Potential Cardiovascular Effects

Historically, platelets were viewed as simple anucleate cells responsible for initiating thrombosis and maintaining hemostasis, but clearly they are also key mediators of inflammation and immune cell activation. An emerging body of evidence links platelet function and thrombosis to vascular inflammation. peroxisome proliferator-activated receptors (PPARs) play a major role in modulating inflammation and, interestingly, PPARs (PPARβ/δ and PPARγ) were recently identified in platelets. Additionally, PPAR agonists attenuate platelet activation; an important discovery for two reasons. First, activated platelets are formidable antagonists that initiate and prolong a cascade of events that contribute to cardiovascular disease (CVD) progression. Dampening platelet release of proinflammatory mediators, including CD40 ligand (CD40L, CD154), is essential to hinder this cascade. Second, understanding the biologic importance of platelet PPARs and the mechanism(s) by which PPARs regulate platelet activation will be imperative in designing therapeutic strategies lacking the deleterious or unwanted side effects of current treatment options.

Humoral immune response to ADAMTS13 in acquired thrombotic thrombocytopenic purpura

The apparently spontaneous development of autoantibodies to ADAMTS13 in previously healthy individuals is a major cause of thrombotic thrombocytopenic purpura (TTP). Epitope mapping studies have shown that in most patients antibodies directed towards the spacer domain of ADAMTS13 are present. A single antigenic surface comprising Arg(660) , Tyr(661) and Tyr(665) that contributes to the productive binding of ADAMTS13 to unfolded von Willebrand factor is targeted by anti-spacer domain antibodies. Antibodies directed to the carboxyl-terminal CUB1-2 and TSP2-8 domains have also been observed in the plasma of patients with acquired TTP. As yet it has not been established whether this class of antibodies modulates ADAMTS13 activity. Inspection of the primary sequence of human monoclonal anti-ADAMTS13 antibodies suggests that the variable heavy chain germline gene segment VH1-69 is frequently incorporated. We suggest a model in which 'shape complementarity' between the spacer domain and residues encoded by the VH1-69 gene segment explain the preferential use of this variable heavy chain gene segment. Finally, a model is presented for the development of anti-ADAMTS13 antibodies in previously healthy individuals that incorporates the recent identification of HLA DRB1*11 as a risk factor for acquired TTP.

Thrombocytopenia following percutaneous coronary intervention

BACKGROUND

Thrombocytopenia following percutaneous coronary intervention (PCI) is an underappreciated condition that is often clinically challenging. There are no guidelines on the management of patients with this condition.

OBJECTIVE

To review recent data in etiologies, risk factors, prevention, management, and prognostic implications of thrombocytopenia following PCI.

EVIDENCE ACQUISITION

Search of MEDLINE, EMBASE, the Cochrane Database, and Google Scholar using the term thrombocytopenia + PCI and other relevant keywords to identify systematic reviews, clinical trials, cohort studies, case series, and case reports. The review was limited to English-language articles published between January 1980 and June 2009. Articles on patients with baseline thrombocytopenia prior to PCI were excluded.

EVIDENCE SYNTHESIS

Thrombocytopenia is not infrequent following PCI. The typical patient with post-PCI thrombocytopenia is on multiple therapies that can potentially cause a decrease in the platelet count. Identification of the cause is critical because management of the condition varies significantly based on the etiology. The severity of the thrombocytopenia also determines the clinical management of the patient. Several observational studies have demonstrated the adverse prognostic impact of the complication on clinical outcomes and have identified risk factors.

CONCLUSIONS

Judicious use of therapies that can cause thrombocytopenia, efficient detection of the cause of the decrease in platelet count, and appropriate management of the condition can potentially improve the quality of care and outcomes following PCI. Further research into risk factors that predispose post-PCI patients to developing thrombocytopenia is warranted.

Review and management of side effects associated with antiplatelet therapy for prevention of recurrent cerebrovascular events

The risk of secondary events following noncardioembolic ischemic stroke or transient ischemic attack (TIA) is high and especially pronounced in the first days and weeks following the initial event; to reduce this risk, it is recommended that antiplatelet therapy be initiated immediately. Although the risk and impact of antiplatelet-associated side effects are generally far less substantial than those of secondary events, some (especially bleeding) can be severe and even life-threatening, and others may reduce adherence to antiplatelet regimens. Therefore, clinicians should implement strategies to reduce the risk of side effects and to manage those that occur. Three antiplatelet regimens have demonstrated substantial reductions in secondary event risk and are currently recommended by consensus panels: aspirin monotherapy at 50-325 mg/day; the combination of aspirin plus extended-release dipyridamole (ER-DP); and clopidogrel monotherapy. Bleeding is potentially the most significant antiplatelet-associated side effect. As bleeding risk with aspirin monotherapy is dose dependent, while preventive efficacy appears similar at all doses above 50 mg/day, aspirin doses should be kept as low as possible. Clopidogrel bleeding risk is similar to aspirin, although a reduced incidence of gastrointestinal bleeding events suggests lower gastrotoxicity. Clopidogrel should not be combined with aspirin after stroke or TIA, as the combination increases bleeding risk without improving antiplatelet efficacy. Patients should be assessed for bleeding risk (especially gastrointestinal bleeding) before initiating antiplatelet therapy; those at elevated risk should be made aware of the signs and symptoms of bleeding events to facilitate prompt treatment. The addition of ER-DP to aspirin does not increase bleeding risk, although ER-DP is associated with risk of headache, which may be severe. The prevalence of headache drops rapidly following initiation of ER-DP, suggesting most patients are able to "push through" this side effect; for those who find headache intolerable, short-term use of a reduced-dose regimen may be helpful.

Complete recovery of ischemic cardiomyopathy from thrombotic thrombocytopenic purpura

A 50 year old male HIV patient on antiretroviral therapy was admitted for chest pain. Upon admission, the patient was found to have elevated cardiac enzymes, acute thrombocytopenia, hemolytic anemia, acute pancreatitis and acute renal failure. The patient was diagnosed with thrombotic thrombocytopenic purpura/haemolytic uremic syndrome and emergency plasma exchange therapy was initiated along with aspirin, beta-blockers, steroids, and antiretroviral therapy. Patient responded well and demonstrated complete resolution of ischemic cardiomyopathy with left ventricular ejection fraction improving from 35% to 55% by the time of discharge. Essentially, prompt diagnosis and treatment can reverse cardiac damage induced by thrombotic thrombocytopenic purpura.

[Thrombotic microangiopathy after extracorporeal circulation: important differential diagnosis]

Thrombotic microangiopathies are characterized by platelet activation, endothelial damage, hemolysis and microvascular occlusion. This group of diseases is primary represented by thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). Patients present with microangiopathic hemolytic anemia and thrombocytopenia as well as occlusion-related organ ischemia to a variable degree. A deficiency of the metalloprotease ADAMTS-13 is a major risk for acute disease manifestation as this is a regulator of unusually large von Willebrand factor (vWF) multimers, which are extremely adhesive and secreted by endothelial cells. In classical TTP an ADAMTS-13 activity below 5% is specific, whereas in other forms of thrombotic microangiopathies activity of ADAMTS-13 ranges from very low to normal. Symptoms of different forms of thrombotic microangiopathy are frequently overlapping and a clear classification according to clinical criteria is often difficult. Due to a high mortality, particularly of TTP, immediate diagnosis and therapy are essential. In this article two cases of thombotic microangiopathy after cardiac surgery are reported. After exclusion of TTP and HUS as well as other etiologies of thrombotic microangiopathy a relationship between the use of extracorporeal circulation and the pathogenesis of thrombotic microangiopathy is assumed.

Thrombotic microangiopathy in haematopoietic cell transplantation: an update

Allogeneic hematopoietic cell transplantation (HCT) represents a vital procedure for patients with various hematologic conditions. Despite advances in the field, HCT carries significant morbidity and mortality. A rare but potentially devastating complication is transplantation-associated thrombotic microangiopathy (TA-TMA). In contrast to idiopathic TTP, whose etiology is attributed to deficient activity of ADAMTS13, (a member of the A Disintegrin And Metalloprotease with Thrombospondin 1 repeats family of metalloproteases), patients with TA-TMA have > 5% ADAMTS13 activity. Pathophysiologic mechanisms associated with TA-TMA, include loss of endothelial cell integrity induced by intensive conditioning regimens, immunosuppressive therapy, irradiation, infections and graft-versus-host (GVHD) disease. The reported incidence of TA-TMA ranges from 0.5% to 75%, reflecting the difficulty of accurate diagnosis in these patients. Two different groups have proposed consensus definitions for TA-TMA, yet they fail to distinguish the primary syndrome from secondary causes such as infections or medication exposure. Despite treatment, mortality rate in TA-TMA ranges between 60% to 90%. The treatment strategies for TA-TMA remain challenging. Calcineurin inhibitors should be discontinued and replaced with alternative immunosuppressive agents. Daclizumab, a humanized monoclonal anti-CD25 antibody, has shown promising results in the treatment of TA-TMA. Rituximab or the addition of defibrotide, have been reported to induce remission in this patient population. In general, plasma exchange is not recommended.

Guidelines for the prevention of stroke in patients with stroke or transient ischemic attack: a guideline for healthcare professionals from the american heart association/american stroke association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of ischemic stroke among survivors of ischemic stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches for atherosclerotic disease, antithrombotic treatments for cardioembolism, and the use of antiplatelet agents for noncardioembolic stroke. Further recommendations are provided for the prevention of recurrent stroke in a variety of other specific circumstances, including arterial dissections; patent foramen ovale; hyperhomocysteinemia; hypercoagulable states; sickle cell disease; cerebral venous sinus thrombosis; stroke among women, particularly with regard to pregnancy and the use of postmenopausal hormones; the use of anticoagulation after cerebral hemorrhage; and special approaches to the implementation of guidelines and their use in high-risk populations.

Thrombotic microangiopathies: multimers, metalloprotease, and beyond

The pathophysiology of various types of thrombotic microangiopathies is coming progressively into focus. Therapeutic advances are likely to follow at a quickening pace. This discussion focuses on thrombotic thrombocytopenic purpura (TTP), the hemolytic-uremic syndrome (HUS), thrombotic microangiopathies associated with transplantation-immunosuppression or anti-angiogenesis therapy, and the preeclampsia/hemolysis-elevated liver enzymes and low platelets syndrome (HELLP).