Sticky platelet syndrome and thrombocythemia

A new decade awaits sticky platelet syndrome: where are we now, how do we manage and what are the complications?

INTRODUCTION

Sticky platelet syndrome is a less known platelet function disorder with a familiar occurrence and likely genetic background. Clinically, it is characterized by an increased risk of venous and arterial thromboembolic events and obstetric placenta-mediated complications. The increased aggregation after low-dose ADP and/or epinephrine is its distinctive laboratory feature. Though described for almost 40 years, several issues regarding its etiology, involved pathomechanisms, genetic background, optimal diagnostic and treatment approach remain controversial.

AREAS COVERED

The work aims to summarize published studies, the actual definition of the syndrome, and point out its drawbacks. A literature search on Medline, Embase, and archives from EHA congresses was performed (terms: 'sticky platelet syndrome' - 'platelet hyperreactivity' - 'platelet hyperaggregability'). The authors added in their unpublished data. The introductory overview of the present understanding is followed by the discussion of the pathophysiologic, diagnostic, and therapeutic problems.

EXPERT OPINION

Despite the growing evidence provided by case reports and series, the lack of robust studies limits the decision-making on diagnostics and management. The diagnostic issues, particularly the standardization of light transmission aggregometry, represent the crucial problem for the broader acceptance of the syndrome.

Platelet hyperaggregability and venous thrombosis risk: results from the RETROVE project

The aim of the study was to determine whether platelet hyperaggregability correlates with short closure times (PFA-100) and if hyperaggregability is associated with the risk of venous thrombosis in a Spanish population. Case--control study (RETROVE project) involving 400 patients with venous thrombosis and 400 healthy controls. We determined platelet aggregation in platelet-rich plasma (PRP) by light transmission aggregometry. Various concentrations of two aggregation agonists [ADP and epinephrine (EPI)] were tested to determine the percentage of maximal aggregation and the percentage area under the curve (AUC). Venous thrombosis risk associated with platelet hyperaggregability was calculated by logistic regression. We estimated the crude and adjusted (by sex and age) odds ratios (OR) for venous thrombosis risk. An agonist concentration of 0.5 μmol/l differentiated between hypo-responders and hyper-responders at the following AUC cut-off values: EPI: the 50th percentile for aggregation with 0.5 μmol/l of EPI (EPI_AUC) was 22.53% (>22.53% = hyper-EPI); the crude risk for venous thrombosis was statistically significant (OR = 1.37; 95% CI 1.03-1.82); ADP: the 75th percentile for aggregation with 0.5 μmol/l of ADP (ADP_AUC) was 29.6% (>29.6% = hyper-ADP), with a significant crude risk for venous thrombosis (OR = 1.44; 95% CI 1.05-1.98). However, after adjustment for confounders (age), the ORs for EPI or ADP aggregation were no longer significant. EPI_AUC and PFA-100 values with the EPI agonist were significantly correlated (R = -0.342, P < 0.01). Only 12% of the PFA-100 values were explained by platelet aggregation. In this case--control study, platelet hyperaggregability was not associated with the risk of developing venous thrombosis.

High Prevalence of Sticky Platelet Syndrome in Patients with Infertility and Pregnancy Loss

Platelet hyperaggregability, known as sticky platelet syndrome (SPS), is a prothrombotic disorder that has been increasingly associated with pregnancy loss. In this retrospective study, we aimed to investigate the clinical and diagnostic relevance of SPS in 208 patients with infertility and unexplained pregnancy loss history. We studied 208 patients that had been referred to undergo a dose-dependent platelet aggregation response to adenosine diphosphate and epinephrine using light transmission aggregometry modified by Mammen during an 11-year period. Patients’ platelet aggregation response was compared with platelet function in 29 female healthy controls of fertile age with no previous history of pregnancy loss. We found a prevalence of SPS type II (33.2%) in 208 female patients with infertility and pregnancy loss. ∆-epinephrine-induced platelet aggregation in patients with SPS was significantly decreased (median 7% and range −21 to 43%) compared to patients without SPS (median 59%, range 7–88% and p < 0.0001) and healthy controls (median 57%, range 8–106% and p < 0.0001). The optimum SPS-diagnostic cutoff value for ∆-epinephrine aggregation was ≤32% (sensitivity 95.7%, specificity 95.2%). SPS patients with low-dose acetylsalicylic acid (ASA) therapy (n = 56) showed improved pregnancy outcome (32 pregnancies; live births n = 18 (56%)) compared to SPS patients without low-dose ASA (n = 13) (3 pregnancies; live births n = 1 (33%)). Our study demonstrates the clinical and diagnostic relevance of platelet hyperaggregation in women with infertility and pregnancy loss history. Further studies should investigate the potential of SPS as a novel decisional tool with both diagnostic and clinical implications in infertility and pregnancy loss.

In vitro Research of the Concentration Dependence of Effect of Adrenaline on Platelets Aggregation

PURPOSE

Paper intended to present experimental evidences that adrenaline has a direct effect of inducing platelets aggregation in the concentration range 1-8µM.

MATERIAL/METHODS

Platelet rich plasma from patients of Colentina Clinical Hospital, following an informed consent. The platelet rich plasma (PRP) was prepared by centrifuging the anticoagulated sample at 200 G for 10 minutes. Aggregation was evaluated by optical aggregometry, classical method of Born, using Helena PACKS-4 Aggregometer.

RESULTS

The curves transmission light-time followed the structure: a lag-time, a first phase aggregation, more or less linear, defined by a "Slope 1", a second wave of aggregation defined by "slope 2" and a "saturation" phase. Slope 1 increases with the concentration of adrenaline. The second slopes of the aggregation curves, maximum aggregation and areas under curves depended linear on adrenaline concentration.

CONCLUSIONS

Adrenaline, in concentrations in the 1-8µM, induce aggregation of human platelets from platelet rich plasma. Linear regression models for slope and area were practically identical suggesting a rather unique than biphasic mechanism of action of adrenaline during the time course of aggregation.

Sticky platelet syndrome: an important cause of life-threatening thrombotic complications

Sticky platelet syndrome (SPS) is a prothrombotic thrombocytopathy with familial occurrence, characterized by hyperaggregability of platelets in response to adenosine diphosphate (ADP), epinephrine (EPI) or both. The syndrome has been identified in approximately 21% of unexplained arterial thrombotic episodes, regarded to be the most common thrombophilia in arterial thrombosis and 13.2% of unexplained venous thromboembolism (VTE). The relatively young age at the first manifestation, relation to fertility and pregnancy, seriousness of the symptoms, easy and effective management of the disorder indicate to the necessity to take it into account in the differential diagnosis of the underlying cause of the thrombotic event. As the various localizations of the thrombosis in SPS have been reported, its management often requires a multidisciplinary approach. This review deals with the clinical aspects of thrombophilia, its etiopathogenesis, diagnosis as well as novel advances in the treatment and outlines the challenges for the further research.

The sticky platelet syndrome during carotid endarterectomy

The sticky platelet syndrome is a congenital disorder, characterized by abnormal platelet aggregation in response to epinephrine and/or adenosine phosphate. We present a case of intraoperative carotid artery thrombosis, after patch angioplasty. The successful repair was only feasible on administration of antiplatelet therapy. Presence of sticky platelet syndrome should be considered during vascular operative interventions, and load of antiplatelet agents should be given in patients with unexplained repeated thrombosis of arterial repair, as we described and reported this case.

Decreased Threshold of Aggregation to Low-Dose Epinephrine is Evidence of Platelet Hyperaggregability in Patients with Thrombosis

Sticky platelet syndrome has been described as a hereditary thrombophilic condition. The aim of this study is to identify the presence of platelet hyperaggregability in patients who have experienced thrombosis. Light-transmittance platelet aggregometry was used to assess for spontaneous platelet aggregation, aggregation in response to full and low-dose (LD) epinephrine (Epi) and adenosine diphosphate, as well as arachidonic acid, and identify a distinct pattern of platelet hyperaggregability. Light-transmittance platelet aggregometry results were correlated with PFA-100® (Dade-Behring, Marburg, Germany) results, when available. An exaggerated response to LD Epi was found in 68% of patients with thrombosis compared to only 36% of healthy controls (P=0.034). Patients with thrombosis, either arterial or venous, demonstrated an exaggerated response to LD Epi nearly twice as frequently as healthy controls, even without significant family history of thrombophilia or other known risk factors for thrombosis. This suggests that platelet hyperaggregability may be multifactorial in nature and not necessarily hereditary.

Primary Thrombophilia in México X

Introduction:

The sticky platelet syndrome (SPS) is a common cause of thrombosis. There are no prospective studies concerning treatment.

Objective:

To analyze changes in platelet hyperaggregability of patients with SPS who were given antiplatelet drugs and to assess its association with rethrombosis.

Methods:

A total of 55 patients with a history of thrombosis and SPS phenotype were prospectively studied before and after treatment with aspirin and/or clopidogrel.

Results:

Patients were followed for 1 to 129 months, median 13. Of 55 patients, 40 received aspirin, 13 received aspirin + clopidogrel, and 2 received only clopidogrel. The platelet aggregation response to adenosine diphosphate and epinephrine significantly diminished after treatment, and only 2 patients developed rethrombosis 52 and 129 months after starting therapy, with the freedom from rethrombosis rate of the patients being 96.4% at 129 months.

Conclusion:

Using antiplatelet drugs, the platelet hyperreactivity of patients with the SPS phenotype was reverted; and this translated into a substantial decrease in the rethrombosis rate.

Platelet Hyperaggregability is Highly Prevalent in Patients With Chronic Kidney Disease

Background:

Platelet hyperaggregation is known to be associated with arterial and venous thromboembolic events. The prevalence of platelet hyperaggregation in patients with chronic kidney disease (CKD) has not been described to date.

Methods:

Platelet hyperaggregation in patients with renal disease was defined by comparison of platelet aggregation patterns to non-CKD patients without thromboembolic disorders and healthy controls.

Results:

Among the 30 hemodialysis patients and 34 renal transplant recipients, 20 (67%) and 28 (82%) showed significantly decreased median Δ-epinephrine aggregation and increased 0.5 mol/L epinephrine response (65% and 54%) compared to healthy controls and non-CKD patients. In concordance to the laboratory finding of platelet hyperaggregability, renal transplant recipients showed a high rate of thromboembolic events (normal platelet aggregation: 0 events and platelet hyperaggregation: 30 events in 13 of 28 patients).

Conclusions:

Patients with CKD exhibit a hitherto unappreciated high prevalence of platelet hyperaggregability indicating sticky platelet syndrome. Laboratory testing of platelet hyperaggregability may supplement the assessment of thromboembolic complications in patients with CKD.

Sticky platelet syndrome in patients with uninduced venous thrombosis

OBJECTIVE

Sticky platelet syndrome (SPS) is a common autosomal dominant inherited platelet disorder. SPS is characterized by platelet hyperreactivity and is associated with arterial and venous thrombosis. The aim of this study was to determine the role of SPS in patients with uninduced venous thrombosis.

MATERIAL AND METHODS

The study included 28 patients (15 male and 13 female) with uninduced venous thrombosis. SPS was defined according to Mammen's aggregation method, which is described in detail elsewhere.

RESULTS

According to the defined ranges for platelet hyperreactivity, 3 (50%) patients, 2 (33%), and 1 (17%) (n =6 [21%]) with a confirmed diagnosis were classified as type II, I, and III SPS, respectively. In 1 patient SPS was the only hereditary abnormality noted. The other 5 patients carried other inherited coagulation defects, in addition to SPS.

CONCLUSION

The present findings indicate that the prevalence of SPS was 21% in the patients with uninduced venous thrombosis. We therefore suggest that SPS should be considered in the differential diagnosis of such cases.

CONFLICT OF INTEREST

None declared.

Platelet hyperreactivity: report of a case with catastrophic arterial thrombosis in a child

Platelet hyperreactivity is an important but under-recognized cause of idiopathic arterial thrombosis. We describe a case of arterial thrombosis in a previously healthy 12-year-old girl after minor trauma to the knee, resulting in lower extremity amputation. Family history was positive for arterial and venous thrombosis, but an extensive work-up for the usual inherited thrombophilia risk factors was negative. The patient was eventually diagnosed with platelet hyperreactivity and remains on life-long antiplatelet therapy.Consideration of platelet hyperreactivity in the evaluation of unusual arterial thrombotic events allows for targeted therapy, potential avoidance of future events, and timely screening of family members.

Primary thrombophilia in Mexico IX

Introduction:

The sticky platelet syndrome (SPS) seems to be a common cause of thrombosis, although no molecular substrate to explain platelet hyperaggregability has been found.

Objective:

To analyze an association between the SPS phenotype and the platelet glycoprotein (GP) IIIa PLA1/A2 (human platelet antigen [HPA]-1a/b) gene polymorphism.

Methods:

Along an 18-month period, Mexican mestizo thrombophilic patients were prospectively accrued. The SPS phenotype was assessed by aggregometry, whereas a tetra-primer amplification refractory mutation system (ARMS) polymerase chain reaction analysis was used to detect the PLA1 and PLA2 alleles.

Results:

A total of 95 individuals with SPS and 127 healthy donors were studied; in 11 of the donors and 16 of the patients with SPS the A2 allele of the GP IIb/IIIA was found, yielding a weak and nonsignificant association (odds ratio 2.14, 95% CI 0.94-4.85).

Conclusion:

In Mexican mestizo patients, the platelet GP IIIa PLA1/A2 gene polymorphism does not lead to the SPS phenotype.

Extensive thrombosis and first-trimester pregnancy loss caused by sticky platelet syndrome

BACKGROUND

Sticky platelet syndrome is an autosomal-dominant thrombophilia characterized by platelet hyperaggregability in the presence of adenosine diphosphate or epinephrine. The result clinically can be widespread thromboses, often arterial, in patients without apparent risk factors for thrombotic disease. Limited data exist regarding its role in adverse pregnancy outcomes.

CASE

A gravid woman with two previous first-trimester miscarriages presented at 11 weeks of gestation with a deep venous thrombosis. Despite anticoagulation, she developed extensive and progressive arterial and venous thromboses and suffered a fetal demise. A thrombophilia panel was unremarkable, but platelet aggregometry demonstrated hyperactive platelets in the presence of adenosine diphosphate and epinephrine consistent with sticky platelet syndrome.

CONCLUSION

Sticky platelet syndrome causes arterial thromboses and may be an underappreciated etiology for adverse pregnancy outcomes.

Myeloproliferative disorders and the hyperviscosity syndrome

Myeloproliferative disorders and the serum hyperviscosity syndrome can rapidly manifest with emergent presentations. Hyperviscosity occurs from pathologic elevations of either the cellular or acellular (protein) fractions of the circulating blood. Classic hyperviscosity syndrome presents with the triad of bleeding diathesis, visual disturbances, and focal neurologic signs. Emergency medicine providers should be aware of these conditions and be prepared to rapidly initiate supportive and early definitive management, including plasma exchange and apharesis. Early consultation with a hematologist is essential to managing these complex patients.

Thrombophilic patterns of coagulation factors in lupus

Our aim was to better define the coagulation abnormalities in patients with systemic lupus erythematosus who had thrombosis or high-risk clinical settings for thrombosis. Clinical and laboratory data of 111 patients with lupus referred for coagulation assessment because of thrombosis, pregnancy loss or high-risk clinical settings for thrombosis were reviewed retrospectively. Increased activity of procoagulant factors and decreased activity of anti-coagulant factors were observed well above the expected 5% prevalence. All comparisons were significant at the P < 0.001 level. Anticardiolipin antibodies were present in 70.5% of patients tested (55/78) in this high-risk group, but usually in low titres. Platelet hyperfunction was detected in the majority of patients tested (85.7%, 78/91). Hypercoagulability in lupus is complex and is better defined by assessing multiple haemostatic factors in addition to platelet function. Platelet hyperfunction contributes significantly to thrombophilia in lupus and this is the key finding of our study.

CIB1 is an endogenous inhibitor of agonist-induced integrin alphaIIbbeta3 activation

In response to agonist stimulation, the alphaIIbbeta3 integrin on platelets is converted to an active conformation that binds fibrinogen and mediates platelet aggregation. This process contributes to both normal hemostasis and thrombosis. Activation of alphaIIbbeta3 is believed to occur in part via engagement of the beta3 cytoplasmic tail with talin; however, the role of the alphaIIb tail and its potential binding partners in regulating alphaIIbbeta3 activation is less clear. We report that calcium and integrin binding protein 1 (CIB1), which interacts directly with the alphaIIb tail, is an endogenous inhibitor of alphaIIbbeta3 activation; overexpression of CIB1 in megakaryocytes blocks agonist-induced alphaIIbbeta3 activation, whereas reduction of endogenous CIB1 via RNA interference enhances activation. CIB1 appears to inhibit integrin activation by competing with talin for binding to alphaIIbbeta3, thus providing a model for tightly controlled regulation of alphaIIbbeta3 activation.