Mean platelet volume as an indicator of platelet activation: methodological issues

Is dynamic change in mean platelet volume related with composite endpoint development after transcatheter aortic valve replacement?

Aortic valve stenosis (AS) is the most common valvular disease, and surgical or transcatheter aortic valve replacement (TAVR) are the treatment options. Diminish in platelet production or dysfunction may occur due to shear stress, advanced age, and other coexisting diseases in AS patients. Bleeding is one of the complications of TAVR and associated with increased mortality. MPV (mean platelet volume) indicates platelet's thrombogenic activity. Overproduction or consumption of platelets in various cardiac conditions may affect MPV values. We aimed to investigate the pre and postprocedure MPV percentage change (MPV-PC) and its association with post-TAVR short-term complications. A total of 204 patients who underwent TAVR with a diagnosis of severe symptomatic AS were included. The mean age was 78.66 ± 6.45 years, and 49.5% of patients were women. Two groups generated according to composite end point (CEP) development: CEP(+) and CEP(-).110 patients(53.9%) formed CEP(+) group. Although baseline MPV and platelet levels were similar between groups, MPV was increased ( P  < 0.001) and platelet was decreased ( P  < 0.001) significantly following the procedure when compared to baseline. MPV-PC was significantly higher in the VARC type 2-4 bleeding ( P   =  0.036) and major vascular, access-related, or cardiac structural complication groups ( P   =  0.048) when CEP subgroups were analyzed individually. Regression analysis revealed that diabetes mellitus [ P   =  0.044, β: 1.806 odds ratio (95% confidence interval): 1.016-3.21] and MPV-PC [ P   =  0.007,β: 1.044 odds ratio (95% confidence interval): 1.012-1.077] as independent predictors of CEP development at 1 month after TAVR. The MPV increase following TAVR may be an indicator of adverse outcomes following TAVR procedure within 1-month.

The Prognostic Utility of Mean Platelet Volume in Patients With Acute Coronary Syndrome: A Systematic Review With Meta-Analyses

Mean platelet volume (MPV) is a hematological index that is routinely measured in clinical settings. Although many studies have been conducted to investigate the prognostic significance of MPV in acute coronary syndromes (ACS), the findings have been inconsistent. The goal of this study was to systematically review all current evidence on the association between admission MPV and clinical outcomes after ACS. PubMed, Scopus, Web of Science, and other databases were searched. The primary endpoints were major adverse cardiovascular events (MACE) and mortality. We applied a Knapp and Hartung adjustment, prediction interval calculations and permutation tests during pairwise meta-analyses. A one-stage dose-response meta-analysis was also conducted. The meta-analysis consisted of 41 studies with 33443 participants. Mean platelet volume, as a continuous variable, was associated with the risk of long-term mortality (hazard ratio 1.33, 95% CI 1.19-1.48). After conducting permutation tests and calculation of prediction intervals, this association remained significant. The results for MACE were nonsignificant. Linear models were the best fitted models during dose-response meta-analyses, trends for nonlinearity were significant for long-term endpoints. Admission MPV was associated with long-term mortality in ACS patients, with nonlinear associations between MPV levels and long-term clinical outcomes.

Effect of metformin on reducing platelet dysfunction in gestational diabetes mellitus: a randomized controlled trial

OBJECTIVES

To evaluate the effect of metformin in improving platelet dysfunction in women with gestational diabetes mellitus (GDM).

PATIENTS AND METHODS

A randomized controlled trial was conducted on pregnant women diagnosed with GDM. Singleton low-risk pregnancies meeting the inclusion criteria were randomly allocated at 27-31 weeks to receive metformin and placebo through the rest of pregnancy. Thirty-seven and 39 cases were recruited into the metformin group and the placebo group, respectively. MPVs, P-selectin, and 8-isoprostane levels were determined at the time of allocation and 6 weeks after treatment. Obstetric and neonatal outcomes were also assessed.

RESULTS

Most baseline characteristics of the two groups were comparable. The levels of P-selectin after 6 weeks of treatment were significantly higher in the metformin group (68.9 ± 14.4 vs 60.6 ± 11.3; P-value = 0.006), indicating more platelet activation. All of the obstetric and neonatal outcomes were comparable except that birth weight was significantly lower in the metformin group (3018 ± 364 g vs 3204 ± 393 g; P-value = 0.037).

CONCLUSION

Metformin, in addition to diet and lifestyle modifications, does not improve or worsen oxidative stress and platelet dysfunction in women with GDM. Nevertheless, metformin significantly reduces fetal weight in women with GDM, theoretically preventing macrosomia.

Comprehensive analysis of immunoglobulin and clinical variables identifies functional linkages and diagnostic indicators associated with Behcet's disease patients receiving immunomodulatory treatment

BACKGROUND

Behcet's disease (BD) is a relapsing systemic vascular autoimmune/inflammatory disease. Despite much effort to investigate BD, there are virtually no unique laboratory markers identified to help in the diagnosis of BD, and the pathogenesis is largely unknown. The aim of this work is to explore interactions between different clinical variables by correlation analysis to determine associations between the functional linkages of different paired variables and potential diagnostic biomarkers of BD.

METHODS

We measured the immunoglobulin proteome (IgG, IgG1-4, IgA, IgA1-2) and 29 clinical variables in 66 healthy controls and 63 patients with BD. We performed a comprehensive clinical variable linkage analysis and defined the physiological, pathological and pharmacological linkages based on the correlations of all variables in healthy controls and BD patients without and with immunomodulatory therapy. We further calculated relative changes between variables derived from comprehensive linkage analysis for better indications in the clinic. The potential indicators were validated in a validation set with 76 patients with BD, 30 healthy controls, 18 patients with Takayasu arteritis and 18 patients with ANCA-associated vasculitis.

RESULTS

In this study, the variables identified were found to act in synergy rather than alone in BD patients under physiological, pathological and pharmacological conditions. Immunity and inflammation can be suppressed by corticosteroids and immunosuppressants, and integrative analysis of granulocytes, platelets and related variables is likely to provide a more comprehensive understanding of disease activity, thrombotic potential and ultimately potential tissue damage. We determined that total protein/mean corpuscular hemoglobin and total protein/mean corpuscular hemoglobin levels, total protein/mean corpuscular volume, and plateletcrit/monocyte counts were significantly increased in BD compared with controls (P < 0.05, in both the discovery and validation sets), which helped in distinguishing BD patients from healthy and vasculitis controls. Chronic anemia in BD combined with increased total protein contributed to higher levels of these biomarkers, and the interactions between platelets and monocytes may be linked to vascular involvement.

CONCLUSIONS

All these results demonstrate the utility of our approach in elucidating the pathogenesis and in identifying novel biomarkers for autoimmune diseases in the future.

Comparison of the Prognostic Value of Platelet-Related Indices in Biliary Tract Cancer Undergoing Surgical Resection

Purpose

Platelet-related indices, including mean platelet volume (MPV) and plateletocrit (PCT), have been reported as new prognostic factors of overall survival (OS) in many cancers, but not yet in biliary tract cancer (BTC). We intended to assess these indices in predicting OS in BTC patients with the aim to build a new prognostic model for patients with BTC after surgical resection.

Materials and Methods

Survival analysis and time receiver operating characteristic analysis were applied to screen the platelet indices. Univariate and multivariate Cox analyses were used to identify independent prognostic factors and develop a new prognostic model. Harrell’s C-statistics, calibration curves, and decisive curve analysis were used to assess the model.

Results

MPV and platelet distribution width (PDW)/PCT showed the best prognostic accuracy among the platelet indices. In multivariable analysis, factors predictive of poor OS were presence of nodal involvement, Non-radical surgery, poor tumor differentiation, carbohydrate antigen 19-9 > 100 U/mL, MPV > 8.1 fl, and PDW/PCT > 190. The new model was found to be superior to the TNM staging system and our new staging system showed higher discriminative power.

Conclusion

MPV and PDW/PCT have high prognostic value in BTC patients, and the novel staging system based on these two indices showed good discrimination and accuracy compared with the American Joint Committee on Cancer 7th TNM staging system.

Variation of red blood cell parameters in Behcet's disease: association with disease severity and vascular involvement

INTRODUCTION/OBJECTIVES

Behcet's disease (BD) is a systemic and chronic inflammatory vasculitis with unknown etiology. Diagnosis is determined by evaluating several clinical criteria, but the lack of specific laboratory diagnostic markers makes the diagnosis of BD more difficult. Therefore, the aim of this study was to determine the changes in hematological parameters in BD patients to investigate their relationship with BD clinical features.

METHOD

A total of 48 BD patients and 96 healthy controls were included in this study. The severity of each BD patient was associated to a severity score according to the entire spectrum of disease manifestations. Several laboratory tests were assessed, and the difference in their results between BD patients and healthy controls was evaluated. Correlation analysis was performed to reveal the interaction of these parameters.

RESULTS

C-reactive protein (CRP), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), neutrophil count, platelet count, and plateletcrit significantly increased in BD patients compared with healthy controls (P < 0.05). CRP was higher in patients with skin lesions, MCH and MCHC were lower in patients with vascular involvement, and the neutrophil count was higher in patients with skin lesions and genital ulcers. In addition, higher CRP and lower MCH and MCHC were associated with a severe condition. Besides, MCH and MCHC were negatively correlated with the platelet count, plateletcrit, and neutrophil count.

CONCLUSIONS

This study revealed that MCH and MCHC are valuable parameters for BD. Their levels help assess the disease severity and indicate the vascular involvement in BD. Key Points • This is the first study reporting MCH and MCHC as important biomarkers in BD. • BD patients with vascular involvement and thrombosis potential have lower levels of MCH and MCHC. • MCH and MCHC are negatively correlated with platelet count, plateletcrit, and neutrophil count. • Lower MCH and MCHC are associated with a severe condition.

Mean platelet volume and coronary artery disease

PURPOSE OF REVIEW

To critically review the literature describing links between mean platelet volume (MPV) and cardiovascular disease (CVD). We will focus on coronary artery disease (CAD). The MPV is measured routinely as part of a routine blood count.

RECENT FINDINGS

There is accumulating evidence showing that the MPV may predict CVD, as well as outcomes in patients with CAD. There is also evidence linking MPV and comorbidities (e.g. diabetes mellitus and impaired glycaemic control) that are expected in patients with CAD. The effect on MPV of drugs commonly used to treat CAD has not been clarified, but there is some evidence that they may exert a beneficial effect on the MPV. More specifically, the MPV may predict the effect of antiplatelet drugs (e.g. clopidogrel). There is also evidence relating MPV to stroke, atrial fibrillation, coronary artery ectasia and periprocedural outcomes after percutaneous coronary intervention (PCI).

SUMMARY

Measuring the MPV may prove useful in CVD risk assessment in patients with established CAD or at risk of developing CAD. Overall, there is evidence pointing to the role of MPV as a contributor rather than simple marker of CVD.

The clinical implications of mean platelet volume and mean platelet volume/platelet count ratio in locally advanced esophageal squamous cell carcinoma

As a hallmark of platelet activation, mean platelet volume (MPV) has been identified to be associated with various malignancies. However, the correlation between MPV, mean platelet volume/platelet count ratio (MPR), and esophageal squamous cell carcinoma (ESCC) remains unclear. The aim of this study is to clarify the relevance of MPV and MPR in patients with locally advanced ESCC. Four hundred and fifty-seven cases with newly diagnosed locally advanced ESCC followed by radical surgery and 240 healthy subjects matched for age and gender were included in this study. We retrospectively compared various hematological variables between groups and analyzed the correlation between MPV, MPR, and patients' clinicopathologic characteristics. Preoperative MPV and MPR were found to be significantly decreased in locally advanced ESCC when compared to healthy controls, they were (8.14 ± 1.09 fL vs. 10.23 ± 0.78 fL, P < 0.0001) and (0.03875 ± 0.02645 vs. 0.04463 ± 0.00972, P = 0.001), respectively. In addition, patients with advanced tumor length (≥4 cm) tended to have lower MPV levels (8.03 ± 1.11 fL versus 8.33 ± 1.21 fL, P = 0.005), while there was no difference between other subgroups. Moreover, decreased MPR was significantly correlated with advanced tumor length (P < 0.001) when divided at a median of 0.03420. Decreased MPV and MPR were significantly associated with locally advanced ESCC. Thus, they might be helpful in screening and risk stratification for locally advanced ESCC in combination with other approaches.

Mean Platelet Volume and Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

AIM

To evaluate the association between mean platelet volume (MPV) and gestational diabetes mellitus (GDM).

METHODS

A systematic literature search was performed in PubMed, EMBASE, Web of Science, and The Cochrane Library up to 4 September 2017. Pooled standardized mean differences (SMD) and 95% confidence interval (CI) were calculated using a random-effect model.

RESULTS

Nineteen studies comprising 1361 GDM patients and 1911 normal pregnant women were included. MPV was increased in GDM patients when compared with healthy pregnant women (SMD: 0.79; 95% CI: 0.43-1.16; P < 0.001). Subgroup analyses revealed that such trend was consistent in the third-trimester (SMD: 1.35; 95% CI: 0.72-1.98), Turkish (SMD: 0.81; 95% CI: 0.43-1.19), and Italian (SMD: 2.78; 95% CI: 2.22-3.34) patients with GDM and the patients diagnosed based on Carpenter and Coustan criteria (SMD: 1.04; 95% CI: 0.42-1.65). Significantly higher MPV also were observed within cross-sectional studies (SMD: 0.99; 95% CI: 0.49-1.49). Remarkable between-study heterogeneity and potential publication bias were observed in this meta-analysis; however, sensitivity analysis indicated that the results were not unduly influenced by any single study.

CONCLUSIONS

GDM patients are accompanied by increased MPV, strengthening the clinical evidence that MPV may be a predictive marker for GDM.

Association between mean platelet volume and hypertension incidence

Mean platelet volume (MPV) is increased in various cardiovascular diseases. We sought to determine the prognostic value of MPV for hypertension. We performed a retrospective cohort study. Baseline characteristics were measured in 9168 individuals without hypertension, and the follow-up period was 9 years. Hypertension was confirmed in 2881 participants during the follow-up period. When the participants were grouped according to MPV quartiles, the hazard ratio of future hypertension gradually increased across the MPV quartiles. The hazard ratios of hypertension for the II, III and IV (high) vs. I (low) quartiles of MPV were 1.13 (95% confidence interval (CI) 1.01-1.25, P=0.027), 1.25 (95% CI 1.12-1.39, P<0.001) and 1.40 (95% CI 1.26-1.55, P<0.001), respectively. In multivariate Cox regression analysis, MPV predicted hypertension independently of age, sex, platelet count, waist circumference, drinking, systolic blood pressure and creatinine levels. The present study indicated that elevated MPV is associated with increased incidence of hypertension independent of other risk factors, which suggests that platelet activity may play a role in hypertension incidence.

Nicotinic acid/laropiprant reduces platelet count but increases mean platelet volume in patients with primary dyslipidemia

INTRODUCTION

Nicotinic acid (NA) has been associated with reduced cardiovascular morbidity and mortality. Of note, beyond its lipid-modifying actions, NA possesses a number of not yet thoroughly defined pleiotropic actions including anti-inflammatory and antithrombotic effects. As a growing body of evidence points towards mean platelet volume (MPV) and platelet distribution width (PDW) as independent risk factors for cardiovascular disease, it would be interesting to evaluate the effect of NA on these platelet indices.

MATERIAL AND METHODS

We recruited 50 consecutive patients with dyslipidemia who were treated with a conventional statin dose (10-40 mg simvastatin or 10-20 mg atorvastatin or 5-20 mg rosuvastatin) and had not achieved the low-density lipoprotein cholesterol (LDL-C) or non-high-density lipoprotein cholesterol (non-HDL-C) goal. Add-on-statin treatment with extended release (ER) NA/laropiprant (1,000/20 mg/day for the first 4 weeks followed by 2,000/40 mg/day for the next 8 weeks) was given to all patients for 3 months.

RESULTS

The ER-NA/laropiprant resulted in a 20% reduction in platelet count (from 277,150/µl (min: 163,000/µl - max: 223,400/µl) to 220,480/µl (min: 141,000/µl - max: 319,000/µl), p < 0.001), while it increased MPV by 3.5% (from 11.4 fl (min: 9.2 fl - max: 13.6 fl) to 11.8 fl (min: 9.5 fl - max: 14.1 fl), p = 0.01), without affecting PDW significantly (from 14.6 fl (min: 10.5 fl - max: 19.3 fl) to 14.5 fl (min: 11 fl - max: 21.1 fl), p = NS).

CONCLUSIONS

The NA is associated with reduced platelet count but with increased MPV, thereby raising questions regarding NA's antithrombotic and vasculoprotective properties.

Are platelet volume indices of clinical use? A multidisciplinary review

Platelet size correlates with platelet activity and can be assessed by platelet volume indices (PVI). The PVI, mean platelet volume (MPV), is universally available with routine blood counts by automated hemograms and therefore is an attractive index to study in clinical scenarios. PVI are useful in assessing the etiology of thrombocytopenia. In addition, a normal platelet distribution width in the setting of thrombocytosis is highly suggestive of a reactive etiology. Higher MPV is also associated with the presence of cardiovascular risk factors, chest pain due to acute coronary syndrome, and adverse outcome after acute coronary syndrome. Results from studies evaluating MPV in patients with peripheral artery disease, unprovoked deep vein thrombosis, and pulmonary embolism further advocate a potential role for MPV in identifying patients at high risk of thrombosis. Nevertheless, most of these data come from retrospective studies some of which have small study populations and confounding factors influencing platelet volume. Moreover, the cut-off values derived from these retrospective studies have not been validated prospectively. Despite the potential for clinical utility evident from these studies, the above-mentioned flaws together with technical problems in measuring MPV currently limit its clinical usefulness. Our review provides a perspective on PVI's potential clinical use.

Hematologic and clinical parameters after transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis

BACKGROUND

Previous studies have demonstrated that platelet activation occurs in patients with aortic stenosis (AS). This study sought to evaluate the changes in hematologic and clinical parameters noted with the improvement in AS following transcatheter aortic valve implantation (TAVI) in patients with severe AS at high risk of surgery.

PATIENTS AND METHODS

The study included 33 patients who underwent TAVI. In addition to biochemical, clinical, and echocardiographic examinations, hematologic blood parameters were recorded before TAVI, at discharge, and at 1 and 4 months.

RESULTS

Mean platelet volume (MPV) showed a progressive decrease after TAVI. On echocardiography at 1 month, aortic valve area significantly increased, with significant decreases in peak and mean gradients. Progressive decreases were also noted in N-terminal proB-type natriuretic peptide levels.

CONCLUSION

Our findings show that TAVI improves hemodynamic parameters of the valve with marked clinical and echocardiographic improvement, resulting in decreased platelet activation and MPV in patients with severe AS.

The relationship between diabetes, metabolic syndrome, and platelet activity as measured by mean platelet volume: the National Health And Nutrition Examination Survey, 1999-2004

OBJECTIVE

The association between platelet activity, diabetes, and glucometabolic control is uncertain. We aim to investigate mean platelet volume (MPV), a marker of platelet size and platelet activity, with the prevalence of diabetes, metabolic syndrome, and degree of glycemic control.

RESEARCH DESIGN AND METHODS

This is a retrospective analysis of 13,021 participants in the National Health and Nutrition Examination Survey from 1999 to 2004. Prevalence of diabetes was defined as nonfasting glucose >200 mg/dL, fasting glucose ≥ 126 mg/dL, or treatment with hypoglycemic agents. Presence of metabolic syndrome was determined by the National Cholesterol Education Program Adult Treatment Panel III definition. Odds ratios and 95% CIs were estimated by logistic regression.

RESULTS

MPV was significantly higher in subjects with diabetes (8.20 vs. 8.06 femtoliter [fL], P < 0.01) but not in subjects with metabolic syndrome (8.09 vs. 8.07 fL, P = 0.24). For the metabolic syndrome components, MPV was significantly higher in abdominal obesity (P = 0.03) and low HDL (P = 0.04), and not different in high blood pressure (P = 0.07), abnormal glucose metabolism (P = 0.71), or hypertriglyceridemia (P = 0.46). There was a significant correlation between MPV and glucose (P < 0.0001) and between MPV and hemoglobin A(1c) (P < 0.0001) in subjects with diabetes. These correlations were no longer significant in those without diabetes. The adjusted odds of diabetes rose with increasing MPV levels and were most pronounced in subjects with MPV levels exceeding the 90th percentile (≥ 9.31 fL). The association between MPV and diabetes was most apparent in those with the poorest glucose control.

CONCLUSIONS

Mean platelet volume is strongly and independently associated with the presence and severity of diabetes.

Mean platelet volume predicting carotid atherosclerosis in atherothrombotic ischemic stroke

BACKGROUND

Platelets are involved in atherosclerosis. Mean platelet volume (MPV) could be a marker of platelet activation. We aim to determine whether MPV levels were correlated with the presence of atherosclerotic disease in carotid arteries of patients with stroke.

METHODS

We recruited 215 patients with atherothrombotic stroke. All the participants underwent ultrasonographic evaluation of their extracranial carotid arteries. MPV was measured in automated hematology analysis system. The subjects were divided according to plaques and severity of carotid stenosis. Univariate and multivariate statistical analyses and a ROC curve to predict carotid stenosis were performed.

RESULTS

Univariate analysis showed a positive relationship between MPV and the degree of carotid atherosclerosis (p < 0.00007), and with carotid intima to media thickness (p < 0.00002). In ROC curve, a MPV cut-off of 11.25 fl was obtained for a sensibility of 70% and a specificity of 71% (p < 0.02). Multivariate analysis showed significant correlation with severity of carotid stenosis, when MPV was higher than 11.25 fl (OR: 2.9, p < 0.00007).

CONCLUSIONS

Our results indicate that an elevated MPV could be an easily measurable marker of severity of carotid stenosis in patients with atherothrombotic stroke.

Mean platelet volume may represent a predictive parameter for overall vascular mortality and ischemic heart disease

OBJECTIVE

An increased mean platelet volume (MPV), as an indicator of larger, more reactive platelets resulting from an increased platelet turnover, may represent a risk factor for overall vascular mortality, including myocardial infarction. We intended to identify patients at higher risk of dying from vascular disease in a large, hospital-based cohort.

METHODS AND RESULTS

A total of 206 554 first-ever admissions to the Allgemeines Krankenhaus Wien for determination of MPV between January 1996 and July 2003 were included. Primary end points were overall vascular mortality and death due to ischemic heart disease. Multivariate Cox regression adjusted for sex, age, and platelet count was applied for analysis. MPV values were categorized into quintiles, with the lowest quintile serving as the reference category. Compared with individuals with lower MPV (<8.7 fL), hazard ratios for overall vascular mortality gradually increased to 1.5 in the highest category (≥11.01 fL). The relationship of MPV to ischemic heart disease was even stronger and increased from 1.2 (8.71 to 9.60 fL category) to 1.8 in the highest category (≥11.01 fL).

CONCLUSIONS

Our results indicate that patients with an increased MPV (≥11.01 fL) are at higher risk of death due to ischemic heart disease, with hazard ratios comparable to those reported for obesity or smoking.

Usefulness of mean platelet volume as a biomarker for long-term outcomes after percutaneous coronary intervention

Larger size platelets have enhanced reactivity. The mean platelet volume (MPV) is a marker of platelet activation and is usually measured as part of blood testing. The aim of the present study was to investigate the utility of the MPV as a biomarker in prognosticating the long-term outcomes after percutaneous coronary intervention (PCI). The baseline MPV values from consecutive patients undergoing PCI were screened. Of the 1,432 patients, the composite primary end point of mortality or myocardial infarction at 1 year occurred in 80 (5.6%). The patients in the highest tertile (MPV >9.1 fL) had an increased frequency of the primary end point compared to those in the mid (8.1 to 9.1 fL) and lowest (<8.1 fL) tertiles (9.0%, 4.5%, and 3.5%, respectively; p <0.01). Logistic regression analysis demonstrated diabetes (odds ratio 2.44, 95% confidence interval 1.48 to 4.00) and highest tertile of MPV (odds ratio 2.42, 95% confidence interval 1.47 to 3.99) as the best predictors of adverse outcomes. In patients with acute coronary syndrome, the preprocedural MPV and troponin levels demonstrated a comparable predictive relation to the primary end point (receiver operator characteristics curve analysis, area under the curve 0.64, p = 0.01; and 0.63, p = 0.01, respectively). In conclusion, an elevated MPV was a strong independent predictor of long-term outcomes after PCI. The preprocedural MPV had prognostic value similar to that of troponin in patients with acute coronary syndrome. These findings could be of importance in the clinical evaluation of patients before PCI and the design of future studies assessing antiplatelet therapies.

The effect of clopidogrel, aspirin and both antiplatelet drugs on platelet function in patients with peripheral arterial disease

Peripheral arterial disease (PAD) is associated with platelet hyperactivity. Aspirin and clopidogrel, two platelet inhibitors, act by different mechanisms. Aspirin inhibits thromboxane A2 synthesis and clopidogrel acts on the P2Y12 platelet ADP receptor. We evaluated the effect of clopidogrel (75 mg/day), aspirin (75 mg/day) and then both drugs on several platelet function indices in patients with PAD (n = 20). There was a significant (P = 0.0001) decrease in ADP-induced aggregation, after clopidogrel but not after taking aspirin. Clopidogrel plus aspirin significantly decreased spontaneous platelet aggregation (SPA) (P = 0.01 to P = 0.002) but SPA was not significantly altered by either aspirin or clopidogrel monotherapy. Similarly, monotherapy did not inhibit serotonin (5HT)-induced aggregation but there was a sigificant inhibition (P = 0.03 to P < 0.02) after combination therapy. ADP (0.8 microM)-induced platelet shape change (PSC) was significantly inhibited by clopidogrel (P = 0.004) or aspirin (P = 0.01). This was also true for 5HT-induced PSC (clopidogrel, P = 0.01; aspirin, P = 0.03). Soluble P-selectin decreased significantly (from 32 +/- 24 to 25 +/- 17 ng/ml, P = 0.04) with combination therapy. Plasma platelet-derived growth factor and intraplatelet 5HT levels were not altered by combination therapy. In PAD, clopidogrel is a more potent inhibitor of ADP-induced platelet activation than aspirin; combination therapy is more effective than clopidogrel or aspirin monotherapy. These potentially clinically relevant findings should be evaluated in appropriately designed trials.

Is elevated mean platelet volume associated with a worse outcome in patients with acute ischemic cerebrovascular events?

BACKGROUND AND PURPOSE

Increased mean platelet volume (MPV), indicating higher platelet reactivity, is associated with an increased risk of myocardial infarction. Higher levels of MPV have been found in patients with acute ischemic stroke than in control subjects. Data from smaller studies regarding an association between MPV and stroke severity and outcome have been controversial. If such an association exists, MPV might help to identify patients at increased risk of a severe course of acute cerebrovascular disease.

METHODS

Within a multicenter, cross-sectional study nested in a cohort, we analyzed the relation between MPV and stroke severity as determined by the modified Rankin Scale after 1 week in 776 patients with acute ischemic stroke or transient ischemic attack. By multivariate logistic regression modeling, we determined the influence of MPV on stroke severity, adjusting for potential confounding factors.

RESULTS

Patients within the highest quintile of MPV had a significantly higher risk of suffering a severe stroke, defined as modified Rankin Scale score of 3 to 6, compared with patients within the lowest quintile (odds ratio=2.6; 95% confidence interval, 1.6 to 4.1; P<0.001). This association remained significant after adjustment for possible confounding factors (odds ratio=2.2; 95% confidence interval, 1.2 to 4.0; P=0.013).

CONCLUSIONS

Our results indicate that an elevated MPV is associated with a worse outcome for acute ischemic cerebrovascular events independent of other clinical parameters.