Influence of platelet size before coronary angioplasty on subsequent restenosis

High-fat diet-induced atherosclerosis promotes neurodegeneration in the triple transgenic (3 × Tg) mouse model of Alzheimer's disease associated with chronic platelet activation

Background

Epidemiological studies link vascular disease risk factors such as atherosclerosis, hypertension, and diabetes mellitus with Alzheimer’s disease (AD). Whether there are direct links between these conditions to β-amyloid (Aβ) aggregation and tau pathology is uncertain.

Methods

To investigate the possible link between atherosclerosis and AD pathology, we subjected triple transgenic (3 × Tg) AD mice to a high-fat diet (HFD) at 3 months of age, which corresponds to early adulthood in humans.

Results

After 9 months of treatment, HFD-treated 3 × Tg mice exhibited worse memory deficits accompanied by blood hypercoagulation, thrombocytosis, and chronic platelet activation. Procoagulant platelets from HFD-treated 3 × Tg mice actively induced the conversion of soluble Aβ40 into fibrillar Aβ aggregates, associated with increased expression of integrin αIIbβ₃ and clusterin. At 9 months and older, platelet-associated fibrillar Aβ aggregates were observed to obstruct the cerebral blood vessels in HFD-treated 3 × Tg mice. HFD-treated 3 × Tg mice exhibited a greater cerebral amyloid angiopathy (CAA) burden and increased cerebral vascular permeability, as well as more extensive neuroinflammation, tau hyperphosphorylation, and neuron loss. Disaggregation of preexisting platelet micro-clots with humanized GPIIIa49-66 scFv Ab (A11) significantly reduced platelet-associated fibrillar Aβ aggregates in vitro and improved vascular permeability in vivo.

Conclusions

These findings suggest that a major contribution of atherosclerosis to AD pathology is via its effects on blood coagulation and the formation of platelet-mediated Aβ aggregates that compromise cerebral blood flow and therefore neuronal function. This leads to cognitive decline.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-021-00890-9.

Do MCHC, MPV, and Procalcitonin Levels Determine Prognosis in Acute Coronary Syndrome?

AIM

Acute coronary syndrome (ACS) continues to be the main cause of mortality and morbidity globally. The aim was to assess serum procalcitonin (PCT), mean corpuscular hemoglobin concentration (MCHC) and mean platelet volume (MPV) levels in terms of complications after myocardial infarctus, triple vein coronary artery disease (TVCAD), and mortality prediction.

MATERIAL AND METHOD

This cross-sectional cohort study included 200 patients with ACS attending the emergency department of our hospital with chest pain and admitted to the cardiology clinic from January 2014 to December 2016. Patients were divided into 4 groups as inferior group, anterior group, NSTEMI group, and UA group according to diagnosis. These groups were compared in terms of complications occurring after MI, TVCAD, and mortality rates.

RESULTS

There were significant differences in terms of complications forming after ACS, TVCAD, and mortality. The inferior subgroup had high PCT and MCHC levels and was found to have more complications developing and mortality compared to other groups. Patients with high PCT and MPV values were identified to have higher mortality and TVCAD. In the anterior subgroup, ischemic heart failure was higher compared to the other groups. In the interior, anterior, and non-ST elevated myocardial infarctus (NSTEMI) groups, the 0-, 6-, and 12-hour cTnI values were significantly higher compared to the UA group, while the anterior group had a significantly higher 12-hour cTnI value compared to the NSTEMI group. Correlation analysis for PCT, MCHC, and MPV with complications developing after MI, mortality, and TVCAD found positive and statistically significant correlations.

CONCLUSION

High PCT, MCHC, and MPV levels in acute coronary syndrome may be beneficial predictive values in terms of complications that may develop, TVCAD, and mortality.

Mean platelet diameter measurements to classify inherited thrombocytopenias

INTRODUCTION

Mean platelet volume (MPV) assists the differential diagnosis of inherited thrombocytopenia (IT) but lacks standardisation and varies between automated analysers. Classification of IT based on mean platelet diameter (MPD) has been proposed by an international collaborative study but has not been validated.

METHODS

To assess the applicability of MPD to classify forms of IT, digital images of blood films from patients with established genetic causes for IT were generated, and the MPD measured (ZEISS Axio-scanner and Image J software) by a blinded reviewer. Comparison was made to the proposed classification system.

RESULTS

Mean platelet volume was measured in thrombocytopenia with different genetic aetiologies, bilallelic BSS (bBSS) (n = 1), monoallelic BSS (mBSS) (n = 2), MYH9-related disorders (MYH9-RD) (n = 11), GFI1B-related thrombocytopenia (RT) (n = 15), FLI1-RT (n = 2), TUBB1-RT (n = 3), ITGA2B/ITGB3-RT (n = 1), RUNX1-RT (n = 2) and controls (n = 54). bBSS and 82% of MYH9-RD samples had MPD >4 μm which correlated with "IT with giant platelets." Only 55% of samples expected in the "large platelet group" had MPD meeting the classification cut-off (MPD >3.2 μm). FLI1-RT MPD were significantly larger than expected whilst ITGA2B/ITGB3-RT MPD were smaller than proposed. MPD in FPD/AML were "normal."

CONCLUSION

Platelet MPD measurements are a useful guide to classify IT, but the time taken to record measurements may limit clinical applicability.

The Impact of Mean Platelet Volume (MPV) and JAK-2 Mutation on Thrombosis in Chronic Myeloproliferative Diseases

Thrombosis and bleeding are the main complications of chronic myeloproliferative diseases. Mean platelet volume (MPV) is an important indicator of the platelet activation. The aim of the present study was to assess the interrelationships between MPV, JAK-2 gene mutation and thromboembolic events in patients with ET and PV. Patients with ET (n = 60) and PV (n = 46) were compared to the secondary erythrocytosis group (n = 19); and a control group of age and sex matched healthy volunteers (n = 52). Besides demographic, clinical and laboratory data; thrombotic and hemorrhagic events were recorded for each patient. Platelet counts, MPV and JAK2 mutations were studied; and their relation with thromboembolic events were investigated using SPSS program for statistical analysis. There was no significant difference between groups regarding age (p = 0.188). Mean platelet count was significantly higher in ET group than other groups (p < 0.0001). Mean platelet count in PV group was significantly higher than control (p < 0.0001) and secondary erythrocytosis groups (p < 0.0001). In the ET group, MPV values were significantly lower than the control group and PV group. In the ET group, those with thromboembolia had lower platelet counts. There was no relation between MPV and thromboembolic event rate in PV, ET and secondary erithrocytosis groups; while no event was recorded in the control group. There was no relation between thromboembolic event rate and JAK 2 mutation. The association of JAK-2 mutation and high MPV especially in ET and PV groups does not contribute to the thromboembolic events.

Platelets and cardiovascular risk

Atherosclerosis and its late sequels are still the number one cause of death in Western societies. Platelets are a driving force not only during the genesis of atherosclerosis, but especially in its late stages, as evidenced by complications such as arterial thrombosis, myocardial infarction, and ischaemic stroke. Platelets are small, anucleate blood elements of critical importance in cardiovascular disease, a major cause of morbidity and mortality. Numerous risk scores exist to identify healthy individuals at increased risk of developing atherosclerosis and cardiovascular disease. However, markers of cardiovascular risk not routinely assessed (i.e. platelet activity, mean platelet volume and P-selectin) may also contribute to be useful in calculating cardiovascular risk. The present review and meta-analysis summarizes the evidence for measuring platelet function indices to identify patients at risk of developing cardiovascular events.

Common Thrombotic Disorders Defined by CBC Platelet Parameters

The Coulter STKS mean platelet volume (MPV), platelet distribution width (PDW), mean corpuscular volume (MCV), and hematocrit (HCT) are assessed in thrombotic diseases. Complete blood counts (CBCs) were studied retrospectively in 645 consecutive hospital cases and, 850 "CBCs with blood films to the pathologist." Because the MPV and PDW are time dependant, nomograms and tables were created for the 0-25- and 26-40-min elapsed time intervals. In this study, abnormal CBC platelet parameters were found in the majority of patients with common thrombotic diseases, such as diabetes, atherosclerosis, hypertension, congestive heart failure, deep vein thrombosis (DVT), and toxemia. Thrombotic disease-related CBC categories include combined elevated MPV and PDW, elevated MPV or PDW alone, "MCV/MPV mismatch" (failure of physiologic "MCV/MPV match"), rheologic problem of elevated HCT and MPV, and mild thrombocytopenia with decreased MPV and high PDW. Anticoagulants and steroids often decrease the MPV. CBC platelet parameter abnormalities provide a new useful classification of thrombotic diseases in daily practice.

Is the preoperative MPV value related to early thrombus formation in microvascular anastomosis?

OBJECTIVE

One of the most common encountered problems in free flap surgeries is anastomotic thrombosis. The mean platelet volume (MPV) may indicate the concentration of intra-platelet proactive substances and the thrombogenic potential of the platelets. MPV is used as a clinical monitoring index in routine blood counts, it has not yet been effectively used in free flap surgery.

METHODS

This study evaluates the relationship between the preoperative MPV value and anastomotic thrombus formation during the postoperative 48 hours in 32 free flap operations from September 2013 to September 2014. The mean patient age was 36.75 years. The preoperative MPV value, which was obtained from the complete blood count, was recorded and correlation of MPV and postoperative thrombus formation was investigated.

RESULTS

Four anastomotic thrombus were encountered in 34 free flaps during the postoperative 48 hours. Two of them were salvaged by performing thrombectomy and/or administration of i.v. heparin. There was no statistical relationship between MPV value and postoperative thrombus formation during 48 hours follow-up (p = 0.925).

CONCLUSION

Even though this study didn't find a correlation between preoperative MPV value and postoperative early anastomotic thrombus, it would be helpful to validate the results using multi-centre and comprehensive studies with larger patient cohorts.

Prognostic effect of mean platelet volume in patients with coronary artery disease. A systematic review and meta-analysis

Large platelets with high haemostatic activity may lead to increased platelet aggregation.. Mean platelet volume (MPV), an indicator of platelet reactivity, may emerge as a prognostic marker in patients with coronary artery disease (CAD). It was the objective of this study to conduct a systematic review and meta-analysis to assess prognostic effects of MPV on cardiovascular events (CVE) in CAD patients. We searched MEDLINE and SCOPUS from inception to January 2, 2014. All studies that reported MPV and the incidence of cardiovascular events in CAD patients were included. Two reviewers independently extracted the data. A random-effects model was applied for pooling the mean difference of MPV between patients with vs without CVE. Among 30 eligible studies, eight studies reported mean difference of MPV between CVE groups, 11 studies reported MPV dichotomous into high vs low MPV groups, and 11 studies reported both. The pooled mean difference was 0.69 fL (95 %CI = 0.36, 1.01), i. e. patients with CVE had a MPV about 0.69 fL higher than non-CVE. Patients with higher MPV were about 12 % more likely to die than patients with lower MPV (RR 1.12; 95 %CI = 1.02-1.24). However, pooling these effects was based on high heterogeneity and the source of heterogeneity could not be identified. This might be explained by many differences among included studies (e. g. study population, outcomes of interest, analysate, time between blood collection and MPV analysis, etc). These findings suggest that MPV may be a useful prognostic marker in patients with CAD.

The causal role of megakaryocyte–platelet hyperactivity in acute coronary syndromes

Platelets are causally involved in coronary artery obstruction in acute coronary syndromes (ACS). This cell type is unique to mammals and its production, which is unlike that of any other mammalian cell, involves polyploid nuclear change in the mother cell (megakaryocyte) and the production of anucleate cells with a log Gaussian distribution of volume. Platelets vary more in cellular volume than any other circulating blood element in mammals. Larger platelets are denser, contain more secretory granules, and are more reactive than their smaller counterparts. A causal relationship between the presence of large, dense, reactive platelets in the circulation and ACS is supported by many clinical studies. Furthermore, the results of two large, prospective, epidemiological studies have demonstrated that mean platelet volume was the strongest independent predictor of outcome in patients with acute myocardial infarction. Notably, evidence indicates that an increase in mean platelet volume in the pathogenesis of ACS can potentially overwhelm current therapeutics. The control system for the physiological and pathophysiological production of large platelets should, therefore, be researched. An understanding of this system might give rise to new therapeutics that could control platelet reactivity and thereby comprehensively prevent ACS.

Original articles: increased platelet volume in patients with adult polycystic kidney disease

Platelet volume is a measure of platelet function. An increased platelet volume is found in acute vascular syndromes and may have a causative role and predict outcome. Patients with autosomal dominant polycystic kidney disease (APKD) are at increased risk of developing, and dying from, premature vascular disease. We hypothesized that platelet volume might be altered in patients with APKD. Platelet volume was measured in 16 normotensive APKD patients with normal renal function and 16 normal volunteers pair-matched for age, gender, race and body mass index. Mean platelet volume was increased by 0.4 fl (95% confidence limits 0.1 to 0.9, 2P=0.017) in patients with APKD as compared with normal subjects: median 8.4 fl (0.7) versus 8.0 fl (0.3) respectively. In contrast, platelet count was lower by 63 × 10(9)/1 (-5 to -108, 2P = 0.031): 225 (40) × 10(9)/1 versus 280 (35) × 10(9)/1 while the platelet mass was not different, -0.36 ml/l (-0.81 to 0.02, 2P=0.070): 1.82 (0.30) ml/l versus 2.28 (0.38) ml/l. Platelet volume and count were inversely correlated across the two groups, r(s)= -0.342 (2P=0.055). Serum levels of erythropoietin, a hormone that contributes to the regulation of thrombopoeisis, were not different between the APKD patients and normal controls, 35 U/1 (-71 to 120, 2P=0.42): 107 U/I (53) versus 84 U/I (57). Although erythropoietin did not correlate with platelet volume, R., = -0.185 (2P =0.36), it was positively associated with platelet count, R., = 0.465 (2P=0.029) and platelet mass, r(s) = 0.466 (2P= 0.028). Since an increased platelet volume is associated with platelet hyperactivity, the increased platelet volume in APKD may be a marker, or even contribute to the development, of premature vascular disease and sudden cardiac death in patients with APKD.

Mean platelet volume has a prognostic value in patients with coronary artery ectasia

The aim of this study was to investigate the prognostic role of mean platelet volume (MPV) in patients with coronary artery ectasia (CAE). The baseline MPV values of 258 patients with CAE were screened. The mean time of follow-up was 49 ± 21 months for major adverse cardiac events (MACEs) defined as the combination of cardiac death, nonfatal myocardial infarction (MI), rehospitalization due to cardiac disorders, and readmission due to chest pain. During follow-up period, 63 (24%) MACEs developed. There were 4 (2%) cardiovascular deaths, 0 nonfatal MI, 14 (5%) rehospitalization, and 45 (17%) readmission. Mean platelet volume values were significantly higher in patients with CAE with MACEs than in patients with CAE without MACEs (9.5 ± 1.2 fL vs 8.9 ± 1.1 fL, respectively, P = .002). The rate of MACE was higher in CAE patients with MPV of >9 fL than those with MVP of ≤9 fL (33% vs. 15%, P = .001). Mean platelet volume has a prognostic value for MACEs in patients with CAE.

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.

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

AIM

To determine whether an association exists between mean platelet volume (MPV) and acute myocardial infarction (AMI) and other cardiovascular events. Platelet activity is a major culprit in atherothrombotic events. MPV, which is widely available in clinical practice, is a potentially useful biomarker of platelet activity in the setting of cardiovascular disease.

METHODS AND RESULTS

We performed a systematic review and meta-analysis investigating the association between MPV and AMI, all-cause mortality following myocardial infarction, and restenosis following coronary angioplasty. Results were pooled using random-effects modeling. Pooled results from 16 cross-sectional studies involving 2809 patients investigating the association of MPV and AMI indicated that MPV was significantly higher in those with AMI than those without AMI [mean difference 0.92 fL, 95% confidence interval (CI) 0.67-1.16, P < 0.001). In subgroup analyses, significant differences in MPV existed between subjects with AMI, subjects with stable coronary disease (P < 0.001), and stable controls (P < 0.001), but not vs. those with unstable angina (P = 0.24). Pooled results from three cohort studies involving 3184 patients evaluating the risk of death following AMI demonstrated that an elevated MPV increased the odds of death as compared with a normal MPV (11.5% vs. 7.1%, odds ratio 1.65, 95% CI 1.12-2.52, P = 0.012). Pooled results from five cohort studies involving 430 patients who underwent coronary angioplasty revealed that MPV was significantly higher in patients who developed restenosis than in those who did not develop restenosis (mean difference 0.98 fL, 95% CI 0.74-1.21, P < 0.001).

CONCLUSIONS

Elevated MPV is associated with AMI, mortality following myocardial infarction, and restenosis following coronary angioplasty. These data suggest that MPV is a potentially useful prognostic biomarker in patients with cardiovascular disease. Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.

The relationship of mean platelet volume with the risk and prognosis of cardiovascular diseases

BACKGROUND

Mean platelet volume (MPV) is arousing increasing interest as a new independent cardiovascular risk factor.

AIM

To provide a comprehensive review on the biological significance, the main determinants and the prognostic implications of MPV.

METHODS

A literature search was performed using key terms, such as 'MPV' or 'mean platelet volume', together with 'stroke', 'myocardial infarction' and 'diabetes and 'obesity'.

RESULTS

Large platelets are likely more reactive: elevated MPV values are associated with a shortened bleeding time and increased thromboxane B2 plasma levels. Thus, MPV could be considered an indicator of platelet function. Platelet size is mainly determined in the bone marrow during megakaryocytopoiesis, and subsequently does not substantially change. MPV is only partially regulated by thrombopoietin: in fact, growth factors and cytokines may also elicit the production of larger and more reactive platelets in the bone marrow, in the presence of conditions capable of increasing their concentrations, such as obesity, endothelial dysfunction and possibly myocardial and cerebral ischaemia. This phenomenon could play an important role in vascular diseases. In fact MPV is predictive of stroke, acute myocardial infarction (AMI) and restenosis of coronary angioplasty, is increased in the presence of obesity, diabetes mellitus, metabolic syndrome, AMI and stroke and has been shown to have a prognostic significance in patients with stroke and AMI.

CONCLUSION

In assessing whole blood count, MPV should not be undervalued, as its increase should suggest a careful assessment of cardiovascular risk.

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

AIM

To determine whether an association exists between mean platelet volume (MPV) and acute myocardial infarction (AMI) and other cardiovascular events. Platelet activity is a major culprit in atherothrombotic events. MPV, which is widely available in clinical practice, is a potentially useful biomarker of platelet activity in the setting of cardiovascular disease.

METHODS AND RESULTS

We performed a systematic review and meta-analysis investigating the association between MPV and AMI, all-cause mortality following myocardial infarction, and restenosis following coronary angioplasty. Results were pooled using random-effects modeling. Pooled results from 16 cross-sectional studies involving 2809 patients investigating the association of MPV and AMI indicated that MPV was significantly higher in those with AMI than those without AMI [mean difference 0.92 fL, 95% confidence interval (CI) 0.67-1.16, P < 0.001). In subgroup analyses, significant differences in MPV existed between subjects with AMI, subjects with stable coronary disease (P < 0.001), and stable controls (P < 0.001), but not vs. those with unstable angina (P = 0.24). Pooled results from three cohort studies involving 3184 patients evaluating the risk of death following AMI demonstrated that an elevated MPV increased the odds of death as compared with a normal MPV (11.5% vs. 7.1%, odds ratio 1.65, 95% CI 1.12-2.52, P = 0.012). Pooled results from five cohort studies involving 430 patients who underwent coronary angioplasty revealed that MPV was significantly higher in patients who developed restenosis than in those who did not develop restenosis (mean difference 0.98 fL, 95% CI 0.74-1.21, P < 0.001).

CONCLUSIONS

Elevated MPV is associated with AMI, mortality following myocardial infarction, and restenosis following coronary angioplasty. These data suggest that MPV is a potentially useful prognostic biomarker in patients with cardiovascular disease. Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.

Studies of biological functions in blood cells from individuals with large platelets

The present study was performed to explore differences in the expression of P-selectin and IL-8 production of blood cells in healthy individuals with large size platelets (MI-families) as compared to people having normal size platelets. A positive correlation between LPS-induced IL-8 production per platelet in whole blood and mean platelet volume (MPV) was found in the large platelet group (R=0.74, P<0.05). When the large and normal groups were combined the correlation was nearly, but not quite significant (R=0.46, P<0.06). There was also a positive correlation between sP-selectin and MPV (R=0.42, P<0.05). Furthermore, IL-8 in serum was positively correlated to sP-selectin in serum (R=0.68, P<0.005). sP-selectin baseline values in citrated plasma correlated significantly with values found in serum (R=0.72, P<0.0005), indicating that sP-selectin in blood originates from the platelets rather than from endothelial cells. Significant correlations were also found in both groups between P-selectin and CD40L (R=0.44, P<0.05) and P-selectin and RANTES (R=0.44, P<0.05). A significant correlation was also found between PDGF and RANTES (R=0.44, P<0.05). Our results suggest that larger platelets enhance the production of IL-8 more than normally sized platelets. This phenomenon is probably mediated through P-selectin exposed on platelets.

The relationship between glycemic control and platelet activity in type 2 diabetes mellitus

AIMS

Platelet activity and aggregation potential, which are essential components of thrombogenesis and atherosclerosis, can be conveniently estimated by measuring mean platelet volume (MPV) as part of whole blood count. It has been shown that MPV was significantly higher in diabetes mellitus (DM); however, the effect of glycemic control on MPV has not been studied. The aim of this study was to investigate the relationship among MPV, glycemic control, and micro- and macrovascular complications in type 2 DM.

METHODS

Seventy patients with type 2 DM and 40 age- and sex-matched healthy individuals were enrolled. Diabetic patients were grouped into those with glycated hemoglobin (HbA1c) levels <or=7% (Group A, n=35 patients) and those with HbA1c >7% (Group B, n=35 patients). Initially, both groups were compared with regard to MPV, HbA1c, serum lipid levels, coronary artery disease, retinopathy, neuropathy, and nephropathy. Thereafter, Group B was called to monthly visits to obtain improved control glycemic control, which was defined as achievement of HbA1c <or=7%. At the end of 3 months of follow-up, Group B was reevaluated.

RESULTS

MPV was significantly higher in patients with DM than in controls (8.7+/-0.8 fl vs. 8.2+/-0.7 fl, P=.002). In diabetic patients, there was a significant positive correlation between MPV and HbA1c levels (r=.39, P=.001) but not diabetic vascular complications. When we compared the two diabetic groups, Group B patients had significantly higher MPV than Group A (9.0+/-0.7 fl vs. 8.4+/-0.8 fl, P=.01). Thirty patients (86%) of Group B achieved improved glycemic control at the end of the 3 months. MPV of the patients with improved glycemic control were significantly decreased compared to baseline MPV (8.4+/-0.8 fl vs. 9.0+/-0.7 fl, P=.003).

CONCLUSIONS

Our results suggested a close relationship between poor glycemic control and increased platelet activity in patients with type 2 DM. Furthermore, platelet activity recovered through improved glycemic control, which may prevent the possible role of platelets in cardiovascular events in these patients.

The effects of maximal treadmill graded exercise testing on haemorheological, haemodynamic and flow cytometry platelet markers in patients with systolic or diastolic heart failure

BACKGROUND

Acute exercise has been associated with activation of thrombosis, and this risk may be accentuated in patients with heart failure. Given the relation of platelets to atherothrombosis, we tested the hypothesis that acute exercise would adversely affect platelet indices and platelet activation markers in patients with systolic and diastolic heart failure.

MATERIALS AND METHODS

We studied 20 patients with systolic heart failure (17 men, 3 women; mean age 64 +/- 10 years, all with ejection fraction (EF) < or = 40%) and 20 patients with diastolic heart failure (14 men, 6 women; mean age 64 +/- 8 years, mean EF = 66%) who were exercised to maximal intensity, who were compared to 13 healthy controls (6 men, 7 women; mean age 60 +/- 4 years, mean EF = 73%). We measured platelet indices (platelet volume, mass and component) and platelet activation markers (platelet-bound CD62P%G, CD63%G and CD40L%G using flow cytometry, as well as plasma sCD40L and soluble P-selectin (sP-sel) levels).

RESULTS

Baseline Mean Platelet Volume (MPV), sP-sel, CD40L%G and CD63%G levels were significantly higher in patients with systolic and diastolic heart failure, when compared with controls. The mean exercise duration and VO(2 )peak in patients with systolic and diastolic heart failure were not significantly different, but lower than that seen in healthy controls. Following exercise, mean haematocrit, CD62P%G, and CD63%G significantly increased in all three subject groups (all P < 0.05). The proportional change in CD62P%G and CD63%G were not significantly different between healthy controls and heart failure patients (P > 0.05).

CONCLUSION

Acute maximal graded exercise increases platelet activation markers, with no disproportionate differences between heart failure patients and healthy controls, despite the former group having a lower exercise tolerance and VO2 peak.

Platelet hyperreactivity: predictive and intrinsic properties

Platelet thrombi are central to the development of most vascular ischemic events. There is marked interindividual variation in platelet responsiveness, with some subjects displaying platelet hyperreactivity. An increasing number of reports indicate that there are laboratory measures of platelet function that predict clinical thrombotic events. Some, but not all, measures of platelet function are reproducible. Platelet hyperreactivity can be assessed with multiple stimuli in multiple assays and is more likely to be present in women and in subjects who have elevated fibrinogen levels.

Mean platelet volume measurement, EDTA or citrate?

Most laboratories use EDTA for anticoagulation of whole blood prior to automated cell counting but due to platelet swelling, mean platelet volume (MPV) values may increase with its use. MPV changes may be less with acid citrate based anticoagulation. As MPV is a marker of platelet function and its precise measurement is important in a number of clinical situations, this study was performed to assess if EDTA and citrate based anticoagulated blood samples can be used interchangeably for MPV measurement. In this cross sectional descriptive study, EDTA and citrate based anticoagulated blood samples of the same patients were assessed by auto-analyzer within 1 h of sampling. In the 61 evaluated patients, there was a close correlation between MPV as measured by EDTA and citrate, but mean MPV measured from EDTA samples was 0.66 fL (9%) more than citrate. There was also a significant negative correlation between platelets count and MPV by both methods. The results of our study reveal that MPV can be measured accurately by both methods of anticoagulation; EDTA and citrate if analysis be performed within 1 h of sampling.

Relationship between Platelet Indexes and Coronary Angiographic Findings in Patients with Ischemic Heart Disease

To understand the mechanisms linking platelets to the risk of coronary artery disease, we investigated the relation between coronary angiographic morphology and platelet indexes--platelet count, mean platelet volume (MPV), platelet-large cell ratio (P-LCR) and platelet distribution width (PDW)--in patients with ischemic heart disease. Eighty-four patients with ischemic heart disease and 120 aged controls (AC) were enrolled in the study. The patients without any signs of acute myocardial infarction and acute coronary syndromes who underwent coronary angiography were divided into two groups, an 'angiographically negative group' (group 0) and an 'angiographically positive group' (group 1), with positive coronary obstruction depending on the diagnostic criteria in our hospital. Platelet indexes were measured in peripheral venous blood. The mean platelet counts were significantly lower in groups 1 and 0 than in AC (p = 0.0128 and p = 0.0041, respectively). MPV, P-LCR and the PDW were significantly higher in group 0 than in group 1 and AC (p = 0.0352 and 0.0433, p = 0.0059 and 0.0052, p = 0.00461 and 0.0146, respectively). The indexes of group 1 were almost the same compared with AC with respect to MPV, P-LCR and PDW. In conclusion, these findings suggest that the measurement of platelet indexes may reflect the underlying pathophysiological state and subsequent clinical events in the patients. In particular, lower P-LCR seems to identify patients with positive coronary angiography.

Effects of Doxazosin and Amlodipine on Mean Platelet Volume and Serum??Serotonin Level in Patients with??Metabolic Syndrome

BACKGROUND AND OBJECTIVE

In addition to reducing blood pressure, antihypertensive drugs should modify other atherosclerotic risk factors. One such risk factor is the prothrombotic state, which is characterised mainly by increased fibrinogen and plasminogen activator inhibitor-1 levels and abnormalities in platelet function. Platelet activity and aggregation potential can be estimated by measuring mean platelet volume (MPV). Serotonin plays a role in vasospasm and increased platelet aggregation capacity, and has been shown to increase MPV in vitro. However, serotonin levels and MPV have not been studied in the metabolic syndrome. We evaluated mean platelet volume (MPV) in patients with the metabolic syndrome, and compared the effects of doxazosin and amlodipine on MPV and serum serotonin level in patients with this condition.

METHODS

Thirty-eight patients who met the Adult Treatment Panel III criteria for the metabolic syndrome and 20 healthy controls were included in the study. Patients were randomised into two groups to receive doxazosin 4 mg/day (n=20) or amlodipine 10 mg/day (n=18). Patients' MPV, serum serotonin, insulin, insulin sensitivity, fasting blood glucose and lipid profiles were measured at baseline and after 8 weeks.

RESULTS

Patients with the metabolic syndrome had a significantly higher MPV compared with the control group. MPV was significantly decreased in the doxazosin-treated group (from 6.9 +/- 1.0 fL at baseline to 6.1 +/- 1.1 fL after treatment; p=0.02) but not in the amlodipine-treated group (6.8 +/- 0.9 fL at baseline vs 6.9 +/- 1.0 fL after treatment; p=0.9). Fasting blood glucose and total cholesterol were also significantly decreased compared with baseline in the doxazosin group. In the amlodipine group, there was a significant increase in serum serotonin levels and a decrease in serum insulin and improved insulin sensitivity.

CONCLUSION

In patients with the metabolic syndrome, doxazosin treatment not only decreases platelet activity, as measured by a change in MPV, but also improves metabolic abnormalities. Amlodipine also has beneficial effects in patients with the metabolic syndrome but has no effect on MPV.

Platelet volume indices in patients with coronary artery disease and acute myocardial infarction: an Indian scenario

AIMS

To study platelet volume indices (PVI) in the spectrum of ischaemic heart diseases.

METHODS

A total of 210 cases were studied; 94 patients had unstable angina (UA) or acute myocardial infarction (AMI) diagnosed on the basis of history, characteristic electrocardiographic changes, and increased cardiac enzyme activities. Seventy patients had stable coronary artery disease (stable CAD) or were admitted for a coronary angiography or coronary artery bypass graft procedure. The third group comprised 30 age and sex matched healthy controls with no history of heart disease and a normal electrocardiogram.

RESULTS

All PVI-mean platelet volume (MPV), platelet distribution width (PDW), and platelet large cell ratio (P-LCR)-were significantly raised in patients with AMI and UA (mean MPV, 10.43 (SD, 1.03) fL; mean PDW, 13.19 (SD, 2.34) fL; mean P-LCR, 29.4% (SD, 7.38%)) compared with those with stable CAD (mean MPV, 9.37 (SD, 0.99) fL; mean PDW, 11.35 (SD, 1.95) fL; mean P-LCR, 22.55% (SD, 6.65%)) and the control group (mean MPV, 9.2 (SD, 0.91) fL; mean PDW, 10.75 (SD, l.42) fL; mean P-LCR, 20.65% (SD, 6.14%)).

CONCLUSIONS

Larger platelets are haemostatically more active and are a risk factor for developing coronary thrombosis, leading to myocardial infarction. Patients with larger platelets can easily be identified during routine haematological analysis and could possibly benefit from preventive treatment. Thus, PVI are an important, simple, effortless, and cost effective tool that should be used and explored extensively, especially in countries such as India, for predicting the possibility of impending acute events.

Mean platelet volume as marker of restenosis after percutaneous transluminal coronary angioplasty in patients with stable and unstable angina pectoris

INTRODUCTION

Several experimental and clinical studies have demonstrated that platelet size and function correlate since large platelets are hemostatically more reactive than platelets of normal size. Since platelets play a crucial role in vascular remodeling after percutaneous transluminal coronary angioplasty (PTCA), we investigated the influence of the mean platelet volume (MPV), a parameter of platelet size, on restenosis after PTCA.

METHODS

The retrospective study comprised 174 patients who underwent elective PTCA and follow-up angiography within 6 months thereafter. According to the follow-up angiograms, the patients were assigned to group A ("restenosis", n=74) or group B ("no restenosis", n=100). Both groups were compared in regard to pre-procedural hematological routine parameters including MPV, platelet count, hematocrit, white blood cell count and fibrinogen.

RESULTS

MPV was significantly increased in group A, compared with that in group B (8.75+/-0.99 fl vs. 8.04+/-0.74 fl, p<0.001). This difference in MPV was evident in patients with stable and unstable angina pectoris. In addition, MPV had an impact on the time-related incidence of angiographic restenosis, as early restenosis was associated with higher pre-procedural MPV values. Platelet count correlated inversely with MPV (r=-0.36, p<0.01) and was significantly lower in group A than in group B. The remaining hematological parameters were not different in both groups.

CONCLUSIONS

The MPV seems to be a marker of coronary restenosis in patients undergoing PTCA. Patients with high pre-procedural MPV values might benefit from an intensified antiplatelet therapy after coronary interventions.

Mean platelet volume in patients with type 2 diabetes mellitus

AIM OF THE STUDY

To evaluate mean platelet volume (MPV) in type 2 diabetic versus non-diabetic patients, as well as to investigate the associations between MPV and diabetic complications.

MATERIALS AND METHODS

This study included 416 patients divided into two groups. Group A comprised 265 type 2 diabetic patients (131 men) with a mean age of 67.4 +/- 9.5 years and a mean diabetes duration of 14.5 +/- 5.7 years. Group B comprised 151 non-diabetic patients (74 men) with a mean age of 68.6 +/- 9.1 years. MPV (blood samples anticoagulated with sodium citrate) was measured in two blood cell counters (Sysmex SF 3000 and Cell-Dyn 3700).

RESULTS

MPV was significantly higher (P = 0.01) in group A (14.2 +/- 2.2 fl) than in group B (7.1 +/- 1.2 fl). In group A MPV was significantly higher (P = 0.043) in patients with retinopathy (15.8 +/- 1.3 fl) than in patients without retinopathy (10.9 +/- 1.1 fl) and also significantly higher (P = 0.044) in patients with microalbuminuria (15.6 +/- 1.2 fl) than in patients without microalbuminuria (10.1 +/- 1.2 fl). No association, however, was found in group A between MPV and age, gender, duration of diabetes, insulin dependency, BMI, HbA1c, coronary artery disease or dyslipidaemia.

CONCLUSIONS

MPV is higher in type 2 diabetic patients than in non-diabetic patients. Among type 2 diabetic patients MPV is higher in those who have microvascular complications (retinopathy or microalbuminuria).

Mean platelet volume and exercise stress test

BACKGROUND

Long-term moderate or strenuous physical activity is associated with a considerable reduction in cardiovascular morbidity and mortality. However acute exercise leads to a transient activation of the thrombotic system. Healthy individuals can react this by increasing their fibrinolytic capacity acutely. However, patients with ischemic heart disease, lacking fibrinolytic potential, may be at considerable risk for acute ischemic events if exposed to heavy physical exertion. Platelet size has been shown to reflect platelet activity. The mean platelet volume (MPV) can reflect changes in either the level of platelet stimulation or rate of platelet production.

DESIGN AND METHODS

We evaluated Treadmill exercise test (TMET) and compared MPV values (fl) before and after TMET in 63 consecutive patients who, then, underwent coronary angiography and found to have significant coronary artery disease in more than one coronary artery (>70% diameter stenosis in left anterior descending, right coronary or circumflex artery and >50% diameter stenosis in left main coronary artery). Sixty-three male patients were enrolled as a patient group with a mean age of 52.43 +/- 4.08 years and with strongly positive exercise test (> or =2 mm ST segment depression, horizontal or down-sloping). Thirty-five patients without significant coronary artery disease were selected as a control group with a mean age of 52.66 +/- 4.39 years having undergone TMET.

RESULTS AND DISCUSSION

In the patient and control groups, mean MPV values before TMET were the same, 8.52 +/- 0.63 and 8.45 +/- 0.58 respectively. Following TMET within 30 minutes, mean MPV were 10.03 +/- 0.96 and 8.50 +/- 0.45 respectively ( p < 0.001). When pre and post-TMET MPV values were evaluated together, the patient group had a significant increase in the MPV ( p < 0.001), whereas, the control group had no significant increase in the MPV ( p = 0.379). It was concluded that exercise possibly makes patients with significant coronary artery disease, more susceptible to a thrombotic event through various routes, one of that is platelet activation that could be measured indirectly via MPV. Healthy subjects react this thrombotic process by increasing their fibrinolytic capacity acutely. Patients with ischemic heart disease, particularly those with significantly narrowed coronary arteries, known to lack fibrinolytic capacity and have high shear stress, on the other hand, might face ischemic events, including sudden death following acute exercise.

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.

Association of mean platelet volume with risk of stroke among 3134 individuals with history of cerebrovascular disease

BACKGROUND AND PURPOSE

Mean platelet volume (MPV) is positively associated with measures of platelet activity and may be a useful indicator of the risk of vascular events in a variety of patient groups.

METHODS

The association of MPV with the risk of stroke was assessed in the Perindopril Protection Against Recurrent Stroke Study (PROGRESS). All participants had a history of cerebrovascular disease at baseline, and analyses were adjusted for the effects of potential confounders.

RESULTS

The study followed 3134 individuals for an average of 3.9 years (mean age, 65 years; 71% male; average MPV, 10.0 fL). Three hundred eighty-three individuals had 402 stroke events, and 160 had major coronary events. MPV was positively associated with the risk of stroke, with an 11% increased relative risk (95% CI, 3% to 19%) of stroke per femtoliter greater MPV. There was no clear association of MPV with the risk of major coronary events (9% decreased relative risk; 95% CI, -23% to 7%). Perindopril did not alter MPV.

CONCLUSIONS

MPV is an independent predictor of the risk of stroke among individuals with a history of stroke or transient ischemic attack. The measurement of MPV may add useful prognostic information for clinicians managing patients with a history of cerebrovascular disease.

Mean platelet volume is an independent risk factor for myocardial infarction but not for coronary artery disease

After rupture of an arteriosclerotic plaque in a coronary artery, platelets play a crucial role in the subsequent thrombus formation, leading to myocardial infarction. An increased mean platelet volume (MPV), as an indicator of larger, more reactive platelets, may represent a risk factor for myocardial infarction. However, this hypothesis is still controversial and most studies addressing the role of MPV were performed comparing patients suffering from myocardial infarction with healthy controls. We intended to identify patients at high risk of suffering myocardial infarction in a group of patients with known coronary artery disease. One hundred and eighty-five consecutive patients with stable coronary artery disease were compared with 188 individuals who had suffered myocardial infarction. Patients within the highest quintile of MPV (> or = 11.6 fl) had a significantly higher risk of experiencing a myocardial infarction compared with patients within the lowest quintile (OR = 2.6, 95% CI 1.3-5.1) in a multivariate analysis that included sex, age, body mass index, hyperlipidaemia, hypertension, smoking and diabetes mellitus. Our results indicate that patients with pre-existing coronary artery disease and an increased MPV (> or = 11.6 fl) are at higher risk of myocardial infarction. These patients can be easily identified during routine haematological analysis and could possibly benefit from preventive treatment.

Thrombopoietin and mean platelet volume in coronary artery disease

BACKGROUND

Large platelets are shown to be hemostatically more active. It has been suggested that mean platelet volume (MPV) is increased during acute myocardial infarction (AMI) and unstable angina pectoris (USAP). However, the underlying mechanism of the phenomenon remains unclear.

HYPOTHESIS

In this study, platelets, MPV, and thrombopoietin (TP) levels were investigated in patients with coronary artery disease (CAD) and healthy controls.

METHODS

Twenty patients with AMI and 20 patients with USAP were included in this study. Seventeen healthy adult subjects served as controls. Venous blood samples of the subjects were drawn within 12 h after admission. Thrombopoietin levels were measured by ELISA and platelet counts and MPV were assayed by autoanalyzer.

RESULTS

Patients with AMI and USAP had higher platelet counts than those in the control group. Although the platelet counts were slightly higher in AMI than in USAP, this did not reach statistical significance. Mean platelet volume and levels of TP were found to be elevated in patients with AMI and USAP compared with control subjects (p < 0.001). Thrombopoietin levels were higher in AMI than USAP, but this was not statistically significant. There was a positive correlation between TP levels and MPV values (p < 0.05).

CONCLUSION

Increased TP levels may increase both platelet counts and platelet size, resulting in hemostatically more active platelets, which may contribute to the development and progression of CAD.

The pre-procedural platelet state predicts clinical recurrence after coronary angioplasty

Percutaneous transluminal coronary angioplasty is an established therapy for coronary artery disease, but restenosis still occurs at a rate of 25%-40%. The aim of this study was to investigate the acute effect of percutaneous transluminal coronary angioplasty on platelet function and the relationship between platelet function and clinical recurrence. Spontaneous platelet aggregation was assessed before and after successful coronary angioplasty in 155 patients (120 men, 35 women). Patients were followed for a mean time of 20 months; follow-up angiography was performed only in patients with clinical recurrence. In 122 of 155 patients (79%) a significant increase in spontaneous platelet aggregation was observed immediately after coronary angioplasty. Baseline spontaneous platelet aggregation in platelet-rich plasma was significantly lower in patients with clinical recurrence than in those without (P<0.05). Kaplan-Meier event-free survival estimate showed a significant difference in clinical recurrence between patients with spontaneous platelet aggregation in platelet-rich plasma below and above the first quintile (P<0.05) with a relative risk of 2.5. In conclusion. these results indicate that percutaneous transluminal coronary angioplasty enhances spontaneous platelet aggregation and that the platelet state before coronary angioplasty affects the risk of clinical recurrence after the procedure.

Platelets and restenosis

Restenosis is currently the major limitation of percutaneous transluminal coronary angioplasty (PTCA). Factors such as elastic recoil, migration of vascular smooth muscle cells from media to intima, neointimal proliferation and vascular remodeling underly the restenotic process. Presently there is no effective therapy available for restenosis. The role of platelets in the development of thrombosis and abrupt closure after PTCA is well recognized. However, the effects of platelets in PTCA extend well beyond the early phase. Although antiplatelet agents such as glycoprotein IIb/IIIa antagonists have been reported to reduce target vessel revascularization, major unresolved controversies still exist. This report reviews the potential role of platelets in restenosis. Various drugs, successfully tested in experimental studies and in a small number of human studies, that inhibit the effect of platelets on the restenotic process are also reviewed.

Megakaryocytes and platelets in vascular disease

Platelets are anucleate cells with no DNA. They are derived from their precursor, the megakaryocyte (MK), whose differentiation is characterized by nuclear polyploidization through a process called endomitosis. Changes in the MK-platelet-haemostasis axis may precede acute thrombotic events. Changes in MK ploidy distribution may be associated with the production of large platelets. Mean platelet volume (MPV) is an important biological variable as it is a determinant of platelet reactivity. Large platelets are denser and more active haemostatically. MPV is increased in patients after myocardial infarction (MI) and is a predictor of a further ischaemic event and death when measured after MI. It has been suggested that changes not only in platelets but also in the parental MK are associated with chronic and acute vascular events. The regulation of megakaryocytopoiesis depends on several haematopoietic factors such as thrombopoietin. An understanding of the signalling system that controls platelet number and size might give insight into a role of platelet production in thrombogenesis and atherogenesis.

Dietary coenzyme Q10 supplementation alters platelet size and inhibits human vitronectin (CD51/CD61) receptor expression

Improved cardiovascular morbidity and mortality have been observed in several clinical studies of dietary supplementation with coenzyme Q10 (CoQ10, ubiquinone). Several mechanisms have been proposed to explain the effects of CoQ10, but a comprehensive explanation of its cardioprotective properties is still lacking. One attractive theory links ubiquinone with the inhibition of platelets. The effect of CoQ10 intake on platelet size and surface antigens was examined in human volunteers. Study participants received 100 mg of CoQ10 twice daily in addition to their usual diet for 20 days. Receptor expression was measured by flow cytometry with monoclonal murine anti-human antibodies CD9 (p24), CD42B (Ib), CD41b (IIb), CD61 (IIIa), CD41a (IIb/IIIa), CD49b (VLA-2), CD62p (P selectin), CD31 (PECAM-1), and CD51/CD61 (vitronectin). An increase of total serum CoQ10 level (from 0.6 +/- 0.1 to 1.8 +/- 0.3 micrograms/ml; p < 0.001) was found at protocol termination. Fluorescence intensity was higher for the large platelets when compared with the whole platelet population. Significant inhibition of vitronectin-receptor expression was observed consistently throughout ubiquinone treatment. Reduction of platelet size was observed at the end of CoQ10 supplementation. Inhibition of the platelet vitronectin receptor and a reduction of the platelet size are direct evidence of a link between dietary CoQ10 intake and platelets. These findings may not be fully explained by the known antioxidant and bioenergetic properties of CoQ10. Diminished vitronectin-receptor expression and reduced platelet size resulting from CoQ10 therapy may contribute to the observed clinical benefits in patients with cardiovascular diseases.

Inhibition of platelet activity by S-nitrosoglutathione during coronary angioplasty

Platelet activation is associated with acute vessel occlusion and chronic restenosis after percutaneous transluminal coronary angioplasty (PTCA). Organic nitrates, which act by releasing the vasodilator and anti-platelet agent nitric oxide (NO), have a predominantly vasodilator action and cause hypotension at doses required to inhibit platelet activation. S-nitrosoglutathione (GSNO) is an NO donor with a preferential action on platelets. We investigated platelet activation in patients undergoing PTCA and the effect of GSNO. Blood was sampled from the coronary sinus to measure platelet surface expression of P-selectin and glycoprotein IIb/IIIa as indices of platelet activation. In 7 control patients, PTCA caused a rise in platelet surface expression of P-selectin and glycoprotein IIb/IIIa, which was maximal 5 minutes after PTCA, indicating increased platelet activation despite treatment with aspirin, glyceryl trinitrate, and heparin. 6 patients received an intracoronary infusion of GSNO, starting 10 min before PTCA. GSNO significantly inhibited the PTCA-induced increase in platelet surface expression of P-selectin and glycoprotein IIb/IIIa without altering blood pressure. These findings show that platelets are activated following PTCA and that GSNO can prevent this activation.

Influence of weight reduction on platelet volume: different effects of a hypocaloric diet and a very low calorie diet

Since platelet volume reflects platelet activity, the mean platelet volume (MPV) is proposed to be a further independent risk factor for cardiovascular disease (CVD). Even if it is well established that weight reduction reduces some of the risk factors of CVD in obese patients, an increase of MPV occurs during periods of weight loss. We therefore prospectively investigated the effects of different weight reduction therapies on platelet mass, platelet volume, body weight and serum lipid profile in patients undergoing an 8 week weight reduction therapy either by a hypocaloric diet (HD) or a nutritionally completed very low calorie diet (VLCD) with a subsequent maintenance period of 40 weeks. In both groups, MPV transiently increased during the 8 week diet period. After 48 weeks the MPV was decreased to initial values. The change in MPV was significantly (P < 0.05) smaller in the VLCD group. We therefore suggest that fasting might alter the control of platelet size with a possible impact on platelet activity. This might result in an increased risk for thromboembolic ischaemic events in atherosclerotic patients. Thus, we conclude that the use of a VLCD is potentially superior for weight reduction in patients with pre-existing atherosclerosis.

The megakaryocyte platelet system and vascular disease

Platelets form a heterogeneous population of cells produced from the uniquely large polyploid cell found in the bone marrow, the megakaryocyte. The platelet megakaryocyte axis forms a dynamic equilibrium varying in normal biology and in disease. Prolonged platelet destruction leads to the production of large platelets from large, high ploidy megakaryocytes. In vivo and ex vivo studies show that such platelets have more haemostatic potential than smaller less dense platelets. The evidence suggesting that prothrombotic changes in the megakaryocyte platelet axis precede coronary artery thrombosis and the importance of platelet reactivity in atherosclerosis will be reviewed.