Mean platelet volume on admission predicts impaired reperfusion and long-term mortality in acute myocardial infarction treated with primary percutaneous coronary intervention

Tirofiban use with clopidogrel and aspirin decreases adverse cardiovascular events after percutaneous coronary intervention for ST-elevation myocardial infarction: a meta-analysis of randomized trials

Current guidelines deemed usefulness of routine early glycoprotein IIb/IIIa inhibitor (GPI) administration in ST-elevation myocardial infarction (STEMI) before primary percutaneous coronary intervention (PCI) with dual antiplatelet therapy as uncertain. We aimed to examine the current evidence for the use of tirofiban, a nonpeptide glycoprotein IIb/IIIa inhibitor, in STEMI patients treated with dual antiplatelet therapy. We performed systematic searches of MEDLINE, EMBASE, and CENTRAL databases for randomized controlled trials (RCTs) of tirofiban use in STEMI patients treated with aspirin and clopidogrel which reported clinical and/or angiographic outcomes after primary PCI. Data were combined using random effect and fixed effect models for heterogeneous and homogeneous outcomes respectively using Review Manager 5 (The Nordic Cochrane Centre, The Cochrane Collaboration, 2008). Six randomized controlled trials were eligible for the inclusion; involving 708 patients in tirofiban group and 721 control subjects. Routine tirofiban use decreased the major adverse cardiovascular events (odds ratio [OR] 0.50; 95% confidence interval [CI], 0.26-0.94). Corrected thrombolysis in myocardial infarction (TIMI) frame count was also reduced with tirofiban (mean difference -8.48 [95% CI, -12.62 to -4.34]). There were no significant differences in the rates of postprocedure TIMI flow grade 3 and TIMI myocardial perfusion/blush grade 3, major bleeding by TIMI criteria, or mortality in the 2 groups. Current analysis of available studies suggests that routine and early tirofiban use before primary PCI may decrease the major cardiovascular events in STEMI patients treated with aspirin and clopidogrel without any significant increase in major bleeding. An adequately powered randomized trial is urgently needed to confirm the above findings and estimate the effect size.

Prognostic Value of Mean Platelet Volume in Patients With Non-ST-Elevation Acute Coronary Syndrome

The aim of this study is to determine mean platelet volume (MPV) in a population with non-ST-elevation acute coronary syndrome (nSTEACS) and explore its relation with prognosis. Patients (n = 329) with a diagnosis of nSTEACS at admission were recruited, with a determination of MPV in the first 12 hours at admission. We also collected blood from 87 healthy controls. A composite end point of cardiovascular death and new ACS was assessed at 6-month follow-up. Patients with nSTEACS showed larger platelets (MPV: 11.0 [10.3-11.8] vs 9.2 [8.6-10.0] fL; P < .001.). In Cox regression analysis, MPV at admission was a significant predictor of cardiovascular adverse events in univariate analysis, hazard ratio (HR) 1.4 95% confidence interval (CI) 1.1-1.8; P = .018; but after adjustment with clinical variables, MPV lost its statistical significance. In conclusion, patients with nSTEACS present with larger platelets than healthy controls, however this parameter did not show an independent prognostic significance at 6-month follow-up.

The genetics of common variation affecting platelet development, function and pharmaceutical targeting

Common variant effects on human platelet function and response to anti-platelet treatment have traditionally been studied using candidate gene approaches involving a limited number of variants and genes. These studies have often been undertaken in clinically defined cohorts. More recently, studies have applied genome-wide scans in larger population samples than prior candidate studies, in some cases scanning relatively healthy individuals. These studies demonstrate synergy with some prior candidate gene findings (e.g., GP6, ADRA2A) but also uncover novel loci involved in platelet function. Here, I summarise findings on common genetic variation influencing platelet development, function and therapeutics. Taken together, candidate gene and genome-wide studies begin to account for common variation in platelet function and provide information that may ultimately be useful in pharmacogenetic applications in the clinic. More than 50 loci have been identified with consistent associations with platelet phenotypes in ≥ 2 populations. Several variants are under further study in clinical trials relating to anti-platelet therapies. In order to have useful clinical applications, variants must have large effects on a modifiable outcome. Regardless of clinical applications, studies of common genetic influences, even of small effect, offer additional insights into platelet biology including the importance of intracellular signalling and novel receptors. Understanding of common platelet-related genetics remains behind parallel fields (e.g., lipids, blood pressure) due to challenges in phenotype ascertainment. Further work is necessary to discover and characterise loci for platelet function, and to assess whether these loci contribute to disease aetiologies or response to therapeutics.

White blood cell count, sex and age are major determinants of heterogeneity of platelet indices in an adult general population: results from the MOLI-SANI project

BACKGROUND

The understanding of non-genetic regulation of platelet indices--platelet count, plateletcrit, mean platelet volume, and platelet distribution width--is limited. The association of these platelet indices with a number of biochemical, environmental and clinical variables was studied in a large cohort of the general population.

DESIGN AND METHODS

Men and women (n=18,097, 52% women, 56±12 years) were randomly recruited from various villages in Molise (Italy) in the framework of the population-based cohort study "Moli-sani". Hemochromocytometric analyses were performed using an automatic analyzer (Beckman Coulter, IL, Milan, Italy). Associations of platelet indices with dependent variables were investigated by multivariable linear regression analysis.

RESULTS

Full models including age, sex, body mass index, blood pressure, smoking, menopause, white and red blood cell counts, mean corpuscular volume, D-dimers, C-reactive protein, high-density lipoproteins, low-density lipoproteins, triglycerides, glucose, and drug use explained 16%, 21%, 1.9% and 4.7% of platelet count, plateletcrit, mean platelet volume and platelet distribution width variability, respectively; variables that appeared to be most strongly associated were white blood cell count, age, and sex. Platelet count, mean platelet volume and plateletcrit were positively associated with white blood cell count, while platelet distribution width was negatively associated with white blood cell count. Platelet count and plateletcrit were also positively associated with C-reactive protein and D-dimers (P<0.0001). Each of the other variables, although associated with platelet indices in a statistically significant manner, only explained less than 0.5% of their variability. Platelet indices varied across Molise villages, independently of any other platelet count determinant or characteristics of the villages.

CONCLUSIONS

The association of platelet indices with white blood cell count, C-reactive protein and D-dimers in a general population underline the relation between platelets and inflammation.

Gene expression profiling in peripheral blood nuclear cells in patients with refractory ischaemic end-stage heart failure

Functional analysis of up- and down-regulated genes might reveal whether peripheral blood cells may be considered as a material of diagnostic or prognostic value in patients with end-stage heart failure (HF). The aim of the present study was to compare the transcriptomic profile of peripheral blood nuclear cells from 6 male patients with ischaemic end-stage HF with those of 6 male patients with asymptomatic cardiac dysfunction. The expression of genes in peripheral blood nuclear cells in both groups of patients was measured using whole-genome oligonucleotide microarrays utilizing 35 035 oligonucleotide probes. Microarray analyses revealed 130 down-regulated genes and 15 up-regulated genes in the patients with end-stage HF. Some of the down-regulated genes belonged to the pathways that other studies have shown to be down-regulated in cardiomyopathy. We also identified up-regulated genes that have been correlated with HF severity (CXCL16) and genes involved in the regulation of expression of platelet activation factor receptor (PTAFR, RBPSUH, MCC, and PSMA7). In conclusion, the identification of genes that are differentially expressed in peripheral blood nuclear cells of patients with HF supports the suggestion that this diagnostic approach may be useful in searching for the molecular predisposition for development of severe refractory HF in patients with post-infarction asymptomatic abnormalities and remodelling of the left ventricle. These results need further investigation and validation.

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.

Platelet indices in patients with colorectal cancer

The interaction between cancer cells and platelets has been known for a long time. Although platelet indices have been also investigated in several clinical settings, it has not been exactly demonstrated in cancer patients. We investigated platelet indices in colorectal cancer patients and compared with healthy subjects. Two hundred and twenty-one colorectal cancer patients and 110 healthy subjects were enrolled into the retrospective study. Data were obtained from computerized medical records of our hospital. Medical record review was performed for all patients regarding thrombocyte indices. Platelet count (325.000/mm3 ± 265.000/mm3 vs 267.000/mm3 ± 67.000/mm3; p=0.025; respectively) and plateletcrit (Pct) (0.25% ± 0.10 vs 0.21 ± 0.05; p<0.001; respectively) were increased in patients compared with healthy subjects while mean platelet volume (MPV) and platelet distribution width (PDW) were similar. The platelet indices were not related to existence of metastasis or acute abdomen. Platelet count and Pct, but not MPV and PDW, are elevated in colorectal cancer patients. Future studies that investigate platelet morphology, function, and putative role of platelets in tumorigenesis and metatasis should be established.

Predicting the no-reflow phenomenon following successful percutaneous coronary intervention

In the setting of acute myocardial infarction, early and adequate reopening of an infarct-related artery is not necessarily followed by a complete restoration of myocardial perfusion. This condition is usually defined as ‘no-reflow’. The pathophysiology of no-reflow is multifactorial since extravascular compression, microvascular vasoconstriction, embolization during percutaneous coronary intervention, and platelet and neutrophil aggregates are involved. In the clinical arena, angiographic findings and easily available clinical parameters can predict the risk of no-reflow. More recently, several studies have demonstrated that biomarkers, especially those related to the pathogenetic components of no-reflow, could also have a prognostic role in the prediction and in the full understanding of the multiple mechanisms of this phenomenon. Thus, in this article, we investigate the role of several biomarkers on admission in predicting the occurrence of no-reflow following successful percutaneous coronary intervention.

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.

A genome-wide meta-analysis identifies 22 loci associated with eight hematological parameters in the HaemGen consortium

The number and volume of cells in the blood affect a wide range of disorders including cancer and cardiovascular, metabolic, infectious and immune conditions. We consider here the genetic variation in eight clinically relevant hematological parameters, including hemoglobin levels, red and white blood cell counts and platelet counts and volume. We describe common variants within 22 genetic loci reproducibly associated with these hematological parameters in 13,943 samples from six European population-based studies, including 6 associated with red blood cell parameters, 15 associated with platelet parameters and 1 associated with total white blood cell count. We further identified a long-range haplotype at 12q24 associated with coronary artery disease and myocardial infarction in 9,479 cases and 10,527 controls. We show that this haplotype demonstrates extensive disease pleiotropy, as it contains known risk loci for type 1 diabetes, hypertension and celiac disease and has been spread by a selective sweep specific to European and geographically nearby populations.

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.

Baseline platelet size is increased in patients with acute coronary syndromes developing early stent thrombosis and predicts future residual platelet reactivity. A case-control study

INTRODUCTION

Pre-procedural predictors of early stent thrombosis (ST) and future response to platelet inhibitors are in demand. We sought to evaluate the impact of baseline platelet indices on the occurrence of early ST and future residual platelet reactivity.

MATERIALS AND METHODS

Hundred and eight patients with acute coronary syndromes (ACS) in whom stents were implanted were included: 36 consecutive ST cases and 72 matched controls. Platelet indices assessed with flow cytometry before stent implantation were retrieved from the department's data base. Residual platelet reactivity specific to aspirin (aspirin reaction units-ARU) and clopidogrel (P2Y12 reaction units-PRU) was assessed prospectively with VerifyNow under dual antiplatelet treatment.

RESULTS

Platelet size reported as mean platelet volume (MPV) or proportion of large platelets (LPLT) was significantly higher in ST cases compared with controls (10.4, 95% confidence intervals [CI], 10.1-10.8 vs. 9.7, CI, 9.5-9.9, P=0.0004 and 35.8, CI, 34.2-37.3 vs. 33.3, CI, 32.2-34.3, P=0.007, respectively). Dual aspirin and clopidogrel poor-responsiveness was diagnosed significantly more often in ST cases than in controls (19.6% vs. 1.4%, P=0.004), whereas no difference was observed for single aspirin or clopidogrel poor-responsiveness. A strong correlation was found between MPV and both, ARU (r=0.66, P<0.0001) and PRU (r=0.55, P<0.0001). Similarly, higher LPLT was associated with higher ARU (r=0.47, P<0.0001) and PRU (r=0.38, P=0.0001).

CONCLUSIONS

Baseline platelet size is increased in patients with ACS developing early ST and correlates with future residual platelet reactivity under aspirin and clopidogrel therapy. Dual but not isolated aspirin or clopidogrel poor-responsiveness appears to be associated with early ST.

Myocardial no-reflow in humans

In a variable proportion of patients presenting with ST-segment elevation myocardial infarction, ranging from 5% to 50%, primary percutaneous coronary intervention achieves epicardial coronary artery reperfusion but not myocardial reperfusion, a condition known as no-reflow. Of note, no-reflow is associated with a worse prognosis at follow-up. The phenomenon has a multifactorial pathogenesis including: distal embolization, ischemia-reperfusion injury, and individual predisposition of coronary microcirculation to injury. Moreover, it is spontaneously reversible in some patients, thus suggesting that it might be amenable to treatment also when we fail to prevent it. Several recent studies have shown that biomarkers and other easily available clinical parameters can predict the risk of no-reflow and can help in the assessment of the multiple mechanisms of the phenomenon. Several therapeutic strategies have been tested for the prevention and treatment of no-reflow. In particular, thrombus aspiration before stent implantation prevents distal embolization and has been recently shown to improve myocardial perfusion and clinical outcome as compared with the standard procedure. However, it is conceivable that the relevance of each pathogenetic component of no-reflow is different in different patients, thus explaining the occurrence of no-reflow despite the use of mechanical thrombus aspiration. Thus, in this review article, for the first time, we propose a personalized management of no-reflow on the basis of the assessment of the prevailing mechanisms of no-reflow operating in each patient.

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.

Relationship of admission hematological indexes with myocardial reperfusion abnormalities in acute ST segment elevation myocardial infarction patients treated with primary percutaneous coronary interventions

BACKGROUND

Elevated values of mean platelet volume (MPV) and elevated white blood cell (WBC) count are predictors of an unfavourable outcome among survivors of ST segment elevation myocardial infarction (STEMI). However, their relationship with reperfusion abnormalities is less clear.

OBJECTIVE

To evaluate the value of admission MPV and WBC count in predicting impaired reperfusion in patients with acute STEMI who are treated with primary percutaneous coronary intervention (PCI).

METHODS

Blood samples were obtained on admission from 368 STEMI patients who underwent successful PCI. According to the 60th minute ST segment resolution ratio, patients were divided into impaired reperfusion and reperfusion groups.

RESULTS

Impaired reperfusion was detected in 40% of study patients. Patients in the impaired reperfusion group had a higher admission MPV (9.8+/-1.3 fL versus 8.6+/-1.0 fL; P<0.001) and a higher WBC count (14.4+/-5.5 x 10(9)/L versus 12.1+/-3.8 x 10(9)/L; P<0.001) compared with the patients in the reperfusion group. In regression analysis, MPV (OR 2.21, 95% CI 1.69 to 2.91; P<0.001) and WBC count (OR 1.08, 95% CI 1.02 to 1.15; P=0.01) were found to be independently associated with impaired reperfusion. The best cut-off value of MPV for predicting impaired reperfusion was determined to be 9.05 fL, with a sensitivity of 74% and a specificity of 73%.

CONCLUSIONS

The results indicate that leukocytes and platelets have a role in the mediation of reperfusion injury. In patients with STEMI who are undergoing PCI, admission MPV may be valuable in discriminating a higher-risk patient subgroup and thus, may help in deciding the need for adjunctive therapy to improve the outcome.

Mean platelet volume predicts patency of the infarct-related artery before mechanical reperfusion and short-term mortality in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND AND AIMS

Patency of infarct-related artery (IRA) before mechanical reperfusion with primary percutaneous coronary intervention (PPCI) has been associated with better prognosis in patients with ST-Elevation myocardial infarction (STEMI). Mean platelet volume (MPV) increases in STEMI patients and may be associated with increased thrombotic potential. In STEMI patients scheduled for PPCI we sought to assess whether mean platelet volume (MPV), as measured at admission, correlates with "spontaneous" reperfusion of the IRA and short-term clinical outcome.

METHODS

Blood samples were obtained on hospital admission in 617 consecutive patients (82% men; age 64 + or - 12 years) with STEMI, before PPCI. 372 (61%) patients were treated with the GP IIb/IIIa blocker abciximab. The main study endpoint was mortality at 30 days.

RESULTS

MPV was significantly lower in patients with basal TIMI flow grade 2 -3 compared to patients with TIMI grade 0-1 (median, 9 vs. 8.5 fL, p<0.0001). After adjustment, MPV remained an independent predictor of the patency of the IRA (OR 0.63, CI 95% 0.51 - 0.78). A cut off value of 8.95 fL had a predictive negative value of 82% to identify patients with patent IRA. Using this cut point, and after adjusting for confounders, MPV was an independent predictor of 30-day mortality (HR 2.92, CI 95% 1.36 - 6.29). When patients were subdivided according to abciximab use, MPV was a marker of worse outcome but only in patients who did not receive abciximab (HR 3.67, CI 95% 1.13 - 11.49).

CONCLUSION

An increased MPV is an independent predictor of both a patent IRA (TIMI flow 2 or 3 before PPCI) and 30-day mortality. This marker may be able to identify patients requiring more aggressive antiplatelet therapy.

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.

Role of reticulated platelets and platelet size heterogeneity on platelet activity after dual antiplatelet therapy with aspirin and clopidogrel in patients with stable coronary artery disease

OBJECTIVES

The aim of this study was to evaluate the relationship between reticulated platelets (RPs), platelet size, and platelet function in patients with stable coronary artery disease (CAD) taking aspirin and clopidogrel.

BACKGROUND

Reticulated platelets are young platelets that are larger and possibly more active than non-RPs.

METHODS

Flow cytometry was used to measure RPs after staining with thiazole orange and to define the upper 20% and lower 20% of platelets by size. Platelet aggregation was measured with light transmission aggregometry (LTA); platelet activation was assessed by measuring activated platelet surface expression of P-selectin and glycoprotein (GP) IIb/IIIa.

RESULTS

Ninety patients were recruited and stratified into tertiles of %RPs. Patients in the upper tertile displayed greater platelet aggregation to 5-mumol/l adenosine diphosphate (ADP) (50.7 +/- 16.4% vs. 34.2 +/- 17.3%, p < 0.001), 1.5-mmol/l arachidonic acid (AA) (27.3 +/- 16.9% vs. 11.7 +/- 9.3%, p < 0.001), and 1-mug/ml collagen (18 +/- 11.6% vs. 12.1 +/- 8.7%, p < 0.05) and greater expression of GP IIb/IIIa (4.7 +/- 1.8% vs. 3.1 +/- 2.2%, p < 0.001). Frequency of low response to aspirin (AA LTA >20%) was higher in the upper tertile (53% vs. 17%, p < 0.001) compared with the lower tertile; low response to clopidogrel (ADP LTA >50%) was also elevated in the upper tertile (50% vs. 13%, p = 0.003). The larger platelet gate had a higher % of RPs compared with the smaller gate (15.4 +/- 16.7% vs. 1.7 +/- 2.3%, p < 0.001) and greater GP IIb/IIIa (5.7 +/- 3.1 vs. 2.1 +/- 1.2, p < 0.001) and P-selectin expression (7.8 +/- 4.9 vs. 4.6 +/- 2.7, p < 0.001).

CONCLUSIONS

The proportion of circulating RPs strongly correlates with response to antiplatelet therapy in patients with stable CAD. Large platelets exhibit increased reactivity despite dual antiplatelet therapy, compared with smaller platelets.

Plasma levels of thromboxane A2 on admission are associated with no-reflow after primary percutaneous coronary intervention

AIMS

Thromboxane A2 (TXA2) is a key mediator of platelet activation and aggregation, and an important mediator of platelet-induced coronary artery constriction. We sought to investigate whether baseline plasma levels of TXA2 are associated with coronary no-reflow after primary percutaneous coronary intervention (PPCI).

METHODS AND RESULTS

A total of 47 consecutive patients (age, 62.5 +/- 12.7; male sex, 76.6%) admitted to our hospital for a first ST-segment elevation myocardial infarction and undergoing PPCI within 12 h of onset of symptoms were enrolled. Admission TXA2 plasma levels were measured by enzyme-linked immunosorbent assay (ELISA). Angiographic no-reflow was defined as a final TIMI flow of <or=2 or final TIMI flow of 3 with a myocardial blush grade of <2, whereas ST-segment resolution from baseline value of <or=50% was used as ECG index of no-reflow. At multivariable analysis TXA2 plasma levels, endothelin-1 (ET-1) plasma levels, and left anterior descending coronary artery (LAD) as culprit vessel were significant predictors of angiographic no-reflow (P = 0.04), whereas TXA2 and ET-1 plasma levels were the only independent predictors of lack of ST-segment resolution (P = 0.013 and 0.04, respectively). Of note, TXA2 tertiles were independent predictors of both angiographic no-reflow and lack of ST-segment resolution (OR, 3.5; 95% CI, 1.1-11; P = 0.03 and OR, 3; 95% CI, 1.3-7; P = 0.01, respectively).

CONCLUSION

TXA2 is an independent indicator of no-reflow that occurs after PPCI. This observation may open new therapeutic opportunity in the setting of PPCI.

Routine hematologic clinical tests as prognostic markers in patients with acute coronary syndromes

Prognostic markers are needed to identify patients with acute coronary syndrome (ACS) who are at high risk for adverse events. Although the search for new biomarkers is quite active, prognostic information is available from routine hematologic tests, such as the complete blood count. For example, elevated white blood cell counts during ACS are associated with increased risk of mortality, heart failure, shock, and left ventricular dysfunction. Anemia is associated with increased risk of mortality, whereas elevated platelet counts predict poorer clinical and angiographic outcomes. In this review, we summarize the literature regarding the use of clinical hematology tests including white blood cell count, hemoglobin and hematocrit values, and platelet count as prognostic markers in patients with ACS, and we describe potential mechanisms to explain these associations.

Morphological and functional platelet abnormalities in Berkeley sickle cell mice

Berkeley sickle cell mice are used as animal models of human sickle cell disease but there are no reports of platelet studies in this model. Since humans with sickle cell disease have platelet abnormalities, we studied platelet morphology and function in Berkeley mice (SS). We observed elevated mean platelet forward angle light scatter (FSC) values (an indirect measure of platelet volume) in SS compared to wild type (WT) (37+/-3.2 vs. 27+/-1.4, mean+/-SD; p<0.001), in association with moderate thrombocytopenia (505+/-49 x 10(3)/microl vs. 1151+/-162 x 10(3)/microl; p<0.001). Despite having marked splenomegaly, SS mice had elevated levels of Howell-Jolly bodies and "pocked" erythrocytes (p<0.001 for both) suggesting splenic dysfunction. SS mice also had elevated numbers of thiazole orange positive platelets (5+/-1% vs. 1+/-1%; p<0.001), normal to low plasma thrombopoietin levels, normal plasma glycocalicin levels, normal levels of platelet recovery, and near normal platelet life spans. Platelets from SS mice bound more fibrinogen and antibody to P-selectin following activation with a threshold concentration of a protease activated receptor (PAR)-4 peptide compared to WT mice. Enlarged platelets are associated with a predisposition to arterial thrombosis in humans and some humans with SCD have been reported to have large platelets. Thus, additional studies are needed to assess whether large platelets contribute either to pulmonary hypertension or the large vessel arterial occlusion that produces stroke in some children with sickle cell disease.

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.

Platelet Activation in Coronary Artery Disease

BACKGROUND

Platelet activation and aggregation play a key role in coronary artery disease, with antiplatelet therapies leading to improved clinical outcomes. Limited data exist as to whether peripheral venous blood measurements of platelet physical indexes (eg, platelet count, volume, and granularity) and soluble markers of platelet activation (eg, P-selectin [sP-sel] and CD40 ligand [CD40L]) reflect the local (intracardiac) coronary environment. Furthermore, how percutaneous coronary interventions (PCIs) affect levels of peripheral/cardiac platelet indexes is unclear.

METHODS

Blood samples were sequentially acquired from the coronary os, aortic root, coronary sinus, and the femoral vein, and where relevant, pre-PCI and post-PCI. Eighty-seven patients undergoing coronary angiography were recruited (mean [+/-SD] age, 59.8+/-10.8 years; 54 men [62%]), of whom 36 proceeded to PCI. Platelet physical indexes and plasma sP-sel and CD40L levels were measured (by enzyme-linked immunosorbent assay).

RESULTS

At baseline, no intracardiac vs peripheral differences were noted in sP sel levels, while CD40L levels were elevated in the aorta compared to the coronary sinus and femoral venous. The mean platelet count (MPC) was similar at all four sites, but within the coronary sinus blood, mean platelet volume (MPV) was significantly lower and mean platelet granularity (MPG) was higher when compared to arterial levels. Though aortic and femoral levels of sP-sel were raised following PCI, transcardiac gradients of plasma sP-sel levels were unaffected. PCI was associated with lower CD40L, MPC, and MPV levels but with a higher MPG level in all sampling sites.

CONCLUSIONS

sP-sel levels measured peripherally reflect the cardiac environment, unlike CD40L, MPC, MPV, and MPG. PCI leads to further platelet activation (raised sP-sel) despite aggressive antiplatelet therapy.

Platelets and white blood cell subpopulations among patients with myocardial infarction and unstable angina

Platelet (PLT)-endothelial cell and PLT-leukocyte interactions at lesion-prone sites might trigger a local inflammatory response early in the genesis of atherosclerosis and contribute to plaque destabilization leading to acute coronary syndromes (ACS). The aim of this study was to assess the PLT count, mean PLT volume (MPV), PLT mass, white blood cell (WBC; including eosinophils) and plasma interleukin (IL)-5, in patients with ACS and controls. PLT count, MPV, PLT mass, WBC and eosinophil percentage were determined in 167 consecutive patients with ACS (86 with acute myocardial infarction, AMI, and 81 unstable angina, UA) and 83 controls. Plasma IL-5 was measured in some patients and controls. Patients were considered in subgroups depending on smoking status and if they had or did not have diabetes mellitus (DM). The PLT count was lower in the UA and AMI groups although this did not always achieve significance. The MPV was significantly raised in all patient groups except in DM non-smokers with UA or AMI. All AMI patients had significantly higher WBC counts compared with controls. The percentage of eosinophils was lower in the UA and AMI groups although this did not always achieve significance. Plasma IL-5 levels were significantly increased in the UA and AMI groups. In conclusion, patients with ACS present with changes in the count of several cell types. These cells may become therapeutic targets and these changes may also act as markers of myocardial damage or prognosis.

Platelet Surface CD62P and CD63, Mean Platelet Volume, and Soluble/Platelet P-Selectin as Indexes of Platelet Function in Atrial Fibrillation

OBJECTIVES

The aim of this work was to comprehensively study the role of platelets in atrial fibrillation (AF), in relation to the underlying cardiovascular diseases and type of AF, and to analyze the effect of antithrombotic treatment on different aspects of platelet activation.

BACKGROUND

Platelet activation is present in nonvalvular AF, but there is debate whether this is due to AF itself and/or to underlying cardiovascular diseases.

METHODS

A total of 121 AF patients were compared with 65 "healthy control subjects" and 78 "disease control subjects" in sinus rhythm. Platelet activation was assessed using 4 different aspects of platelet pathophysiology: 1) platelet surface expression of CD62P (P-selectin) and CD63 (a lysosomal glycoprotein) (by flow cytometry); 2) mean platelet volume (MPV) (by flow cytometry); 3) plasma levels of soluble P-selectin (sP-selectin, enzyme-linked immunoadsorbent assay); and 4) total amount of P-selectin per platelet (pP-selectin) ("platelet lysis" assay).

RESULTS

Both AF patients and "disease control subjects" had higher levels of CD62P (p < 0.001), CD63 (p < 0.001), and sP-selectin (p < 0.001) compared with "healthy control subjects," with no difference between AF patients and "disease control subjects." Patients with permanent AF had higher levels of sP-selectin (p = 0.014) and MPV (p = 0.025) compared with those with paroxysmal AF. The presence of AF independently affected the levels of CD62P expression, while "high-risk" AF patients (CHADS score > or =2) had higher levels of CD62P compared with those with "low risk." Introducing warfarin resulted in a reduction of pP-selectin (p = 0.013).

CONCLUSIONS

There is a degree of excess of platelet activation in AF compared with "healthy control subjects," but no significant difference between AF patients and "disease control subjects" in sinus rhythm. Platelet activation may differ according to the subtype of AF, but this is not in excess of the underlying comorbidities that lead to AF. Platelet activation in AF may be due to underlying cardiovascular diseases, rather than due to AF per se.

Association of haematological indices with the degree of microvascular injury in patients with acute anterior wall myocardial infarction treated with primary percutaneous coronary intervention

BACKGROUND

In acute myocardial infarction (AMI), increased neutrophil count has been associated with more severe coronary artery disease and larger infarct size. Increased mean platelet volume (MPV) is also associated with poor clinical outcome and impaired angiographic reperfusion in patients with AMI. However, the associations of neutrophil count and MPV with the indices of tissue level reperfusion were not fully elucidated.

AIM

To elucidate the relationship between baseline neutrophil count and MPV on presentation and microvascular injury in patients with anterior AMI treated with primary percutaneous coronary intervention (pPCI).

METHODS

41 patients with anterior wall AMI treated successfully with pPCI were included. The leucocyte count, neutrophil count and MPV were obtained on admission, and the percentage of neutrophils was calculated. After PCI thrombolysis in myocardial infarction, grade 3 flow was established in all patients. The coronary flow velocity pattern (diastolic deceleration time (DDT)) was examined with transthoracic echocardiography and measured intracoronary pressures with fibreoptic pressure-temperature sensor-tipped guidewire in the left anterior descending artery within 48 h after pPCI. Thermodilution-derived coronary flow reserve (CFR) was calculated. Index of microvascular resistance (IMR) was defined as simultaneously measured distal coronary pressure divided by the inverse of the thermodilution-derived hyperaemic mean transit time. Subsequently, a short compliant balloon was placed in the stented segment and inflated to measure coronary wedge pressure (CWP).

RESULTS

Higher neutrophil counts were strongly associated with higher IMR (r = 0.86, p<0.001), lower CFR (r = -0.60, p<0.001), shorter DDT (r = -0.73, p<0.001) and higher CWP (r = 0.73, p<0.001). Likewise, there were significant correlations among the percentage of neutrophils and CFR (r = -0.34, p = 0.02), IMR (r = 0.46, p = 0.002), DDT (r = -0.36, p = 0.01) and CWP (r = 0.49, p = 0.001). Relationships among leucocyte count and IMR (r = 0.38, p = 0.01), CFR (r = -0.33, p = 0.03), DDT (r = -0.36, p = 0.01) and CWP (r = 0.32, p = 0.026) were slightly significant. Higher neutrophil count remained independently associated with indices of microvascular perfusion in multivariable models controlling for age, smoking habits and time to treatment. Also, higher MPV on admission was strongly associated with higher IMR (r = 0.89, p<0.001), steeper DDT (r = -0.64, p<0.001), lower CFR (r = -0.43, p = 0.004) and higher CWP (r = 0.77, p<0.001).

CONCLUSION

Absolute and relative neutrophilia and higher MPV on admission were independently associated with impaired microvascular perfusion in patients with anterior AMI treated with pPCI. It is possible that neutrophilia and high MPV are simple surrogate markers of worse microvascular injury in patients with AMI.