The impact of platelet count on mortality in unstable angina/non-ST-segment elevation myocardial infarction

Baseline Platelet Count Predicts Infarct Size and Mortality after Acute Myocardial Infarction

INTRODUCTION

 Platelets greatly contribute to cardiovascular diseases. We sought to explore the association of platelet counts with infarct size and outcome in patients presenting with acute ST-segment elevation MI (STEMI) treated with primary percutaneous coronary intervention (PPCI).

METHODS AND RESULTS

 In this retrospective study, we grouped 1,198 STEMI patients into tertiles (T) based on platelet count on admission: T1 = 102-206 [109 platelets/L] (n = 402), T2 = 207-259 [109 platelets/L] (n = 396), and T3 = 260-921 [109 platelets/L] (n = 400). Primary endpoint was 1-year all-cause mortality. Patients with highest platelet counts on admission showed the greatest area at risk and infarct size: area at risk (median) was 22.0% (interquartile range [IQR]: 12.0-39.8%) in T1, 21.0% (IQR: 11.0-37.1%) in T2, and 26.0% (IQR: 14.9-45.0%) of the left ventricle in T3 (p = 0.003); final infarct sizes after 7 to 14 days were as follows: 10.0% (IQR: 2.0-21.0%) in T1, 9.0% (IQR: 2.0-20.7%) in T2, and 12.0% (IQR: 3.0-27.3%) of the left ventricle in T3 (p = 0.015) as serial imaging revealed. At 1 year, 16 all-cause deaths occurred in T1, 5 in T2, and 22 in T3 (log-rank test, p = 0.006). After adjustment, T1 and T3 were associated with all-cause 1-year mortality (T1: hazard ratio [HR] = 3.40, 95% confidence interval [CI] = 1.23-9.54, p = 0.02; T3: HR = 3.55, 95% CI = 1.23-9.78, p = 0.01) compared with T2. At 5 years, all-cause mortality remained numerically higher in the T1 and T3.

CONCLUSIONS

 In patients with STEMI undergoing PPCI, low and high blood platelet levels on admission were associated with increased long-term mortality (Fig. 1).

Systemic immune-inflammation index as a predictor of prognosis after carotid artery stenting compared with C-reactive protein

BACKGROUND

Immune-inflammatory processes are highly associated with the progression of atherosclerosis. The systemic immune-inflammation index (SII) is a potential predictor for clinical outcomes in patients with stroke and ischemic heart disease. Therefore, this study aimed to investigate whether SII can accurately predict the short- and long-term prognoses in patients who underwent carotid artery stenting (CAS) compared to that with C-reactive protein (CRP).

METHODS

This study was a single-center retrospective investigation. Overall, 129 patients who underwent CAS were categorized into tertiles based on their SII levels. We primarily investigated the long-term major adverse cardiac and cerebrovascular events (MACCE) and secondarily the in-hospital and long-term stroke incidence, as well as all-cause death.

RESULTS

The in-hospital stroke rate tended to increase with a rise in SII (P = 0.13). Over the 5-year follow-up period, the Kaplan-Meier overall incidence of MACCE was 9.3%, 16.3%, and 39.5% in the lowest to highest tertiles, respectively (log-rank trend test, P<0.001). The rates of stroke and MACCE during the long-term follow-up were significantly higher with increasing SII. Cox regression analysis showed that the highest tertile of SII (>647) was a predictor of the incidence of long-term stroke (hazard ratio (HR), 21.3; 95% confidence interval (CI), 2.41-188; P = 0.006) and MACCE (HR, 3.98; 95% CI, 1.80-8.81; P<0.001). However, after adjusting for both SII and CRP, only SII remained a significant independent predictor, whereas CRP became less relevant. The receiver operating characteristic curve analysis of long-term MACCE showed that the area under the curve (AUC) for SII (AUC, 0.72; 95% CI, 0.60-0.84; P<0.001) was greater than that of CRP (AUC, 0.64; 95% CI, 0.51-0.77; P = 0.040).

CONCLUSION

SII was shown to be an independent predictor of long-term prognosis in patients who underwent CAS and was suggested to be superior to CRP as an inflammatory prognosis predictor.

Association between Platelet Count and Treatment Effect of Ticagrelor or Prasugrel in Patients with Acute Coronary Syndromes

BACKGROUND

 The relative efficacy and safety of ticagrelor and prasugrel based dual antiplatelet therapy strategies according to the platelet count (PC) in patients with acute coronary syndromes (ACS) have not been defined.

METHODS

 This is a posthoc analysis of the ISAR-REACT 5 trial, in which patients presenting with ACS were randomized to treatment with ticagrelor versus prasugrel. Patients were divided into quartiles according to PC. The primary endpoint was incidence of death, myocardial infarction, or stroke, and the safety endpoint was incidence of BARC (Bleeding Academic Research Consortium) type 3 to 5 bleeding at 12 months.

RESULTS

 A total of 3,943 patients with known PC (997 patients in quartile 1 (Q1), 1,003 in quartile 2 (Q2) [205 ± 10.3 × 109/L], 961 patients in quartile 3 (Q3) [241 ± 11.7 × 109/L], and 982 patients in quartile 4 (Q4) [317 ± 68.6 × 109/L]). There was no significant interaction between treatment arm (ticagrelor vs. prasugrel) and PC group with respect to primary endpoint (Q1: 8.8 vs. 6.3%, hazard ratio [HR] =1.41, 95% confidence interval [CI]: 0.89-2.23; p = 0.148; Q2: 9.9 vs. 5.8%, HR = 1.68, 95% CI: 1.06-2.66; p = 0.027; Q3: 7.8 vs. 5.5%, HR = 1.43, 95% CI: 0.87-2.37; p = 0.159; Q4: 10.1 vs. 10.1%, HR = 1.05, 95% CI: 0.71-1.57; p = 0.799; p for interaction [p int] = 0.482) and with respect to bleeding endpoint (Q1: 5.8 vs. 4.2%, HR = 1.41, 95% CI: 0.76-2.63; p = 0.279; Q2: 6.4 vs. 3.7%, HR = 1.62, 95% CI: 0.85-2.06; p = 0.140; Q3: 4.4 vs. 3.0%, HR = 1.53, 95% CI: 0.73-3.18; p = 0.258; Q4: 5.6 vs. 8.5%, HR = 0.67, 95% CI: 0.40-1.14; p = 0.138, p int = 0.102).

CONCLUSIONS

 In this analysis, incidences of ischemic and bleeding events at 12 months are comparable across quartiles of platelet count.

Sexual Effect of Platelet-to-Lymphocyte Ratio in Predicting Cardiovascular Mortality of Peritoneal Dialysis Patients

BACKGROUND

The study is aimed at exploring the relationship of platelet-to-lymphocyte (PLR), all-cause, and cardiovascular disease (CVD) mortality in peritoneal dialysis (PD) patients based on gender.

METHODS

A total of 1438 PD patients from January 1,2007 to December 31, 2014 in PD center at The First Affiliated Hospital, Sun Yat-sen University, were included. Patients were followed up until December 31, 2019. The endpoint was all-cause mortality and CVD mortality. Cox proportional hazards regression models were used to evaluate the association of PLR with all-cause and CVD mortality to calculate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

After a median of 48.9 (interquartile range [IQR]: 23.4-79.3) months of follow-up, 406 (28.2%) patients died based on all-cause death, among which 200 (49.3%) patients died from CVD. In the multivariate Cox regression model, we found that PLR was independently related to an increased risk of CVD mortality only in female PD patients, with HR of 1.003 (95% CI: 1.001-1.006). Interaction test showed that the correlation between PLR level for all-cause and CVD mortality varied with gender (p = 0.042 and p = 0.012, respectively).

CONCLUSION

Higher PLR was associated with a higher risk of CVD mortality in female PD patients.

Platelet-lymphocyte ratio as a new predictor of in-hospital mortality in cardiac intensive care unit patients

It has been discovered that both inflammation and platelet aggregation could cause crucial effect on the occurrence and development of cardiovascular diseases. As a combination of platelet and lymphocyte, platelet-lymphocyte ratio (PLR) was proved to be correlated with the severity as well as prognosis of cardiovascular diseases. Exploring the relationship between PLR and in-hospital mortality in cardiac intensive care unit (CICU) patients was the purpose of this study. PLR was calculated by dividing platelet count by lymphocyte count. All patients were grouped by PLR quartiles and the primary outcome was in-hospital mortality. The independent effect of PLR was determined by binary logistic regression analysis. The curve in line with overall trend was drawn by local weighted regression (Lowess). Subgroup analysis was used to determine the relationship between PLR and in-hospital mortality in different subgroups. We included 5577 CICU patients. As PLR quartiles increased, in-hospital mortality increased significantly (Quartile 4 vs. Quartile 1: 13.9 vs. 8.3, P < 0.001). After adjusting for confounding variables, PLR was proved to be independently associated with increased risk of in-hospital mortality (Quartile 4 vs. Quartile 1: OR 95% CI 1.55, 1.08–2.21, P = 0.016, P for trend < 0.001). The Lowess curves showed a positive relationship between PLR and in-hospital mortality. The subgroup analysis revealed that patients with low Acute Physiology and Chronic Health Evaluation IV (APACHE IV) or with less comorbidities had higher risk of mortality for PLR. Further, PLR quartiles had positive relation with length of CICU stay (Quartile 4 vs. Quartile 1: 2.7, 1.6–5.2 vs. 2.1, 1.3–3.9, P < 0.001), and the length of hospital stay (Quartile 4 vs. Quartile 1: 7.9, 4.6–13.1 vs. 5.8, 3.3–9.8, P < 0.001). PLR was independently associated with in-hospital mortality in CICU patients.

Linking Neutrophil Extracellular Traps and Platelet Activation: A Composite Biomarker Score for Predicting Outcomes after Acute Myocardial Infarction

BACKGROUND

 Activation of both platelets and neutrophils can contribute to the risk of major adverse cardiovascular events (MACE) following acute myocardial infarction (AMI). Neutrophil extracellular traps (NETs) are an important product of the platelet-neutrophil axis and exaggerate vascular damage in cardiovascular disease. Additionally, activated platelets can drive NETosis and are directly linked to thromboembolic risk. Investigating the combined effect of biomarkers for NETosis and platelet activation represents a novel approach to risk prediction post-AMI. Here, we examined the utility of a composite biomarker score, inclusive of both pathways, for predicting MACE post-AMI.

METHODS AND RESULTS

 In a case-control design, 100 case patients who experienced MACE within 1 year of index admission were matched in a 1:2 ratio with control patients. Serum levels of myeloperoxidase-DNA, neutrophil elastase-DNA, and citrullinated histone H3 were assayed by enzyme-linked immunosorbent assay (ELISA) as markers of NET burden. To measure platelet activation, soluble P-selectin was assayed by ELISA in parallel. Platelet and neutrophil counts were also recorded. Composite biomarker scores, inclusive of biomarkers for NETosis and platelet activation, were assessed using multivariate regression modeling. These composite biomarker scores were independent predictors of 1-year MACE. The strongest association with MACE was observed using a composite of platelet count, soluble P-selectin, and all NET markers (odds ratio: 1.94; 1.16-3.25).

CONCLUSION

 Here, we demonstrate the importance of combining biomarkers of NETosis and platelet activation for risk prediction in patients with AMI. Combining biomarkers from closely linked, but distinct, biological pathways was more effective than utilizing either type of biomarker alone.

Mean Platelet Volume/Platelet Count Ratio and Culprit Plaque Morphologies: An Optical Coherence Tomography Study in Patients with ST Segment Elevation Myocardial Infarction

This study aimed to investigate the predictive value of mean platelet volume/platelet count ratio (MPR) for coronary plaque features in patients with ST segment elevation myocardial infarction (STEMI). A total of 275 STEMI patients undergoing preintervention optical coherence tomography examination were included, with 142 categorized as plaque rupture (PR) and 133 as plaque erosion (PE). Multivariable logistic regression showed higher MPR was an independent predictor of PR (tertile 3 vs tertile 1, odds ratio: 6.257, 95% confidence interval: 1.586-24.686, P = 0.009). MPR showed better diagnostic performance than other platelet indices. The optimal MPR threshold for diagnosing PR was 0.0473 (sensitivity: 0.721, specificity: 0.647). When added to models of established risk factors, MPR significantly improved the predictive accuracy of PR (area under the curve: 0.767 vs 0.722, P _difference = 0.004). In conclusion, for STEMI patients, MPR was an independent predictor of PR and improved diagnostic performance for PR.

Association of platelet to lymphocyte ratio with in-hospital major adverse cardiovascular events and the severity of coronary artery disease assessed by the Gensini score in patients with acute myocardial infarction

Background:

The platelet to lymphocyte ratio (PLR) has recently emerged as a potential inflammatory biomarker and has been shown to be significantly associated with atherosclerotic coronary artery disease (CAD). Therefore, we aimed to explore the association of PLR with in-hospital major adverse cardiovascular events (MACEs) and the severity of CAD assessed by the Gensini score (GS) in patients with acute myocardial infarction (AMI) undergoing coronary angiography.

Methods:

A total of 502 patients with AMI consecutively treated at the Affiliated Hospital of Qingdao University (Qingdao, China) and underwent coronary angiography from August 2017 to December 2018 were recruited in this study. The demographic, clinical, angiographic characteristics, and laboratory parameters were collected. According to the presence of in-hospital MACEs, the included patients were divided into the MACE group (n = 81) and the non-MACE group (n = 421). Further, according to tertiles of the GS, the patients were classified into three groups: the low GS group (GS ≤ 32 points, n = 173), medium GS group (32 points < GS ≤ 60 points, n = 169), and high GS group (60 points < GS ≤ 180 points, n = 160). The main statistical methods included Chi-squared test, non-parametric Mann-Whitney U test, Kruskal-Wallis H test, logistic regression, and receiver operating characteristic curves.

Results:

The PLR in the MACE group was significantly higher than that in the non-MACE group (179.43 [132.84, 239.74] vs. 116.11 [87.98, 145.45], Z = –8.109, P < 0.001). Further, there were significant differences in PLR among the tertiles of GS (110.05 [84.57, 139.06] vs. 119.78 [98.44, 157.98] vs. 140.00 [102.27, 191.83], H = 19.524, P < 0.001). PLR was demonstrated to be an independent risk factor of in-hospital MACEs (odds ratio [OR]: 1.012, 95% confidential interval [CI]: 1.006–1.018, P < 0.001) and severe CAD assessed by the GS (OR: 1.004, 95% CI: 1.002–1.009, P = 0.042). The cutoff value of PLR for predicting the development of in-hospital MACEs was 151.28 with a sensitivity of 66.7% and a specificity of 78.1% (area under the curve [AUC]: 0.786, 95% CI: 0.730–0.842, P < 0.001), and a PLR of 139.31 was also identified to be an effective cutoff point for detecting a high GS (>60 points) with a sensitivity of 49.4% and a specificity of 69.6% (AUC: 0.611, 95% CI: 0.556–0.666, P < 0.001).

Conclusions:

PLR as a novel inflammatory marker is significantly and independently associated with the occurrence of in-hospital MACEs and the severity of CAD assessed by the GS in patients with AMI. As an easily available and inexpensive inflammatory indicator, PLR could be widely used as an efficient inflammatory biomarker for identifying high-risk patients and for individualizing targeted therapy to improve the prognosis of AMI.

Incidence and Impact of Thrombocytopenia in Patients Undergoing Percutaneous Coronary Intervention With Drug-Eluting Stents

Platelets are crucial in the pathophysiology of coronary artery disease and are a major target of antithrombotic agents in patients receiving percutaneous coronary intervention (PCI). We sought to evaluate the incidence and prognostic impact of thrombocytopenia on clinical outcomes in patients undergoing PCI with drug-eluting stents (DES). We evaluated consecutive patients who received PCI with DES in the IRIS-DES registry between April 2008 and December 2017. Patients were divided into 2 groups based on the presence of thrombocytopenia (platelet count <150 × 10⁹/L) at baseline. The primary outcome was all-cause mortality, and secondary outcomes included the composite outcome of death, myocardial infarction (MI), and stroke, and major bleeding. Complete follow-up data were available for 1 to 5 years (median, 3.1). Among 26,553 eligible patients, 1,823 (6.9%) had thrombocytopenia at baseline. At 5 years, the incidences of all-cause mortality (15.6% vs 8.1%, p <0.001), composite outcome (23.2% vs 15.6%, p <0.001), and major bleeding (3.7% vs 2.2%, p <0.001) were significantly higher in patients with thrombocytopenia than in those without thrombocytopenia. In multivariable Cox proportional-hazards models, thrombocytopenia was significantly associated with increased risks of all-cause mortality (hazard ratio 1.26, 95% confidence interval 1.07 to 1.48, p = 0.01) and major bleeding (hazard ratio 1.41, 95% confidence interval 1.04 to 1.91, P=0.03). In conclusion, among who patients underwent PCI with DES, the incidence of thrombocytopenia was 6.9%. Baseline thrombocytopenia was significantly associated with increased risks of mortality and major bleeding.

Ischemic and Bleeding Events Associated with Thrombocytopenia and Thrombocytosis after Percutaneous Coronary Intervention in Patients with Acute Myocardial Infarction

The early and late ischemic and bleeding clinical outcomes according to baseline platelet count after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) remain unclear. Overall, 10,667 patients from the Cardiovascular Risk and identification of potential high-risk population in AMI (COREA-AMI) I and II registries were classified according to the following universal criteria on baseline platelet counts: (1) moderate to severe thrombocytopenia (platelet < 100 K/μL, n = 101), (2) mild thrombocytopenia (platelet = 100~149 K/μL, n = 631), (3) normal reference (platelet = 150~450 K/μL, n = 9832), and (4) thrombocytosis (platelet > 450 K/μL, n = 103). The primary endpoint was the occurrence of major adverse cardiovascular events (MACE). The secondary outcome was Bleeding Academic Research Consortium (BARC) 2, 3, and 5 bleeding. After adjusting for confounders, the moderate to severe thrombocytopenia (HR, 2.03; 95% CI, 1.49-2.78); p < 0.001), mild thrombocytopenia (HR, 1.15; 95% CI, 1.01-1.34; p = 0.045), and thrombocytosis groups (HR, 1.47; 95% CI, 1.07-2.03; p = 0.019) showed higher 5-year MACE rates than the normal reference. In BARC 2, 3, and 5 bleeding outcomes, the bleedings rates were higher than the normal range in the moderate to severe thrombocytopenia (HR, 2.18; 95% CI, 1.36-3.49; p = 0.001) and mild thrombocytopenia (HR, 1.41; 95% CI, 1.12-1.78; p = 0.004) groups. Patients with AMI had higher 5-year MACE rates after PCI if they had lower- or higher-than-normal platelet counts. Thrombocytopenia revealed higher early and late bleeding rates whereas thrombocytosis showed long-term bleeding trends, although these trends were not statistically significant.

Long-Term Prognostic Significance of High-Sensitive Troponin I Increase during Hospital Stay in Patients with Acute Myocardial Infarction and Non-Obstructive Coronary Arteries

Background and Objectives: A topic already widely investigated is the negative prognostic value regarding the extent of high sensitive troponin I (hs-TnI) increases among patients with myocardial infarction (MI) and obstructive coronary atherosclerosis compared to a group of patients with MI and non-obstructive coronary atherosclerosis (MINOCA). Thus, the aim of this study was to evaluate the prognostic value concerning the extent of hs-TnI increase on clinical outcomes among patients with a MINOCA working diagnosis. Materials and Methods: We selected 337 consecutive patients admitted to hospital with a working diagnosis of MINOCA. The patients were divided in three groups according to the extent of hs-TnI increase during hospitalization (increase ≤5-times above the limit of the upper norm, >5 and ≤20-times, and >20-times). The study endpoints included all-cause mortality and major adverse cardiac and cerebrovascular events (MACCE; cerebral stroke and transient ischemic attacks, MI, coronary artery revascularization, either percutaneous coronary intervention or coronary artery bypass grafting and all-cause mortality). Results: During the mean follow-up period of 516.1 ± 239.8 days, using Kaplan-Meier survival curve analysis, significantly higher mortality rates were demonstrated among patients from the group with the greatest hs-TnI increase compared to the remaining groups (p = 0.01) and borderline values for MACCE (p = 0.053). Multivariable cox regression analysis did not confirm hs-TnI among factors related to increased MACCE or all-cause mortality rates. Conclusion: While a relationship between clinical outcomes and the extent of the hs-TnI increase among patients with a MINOCA working diagnosis remains, it does not seem to be not as strong as it is in patients with obstructive coronary atherosclerosis.

Blood Platelet Count at Hospital Admission Impacts Long-Term Mortality in Patients with Acute Coronary Syndrome

INTRODUCTION

Platelets play a fundamental role in the pathogenesis of acute coronary syndrome (ACS). The platelet count (PC) at hospital admission is easy to obtain, but whether thrombocytopenia or/and thrombocytosis impact long-term mortality (LTM) after ACS is unclear.

OBJECTIVE

To evaluate the effect of PC at hospital admission on LTM in patients with ACS.

METHODS

This retrospective cohort study included patients with the ICD-10 codes for unstable angina (I.20) and acute myocardial infarction (I.21, I.22). Thrombocytopenia was defined as a blood PC <150 G/L and thrombocytosis as a PC >450 G/L. Additional platelet indices which were tested included plateletcrit (PCT), the mean platelet volume (MPV), the platelet distribution width (PDW), and the platelet larger cell ratio (P-LCR). Data on all-cause death were obtained from the National Health Fund database.

RESULTS

The study included 3,162 patients with a median follow-up of 27.2 months (interquartile range 12.5-46.8 months; max 68.7 months). Patients with thrombocytopenia and thrombocytosis yielded a higher maximal analyzed 5-year mortality rate in comparison with normal PC patients (45.8 and 47.7 vs. 24.2%, respectively; p < 0.00001) which was mainly driven by higher deaths at 1-2 years after ACS. The 5-year LTM was also significantly higher in patients with abnormal PCT and MPV levels in comparison with patients with PCT and MPV within the normal range. Other platelet indices (PDW, P-LCR) were not associated with a worse outcome. The Cox proportional hazards model revealed that thrombocytopenia at admission was independently associated with higher LTM after ACS (RR 1.83; 95% CI 1.1-3.0; p = 0.01).

CONCLUSIONS

Both thrombocytopenia and thrombocytosis at hospital admission in post-ACS patients are associated with a significant almost two times higher 5-year mortality rate.

Higher Platelet-to-Lymphocyte Ratio Is Associated With Worse Outcomes After Intravenous Thrombolysis in Acute Ischaemic Stroke

Objective: The platelet-to-lymphocyte ratio (PLR) is a new marker of atherosclerotic inflammation and has been identified as a predictive factor in cardiovascular diseases, but its significance in patients with acute ischaemic stroke (AIS) who have undergone intravenous thrombolysis (IVT) is still unknown.

Methods: Consecutive patients who were treated with IVT using recombinant tissue plasminogen activator (rtPA) for AIS were included from May 2012 to August 2018. The PLR was calculated according to platelet and lymphocyte counts within 24 h after thrombolysis therapy. Functional outcomes were assessed by the modified Rankin Scale (mRS) at 3 months after thrombolysis. Stroke severity was assessed by National Institutes of Health Stroke Scale (NIHSS) scores. The primary endpoint was an unfavorable outcome (mRS > 2), and the secondary endpoint was death at 3 months.

Results: A total of 286 patients were included in the study. The median age was 69.5 (59.0–80.0) years, and 59.1% of patients were men. A total of 120 (42.0%) patients had an unfavorable outcome, and 38 (13.2%) died. Patients with an unfavorable outcome had significantly higher PLR values compared with those with a favorable outcome [172.5 (105.3–239.0) vs. 139 (97.0–194.5), P = 0.008], and the PLR values of the patients who died at 3 months were higher than those of the surviving patients [189.5 (127.5–289.0) vs. 142.0 (98.0–215.5), P = 0.006]. After adjustment for other variables, the PLR was independently associated with the two endpoints: unfavorable outcome (OR 2.220, 95% CI 1.245–3.957, P = 0.007) and death (OR 2.825, 95% CI 1.050–7.601, P = 0.040) at 3 months after thrombolysis. In addition, PLR was correlated with the NIHSS score (R = 0.230, P < 0.001).

Conclusions: Higher PLR levels were independently associated with an unfavorable outcome and death at 3 months in AIS patients treated with IVT.

Shuxuening injection protects against myocardial ischemia-reperfusion injury through reducing oxidative stress, inflammation and thrombosis

Background

Shuxuening injection (SXNI) has a good effect on cardiovascular and cerebrovascular diseases. Here, our study aims to investigate whether SXNI have the protective effect on myocardial ischemia-reperfusion injury (MIRI) and elucidate the mechanism of SXNI's cardiac protection.

Methods

In this experiment, the coronary arteries of Sprague-Dawley (SD) rats were ligated for the induction of a MIRI model. TTC staining and haematoxylin-eosin (HE), as well as troponin I (TnI), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK) and CK-MB levels, were used to detect the protective effect of SXNI. In rat cardiac tissue, superoxide dismutase, catalase, glutathione and malondialdehyde (MDA) activities and glucose-regulated protein 78 (GRP78), calreticulin (CRT), CCAAT/enhancer binding protein homologous protein (CHOP) and caspase-12 expression levels were detected. In rat serum, the levels of inflammatory factors, including high-sensitivity C-reactive protein, monocyte chemoattractant protein-1, tumour necrosis factor-α, interleukin-6 (IL-6) and IL-1β, were measured by Elisa. In the rat arterial tissue, Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) expression was measured by western blot. In the rat plasma, ELISA was used to assay the levels of coagulation and plasmin system indicators, including platelet activating factor, endothelin, tissue factor (TF), plasminogen inhibitor, thromboxane B2, plasma fibrinogen.

Results

The results showed that SXNI can reduce the infarct size of myocardial tissue, decrease the myocardial enzyme and TnI levels and decrease the degree of myocardial damage compared with the model group. Additionally, SXNI can increase the activity of antioxidant enzymes, reduce the MDA level and decrease the GRP78, CRT, CHOP and caspase-12 expression levels. SXNI also decreased the levels of inflammatory cytokines in rat serum, lowered the level of procoagulant molecules in plasma and reduced the TLR4/NF-κB expression.

Conclusions

SXNI has protective effect on MIRI mainly by inhibiting oxidative stress and endoplasmic reticulum stress (ERS), thereby regulating TLR4/NF-κB pathway to reduce inflammation, and lowing procoagulant-related factors levels to reduce the risk of thrombosis.

Platelet Count Predicts Adverse Clinical Outcomes After Ischemic Stroke or TIA: Subgroup Analysis of CNSR II

Background: The clinical significance of platelet count (PC) for ischemic cerebrovascular disease is not well-established and further risk stratification according to baseline PC within normal range has not been reported before. We aim to evaluate the prognostic effect of baseline circulating PC within normal range on the risk of long-term recurrent stroke, mortality and functional outcomes after ischemic stroke or TIA.

Methods: We derived data from eligible patients with ischemic stroke or TIA from the China National Stroke Registry (CNSR) II. Participants were divided into quintiles according to baseline PC within normal range (100–450 × 10⁹/L). Multivariable cox regression and logistic regression were adopted to explore the correlation of baseline PC with recurrent stroke, mortality and poor functional outcomes (modified Rankin Scale 3~6) within 1-year follow-up.

Results: Among the16842 eligible participants, the average age was 64.7 ± 11.9, 1,241 (7.4%) had recurrent stroke, 1,377 (8.2%) died, and 3,557 (21.1%) ended up with poor functional outcomes after 1-year follow-up. Compared with the third PC quintile (186–212 × 10⁹/L), patients in the top quintile (249–450 × 10⁹/L) presented with increased risk of recurrent stroke (adjusted hazard ratio 1.21, [1.02–1.45]), all-cause mortality (adjusted hazard ratio 1.43, [1.19–1.73]), and poor functional outcome (adjusted odds ratio 1.49, [1.28–1.74]), while patients in the lowest PC quintile(100–155 × 10⁹/L) had higher risk of poor functional outcome (adjusted odds ratio 1.19, [1.02–1.38]).

Conclusion: In ischemic stroke or TIA patients with platelet count within normal range, platelet count may be a qualified predictor for long-term recurrent stroke, mortality, and poor functional outcome.

Thrombocytopenia and declines in platelet counts: predictors of mortality and outcome after mechanical thrombectomy

BACKGROUND AND PURPOSE

Acute ischemic stroke (AIS) has well-known risk factors. The role of platelets in patients treated using mechanical thrombectomy (MT) has not been studied. The aim of this study was to study if there is an association of initial thrombocytopenia (TP) and a decline of platelets counts (DPC) with the clinical outcomes, mortality and intracranial hemorrhage (ICH) rates in AIS patients treated with MT.

MATERIALS AND METHODS

In a case-control study consecutive MT-stroke patients were analyzed. A multivariate logistic regression model was used to test for good clinical outcome (mRS 90 days <= 2) and mortality adjusting for age, initial NIHSS, pretreatment with tPA, statins and platelet inhibitors, occlusion site, time from symptom onset to recanalization, initial TP (< 150 × 10⁹/L) and DPC (> 26%). Additionally, rates of ICH were compared.

RESULTS

Of 294 patients included, 9.6% had an initial TP and 23.8% a DPC > 26%. The mortality rate in patients with normal platelet counts was 26.1% vs. 48.3% (p = 0.002) in patients with initial TP with an aOR of 3.47 (CI 1.28-9.4, p = 0.005). No difference regarding the rate of good clinical outcome (p = 0.204) and ICH (p = 0.18) was observed. A DPC of more than 26% during the first 5 days of hospitalization predicted the rate of mortality (aOR 2.4 CI 1.14-5.04, p = 0.021) and the chances of a good clinical outcome (aOR 0.291 CI 0.128-0.666, p = 0.003) without significant differences of ICH rates (p = 0.735).

CONCLUSION

In AIS patients treated with MT an initial TP was independently associated with higher mortality rates and a marked DPC with higher mortality rates as well as poorer clinical outcomes.

Association between baseline platelet count and severe adverse outcomes following percutaneous coronary intervention

Objective

The aim is to evaluate the association between baseline platelet count (PC) and severe adverse outcomes following percutaneous coronary intervention (PCI) in current real-world practice.

Methods

A total of 18,788 patients underwent PCI with drug-eluting stents constituted the study population. Patients were categorized as having low (< 150 × 1000/µL), normal (150–300 × 1000/µL), and high (≥ 300 × 1000/µL) baseline PC. The primary endpoints included in-hospital and follow-up all-cause mortality. The secondary endpoint was major bleeding requiring a blood transfusion.

Results

In-hospital mortality rates for patients with low, normal, and high baseline PC were 0.6%, 0.4%, and 0.4%, respectively (P = 0.259). Similarly, mortality rates during long-term follow-up (median 23.8 months) for patients with low, normal, and high baseline PC were 0.9%, 0.6%, and 0.7%, respectively (P = 0.079). After multivariate adjustment, patients with low or high baseline PC tended to have similar risks for both in-hospital and follow-up mortality compared with the normal group. Subgroup analyses failed to demonstrate an independent prognostic value of baseline PC in specific population groups except patients who undwent transfemoral PCI. There was also no significant difference in the incidence of major bleeding requiring a blood transfusion in the low, normal, and high groups (0.5%, 0.3%, and 0.3%, respectively; P = 0.320). After multivariate adjustment, low or high baseline PC did not significantly increase the risk of major bleeding.

Conclusion

There is no significant association between baseline PC and severe adverse outcomes following PCI in current real-world practice.

Baseline platelet parameters for predicting early platelet response and clinical outcomes in patients with non-cardioembolic ischemic stroke treated with clopidogrel

Purpose

The present study investigated whether routine baseline platelet parameters(BPPs) detected before clopidogrel therapy in acute non-cardioembolic ischemic stroke(NCIS) could predict early platelet response and future clinical outcomes.

Results

The CYP2C19 polymorphisms constituted independent risk factors for LCR. The number of female patients, the incidence of diabetes mellitus (DM), the level of low-density lipoprotein(LDL) cholesterol, and the neutrophil-to-lymphocyte ratio(NLR) were significantly high in the clinical clopidogrel resistance (CCR) group. However, none of the BPPs had a significant association with laboratory clopidogrel resistance (LCR) or discriminated with the cut-off values regarding LCR or CCR. The patients were divided into two groups according to the average mean platelet volume(MPV) or platelet count(PC). We found that the HbA1c level, the number of female patients, and the CCR were higher in the groups with elevated MPV (≥ 10.6fL) and PC (≥ 235 × 10⁹/L); the LCR, the NIHSS score at discharge, and elevated MPV and PC were risk predictors for CCR.

Materials and Methods

This study included 196 patients with acute NCIS who underwent routine blood tests upon admission, were treated with clopidogrel, and were followed up for 6 months. Early platelet response was assessed and the CYP2C19 genetic variants were screened for. All participants were categorized into either laboratory clopidogrel resistance(LCR) or clinical clopidogrel resistance (CCR) groups.

Conclusions

Elevated baseline MPV and PC before clopidogrel therapy, as well as CYP2C19 gene variants, should be included in a risk algorithm for NCIS. Furthermore, other nongenetic clinical risk factors should be assessed for optimal prediction of the risk for thrombotic events because of individual variability in platelet response to clopidogrel.

Platelet index levels and cardiovascular mortality in incident peritoneal dialysis patients: a cohort study

Prior studies have shown that the levels of some platelet (PLT) indices were associated with mortality in patients undergoing hemodialysis. We aimed to investigate whether the changes in PLT indices associated with mortality in patients on peritoneal dialysis (PD). A single-center, retrospective observational cohort study was conducted in incident PD patients from 1 January 2006 to 31 December 2012, and followed up until 31 December 2014. Cox proportional hazard models were used to examine the relationships between the levels of PLT indices including PLT, plateletcrit (PCT), mean platelet volume (MPV), platelet distribution width (PDW), platelet large cell ratio (PLCR), and mortality. Of 1324 patients, 276 (20.8%) died during follow-up (median, 37; IQR, 3-107.4 months), among which 134 were due to cardiovascular diseases (CVD). The highest tertile of PLT levels at baseline was associated with increased risk for cardiovascular mortality after adjustment for demographic, clinical characteristics, and laboratory variables (hazard ratio [HR]:1.93; 95% confidence interval [CI]: 1.16-3.20). The similar treads were also observed in the middle and the highest tertile of the PCT level (HR: 1.68, 95%CI: 1.00-2.81 and HR: 1.89, 95%CI: 1.14-3.14, respectively). In addition, the highest tertile of PCT was associated with increased all-cause mortality (HR: 1.41, 95%CI: 1.01-1.96). However, none of the associations in MPV, PDW, and PLCR analyses reached statistical significance (HR: 0.71, 95%CI: 0.43-1.16; HR: 0.72, 95%CI: 0.45-1.18 and HR: 0.74, 95%CI: 0.46-1.19, respectively). These results suggest that higher PLT and PCT may be associated with higher risk for cardiovascular mortality in incident PD patients. Additional studies are needed to investigate whether correction of these two PLT indices reduces the risk.

Platelet counts on admission affect coronary flow, myocardial perfusion and left ventricular systolic function after primary percutaneous coronary intervention

BACKGROUND

Patients with acute ST-elevation myocardial infarction (STEMI) and increased platelet count treated by fibrinolysis have worse outcomes.

AIM

The aim of this study was to test the hypothesis that platelet blood count at admission in patients with acute STEMI treated by primary percutaneous coronary intervention affects coronary flow, myocardial perfusion and recovery of left ventricular systolic function.

METHODS

A total of 174 patients presenting with acute anterior STEMI and treated with primary percutaneous coronary intervention were included and divided into subgroups of admission platelet blood count of <200 K, 200-300 K, 300-400 K and >400 K. Evaluation of coronary artery flow and myocardial blush grade was performed according to the TIMI criteria. Electrocardiographic ST elevation resolution post-primary percutaneous coronary intervention was evaluated. Doppler echocardiographic evaluation of left anterior descending coronary artery velocities early and late after primary percutaneous coronary intervention and assessment of left ventricular ejection fraction and wall motion score index (WMSI) of left ventricular and left anterior descending coronary artery territory were performed.

RESULTS

Post-primary percutaneous coronary intervention TIMI, myocardial blush grade and ST elevation resolution were similar in all groups. Patients with platelet counts <200 K had higher peak diastolic left anterior descending coronary artery velocity both early and late after primary percutaneous coronary intervention, and higher prevalence of left anterior descending coronary artery velocity deceleration time exceeding 600 ms, (45.5% vs. 40%, P<0.05). Patients with platelet counts >400 K presented with worse left ventricular ejection fraction, left ventricular WMSI and left anterior descending coronary artery WMSI, and before discharge this subgroup had worse left ventricular WMSI and left anterior descending coronary artery WMSI, P<0.01.

CONCLUSIONS

Patients with anterior STEMI treated by primary percutaneous coronary intervention with lower admission platelet count had higher left anterior descending coronary artery diastolic velocities, better myocardial perfusion with more patients having left anterior descending coronary artery-descending coronary artery velocity deceleration time >600 ms. Patients with higher platelet counts had lower left ventricular systolic function both at admission and before discharge.

The Impact of Thrombocytopenia on Outcome in Patients with Acute Coronary Syndromes: A Single Center Retrospective Study

Background. In acute coronary syndromes (ACS), treated by combined antithrombotic therapy and percutaneous coronary interventions (PCI), thrombocytopenia may occur. Our aim was to evaluate predictors and the impact of thrombocytopenia on mortality in high-risk ACS patients. Methods. We retrospectively evaluated high-risk ACS patients. Thrombocytopenia was defined as platelet count <140.000/mL or a drop in platelet count of >50% during in-hospital stay. We compared demographic, laboratory, clinical, and mortality data between nonthrombocytopenic and thrombocytopenic ACS patients and evaluated independent predictors of thrombocytopenia. Results. In 371 ACS patients, thrombocytopenia was observed in 21.3%. Thrombocytopenic patients were significantly older and, less likely treated by PCIs (72.1% versus 89.7%, p < 0.001) and combined antithrombotic therapy, with increased incidence of in-hospital complications and the use of additional treatments, but with increased mortality at 30 days (27.8% versus 10.2%, p < 0.001) and 6 months (35.4% versus 13.6%, p < 0.001) when compared to nonthrombocytopenic patients. The use of antibiotics, transfusions, insertion of intra-aortic balloon pump (IABP), and prior stroke independently predicted thrombocytopenia. Conclusions. Thrombocytopenia, observed in about 20% of high-risk ACS patients, was associated significantly with in-hospital complications and mortality. Predictors of thrombocytopenia were the use of antibiotics, transfusions, insertion of IABP, and prior stroke.

The prognostic value of admission red cell distribution width-to-platelet ratio in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

OBJECTIVE

Red cell distribution width (RDW) is a measure of variation in the size of circulating red blood cells. Recent studies have reported a strong independent relation between elevated RDW and short- and long-term prognosis in various disorders. The aim of the present study was to investigate the relationship between admission RDW-to-platelet ratio (RPR) and in-hospital and long-term prognosis in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

METHODS

A total of 470 consecutive patients with a diagnosis of STEMI who underwent primary PCI were included in this prospective study. The patients were divided into two groups based on their admission RPR: high (>0.061) RPR group and low (≤0.061) RPR group. The patients were followed for adverse clinical outcomes in-hospital and for up to one year after discharge.

RESULTS

In-hospital cardiovascular mortality, major adverse cardiovascular events (MACE), advanced heart failure and cardiogenic shock were significantly higher in the high RPR group (p<0.05). All-cause and cardiovascular mortality, MACE, fatal reinfarction, advanced heart failure, and rehospitalization for cardiac cause were more frequent in the high RPR group in one-year follow-up (p<0.05). High RPR was found to be a significant independent predictor of one-year cardiovascular mortality in multivariate analysis (p=0.003, OR: 3.106, 95% CI: 1.456-6.623).

CONCLUSION

RPR is an inexpensive and readily available biomarker that provides an additional level of risk stratification beyond that provided by conventional risk parameters in predicting long-term MACE and cardiovascular mortality in STEMI.

Platelet indices are novel predictors of hospital mortality in intensive care unit patients

BACKGROUND AND OBJECTIVE

Platelet volume indices (PVIs) are inexpensive and readily available in intensive care units (ICUs). However, their association with mortality has never been investigated in a critical care setting. Our study aimed to investigate the association of PVI and mortality in unselected ICU patients.

METHODS

This was a retrospective study conducted in a mixed 24-bed ICU from September 2010 to December 2012. Platelet indices including mean platelet volume (MPV), platelet distribution width (PDW), platelet count, and plateletcrit were measured on ICU entry. Univariable analyses were performed to screen for variables that were associated with mortality. Variables with P < .1 were incorporated into a regression model to adjust for the odds ratio of platelet indices.

RESULTS

A total of 1556 patients were included during the study period, including 1113 survivors and 443 nonsurvivors (mortality rate: 28.47%). Platelet distribution width and MPV were significantly higher in nonsurvivors than in survivors. Platelet distribution width greater than 17% and MPV greater than 11.3 fL were independent risk factors for mortality (adjusted odds ratio: 1.92 and 1.84, respectively) and survival time (hazards ratio: 1.77 and 1.75, respectively).

CONCLUSION

Higher MPV and PDW are associated with increased risk of death, whereas the decrease in plateletcrit is associated with increased mortality risk.

Platelet/lymphocyte ratio and risk of in-hospital mortality in patients with ST-elevated myocardial infarction

Background

Platelet-to-lymphocyte ratio (PLR) is a new prognostic marker in coronary artery disease. We aimed to evaluate the relationship between PLR and in-hospital mortality in patients with ST-elevated acute myocardial infarction (AMI).

Material/Methods

The present study included 636 patients with ST-elevated AMI. The study population was divided into tertiles based on their admission PLR. Patients having values in the third tertile was defined as the high PLR group (n=212) and those having values in the lower 2 tertiles were defined as the low PLR group (n=424).

Results

Risk factors of coronary artery disease and treatments administered during the in-hospital period were similar between the groups. Male patient ratio was found to be lower in the high PLR group (73% vs. 82.8%, p=0.004). In-hospital mortality was increased in the high PLR group when compared to the low PLR group (12.7% vs. 5.9%, p=0.004). The PLR >144 was found to be an independent predictor of in-hospital cardiovascular mortality (HR: 2.16, 95% CI: 1.16–4.0, p=0.014).

Conclusions

This study showed that PLR is an independent predictor of cardiovascular mortality in patients with ST-elevated AMI.

Platelet count predicts cardiovascular mortality in very elderly patients with myocardial infarction

BACKGROUND

The prognosis of elderly patients with acute myocardial infarction (AMI) is poor, and information on specific risk factors remains scarce. The aim of our study was to assess the influence of platelet count on cardiovascular mortality in very elderly patients with acute myocardial infarction (≥ 85 years of age).

METHODS

We identified 208 elderly AMI patients and compared the platelet count with 208 matched young AMI patients (≤ 65 years) and 208 matched intermediate age AMI patients (66-84 years) who derived from the same cohort.

RESULTS

During a median follow-up of 4·7 years, 25% of patients (n = 156) died of cardiovascular causes (97 very elderly, 46 intermediate age and 13 young age patients). We detected a mean platelet count of 227G/l (SD ± 83) in very elderly AMI patients, of 236G/l (SD ± 78) in the intermediate AMI group and of 254G/l (SD ± 79) in 208 young AMI patients (ANOVA P = 0·002). We revealed a significant interaction between age and platelet count with regard to cardiovascular mortality (p for interaction = 0·014). Platelet count displayed a significant risk transformation from an independent risk factor for cardiovascular mortality in very elderly AMI patients (adj. hazard ratio (HR) per 1-SD increase 1·25;95%CI 1·02-1·54;P = 0·028), via displaying no association with mortality in the intermediate age group (P = 0·10), to a strong inverse association in young patients (adj. HR 0·36;95%CI 0·18-0·68;P = 0·002).

CONCLUSION

Our study demonstrates an independent association between elevated platelet count and long-term cardiovascular mortality in the growing and vulnerable group of very elderly AMI patients. Nevertheless, the pathophysiologic mechanisms underlying this age-dependent effect have to be further clarified.

Influence of platelet reactivity on clinical outcome of patients with stable coronary artery disease

Single antiplatelet therapy with aspirin is actually recommended for cardiovascular prevention in patients with stable coronary disease, whereas dual antiplatelet therapy (aspirin and clopidogrel) represents the established treatment in patients with acute coronary syndromes or stable angina undergoing percutaneous coronary intervention. However, recurrent ischemic events occur in patients on treatment with clopidogrel; this may be due to low responsiveness to this agent, a phenomenon influenced by environmental, clinical, and genetic factors. Different strategies have been tested to overcome this phenomenon, such as increase in clopidogrel loading and maintenance doses and use of newer P2Y12 inhibitors (prasugrel and ticagrelor), which are by now indicated for patients with acute coronary syndromes; the latter agents have been associated with stronger antiplatelet effect than clopidogrel even in patients with stable coronary disease, but further studies are needed to test their net clinical benefit in this setting (reduction of ischemic events without increase in bleeding).

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.

Hematologic parameters, atherosclerotic progression, and prognosis in patients with previous coronary artery bypass grafting (from the Post CABG Trial)

Although inflammatory markers and anemia have both been associated with prognosis in patients with cardiovascular disease, their relation with atherosclerotic progression in patients with previous coronary artery bypass grafting (CABG) is unknown. A total of 1,273 patients enrolled in the Post CABG Trial who had undergone CABG 1 to 11 years before entry were studied. Subjects were randomly assigned to lovastatin in low or high doses and low-dose warfarin or placebo in a factorial design. Subjects underwent coronary angiography at baseline and after a mean follow-up of 4.3 years. White blood cells (WBCs), hemoglobin, and platelets were measured at baseline in all subjects. Graft progression was defined as a decrease > or =0.6 mm in lumen diameter at the site of greatest change at follow-up. During follow-up, 195 subjects sustained a clinical event and 857 grafts developed significant worsening. Risk of clinical events tended to be greater with higher WBC counts, with hazard ratios for ascending quartiles of 1.4 (95% confidence interval [CI] 0.9 to 2.2), 1.6 (95% CI 1.0 to 2.6), and 1.6 (95% CI 1.0 to 2.7). WBC count also tended to be associated with significant atherosclerotic progression, particularly in subjects assigned to placebo rather than warfarin (p interaction = 0.04). There was no association of hemoglobin or platelet count with risk of clinical events or graft progression, but few trial subjects were anemic. In conclusion, WBC count is associated with a graded increase in cardiovascular events in patients with coronary artery bypass grafts.

Effect of ambient particulate matter exposure on hemostasis

Epidemiological studies have linked levels of particulate matter (PM) in ambient air to cardiovascular mortality and hospitalizations for myocardial infarction (MI) and stroke. Thrombus formation plays a primary role in potentiating acute cardiovascular events, and this study was undertaken to determine whether pulmonary exposure to PM alters hemostasis. PM was collected from the Chapel Hill, NC airshed and was administered to mice by intratracheal instillation at a dose previously shown to exacerbate myocardial ischemia-reperfusion injury. Twenty-four hours after exposure, an increase occurred in the number of circulating platelets and plasma concentrations of fibrinogen and soluble P-selectin. The concentration of tissue factor pathway inhibitor (TFPI) in plasma was decreased, whereas the plasma concentration of plasminogen activator inhibitor (PAI-1) was increased. Consistent with these observations, bleeding time from a tail-tip transection was shortened. These results provide evidence that PM exposure alters hemostasis in otherwise healthy animals and may thereby promote clot formation and impede clot resolution in susceptible individuals. The results also establish definite hemostatic endpoints that can be used to further investigate the effects of dose and particle characteristics on the toxicity of ambient particles.