High platelet reactivity on aspirin in patients with acute ST elevation myocardial infarction

Immature platelets and platelet reactivity in patients with acute ST-segment Elevation Myocardial Infarction using whole blood flow cytometry with SYTO-13 staining

BACKGROUND

Reduced effect of antiplatelet therapy has been reported in patients with ST-segment elevation myocardial infarction (STEMI). Multiple factors may concur to explain this, including increased amount of highly reactive immature platelets.

OBJECTIVES

To investigate the association between immature platelets and reactivity determined with multicolour flow cytometry using the SYTO-13 dye in STEMI patients.

METHODS

We conducted an observational study of 59 patients with acute STEMI. Blood samples were obtained within 24 h after admission and after loading doses of dual antiplatelet therapy. For comparison, samples were obtained from 50 healthy individuals. Immature platelets and platelet reactivity were investigated using multicolour flow cytometry including the SYTO-13 dye that binds to platelet RNA and thus provides a method for subdividing platelets into immature and mature platelets. Additionally, we assessed platelet aggregation, serum-thromboxane B2 levels and standard immature platelet markers.

RESULTS

Immature platelets were more reactive than mature platelets in both STEMI patients and healthy individuals (p-values < 0.05). STEMI patients had lower platelet aggregation and thromboxane B2 levels than healthy individuals. We found a positive association between automatically determined immature platelet markers and CD63 expression on activated platelets (Spearman's rho: 0.27 to 0.58, p-values < 0.05).

CONCLUSIONS

Our study shows that immature platelets identified with a multicolour flow cytometric method using the SYTO-13 dye are more reactive than mature platelets in patients with acute STEMI and in healthy individuals. The presence of immature platelets may be important for the overall platelet reactivity, which may have implications for the effect of antiplatelet therapy.

Protective Value of Aspirin Loading Dose on Left Ventricular Remodeling After ST-Elevation Myocardial Infarction

Aims

Left ventricular (LV) remodeling after ST-elevation myocardial infarction (STEMI) is a complex process, defined as changes of LV volumes over time. CMR feature tracking analysis (CMR-FT) offers an accurate quantitative assessment of LV wall deformation and myocardial contractile function. This study aimed to evaluate the role of myocardial strain parameters in predicting LV remodeling and to investigate the effect of Aspirin (ASA) dose before primary coronary angioplasty (pPCI) on myocardial injury and early LV remodeling.

Methods and Results

Seventy-eight patients undergoing CMR, within 9 days from symptom onset and after 6 months, were enrolled in this cohort retrospective study. We divided the study population into three groups based on a revised Bullock's classification and we evaluated the role of baseline CMR features in predicting early LV remodeling. Regarding CMR strain analysis, worse global circumferential and longitudinal strain (GCS and GLS) values were associated with adverse LV remodeling. Patients were also divided based on pre-pPCI ASA dosage. Significant differences were detected in patients receiving ASA 500 mg dose before pPCI, which showed lower infarct size extent and better strain values compared to those treated with ASA 250 mg. The stepwise multivariate logistic regression analysis, adjusted for covariates, indicated that a 500 mg ASA dose remained an inverse independent predictor of early adverse LV remodeling.

Conclusion

GCS and GLS have high specificity to detect early LV adverse remodeling. We first reported a protective effect of ASA loading dose of 500 mg before pPCI on LV myocardial damage and in reducing early LV adverse remodeling.

Is platelet function testing at the acute phase under P2Y12 inhibitors helpful in predicting bleeding in real-life patients with acute coronary syndrome? The AVALANCHE study

BACKGROUND

In patients with acute coronary syndrome (ACS), current international guidelines recommend newer potent and predictable P2Y₁₂ inhibitors as first-line treatment despite a greater bleeding risk compared with clopidogrel.

AIM

To determine if platelet function testing can predict bleeding in real-life patients with ACS treated with newer P2Y₁₂ inhibitors.

METHODS

In this retrospective study, all consecutive adults admitted to the Lariboisière University Hospital for ACS, whatever the P2Y₁₂ inhibitor prescribed, who had platelet function testing (vasodilator-stimulated phosphoprotein phosphorylation [VASP] index and aggregation tests) during the initial hospital stay were included. Follow-up was performed to record bleeding events according to the Bleeding Academic Research Consortium (BARC) classification.

RESULTS

A total of 364 patients were included, treated with ticagrelor (n=123), prasugrel (n=105) or clopidogrel (n=136); 42.3% after an ST-segment elevation myocardial infarction, 27.1% after a non-ST-segment elevation myocardial infarction and 30.6% with unstable angina. Mean age was 64±11 years. Median VASP index was significantly lower with the newer P2Y₁₂ inhibitors (14% under ticagrelor, 14% under prasugrel) than with clopidogrel (42%). Despite these differences in the degree of platelet inhibition, the occurrence of bleeding (BARC 2-5) during follow-up was 7.7% overall, and was similar for all P2Y₁₂ inhibitors (ticagrelor 8.9%; prasugrel 6.6%; clopidogrel 7.4%). For each P2Y₁₂ inhibitor, it was impossible to determine a VASP index threshold under which bleeding was significantly greater during follow-up. Similarly, ADP-induced aggregation was more profoundly inhibited by ticagrelor and prasugrel than by clopidogrel, but this did not allow a threshold to be set for increased haemorrhagic risk.

CONCLUSIONS

Despite the substantial occurrence of bleeding in patients with ACS during follow-up, neither the VASP index nor platelet aggregation test results measured at the acute phase were helpful in predicting bleeding risk. Whether platelet function testing could be helpful later in the course of treatment remains to be evaluated.

Ticagrelor or Prasugrel in Patients With ST-Segment–Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

Background:

Data on the comparative efficacy and safety of ticagrelor versus prasugrel in patients with ST-segment–elevation myocardial infarction undergoing primary percutaneous coronary intervention are limited. We assessed the efficacy and safety of ticagrelor versus prasugrel in a head-to-head comparison in patients with ST-segment–elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Methods:

In this prespecified subgroup analysis, we included 1653 patients with ST-segment–elevation myocardial infarction randomized to receive ticagrelor or prasugrel in the setting of the ISAR REACT-5 trial (Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment 5). The primary end point was the incidence of death, myocardial infarction, or stroke at 1 year after randomization. The secondary end point was the incidence of bleeding defined as BARC (Bleeding Academic Research Consortium) type 3 to 5 bleeding at 1 year after randomization.

Results:

The primary end point occurred in 83 patients (10.1%) in the ticagrelor group and in 64 patients (7.9%) in the prasugrel group (hazard ratio, 1.31 [95% CI, 0.95–1.82]; P =0.10). One-year incidence of all-cause death (4.9% versus 4.7%; P =0.83), stroke (1.3% versus 1.0%; P =0.46), and definite stent thrombosis (1.8% versus 1.0%; P =0.15) did not differ significantly in patients assigned to ticagrelor or prasugrel. One-year incidence of myocardial infarction (5.3% versus 2.8%; hazard ratio, 1.95 [95% CI, 1.18–3.23]; P =0.010) was higher with ticagrelor than with prasugrel. BARC type 3 to 5 bleeding occurred in 46 patients (6.1%) in the ticagrelor group and in 39 patients (5.1%) in the prasugrel group (hazard ratio, 1.22 [95% CI, 0.80–1.87]; P =0.36).

Conclusions:

In patients with ST-segment–elevation myocardial infarction undergoing primary percutaneous coronary intervention, there was no significant difference in the primary end point between prasugrel and ticagrelor. Ticagrelor was associated with a significant increase in the risk for recurrent myocardial infarction.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01944800.

Factors Influencing Aspirin Hyporesponsiveness in Elderly Chinese Patients

Background

Aspirin hyporesponsiveness increases the risk of ischemic events. Therefore, it is important to investigate the factors influencing aspirin hyporesponsiveness.

Material/Methods

Patients aged 60 years or older who did not take aspirin before enrollment were included, with aspirin 100 mg/day administered after enrollment. The arachidonic acid-induced platelet aggregation rate (Ara) was measured by light transmission assay to evaluate aspirin responsiveness. Patients with Ara in the upper quartile after taking aspirin were assigned to the aspirin hyporesponsive group (Ara-Q4).

Results

A total of 292 elderly patients were included. The median value of Ara after taking aspirin was 5.87% (interquartile range 3.86–10.04%). Compared with the aspirin non-hyporesponsive group (Ara-Q1-3, Ara ≤10.04%, n=220), the level of uric acid (UA) (341.30 μmol/L vs. 299.10 μmol/L, p=0.027) and the ratios of β-blockers (9.72% vs. 2.27%, p=0.015) and diuretics (6.94% vs. 1.36%, p=0.036) were higher in the aspirin hyporesponsive group (Ara-Q4, Ara >10.04%, n=72). After multivariate adjustment, the results demonstrated baseline Ara (odds ratio [OR]: 1.030, 95% confidence interval [CI]: 1.004–1.056, p=0.021), UA level (OR: 1.003, 95% CI: 1.000–1.006, p=0.038), and β-blockers use (OR: 5.487, 95% CI: 1.515–19.870, p=0.010) were independently and positively associated with aspirin hyporesponsiveness.

Conclusions

This study found that baseline Ara, UA level, and β-blockers use were independently and positively associated with aspirin hyporesponsiveness in elderly Chinese patients, which needs to be validated in large-scale studies.

Platelet aggregation and the risk of stent thrombosis or bleeding in elective percutaneous coronary intervention patients

: Platelet aggregation monitoring in patients after stent implantation is a promising way of preventing stent thrombosis and bleeding. The aim of the study was to verify whether clopidogrel (ADPtest) and aspirin (ASPItest) response measured by Multiplate (Dynabyte, Munich, Germany) analyzer in elective percutaneous coronary implantation patients predict the risk of stent thrombosis or other ischemic adverse events and bleeding. In this prospective, observational study 697 elective percutaneous coronary implantation patients were analyzed. The median ASPItest was 86 AU min. In 69 patients (9.9%), an ASPI result of more than 203 AU min was observed. The median ADP-dependent platelet aggregation was 212 AU min. In 36 (5.2%) patients, the result was at least 468 AU min. Cox regression analysis showed the prognostic factors of definite or probable stent thrombosis and cardiac death at 1 year were higher ASPItest result [odds ratio (OR) 1.006, 95% confidence interval (CI) 1.004-1.008, P < 0.001], ASPItest more than 203 AU min (OR 7.61, 95% CI 2.83-20.43, P < 0.001), higher ADPtest result (OR 1.005, 95% CI 1.003-1.007, P < 0.001) and ADPtest at least 468 AU min (OR 12.54, 95% CI 4.56-35.53, P < 0.001). In turn, ADPtest 188 AU min or less predicted GUSTO scale major and moderate bleeding (OR 4.15, 95% CI 1.12-15.32, P = 0.033). There was also a strong trend toward higher rate of major and moderate bleeding for the ASPItest less than 35 AU min (lowest quintile) - (OR 3.04, 95% CI 0.96-9.58, P = 0.058). Lower creatinine clearance and lower hemoglobin level were associated with both ischemic and bleeding complications. The results of this study show that impaired platelet response to clopidogrel and aspirin measured by the Multiplate analyzer results in increased risk of stent thrombosis and cardiac death. Furthermore, the study showed that increased response to clopidogrel is related to major and moderate bleeding events.

Platelet aggregation and risk of stent thrombosis or bleeding in interventionally treated diabetic patients with acute coronary syndrome

Background

Platelet aggregation monitoring in diabetic patients treated with coronary interventions (PCI) for an acute coronary syndrome (ACS) is a promising way of optimizing treatment and outcomes in this high risk group. The aim of the study was to verify whether clopidogrel response measured by Multiplate analyzer (ADPtest) in diabetic ACS patients treated with PCI predicts the risk of stent thrombosis or cardiovascular mortality and bleeding.

Methods

Into this prospective, observational study 206 elective PCI patients were enrolled. Two cutoff points of ADPtest were used in analysis to divide patients into groups. One (345 AU x min) was calculated based on ROC curve analysis; this cutoff provided the best ROC curve fit, although it did not reach statistical significance. The other (468 AU x min) was accepted based on the consensus of the Working Group on On-Treatment Platelet Reactivity. The risk of stent thrombosis and mortality was assessed using Cox regression analysis and Kaplan-Meier curves.

Results

The risk of stent thrombosis was higher in the group of patients with impaired clopidogrel response for either cutoff value (for >354 AU x min - HR 12.33; 95% CI 2.49–61.1; P = 0.002). Cardiovascular mortality was also higher in the impaired clopidogrel response group (for >354 AU x min - HR 10.58; 95% CI 2.05–54.58; P = 0.005). We did not find a clear relation of increased clopidogrel response to the risk of bleeding.

Conclusions

The results of this study show that in diabetic ACS patient group treated with PCI an impaired platelet response to clopidogrel measured by the Multiplate analyzer results in increased risk of stent thrombosis and cardiac death.