Enhanced Platelet Reactivity under Aspirin Medication and Major Adverse Cardiac and Cerebrovascular Events in Patients with Coronary Artery Disease.

Aspirin is indispensable in secondary prevention of ischemic events in patients with coronary artery disease (CAD). However, insufficient platelet inhibition despite aspirin medication is frequent. This is referred to as high on-treatment platelet reactivity (HTPR). Nevertheless, if this is associated with clinical outcome instead of only laboratory phenomenon remains unclear so far. In this study, we test whether patients with ischemic events have higher platelet reactivity despite aspirin medication than patients without ischemic events. In this prospective study of 72 CAD patients, we determined pharmacodynamic response to aspirin by arachidonic acid induced aggregation via light-transmission aggregometry and expressed as maximum of aggregation (MoA). During a mean follow-up duration of 3.2 years, major adverse cardiac and cerebrovascular events (MACCE), mortality, non-ST-elevation myocardial infarction (NSTEMI), and stroke were assessed as endpoints via yearly telephone interviews with the treating physician of the patients. Patients who suffered from MACCE, death, and NSTEMI had a significantly higher MoA than those without (MACCE: 5.4 vs. 16.4%, p < 0.05; death: 5.6 vs. 16.8%, p < 0.05; NSTEMI: 1.8 vs. 21%, p < 0.001). MoA did not differ with regard to the occurrence of stroke (10.1 vs. 14.9%, p = 0.59). Patients with MACCE, death, and NSTEMI show enhanced platelet reactivity despite aspirin medication as compared to patients without ischemic events. Hence, insufficient response to aspirin medication should be regarded as risk factor for ischemic events in CAD patients. Further trials are needed to assess options to overcome HTPR to aspirin.

Cardioprotection by very mild hypothermia in mice.

Target temperature management is recommended in post-resuscitation care. Additionally, hypothermia is a promising option in adjunctive therapy of acute myocardial infarction (MI). However, first in men data are contradicting. There are still many open questions to identify the optimal regimen and target temperature. In this study, we aimed to investigate the effect of very mild hypothermia on infarct size (IS) in mice. Mice underwent cardiac ischemia by temporary occlusion of the left anterior descending (LAD) artery under conditions of very mild hypothermia (34-36 °C). Hypothermia was reached within the first 5 minutes of ischemia (temperature: 34.6±0.5 vs. 36.8±1.1 °C, P=0.035). Very mild hypothermia reduced IS in mice undergoing 30 minutes ischemia [IS/area at risk (AAR): 45±12% vs. 22±4%, P=0.018] as well as mice undergoing 60 minutes ischemia [IS/AAR: 67±7% vs. 28±2%, P=0.0003]. Very mild hypothermia reduces IS. This new approach in adjunctive therapy of patients with acute MI should be investigated in clinical trials.

Platelet Reactivity in Patients on Aspirin and Clopidogrel Therapy Measured by a New Bedside Whole-Blood Assay.

Various tests are available for measuring on-treatment platelet reactivity. The pharmacologically most specific assays are time-consuming and elaborate. A highly specific and convenient assay would be desirable for clinical routine. In this pilot study, we aimed to examine the ability of a novel bedside whole-blood assay-ROTEM platelet-to evaluate platelet inhibition compared with established assays. Platelet reactivity was investigated in 93 patients. Forty-Seven patients were on permanent aspirin therapy and 46 on dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. We used ROTEM platelet impedance aggregometry (ROTEM-PTL), light transmission aggregometry (LTA), Multiplate electrode aggregometry (MEA) and vasodilator-stimulated phosphoprotein flow cytometry. Receiver operating characteristic (ROC) analyses showed ROTEM-PTL differentiates well between patients on medication and healthy individuals: aspirin: ROCAUC 0.99 (95% confidence interval, 0.97-1.01); P < 0.0001; DAPT treatment: ROCAUC 0.80 (95% confidence interval, 0.69-0.91); P < 0.001. Pearson regression analyses showed moderate correlations between assays. Aspirin: MEA versus ROTEM-PTL r = 0.435, P ≤ 0.001; LTA versus ROTEM-PTL r = 0.048, P = 0.180. DAPT: MEA versus ROTEM-PTL r = 0.398, P = 0.001; LTA versus ROTEM-PTL r = 0.409, P = 0.001; vasodilator-stimulated phosphoprotein versus ROTEM-PTL r = 0.164, P = 0.055. ROTEM platelet distinguished well between treated and healthy individuals but correlated moderately with other assays. Clinical trials are needed to investigate the ability of this new assay to identify patients at risk of adverse events.

Malondialdehyde Assay in the Evaluation of Aspirin Antiplatelet Effects.

Aspirin is essential in secondary prevention of patients after myocardial infarction and with coronary artery disease. However, impaired pharmacodynamic response to aspirin is frequent (high on-treatment platelet reactivity [HTPR]). This leads to an enhanced prevalence of cardiovascular events and to an impaired clinical outcome. The current specific assays to evaluate aspirin antiplatelet effects are complex, time-consuming and demand for a high laboratory expertise. Therefore, we developed a potentially bedside assay based on the determination of malondialdehyde (MDA). MDA is a by-product of the thromboxane (TX) formation, which is synthesized in equimolar concentrations. In this study, we compared this MDA assay to the conventional assays in determination of pharmacodynamic aspirin response. For this, aspirin antiplatelet effects were measured in 22 healthy individuals and 63 aspirin treated patients using TX B2 formation enzyme-linked antibody assay, arachidonic acid induced light transmission aggregometry (LTA) and the new fluorometric MDA assay. In patients, MDA levels correlated well with TX formation (R = 0.81; 95% CI 0.69-0.88; p < 0.001) and LTA (R = 0.84; CI 0.74-0.91; p < 0.001). Receiver operating characteristic analyses revealed that the MDA assay does detect HTPR to aspirin sufficiently (area under the curve: 0.965; p < 0.001). The optimal cut-off was > 128 nmol/L (sensitivity of 100%, specificity of 91%). The new MDA assay is reliable in detecting HTPR. It is highly specific in the evaluation of antiplatelet effects by aspirin. This promising and potential bedside assay needs to be evaluated in clinical practice.

Safety and Efficacy in Prasugrel- Versus Ticagrelor-Treated Patients With ST-Elevation Myocardial Infarction.

Prasugrel and ticagrelor are recommended over clopidogrel in patients with ST-elevation myocardial infarction (STEMI). In this registry analysis, we compared efficacy and safety of ticagrelor and prasugrel P2Y12 inhibition in patients with STEMI. We included 318 patients in this single-center analysis. Twelve-month follow-up was conducted during ambulatory care at our department. Patients were on dual antiplatelet therapy with aspirin and ticagrelor or prasugrel during the follow-up period. Prescription of prasugrel or ticagrelor, respectively, was according to the preference of the treating physician. Major adverse cardiac and cerebrovascular events (MACCE) [death, myocardial infarction (MI), stroke, and unplanned reintervention] and thrombolysis in myocardial infarction (TIMI) bleeding (major/minor) were registered during hospitalization and follow-up. TIMI bleeding events were more frequent in ticagrelor-treated patients [17 vs. 5 patients, hazard ratio (HR) 2.85, 95% confidence interval (CI) 1.2-6.6; log-rank P value = 0.01]. Prasugrel-treated patients were significantly younger (ticagrelor 63 ± 12 years vs. prasugrel 57 ± 10; P < 0.0001). Besides that, patients' characteristics were similar in both groups. Multivariate analysis revealed that ticagrelor medication was independently associated with bleeding risk after adjustment for age, percutaneous coronary intervention approach (femoral vs. radial), diabetes mellitus, and kidney function (HR 3.01; 95% CI 1.0-7.4; P = 0.043). In patients treated with ticagrelor, 35 MACCE were detected. There was no difference as compared to prasugrel-treated patients (24 events, HR 1.24, 95% CI 0.79-2.09; log-rank P value = 0.41). TIMI bleeding events were more frequent in ticagrelor-treated patients with STEMI during 12-month follow-up. There were no differences in MACCE between groups in this registry analysis.

Major adverse cardiac events and drug-coated balloon size in coronary interventions.

OBJECTIVE: In-stent restenosis (ISR) is a feared complication after coronary stent implantation. Drug-coated balloon (DCB) is being promoted as a treatment option for ISR. However, the benefit-risk ratio of DCB length has not been investigated. Longer DCBs release more anti-proliferative drug to the vessel wall; however, they are associated with a higher lesion length and vessel injury. HYPOTHESIS: DCB length is associated with clinical outcome. METHODS: We analyzed 286 consecutive Pantera Lux (Biotronik, active component Paclitaxel) DCB-treated patients between April 2009 and June 2012. Of them, 176 patients were treated using a 15-mm DCB and 109 were treated using a 20-mm DCB. Baseline characteristics and major adverse cardiac events (MACE; death, myocardial infarction, and target lesion revascularization) during initial hospital stay and a 2-year follow-up period were obtained. RESULTS: Patients characteristics such as cardiovascular risk factors, prior diseases, co-medication, clinical presentation, target vessel, and left ventricular function did not differ between the groups. MACE during hospital course was similar [1.7% vs. 2.8%, relative risk (RR) 1.6, 95% confidence interval (CI) 0.3-7.9, p=0.554]. Likewise, at 2-year follow-up, MACE did not differ between the groups (23.2% vs. 27.5%, RR 1.2, 95% CI 0.6-1.5, p=0.408). CONCLUSION: DCB length was not associated with clinical outcome during a 2-year follow-up period.

Aspirin Inhibits Platelet-Derived Sphingosine-1-Phosphate Induced Endothelial Cell Migration.

BACKGROUND: Aspirin plays a crucial role in the prevention of cardiovascular diseases. We previously described that aspirin has effects beyond inhibition of platelet aggregation, as it inhibited thrombin-mediated release of sphingosine-1-phosphate (S1P) from human platelets. S1P is a bioactive lipid with important functions on inflammation and apoptosis. In endothelial cells (EC), S1P is a key regulator of cell migration. In this study, we aimed to analyze the effects of aspirin on platelet-induced EC migration. METHODS: Human umbilical EC migration was measured by Boyden chamber assay. EC migration was induced by platelet supernatants of thrombin receptor-activating peptide-1 (AP1) stimulated platelets. To investigate the S1P receptor subtype that promotes EC migration, specific inhibitors of S1P receptor subtypes were applied. RESULTS: S1P induced EC migration in a concentration-dependent manner. EC migration induced by AP1-stimulated platelet supernatants was reduced by aspirin. S1P1 receptor inhibition almost completely abolished EC migration induced by activated platelets. The inhibition of S1P2 or S1P3 receptor had no effect. CONCLUSION: Aspirin inhibits EC migration induced by activated platelets that is in part due to S1P and mediated by the endothelial S1P1 receptor. The clinical significance of this novel mechanism of aspirin action has to be investigated in future studies.