Jacek Kaczmarski

Effect of Glycemic Control on Response to Antiplatelet Therapy in Patients With Diabetes Mellitus and ST-Segment Elevation Myocardial Infarction

Impaired glycemic control (GC) is a troubling clinical condition with an unclear prognostic value that is frequent in diabetics, especially in the setting of acute coronary syndrome. Residual platelet reactivity can be also affected by GC. We evaluated the relation between response to dual antiplatelet therapy and GC in diabetics with STEMI treated with primary coronary angioplasty (PCI). Sixty diabetic patients were prospectively enrolled in the study. All patients were treated with clopidogrel and aspirin. Platelet reactivity (whole blood aggregation and phosphorylation of vasodilator-stimulated phosphoprotein, VASP) were assessed serially before and 24 hours, 7 days, and 30 days after the PCI. Blood glucose >8.5 mmol/L on admission was an independent predictor of a impaired clopidogrel response measured with platelet reactivity index (PRI) >50% on admission (OR 7.8, 95% CI 1.4-17.7, p<0.02) and 24 hours after PCI (OR 13.1, 95% CI 3.4-28.1, p<0.01). In conclusion, diabetic patients with STEMI and glycemia >8.5 mmol/L on admission is related to a poorer response to clopidogrel. There were no interaction between glycated hemoglobin level or glycemia on admission and platelet reactivity measured with collagen, arachidonic acid or thrombin receptor agonist peptide-induced aggregation. Further clinical studies of the role of GC in the efficacy of antiplatelet agents are warranted.

Predicting Bleeding Risk by Platelet Function Testing in Patients Undergoing Heart Surgery

Predicting bleeding events in patients with coronary artery bypass grafting (CABG) represents an unmet medical need that may improve CABG outcomes.

Von Willebrand factor in patients on mechanical circulatory support - a double-edged sword between bleeding and thrombosis.

Mechanical circulatory support (MCS) is an umbrella term describing the various technologies used in both short- and long-term management of patients with either end-stage chronic heart failure (HF) or acute HF. Most often, MCS has emerged as a bridge to transplantation, but more recently it is also used as a destination therapy. Mechanical circulatory support includes left ventricular assist device (LVAD) or bi-ventricular assist device (Bi-VAD). Currently, 2- to 3-year survival in carefully selected patients is much better than with medical therapy. However, MCS therapy is hampered by sometimes life-threatening complications including bleeding and device thrombosis. Von Willebrand factor (vWF) has two major functions in haemostasis. First, it plays a crucial role in platelet-subendothelium adhesion and platelet-platelet interactions (aggregation). Second, it is the carrier of factor VIII (FVIII) in plasma. Von Willebrand factor prolongs FVIII half-time by protecting it from proteolytic degradation. It delivers FVIII to the site of vascular injury thus enhancing haemostatic process. On one hand, high plasma levels of vWF have been associated with an increased risk of thrombosis. On the other, defects or deficiencies of vWF underlie the inherited von Willebrand disease or acquired von Willebrand syndrome. Here we review the pathophysiology of thrombosis and bleeding associated with vWF.

Low platelet activity predicts 30 days mortality in patients undergoing heart surgery

Despite advanced techniques and improved clinical outcomes, patient survival following coronary artery bypass grafting (CABG) is still a major concern. Therefore, predicting future CABG mortality represents an unmet medical need and should be carefully explored. The objective of this study is to assess whether pre-CABG platelet activity corresponds with 30 days mortality post-CABG. Retrospective analyses of platelet biomarkers and death at 30 days in 478 heart surgery patients withdrawn from aspirin or/and clopidogrel. Platelet activity was assessed prior to CABG for aspirin (ASPI-test) with arachidonic acid and clopidogrel (ADP-test) utilizing Multiplate impedance aggregometer. Most patients (n = 198) underwent conventional CABG, off-pump (n = 162), minimally invasive (n = 30), artificial valve implantation (n = 48) or valves in combination with CABG (n = 40). There were 22 deaths at 30 days, including 10 in-hospital fatalities. With the cut-off value set below 407 area under curve (AUC) for the ASPI-test, the 30-day mortality was 5.90% for the lower cohort and 2.66% for patients with significantly higher platelet reactivity (P = 0.038). For the ADP-test with a cut-off at 400AUC, the 30-day mortality was 9.68% for the lower cohort and 3.66% for patients with higher platelet reactivity, representing a borderline significant difference (P = 0.046). Aside from the platelet indices, patients who received red blood cell (RBC) concentrate had a highly significant (P < 0.0001) risk of death at 30 days. Both aspirin and clopidogrel tests were useful in predicting 30 days mortality following heart surgery, suggesting the danger of diminished platelet activity prior to CABG in such high-risk patients. These preliminary evidence supports early discontinuation of antiplatelet therapy for elective CABG and requires adequately powered randomized trials to test the hypothesis and potentially improve survival.

Aspirin 'resistance': impact on no-reflow, platelet and inflammatory biomarkers in diabetics after ST-segment elevation myocardial infarction.

Background: The no-reflow (NR) phenomenon exists despite percutaneous coronary intervention (PCI), and is especially prevalent in diabetics. The causes(s) of NR are not fully elucidated, but may be associated with impaired residual platelet and inflammatory reactivity during dual-antiplatelet therapy. Objective: To assess the relationship between dual-antiplatelet therapy, NR and conventional biomarkers suggestive of platelet and inflammatory response in diabetics following ST-segment elevation myocardial infarction (STEMI) treated with PCI. Methods: Sixty diabetics with (n = 27) and without NR (n = 33) were prospectively enrolled. All patients were treated with clopidogrel and aspirin. Platelet and inflammatory biomarkers were assessed serially in the peripheral blood and right atrium before and after PCI and then at 24 h, 7 days and 30 days. Results: Arachidonic acid (AA)-induced platelet aggregation and the serum thromboxane B2 level before and after PCI (in the peripheral and right atrium blood) were significantly higher in the NR patients than in those with no NR. AA-induced aggregation >100 (AUC*min) before PCI predicted NR in diabetic patients with 96.2% sensitivity and 38.5% specificity (AUC 0.66; 95% CI 0.52-0.71; p = 0.029). There were no other correlations between NR and platelet reactivity (collagen, adenosine diphosphate, thrombin receptor agonist peptide-induced aggregation, vasodilator-stimulated phosphoprotein platelet reactivity index, soluble P-selectin, soluble CD40 ligand, platelet-derived growth factor AB and the level of platelet-monocyte aggregates) or between NR and inflammatory indices (i.e. high-sensitivity C-reactive protein, interleukin 6 and interleukin 10). Conclusion: An inadequate response to aspirin, but not to clopidogrel, may be associated with the occurrence of the NR phenomenon in diabetics with STEMI who have been treated with primary PCI.

Thrombin Generation and Platelet Reactivity at Hospital Discharge and 6-Month Outcome after the Acute Coronary Syndrome in Diabetic and Nondiabetic Patients

Objectives: Increased plasma thrombogenesis and blood platelet reactivity are associated with a worse outcome in patients with the acute coronary syndrome (ACS). The aim of this study was to test the clinical utility of combining a thrombin generation test and platelet aggregation in predicting future ischemic events after ACS. Methods: The study included patients hospitalized due to ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention with stent implantation. Blood for platelet aggregation and thrombin generation was collected at hospital discharge. We performed whole-blood platelet aggregation with arachidonic acid (AA), collagen, adenosine diphosphate and thrombin receptor-activating peptide (TRAP) as agonists and the thrombin generation test using a fluorescence method. Patients were followed for up to 6 months. The combined end point of the study consisted of death, stroke, myocardial infarction or repeated target vessel revascularization. Results: The study enrolled 161 patients. The end point occurred in 30 patients (18.6%). Thrombin generation showed a significantly prolonged lag time, time to thrombogram peak and start of the tail of the thrombogram in diabetic patients who reached the study end point but not in nondiabetics. End point occurrence was not connected with platelet reactivity at hospital discharge in the whole group. In the diabetic subgroup, increased platelet aggregation induced with AA and TRAP at hospital discharge was connected with a more frequent occurrence of the study end point. Conclusions: In diabetic patients after STEMI, thrombin generation measures as well as TRAP- and AA-induced platelet aggregation at hospital discharge are associated with an ensuing ischemic event during the 6-month follow-up.

MMP-2, MMP-9, and TIMP-4 and Response to Aspirin in Diabetic and Nondiabetic Patients with Stable Coronary Artery Disease: A Pilot Study

Background High on-aspirin treatment platelets reactivity (HPR) is a significant problem in long-term secondary prevention of cardiovascular events. We hypothesize that imbalance between platelets MMPs/TIMPs results in cardiovascular disorders. We also explored whether chronically elevated blood glucose affects MMP-2/TIMP-4 release from platelets. Materials and Methods Seventy patients with stable coronary artery disease, supplemented with aspirin, participated in this pilot study. The presence of HPR and/or diabetes mellitus was considered as the differentiating factor. Light aggregometry, impedance aggregometry, and ELISA tests for TXB2, MMP-2, MMP-9, and TIMP-4 were performed in serum, plasma, platelet-rich plasma, and platelets-poor plasma, as appropriate. Results Aspirin-HPR did not affect plasma MMP-2, MMP-9, and TIMP-4. Arachidonic acid-induced aggregation of platelets from aspirin-HPR patients did not lead to increased release of MMP-2, MMP-9, and TIMP-4. Studying patients at the lowest TXB2 serum concentration quartile revealed that high concentration of plasma TIMP-4 and TIMP-4 negatively correlated with TXB2 and platelet aggregation. Diabetics showed an increased plasma MMP-2 as well as an increased MMP-2 in supernatants after platelet aggregation. However, diabetes mellitus did not affect MMP-9 and TIMP-4. Conclusion Aspirin-HPR did not affect the translocation and release of MMPs and TIMP-4 from platelets. TIMP-4 may serve as a marker of TXA2-mediated platelet aggregation. Chronically elevated plasma glucose increases plasma MMP-2, and HPR potentiates this phenomenon.

No-reflow and platelet reactivity in diabetic patients with ST-segment elevation myocardial infarction: is there a link?

Introduction The no-reflow phenomenon in percutaneous coronary intervention (PCI) is defined classically as the absence of flow after restoration of arterial patency. Further research has shown that despite flow restoration in myocardial infarction (MI) there is still a considerable percentage of patients with a lack of perfusion at the level of the microvasculature caused by microvascular obstruction (MVO) [1]. This has a deleterious effect on outcomes and should be considered as a form of no-reflow [2]. It can be diagnosed with angiography or as the absence of ST-segment normalization in ECG after PCI, but the reference method for MVO diagnosis is contrast-enhanced cardiac magnetic resonance (CMR) [3]. Causes of MVO are thought to include peripheral embolism caused by debris originating in and flushed from the atherosclerotic plaque, ischemia/reperfusion injury, and individual predispositions such as diabetes [4]. Recently, increased platelet reactivity was proposed as one of the reasons for MVO occurrence [5–7]. Increased platelet reactivity is present in diabetes and together can increase MVO. Nevertheless, there is still a considerable lack of data regarding platelet reactivity and MVO assessed with the reference method of CMR in diabetic patients with ST-segment elevation MI (STEMI).

Relationship between high on aspirin platelet reactivity and oxidative stress in coronary artery by-pass grafted patients.

The aim of the study was to assess the responsiveness of blood platelets to acetylsalicylic acid (ASA) in patients following coronary artery bypass grafting (CABG) surgery with relation to oxidative and antioxidative plasma status. The study included 37 patients treated with the CABG procedure. During the first 24 h after CABG patients were given 300 mg of ASA with the following dose of 150 mg daily. The blood was collected before the procedure and 10 days after. Whole blood platelet aggregation induced with arachidonic acid, collagen and adenosine diphosphate (ADP) was performed together with whole blood generation of thromboxane B2 (TxB2). Oxidative stress was measured before and 10 days after CABG with total oxidative plasma status (TOS) and total antioxidative status of the plasma (TAS). TOS/TAS index was calculated. We observed a significant increase in the TOS and TOS/TAS index and ADP-induced aggregation 10 days after CABG in comparison with its level before operation. There was a significant decrease in the arachidonic acid-induced aggregation and serum TxB2 level. Patients with ADP-induced and collagen-induced aggregation in the upper quartile had significantly higher TOS and TOS/TAS index before (ADP) and after the operation (ADP and collagen). There were 19 patients (51%) with high on aspirin platelet reactivity after CABG who had also higher TOS and TOS/TAS index and lower TAS value in comparison with aspirin responders. Despite ASA use, increased oxidative stress after CABG can overcome its antiplatelet effect and increase platelet activation through other pathways.

Response to Dual Antiplatelet Therapy Does Not Impact Bleeding Risks in Patients Undergoing Oral Surgery after Acute Coronary Syndromes

Introduction: Oral surgery (OS) in patients on antecedent dual antiplatelet therapy (DAPT) may be associated with extra bleeding risks. Monitoring platelet activity in such patients may be beneficial for safety when performing OS. Objectives: The aim of this study was to assess whether platelet function during DAPT impacted the risk of bleeding following OS in patients with acute coronary syndromes (ACS). Patients and Methods: Patients who required OS on top of DAPT with aspirin and clopidogrel (n = 55) for invasively treated ACS were included. The control group (n = 33) consisted of patients who underwent OS with no antiplatelet agent. Platelet aggregation before OS was assessed with a Multiplate® analyzer. Bleeding during OS and at days 1, 3, 7 and 10 after surgery was serially evaluated. Results: All 88 patients completed the study. An incomplete response to aspirin or clopidogrel was observed in 43.6% of the patients. In 11% of the cases, an excessive response to clopidogrel was demonstrated. No excessive bleeding upon OS was exhibited in either group during the entire follow-up. Platelet aggregation values and the use of DAPT did not impact the performance of OS. Conclusion: Therapy with clopidogrel and aspirin after ACS does not seem to increase the risk of real-life bleeding following OS, regardless of the platelet activity response to DAPT.