Managing the acute coronary syndrome patient: Evidence based recommendations for anti-platelet therapy

International guideline comparison of lifestyle management for acute coronary syndrome and type 2 diabetes mellitus: A rapid review

Acute coronary syndrome (ACS) is a life-threatening condition, with ACS-associated morbidity and mortality causing substantial human and economic challenges to the individual and health services. Due to shared disease determinants, those with ACS have a high risk of comorbid Type 2 diabetes mellitus (T2DM). Despite this, the two conditions are managed separately, duplicating workload for staff and increasing the number of appointments and complexity of patient management plans. This rapid review compared current ACS and T2DM guidelines across Australia, Canada, Europe, Ireland, New Zealand, the UK, and the USA. Results highlighted service overlap, repetition, and opportunities for integrated practice for ACS-T2DM lifestyle management across diet and nutrition, physical activity, weight management, clinical and psychological health. Recommendations are made for potential integration of ACS-T2DM service provision to streamline care and reduce siloed care in the context of the health services for ACS-T2DM and similar comorbid conditions.

Clopidogrel Resistance in a Murine Model of Diet-Induced Obesity Is Mediated by the Interleukin-1 Receptor and Overcome With DT-678

OBJECTIVE

Clopidogrel is a commonly used P2Y₁₂ inhibitor to treat and prevent arterial thrombotic events. Clopidogrel is a prodrug that requires bioactivation by CYP (cytochrome P450) enzymes to exert antiplatelet activity. Diabetes mellitus is associated with an increased risk of ischemic events, and impaired ability to generate the active metabolite (AM) from clopidogrel. The objective of this study is to identify the mechanism of clopidogrel resistance in a murine model of diet-induced obesity (DIO). Approach and Results: C57BL/6J mice and IL-1R^-/- mice were given high-fat diet for 10 weeks to generate a murine model of diet-induced obesity. Platelet aggregation and carotid arterial thrombosis were assessed in response to clopidogrel treatment. Wild-type DIO mice exhibited resistance to antiplatelet and antithrombotic effects of clopidogrel that was associated with reduced hepatic expression of CYP genes and reduced generation of the AM. IL (Interleukin)-1 receptor-deficient DIO (IL1R^-/- DIO) mice showed no resistance to clopidogrel. Lack of resistance was accompanied by increased exposure of the clopidogrel AM. This resistance was also absent when wild-type DIO mice were treated with the conjugate of the clopidogrel AM, DT-678.

CONCLUSIONS

These findings indicate that antiplatelet effects of clopidogrel may be impaired in the setting of diabetes mellitus due to reduced prodrug bioactivation related to IL-1 receptor signaling. Therapeutic targeting of P2Y₁₂ in patients with diabetes mellitus using the conjugate of clopidogrel AM may lead to improved outcomes.

Correlation between platelet thrombus formation on collagen-coated beads and platelet aggregation induced by ADP

BACKGROUND

The thrombus-forming ability is a critical in vitro parameter to assess platelets (PLTs), but flow-based methods using collagen-coated materials generally require multistep, proficiency, and advanced analysis.

STUDY DESIGN AND METHODS

Commercially available collagen-coated bead columns were examined to assess thrombus-forming ability of PLTs. The retention rate as an index of thrombus formation was calculated using the PLT count before and after column passage. Thrombi were imaged by anti-CD41 using a fluorescent microscope. PLT aggregation was measured by light-transmitting aggregometry.

RESULTS

The retention rate was low when apheresis-collected PLT concentrates (PCs) were suspended in plasma either with or without Ca²⁺. Reconstitution of PCs with red blood cells (RBCs) increased the retention rate with good reproducibility on repeated-measurements, and therefore, PLT samples were reconstructed with RBCs in subsequent experiments. The retention rate of PCs varied widely in a product-dependent manner, and was correlated with the aggregation rate induced by ADP, but not that by collagen. Using platelet-rich-plasma, antagonists of P2Y₁ or P2Y₁₂ receptors for ADP reduced both the retention and aggregation of PLTs. Acetylsalicylic acid reduced retention, although it had no effect on ADP-induced aggregation. Prostaglandin E₁ significantly inhibited both retention and aggregation. These anti-PLT reagents resulted in reduced or no thrombus formation on the beads.

CONCLUSION

The collagen-coated bead column was useful to readily examine the thrombus-forming ability of PLTs. Variance of the PLT retention rate was correlated with responsiveness to ADP. Results from anti-PLT reagents revealed that thrombus formation on collagen-coated beads was similar to in vivo thrombus development.

All-cause mortality, cardiovascular events, and health care costs after 12 months of dual platelet aggregation inhibition after acute myocardial infarction in real-world patients: findings from the Platelet-aggregation Inhibition: Persistence with treatment and cardiovascular Events in Real world (PIPER) study

Objectives

The aim of the study was to assess all-cause mortality and cardiovascular (CV) events in patients after a period of 12 months of treatment with dual antiplatelet therapy (DAPT) after hospitalization for acute myocardial infarction (AMI) in a real-world setting. Health care costs for the management of patients post-AMI was also assessed.

Methods

A retrospective analysis using data from the administrative databases of six local health units (LHUs) was performed. All beneficiaries of these LHUs hospitalized with AMI between January 01, 2010, and December 31, 2011, and exposed to a treatment period with DAPT up to 12 months after AMI discharge were included. All-cause mortality, CV hospitalizations, and health care costs occurring during the 36-month follow-up period from end of treatment with DAPT were considered. For the cost analysis, only patients still alive at the end of the follow-up period were included.

Results

A total of 2,721 patients were included (mean ± SD age 63.6±17.3 years, 67.8% males). About 17% and 18% of all patients had CV events and died during the follow-up period, respectively. The annual mean cost per patient was €3,523.27. During the follow-up period, 63 patients had a second AMI event; for whom, the mean health care cost per patient was €19,570.70.

Conclusion

In a real-world setting in Italy, considering a 36-month follow-up period, all-cause mortality, CV events, and related health care cost of patients hospitalized with an AMI undergoing a 12-month treatment period with DAPT remained relevant. This study suggests that increased efforts aimed at the prevention of recurrent AMI are warranted, as well as an accurate risk stratification in order to improve long-term outcome.

Thieno[2,3-b]pyridine derivatives are potent anti-platelet drugs, inhibiting platelet activation, aggregation and showing synergy with aspirin

Drugs which inhibit platelet function are commonly used to prevent blood clot formation in patients with Acute Coronary Syndromes (ACS) or those at risk of stroke. The thieno[3,2-c]pyridine class of therapeutic agents, of which clopidogrel is the most commonly used, target the P2Y₁₂ receptor, and are often used in combination with acetylsalicylic acid (ASA). Six thieno[2,3-b]pyridine were assessed for in vitro anti-platelet activity; all derivatives showed effects on both platelet activation and aggregation, and showed synergy with ASA. Some compounds demonstrated greater activity when compared to clopidogrel. These compounds, therefore, represent potential novel P2Y₁₂ inhibitors for improved treatment for patients.

Parathyroid Hormone Levels and High-Residual Platelet Reactivity in Patients Receiving Dual Antiplatelet Therapy With Acetylsalicylic Acid and Clopidogrel or Ticagrelor

BACKGROUND

High-residual-on-treatment platelet reactivity still represents a challenging issue, potentially vanishing the benefits of dual antiplatelet treatment in patients with coronary artery disease. However, very few is known on the determinants of suboptimal response to antiplatelet agents. Recent interests have emerged on the potential prothrombotic effect of parathyroid hormone (PTH). Therefore, the aim of the present study was to assess the impact of parathyroid hormone (PTH) on platelet reactivity in patients receiving DAPT after an acute coronary syndrome or PCI.

METHODS

Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30- to 90-days postdischarge. By whole blood impedance aggregometry, HRPR was considered for ASPI test >862 AU*min (for ASA) and ADP test values ≥417 AU*min (for ADP antagonists).

RESULTS

We included 362 patients on DAPT, 125 (34.5%) receiving clopidogrel, and 237 (65.5%) on ticagrelor. Patients were divided according to PTH quartiles values (<45.8; 45.8-60.3; 60.4-88; ≥88.1 pg/mL). Higher PTH was associated with older age (P = 0.001); renal failure (P < 0.001), higher HDL cholesterol (P = 0.006) and creatinine (P < 0.001) and lower 25-OH cholecalciferol (P < 0.001). Suboptimal response to ASA was infrequent (2.8%), and not influenced by the levels of PTH (P = 0.57). ADP-mediated platelet aggregation was significantly increased in patients with higher PTH (P = 0.03), with an absolute increase in the prevalence of HRPR to ADP antagonists for higher PTH (24.7% vs. 40%, P = 0.007 for 4th vs. 1-3rd quartiles, adjusted OR[95%CI] = 2.04[1.14-3.64], P = 0.02). By the use of the ROC curve, we identified PTH levels above 96.7 pg/mL as the best predictor of HRPR with ADP antagonists (adjusted OR[95%CI] = 2.52[1.31-4.87], P = 0.006). Higher rate of HRPR was confirmed for PTH >96.7 pg/mL among the subgroup of patients on clopidogrel (51.5 vs. 85.7%, P = 0.001; adjusted OR[95%CI] = 12.5[2.6-60.9], P = 0.002), but not among ticagrelor-treated patients (11.3 vs. 16.7%, P = 0.31; adjusted OR[95%CI] = 1.55[0.56-4.6], P = 0.42).

CONCLUSION

In patients receiving dual antiplatelet therapy for coronary artery disease, higher PTH levels are associated with an increased ADP-mediated platelet reactivity and suboptimal response to clopidogrel, especially for values above 96.7 pg/mL, while not influencing the effectiveness of ASA and ticagrelor.

Antiplatelet therapy - a summary for the general physicians

Platelets play a very important role in physiological haemostasis and thrombus formation. Platelet aggregation is the key pathophysiological factor in the development of arterial ischaemic events, including coronary artery disease, cerebrovascular accidents and peripheral arterial disease. As such, antiplatelet therapy plays a very important role in preventing recurrent events in the individuals who are affected by one of these conditions. Until recently, the repertoire of antiplatelet therapy was limited to aspirin and clopidogrel. However, this landscape has changed dramatically with the advent of newer and more potent agents, prasugrel and ticagrelor and also the glycoprotein IIb/IIIa antagonists. This armamentarium is likely to expand further with the advent of protease-activated receptor-1 antagonists and the intravenous cangrelor. This review summarises the different agents available and some practical considerations for their use from a general physician's perspective.

Novel oral P2Y12 inhibitor prasugrel vs. clopidogrel in patients with acute coronary syndrome: evidence based on 6 studies

BACKGROUND

Whether prasugrel can take the place of clopidogrel for patients with acute coronary syndrome (ACS) is not clear. The aim of this study was to perform a meta-analysis for systematically reviewing the evidence on prasugrel in comparison to clopidogrel in patients with ACS.

MATERIAL/METHODS

Relevant prospective and retrospective studies were searched in databases. Six studies were finally included. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated to assess all causes of death, myocardial infarction (MI), stroke, major bleeding, major/minor bleeding, and stent thrombosis (for PCI performed).

RESULTS

Compared with clopidogrel, prasugrel had similar risks of all cause of death (Pooled RR: 0.83; 95% CI: 0.64-1.06, p=0.14, I2=55%), MI (Pooled RR: 0.86; 95% CI: 0.71-1.04, p=0.12) and stroke (pooled RR: 0.88; 95% CI: 0.70-1.10, p=0.25). However, prasugrel was associated with significantly higher risk of both major bleeding (Pooled RR: 1.19; 95% CI: 0.99-1.44, p=0.06, I2=0%) and the risk of total major and minor bleeding (Pooled RR: 1.30; 95% CI: 1.15-1.48, p<0.0001, I2=0%). For the patients who underwent percutaneous coronary intervention (PCI), prasugrel was associated with significantly lower risk of stent thrombosis (Pooled RR: 0.47; 95% CI: 0.34-0.61, p<0.00001, I2=0%).

CONCLUSIONS

Prasugrel has similar effects as clopidogrel in terms of all causes of death, MI, and stroke in ACS patients. For the patients who underwent PCI, prasugrel contributes to lower risk of stent thrombosis. However, prasugrel is associated with significantly higher risk of bleeding. For the patients with active pathological bleeding or a history of stroke and/or TIA, prasugrel should not be recommended.