New antithrombotic agents: are they needed and what can they offer to patients with a non-ST-elevation acute coronary syndrome?

Lipids and Antiplatelet Therapy: Important Considerations and Future Perspectives

Lipids play an essential role in platelet functions. It is known that polyunsaturated fatty acids play a role in increasing platelet reactivity and that the prothrombotic phenotype plays a crucial role in the occurrence of major adverse cardiovascular events. The ongoing increase in cardiovascular diseases' incidence emphasizes the importance of research linking lipids and platelet function. In particular, the rebound phenomenon that accompanies discontinuation of clopidogrel in patients receiving dual antiplatelet therapy has been associated with changes in the lipid profile. Our many years of research underline the importance of reduced HDL values for the risk of such a rebound effect and the occurrence of thromboembolic events. Lipids are otherwise a heterogeneous group of molecules, and their signaling molecules are not deposited but formed "on-demand" in the cell. On the other hand, exosomes transmit lipid signals between cells, and the profile of such changes can be monitored by lipidomics. Changes in the lipid profile are organ-specific and may indicate new drug action targets.

Antiplatelet and anticoagulant therapy for atherothrombotic disease: the role of current and emerging agents

Coronary atherothrombotic disease, including chronic stable angina and acute coronary syndromes (ACS), is associated with significant global burden. The acute clinical manifestations of atherothrombotic disease are mediated by occlusive arterial thrombi that impair tissue perfusion and are composed of a core of aggregated platelets, generated by platelet activation, and a superimposed fibrin mesh produced by the coagulation cascade. Long-term antithrombotic therapies, namely oral antiplatelet agents and anticoagulants, have demonstrated variable clinical effects. Aspirin and P2Y12 adenosine diphosphate (ADP) receptor antagonists have been shown to reduce the risk for thrombosis and ischaemic events by blocking the thromboxane (Tx) A2 and platelet P2Y12 activation pathways, respectively, whereas the benefits of oral anticoagulants have not been consistently documented. However, even in the presence of aspirin and a P2Y12 receptor antagonist, the risk for ischaemic events remains substantial because platelet activation continues via pathways independent of TxA2 and ADP, most notably the protease-activated receptor (PAR)-1 platelet activation pathway stimulated by thrombin. Emerging antithrombotic therapies include those targeting the platelet, such as the new P2Y12 antagonists and a novel class of oral PAR-1 antagonists, and those inhibiting the coagulation cascade, such as the new direct factor Xa antagonists, the direct thrombin inhibitors, and a novel class of factor IX inhibitors. The role of emerging antiplatelet agents and anticoagulants in the long-term management of patients with atherothrombotic disease will be determined by the balance of efficacy and safety in large ongoing clinical trials.

Implications of new anticoagulants in primary practice

BACKGROUND

Effective prophylaxis and treatment of thromboembolic disorders remain suboptimal in many healthcare systems, partly owing to limitations of traditional anticoagulants. New oral anticoagulants have been developed and among these, rivaroxaban, apixaban and dabigatran etexilate are in the most advanced stage of clinical development.

METHOD

A literature search using the PubMed and ClinicalTrials.gov databases was performed to identify English-language publications. The search was performed up to 31 December 2011 with the terms rivaroxaban OR Xarelto, apixaban OR Eliquis and dabigatran OR Pradaxa. Ongoing, completed and published phase III randomised controlled trials were selected as the primary source of information for the clinical development programme of each drug.

RESULTS

The new oral agents demonstrate several advantages over traditional anticoagulants, including administration at fixed doses and no requirement for routine coagulation monitoring On the basis of phase III clinical trials, rivaroxaban, apixaban and dabigatran etexilate have been approved in many countries for the prevention of venous thromboembolism after hip and knee replacement surgery. Dabigatran etexilate and rivaroxaban have also been approved for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation in Europe and the US. In addition, rivaroxaban has been approved in Europe for the treatment of acute deep vein thrombosis and prevention of recurrent venous thromboembolism. Approval of these agents and postapproval monitoring of their safety and efficacy will have implications for primary care.

CONCLUSION

Rivaroxaban, apixaban and dabigatran etexilate offer the possibility of simplified prevention and treatment strategies for thromboembolic disorders in the outpatient setting.

Timing of angiography after fibrinolysis for ST-elevation acute myocardial infarction

PURPOSE OF REVIEW

Despite its limited efficacy in opening occluded coronary arteries in ST-elevation myocardial infarction, fibrinolysis remains the major reperfusion strategy used worldwide. Apart from bleeding, early reocclusion of the culprit artery is a common complication of the therapy and usually leads to a worse prognosis.

RECENT FINDINGS

During the last 7 years routine percutaneous coronary intervention after fibrinolysis has been shown to improve early and long-term outcome in six large randomized trials.

SUMMARY

The optimal time window to perform percutaneous coronary intervention is between 3 and 24 h after fibrinolysis.