Evaluation of platelet activity by multiple electrode impedance aggregometry in acute coronary syndromes: pilot study in a Brazilian tertiary-care public hospital

There is no definite recommendation for testing platelet aggregation (PA) in acute coronary syndromes (ACS) due to inconclusive evidence on the usefulness of platelet function tests to guide therapy and improve clinical outcomes. The evaluation of PA with multiple electrode impedance platelet aggregometry (MEA) may be useful to manage antiplatelet therapy and possibly influence patient outcome. The primary aim of this study was to measure PA with MEA in Brazilian patients with ACS and evaluate the association between PA and adverse clinical outcomes. Forty-seven consecutive patients admitted with ACS to a Brazilian tertiary-care public hospital were studied and PA was evaluated using MEA. Patients were followed for six months for the occurrence of all-cause death, acute myocardial infarction, or stroke. Suboptimal inhibition of PA was found in 7 patients (14.9%); 5 (10.6%) in response to ASA (acetylsalicylic acid), 2 (5.0%) to clopidogrel, and none to ticagrelor. Inadequate PA inhibition in response to ASA was significantly associated with the composite end point, but there was no significant association for insufficient PA inhibition in response to clopidogrel. This study suggested that the evaluation of PA in ACS using MEA may identify non-responders to ASA. Larger studies are necessary to define, in a public health scenario, the value of MEA in the management of ACS.

Antiplatelet therapy: present status and its future directions.

Anti-platelets drugs play an important role in the prevention or treatment of cardiovascular diseases e.g. coronary artery disease, stroke, etc., which cause high mortality and morbidity in the present day world. These drugs either inhibit the platelet activation, aggregation or other signaling pathways, thereby inhibiting the clot formation. The anti-platelet drugs currently used are aspirin, ADP receptor inhibitors (ticlopidine and clopidogrel)and glycoprotein (GP)IIb/IIIa inhibitors (abciximab, tirofi ban and eptifi batide). Aspirin was and still continues to be the main anti-platelet therapy. A combination regimen of aspirin and clopidogrel is commonly used for the prevention of platelet activation, thrombosis and stroke. However, many of the current anti-platelet drugs face limitations due to narrow therapeutic window and limited effi cacy. The four possible targets for novel anti-platelet action are: Inhibition of agonist generation, receptor inhibition, G protein inhibition and inhibition of enzymatic cascades. Newer P2Y12 antagonists e.g. prasugrel, ticagrelor, cangrelor, etc., have better effi cacy and low bleeding risk. The thrombin receptor (PAR1 and 4) inhibitors are said to decrease the hemorrhagic complications. Drugs which inhibit TXA2 Synthase or TXA2 receptor are also promising in their anti-platelet action. Another novel group is of collagen receptor antagonists such as GPVI antagonists, GPIb receptor antagonists, etc. The other targets being explored are von Willebrand Factor antagonists, platelet Gq antagonists, etc. However, there still lies a bundle of unresolved issues regarding the effi cacy and safety, optimal dosage, administration requirements, combination therapy, clinical evaluation, cost-effectiveness, and the resistance phenomena of these drugs.