Prasugrel loading dose in diabetic patients with acute STEMI – Always sufficiently effective? Observation in two cases and review of current knowledge

The activation and subsequent platelet aggregation play a key role in the formation of arterial thrombosis and therefore is the key therapeutic target in the treatment of acute coronary syndromes. Dual antiplatelet therapy containing aspirin and P2Y12 ADP receptor antagonist forms currently the basis in acute ST – elevation myocardial infarction (STEMI) pharmacological treatment. Nevertheless, there is a wide variability in pharmacodynamic response to administration of clopidogrel, the most frequently used P2Y12 ADP receptor antagonist. High platelet reactivity after clopidogrel administration is associated with increased risk of stent thrombosis and points to the suitability of laboratory monitoring of antiplatelet therapy efficacy in clinical practice. Laboratory monitoring of antiplatelet therapy by ex vivo platelet function tests may help to identify individuals with poor antiplatlet response. Recently, there is a growing number of data reporting a failure in antiplatelet response following clopidogrel administration, which is specifically associated with insulin resistance and diabetes mellitus. Prasugrel, a new, potent P2Y12 ADP receptor antagonist, provides faster and more consistent inhibition of platelet function compared with clopidogrel. Prasugrel therapy was repeatedly described as an effective method to overcome clopidogrel resistance and prasugrel resistance has not yet been reliably described. We report two cases of patients with diabetes mellitus type 2 at the stage of organ complications, in whom a prasugrel loading dose of 60 mg did not reach adequate antiplatelet response in 60 min after prasugrel administration. The antiplatelet response was measured by light transmission aggregometry and by VASP protein phosphorylation assessment.