PB0145 - MRP-4 («Multidrug Resistance Protein-4) PROTEIN EXPRESSION IN PATIENTS WITH ACUTE CORONARY SYNDROME (ACS) UNDER CHRONIC ASPIRIN TREATMENT

Background: Aspirin reduces cardiovascular events. However, Aspirin causes «High-on Aspirin Residual Platelet Reactivity» (HARPR) phenomenon.
Some patients under chronic aspirin treatment present MRP-4 overexpression and those who have high MRP4 levels correlate with HARPR, suggesting that platelet MRP-4 overexpression is an additional CV risk factor.

Aims: To evaluate whether platelets over-expression is an additional CV risk factor, we performed a study in which we investigated amounts of platelets MRP4 between the ACS population and control population (patients under chronic aspirin without ACS).

Methods: We enrolled patients with ACS on chronic aspirin therapy (75-100 mg/die) for at least two months (N=51) and patients on chronic aspirin therapy (75-100 mg/die) for at least two months, in the absence of ACS (ASA; N=30) from San Camillo Interventional Cardiology Unit and Platelet physiopatology Lab, Policlinico Umberto I respectively.
Levels of platelets MRP4 expression were evaluated with WB analysis comparing the densitometric values of protein expression of each individual belonging ACS and ASA populations. Data were expressed as percentage of the densitometric mean of each sample compared to the average of the densitometric values obtained from three healthy volunteers (HV). Each gel data were normalized using the same HV samples.

Results: 1. ASA patients showed an increase of platelets MRP4 expression compared to HV subjects similarly to what was reported in previous work.
2. MRP4 levels in platelets obtained from in ACS patients are higher compared to ASA patients (52±12% vs 34±6% ).

Conclusion(s): Reduced sensitivity to aspirin by MRP-4 could be one of the causes of SCA events. Platelet MRP4 levels may be a useful tool to identify patients less sensible to aspirin treatment and at high CV risk factor. In the context of precision medicine MRP4 platelet amount could be important to identify patients that required antiplatelet treatment variation, so as to create a personalized treatment.