ADP-Induced Recalcified Blood Clotting Time as a Marker of Rethrombosis Risk and Effectiveness of Antiplatelet Therapy in Acute Coronary Syndrome

Purpose: to assess the possibility of the use of ADP induced blood-clotting time measurement in clinical practice prognostication of the course of acute coronary syndrome (ACS) and assessment of effectiveness of antiplatelet therapy (APT). Materials and methods. We enrolled in the study 163 male patients admitted to the coronary unit for acute coronary syndrome (ACS) and 38 male practically healthy volunteers (PHV). ADP induced blood-clotting time (ADP BCT) was measured as time (sec) between addition of ADP (10 μcmol) to recalcificated sample of citrate blood and clot formation. In healthy volunteers ADP BCT was determined before and 45 minutes after oral administration of acetylsalicylic acid (ASA, 250 mg). Risk of cardiovascular death was calculated using the GRACE score. Platelet function tests were performed by optical aggregometry. Follow-up period for patients with ACS was 24 months. The primary end point (PEP) was the composite of cardiovascular death and rehospitalization. Results. In ACS patients ADP BCT was significantly lower than in PHV: 134.8 (109.9; 161.3) vs 85.7 (60.5; 108.7) sec, p=0.015. In PHV ASA increased ADP BCT - 103.2 (95.1; 130.7) vs 133.1 (102.8; 154.3) sec, p=0.041. ADP BCT correlated with age in both PHV and patients (R= -0.431, p<0.05 and R= -0.398, p<0.05). In patients ADP BCT correlated with hematological and coagulation parameters, and with calculated cardiovascular death risk (R= -0.51, р<0.05). 24-months mortality of patients was 10.42%. ADP BCT <80 sec was associated with significant increase in the risk of occurrence of PEP (hazard ratio 2.7, 95% confidence interval 1.1 to 6.4). Conclusion. ADP BCT is a quantitative easily performed test characterizing platelet hemostasis and may be used in clinical practice for monitoring APT. In patients with ACS ADP BCT correlates with cardiovascular death risk. ADP BCT <80 sec (during APT) is a marker of increased 24-months risk of recurrent cardiovascular thrombotic complications.