FREQUENT SAMPLING BY CLEAR VENIPUNCTURE IN UNSTABLE ANGINA IS A RELIABLE METHOD TO ASSESS HEMOSTATIC SYSTEM ACTIVITY

Sudden limitations in coronary flow account for the majority of cases of UA. Measurement of TAT in peripheral blood represent a reliable mar ker of an ongoing thrombotic process. The aim of the study was to asse ss the reliability of frequent blood sampling (Phase A) and to correla te TAT fluctuation to clinical symptoms of ischemia in patients with U A (Phase B). We included into the study 6 normal volunteers (Phase A) and 31 patients with unstable angina admitted to our Coronary Care Uni t within 24 hours from the last ischemic episode (Phase B). In both gr oups the blood was collected every 6 hours for 24 hours and then every day for 2 days. After venipuncture the blood was immediately collecte d in CTAD tubes placed in melting ice and centrifuged at 2000 g and 4 degrees C for 20 minutes, plasma aliquots of 500 mu l were snap-frozen and stored at -80 degrees C. The aliquots were assayed for TAT comple xes using a commercially available ELISA assay. TAT levels in normals remained stable and below pathologic levels during the study and no si gnificant increase was observed with repeated venipuncture. In 11 out of 31 patients (35%) no episode of TAT increase was observed, in 20 (6 5%) at least 1 episode was observed. Five patients without episodes of TAT increase did not have any ischemic event during the hospitalizati on, but all patients with episodic elevation had recurrent ischemia du ring the study (p < 0.005). Our data demonstrate that sampling by clea r venipuncture do not cause itself an activation of the haemostatic sy stem and suggest that frequent sampling might be important for better understanding the pathophysiology of UA.