title: Utility of a whole blood single platelet counting assay to monitor the effects of tirofiban in patients with acute coronary syndromes scheduled for coronary intervention.
abstract: This study aimed to establish the utility of a whole-blood single-platelet counting (WBSPC) assay, a measure of microaggregation, in monitoring the effects of tirofiban, comparing this with optical aggregometry (OA) and the Ultegra TRAP cartridge system (UTC), measures of macroaggregation. Fifty-nine patients with acute coronary syndrome scheduled for coronary angiography +/- angioplasty were studied. WBSPC assay (ADP 0.3-100 microM, Sysmex KX21 analyzer), OA (ADP 20 microM) and UTC were performed: before starting tirofiban; 30 min, 4 and 24 h after starting tirofiban; and 1 and 2 h after stopping tirofiban. Thirty minutes after starting tirofiban, there was substantial inhibition of platelet aggregation (40 +/- 30%; WBSPC, 2 minutes after addition of ADP 30 microM) and this remained stable at 4 and 24 h. OA (86 +/- 17%; inhibition of maximal aggregation, ADP 20 microM) and UTC (93 +/- 7%) showed marked inhibition with less inter-individual variation. There was no significant correlation between OA and UTC results (R(2) = 0.006), but fair correlation between OA and WBSPC results (R(2) = 0.37). Greater inhibition of macroaggregation (OA and UTC) was seen compared to microaggregation (WBSPC) such that WBSPC was more discriminating in the therapeutic range when macroaggregation was often completely inhibited. A WBSPC assay of platelet microaggregation shows promise for monitoring GPIIb/IIIa antagonists.
authors.affiliation: Cardiovascular Research Unit, University of Sheffield, Clinical Sciences Centre, Northern General Hospital, Sheffield, United Kingdom.
authors.forename: Anjan
authors.initials: A
authors.lastname: Siotia
authors.forename: Robert
authors.initials: R
authors.lastname: Buckland
authors.forename: Heather M
authors.initials: HM
authors.lastname: Judge
authors.forename: Padmini
authors.initials: P
authors.lastname: Sastry
authors.forename: Robert F
authors.initials: RF
authors.lastname: Storey
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015906:Angioplasty, Balloon, Coronary; D017023:Coronary Angiography; D003327:Coronary Disease / Q000097:blood / Q000188:drug therapy* / Q000628:therapy; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D010976:Platelet Count; D010979:Platelet Function Tests / Q000379:methods; D011446:Prospective Studies; D013577:Syndrome; D000077466:Tirofiban; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D014443:Tyrosine; D000077466:Tirofiban