Intracoronary thrombus and platelet glycoprotein IIb/IIIa receptor blockade with tirofiban in unstable angina or non-Q-wave myocardial infarction - Angiographic results from the PRISM-PLUS trial (Platelet receptor inhibitionfor ischemic syndrome management in patients limited by unstable signs andsymptoms)

Background-The present study describes the effects of tirofiban, a nonpepti de platelet glycoprotein (GP) IIb/IIIa receptor blocker, on the characteris tics of culprit lesions in patients with unstable angina (UA) or non-Q-wave myocardial infarction (NQWMI). Methods and Results-Of 1915 patients enrolled in PRISM-PLUS, 1491 bad a rea dable film obtained a median of 65 hours after randomization. A core labora tory examined the culprit lesions for intracoronary thrombus burden (primar y end point) and for TIMI flow grade distribution and severity of the obstr uction and of underlying coronary artery disease (secondary end points). Th e combination of tirofiban plus heparin compared with heparin alone signifi cantly reduced the intracoronary thrombus burden of the culprit lesions (OR = 0.77, P = 0.022), improved the perfusion grade (OR = 0.65, P = 0.002), a nd decreased the severity of the obstruction (P = 0.037), but it did not in fluence the severity of the underlying plaque. Persistence of a thrombus in 45% of patients was associated with a 2.4-fold increase in the odds of dea th at 30 days (P = 0.005) and a 2-fold increase in the odds of myocardial i nfarction (P = 0.002), Conclusions-The addition of tirofiban to heparin reduced the thrombus burde n of the culprit lesion and improved distal perfusion in patients with UA o r NQWMI, which supports the clinical benefit observed with the combination treatment.