Background: Recently, we demonstrated that angiographic morphologic features of high-burden thrombus formation are independent predictors of combined slow flow (ie, Thrombolysis in Myocardial Infarction [TIMI] grade 2) and no reflow (ie, ≤ TIMI grade 1) in the infarct-related artery (IRA) after direct percutaneous coronary intervention (d-PCI) for the treatment of acute myocardial infarction (AMI). Current data have demonstrated that when administered in conjunction with PCI for acute coronary syndrome, platelet glycoprotein IIb/IIIa inhibitors can provide additional clinical benefits. Thus, we hypothesized that after pretreatment with tirofiban, angiographic morphologic features of high-burden thrombus formation would no longer be independent predictors of combined slow flow and no reflow after treatment with d-PCI.
Methods and results: Between January 2001 and April 2002, tirofiban was administered to 210 consecutive patients with ST-segment elevated AMI before coronary angiography was performed, and 84 patients (40.0%) were found to have high-burden thrombus formation in the IRA. The TIMI flow grade of the IRA was assessed immediately after the performance of d-PCI, and the 30-day clinical outcomes were evaluated prospectively. The incidence of restoration of normal coronary flow in the IRA was 83.6%. Three baseline angiographic morphologic features indicating high-burden thrombus formation, including (1) the cutoff pattern of occlusion in the IRA (p = 0.0001), (2) the accumulated thrombus proximal to the occlusion (p = 0.0001), and (3) a reference lumen diameter of the IRA of ≥ 4.0 mm (p = 0.001), were independent predictors of combined slow flow and no reflow. In stratified analysis, the rates of slow flow and no reflow after d-PCI rose rapidly as the number of independent predictors increased (0 predictors, 3.8%; 1 predictor, 29.0%; and 2 predictors, 70.6%). The overall 30-day mortality rate was 6.7%. The mortality rate was significantly higher in patients with TIMI flow lower than or equal to grade 2 than in those with TIMI grade 3 flow (15% vs 1.3%, respectively; p = 0.003).
Conclusions: Tirofiban did not provide additional clinical benefits when administered in conjunction with d-PCI for AMI, even in the subgroup of patients with a high-burden thrombus. Those distinct angiographic morphologic features of high-burden thrombus formation remained as independent predictors of combined slow flow and no reflow after d-PCI, and were independent of the use of tirofiban.