Abciximab therapy during primary percutaneous coronary intervention (PCI) has shown to ameliorate left ventricular (LV) function recovery in patients with ST elevated myocardial infarction. High-dose bolus tirofiban has similar effect on platelet inhibition. Whether this is associated with comparable efficacy on LV function recovery remains unclear. We sought to evaluate the impact on LV function of high-dose bolus tirofiban or abciximab in patients undergoing primary PCI with the predictors of favorable (> or = 50%) LV ejection fraction (EF) and LV function recovery at 30 days. We studied 314 patients (abciximab n = 154; tirofiban n = 160) undergoing primary PCI in the randomized Facilitated Angioplasty with Tirofiban or Abciximab (FATA) Trial. LVEF was assessed within 48 hours and at 30 days after primary PCI. In patients with systolic dysfunction at baseline, LV function recovery was defined by either increase of LVEF > or = 10% compared with baseline or LVEF > or = 50%. Similar LVEF was observed in the 2 groups postprocedure (abciximab 49.7 +/- 10.1% vs tirofiban 49.3 +/- 10.1%, p = 0.9) and at 30 days (abciximab 53.1 +/- 9.8% vs tirofiban 52.5 +/- 10.2%, p = 0.6). Independent predictors of 30-day LVEF > or = 50% were preprocedure Thrombolysis In Myocardial Infarction flow class >0 (odds ratio = 2.4, 95% confidence interval 1.32 to 4.34), anterior location (odds ratio = 0.25, 95% confidence interval 0.15 to 0.42), and age (odds ratio = 0.97, 95% confidence interval 0.95 to 0.99). Preprocedure Thrombolysis In Myocardial Infarction flow grade >0 was the only predictor of LV function recovery (odds ratio = 6.73, 95% confidence interval 2.69 to 16.88). In conclusion, this study showed no difference in LV function recovery in patients undergoing primary PCI treated either with abciximab or high-dose bolus tirofiban. Preprocedure Thrombolysis In Myocardial Infarction flow grade >0 seems to be the most important predictor of favorable LVEF and LV function recovery at 30 days.