We hypothesized that when tirofiban is administered via intracoronary route, a bolus-only strategy may even be superior to intravenous bolus plus infusion strategy in maintaining myocardial perfusion. In order to evaluate microvascular function, we used a guidewire tipped with pressure and temperature sensors and measured the coronary hemodynamic parameters, as the index of microvascular resistance and coronary flow reserve, measures which have been closely associated with microvascular damage. In order to increase the predictive value of these indices, we performed these measurements four to five days after MI, because it has been shown that the extent of microvascular dysfunction changes, particularly within first 48 hours after reperfusion and stabilizes between 2 days and 1 week after perfusion