This study is a randomized, double-blind, multi-center study designed to compare differences in rates of myonecrosis (measured as an elevation of CK-MB ratio ≥ 2 times ULN) within 24 hours following low-medium risk percutaneous coronary intervention (PCI) in aspirin or clopidogrel non-responsive patients who are randomized to heparin with or without eptifibatide therapy during PCI. The primary objective of this study is to determine if the use of eptifibatide is associated with a significant difference in post-PCI myonecrosis (measured as an elevation of CK-MB ratio ≥ 2 times upper limit of normal [ULN]) within 24 hours of low-medium risk PCI in patients who are aspirin or non-responsive as determined by VerifyNow Aspirin and P2Y12 testing.