Clinical follow-up (office visit) and post-PCI VerifyNow maintenance testing will occur at 2 weeks, 3 months, and 6 months for patients in the guided therapy group. VerifyNow testing, adverse event occurrence and drug compliance will be performed as part of follow-up. Patients having a measurement of ≥ 230 PRU at 2 weeks or the 3 month visit will be reloaded with 60 mg prasugrel and receive standard maintenance dosing thereafter until the 6-month visit. Patients in guided and control study arms will return at 6 months for clinical follow-up and VerifyNow testing. After completing 6 months of the study treatment period, further antiplatelet therapy will be at the physician's discretion. At 1 year, study subjects will be contacted via phone for clinical assessment and antiplatelet compliance. Physicians adjudicating events will be blinded to the therapy assignment.