The Tailored Antiplatelet Therapy to Lessen Outcomes after Percutaneous Coronary Intervention (TAILOR-PCI) Study, launched in 2013 by the Center for Individualized Medicine and the Division of Cardiovascular Diseases at Mayo Clinic, aims to settle this debate. The study examines whether prescribing heart medication based on a patient's CYP2C19 genotype will help prevent heart attack, stroke, unstable angina, and cardiovascular death in patients who undergo percutaneous coronary intervention, commonly called angioplasty.

"The current standard of care after angioplasty is to prescribe clopidogrel for one year, regardless of a person's individual genotype, even though we have known for several years that variation in the CYP2C19 gene may diminish the benefit from the drug," says Naveen Pereira, M.D., a Mayo Clinic cardiologist and principal investigator of TAILOR-PCI. "What we don't know — and why there is such confusion in the cardiovascular community — is how these genetic changes affect long-term clinical outcomes and whether we can decrease overall health care costs."

Antiplatelet medication reduces the risk of heart attack, unstable angina, stroke and cardiovascular death after stent placement by reducing the possibility of blood clots around the surgical site. Plavix, however, remains ineffective until the liver enzyme CYP2C19 metabolizes the drug into its active form. Some alternative medications, including Brilinta (ticagrelor), do not require activation through the same genetic pathway.

"Ticagrelor has its own risks, including serious or life-threatening bleeding. Additionally, this alternative therapy costs approximately six to eight times as much and must be taken twice a day," says Dr. Pereira. "Ultimately, what we're trying to do with TAILOR is use pharmacogenomics to determine whether choosing medication based on individual genotype will help patients live longer and whether the benefits will outweigh the risks of alternative therapies."

Heart disease is the No. 1 killer of men and women in the United States, and up to one-third of patients currently taking Plavix (up to half of some Asian populations) have a genomic variant implicated in diminished drug response. Study teams at 15 hospitals in three countries have teamed up to enroll 5,300 patients into TAILOR-PCI and deliver results in three years. The Pharmacogenomics Program in the Center for Individualized Medicine administers this study.

Gianrico Farrugia, M.D., director of the Center for Individualized Medicine, says, "TAILOR-PCI is exactly the type of research we do every day — the kind that translates into better health for our patients and improves the delivery of care for millions of patients around the world."