Cardiovascular Disease: TAILOR-PCI Study

The Tailored Antiplatelet Initiation to Lessen Outcomes Due to Decreased Clopidogrel Response After Percutaneous Coronary Intervention (TAILOR-PCI) study used genetic information to determine the best medication for patients who underwent coronary angioplasty, also known as percutaneous coronary intervention.

The current standard of practice is to prescribe clopidogrel (Plavix) for one year. However, up to 30% of those who undergo angioplasty have a genetic variation in the CYP2C19 liver enzyme that interferes with clopidogrel metabolization. For these patients, an alternative anti-platelet medication, such as ticagrelor (Brilinta), may be more effective, have fewer side effects, and reduce repeat hospital and clinic visits.

The TAILOR-PCI study used rapid genotyping to identify people who were intermediate or poor metabolizers of clopidogrel and, therefore, at potentially high risk of having a decreased response to clopidogrel. This information is used to guide antiplatelet medication decisions in patient care.

If genotyping can predict the right drug for each person, it minimizes side effects and improves outcomes. The results of this study could immediately affect patient care and impact the practices in cardiac catheterization labs around the country — and potentially around the world.


The TAILOR-PCI study is no longer open for enrollment.

Participants underwent coronary angioplasty at Mayo Clinic and participated in three follow-up phone interviews.

Eligible participants included those who:

  • Planned to undergo coronary angioplasty for acute coronary syndrome or coronary artery disease
  • Required anti-platelet therapy for one year after angioplasty

Participants were closely monitored by the study team. Those among the 30% who had an abnormal variant of the CYP2C19 liver enzyme — which interferes with the ability to metabolize clopidogrel — received a medication that may have been more effective for them (dependent on randomization).

Participants were randomly assigned to one of two study groups. The first group received rapid genetic testing in the form of a cheek swab at the time of enrollment. The other group received standard anti-platelet treatment of clopidogrel and genetic testing after one year.

Those in the rapid genetic testing group received either clopidogrel or ticagrelor based on their genetic test results. Those participants with a variant in the CYP2C19 liver enzyme gene received ticagrelor. All others were prescribed clopidogrel.


The study team enrolled 5,302 participants who had been treated for artery blockage with one or more stents through an international collaboration of 25 hospitals in the United States, Canada and South Korea.

The results showed a statistically not significant 34% reduction in blood-clotting events in the participants who had an abnormal variant of the CYP2C19 liver enzyme and were assigned to ticagrelor in the genotype-guided group. The participants who had an abnormal variant of the CYP2C19 liver enzyme and received clopidogrel showed a 5.9% event rate, versus a 4.4% event rate in those who received genotype-guided ticagrelor treatment. The study narrowly missed its statistical goal, which was a 50% reduction in blood-clotting events.

The trial was positioned for participant evaluation at one year and just missed statistical significance. However, data at the three-month mark hold important implications for pharmacogenetics. In the first three months after the procedure, the TAILOR-PCI study showed an 80% risk reduction in participants with the CYP2C19 gene variation who were given ticagrelor.

Furthermore, when evaluating the total number of events experienced per participant, genetically guided treatment showed a statistically significant 40% reduction in events, compared with those who received standard treatment.


Contact the Center for Individualized Medicine for information on previous and ongoing studies and trials.