Abstract Body (Do not enter title and authors here): Introduction:
CYP2C19 genotyping is a genetic test that checks for variations in the gene that codes for an enzyme that metabolizes clopidogrel. Testing has been shown to accurately predict response to clopidogrel; however, the impact of testing on mortality is not currently known.

Hypothesis:
Our objective was to compare the mortality among patients with a history of in-stent restenosis after percutaneous coronary intervention and initiation of dual antiplatelet therapy who have undergone CYP2C19 genotyping to those who have not undergone CYP2C19 genotyping. We hypothesize that patients who underwent CYP2C19 genotyping will have decreased 5 and 10-year mortality.

Methods:
A large retrospective database, Trinetix, was used to identify patients aged greater than 18 years old with a history of in-stent restenosis after percutaneous coronary intervention and initiation on dual antiplatelet therapy with either CYP2C19 genotyping or without CYP2C19 genotyping. Two cohorts were subsequently followed depending on if genotyping was performed. Student’s t-test was performed to compare baseline characteristics between cohorts. Demographics and comorbidities were used for 1:1 propensity matching. Kaplan-Myer curves and hazard-ratios were calculated to compare 5 and 10-year mortality.

Results:
Patients that underwent CYP2C19 genotyping (n=144) and did not undergo CYP2C19 genotyping (n=35,039) were propensity matched yielding 142 patients per cohort. In patients with a history of in-stent restenosis, CYP2C19 genotyping was associated with a decreased 5-year mortality (18.98% vs 29.93%; HR=0.542; 95% CI [0.331, 0.887], log-rank p= 0.0134) and 10-year mortality (23.36% vs. 34.31%; HR=0.542; 95% CI [0.345, 0.852], log-rank p=0.0071) compared to no CYP2C19 genotyping.

Conclusion:
In patients with a history of in-stent restenosis, undergoing CYP2C19 genotyping was associated with a decreased risk for mortality when compared to not undergoing CYP2C19 genotyping. Prospective randomized trials are needed to further guide patient selection for CYP2C19 genotyping.