Prior Oral Contraceptive Use and Longer Term Mortality Outcomes in Women with Suspected Ischemic Heart Disease

Background: Previous Women's Ischemia Syndrome Evaluation (WISE) work demonstrated prior oral contraceptive (OC) use was associated with lower coronary artery disease (CAD) in women with suspected ischemia. The association of prior OC use with longer term all-cause and cardiovascular disease (CVD) mortality is unclear. Methods: WISE women undergoing coronary angiography for suspected ischemia (enrolled 1996-2001) with prior OC use history and 10-year follow-up data were analyzed. A blinded core laboratory assessed atherosclerotic CAD severity. Kaplan-Meier analyses evaluated prior OC use relative to all-cause and CVD mortality. Cox regression analyses adjusted for baseline differences. Mediation, interaction, and multicollinearity were analyzed. Results: Our 686 women had a mean age 62.5 +/- 9.6 years, multiple cardiac risk factors, and 39% previously used OC. Prior OC users were younger, with less lipid-lowering medication use and lower atherosclerotic CAD severity scores (all p < 0.05). Prior OC use was associated with lower 10-year all-cause (p = 0.007) and CVD mortality (p = 0.019). After adjustment, this was no longer significant (p = 0.77 and p = 0.90, respectively). Atherosclerotic CAD severity score mediated one-third of the observed association. Prior OC use was associated with increased CVD mortality among women with very elevated menopausal systolic blood pressure (SBP). Conclusions: Unadjusted prior OC use was associated with lower longer-term all-cause and CVD mortality. One-third of this observed effect appears mediated by the atherosclerotic CAD severity score. Prior OC was adversely associated with CVD mortality in women with very elevated menopausal SBP. Additional investigation is needed to understand the potential benefits and harms of prior OC use. Clinical Trial Number: NCT00000554, or https://www.clinicaltrials.gov/ct2/show/NCT00000554