BackgroundPost-traumatic stress disorder (PTSD) is associated with increased rates of incident ischemic heart disease (IHD) in women. ObjectivesThe purpose of this study was to determine mechanisms of the PTSD-IHD association in women. MethodsIn this retrospective longitudinal cohort study, data were obtained from electronic health records of all U.S. women veterans who were enrolled in Veterans Health Administration care from January 1, 2000 to December 31, 2017. Propensity score matching was used to match women with PTSD to women without PTSD on age, number of prior Veterans Health Administration visits, and presence of various traditional and nontraditional cardiovascular risk factors at index visit. Cox regression was used to model time until incident IHD diagnosis (ie, coronary artery disease, angina, or myocardial infarction) as a function of PTSD and potential mediating risk factors. Diagnoses of IHD, PTSD, and risk factors were defined by International Classification of Diseases-9th or -10th Revision, and/or Current Procedural Terminology codes. ResultsPTSD was associated with elevated rates of developing each risk factor. Traditional risk factors (hypertension, hyperlipidemia, smoking, diabetes) accounted for 24.2% of the PTSD-IHD association, psychiatric risk factors (eg, depression, anxiety, substance use disorders) accounted for 33.8% of the association, and all 13 risk factors accounted for 48.5% of the association. ConclusionsTraditional IHD risk factors explained a quarter of the PTSD-IHD association in women veterans, and over half of the risk of IHD associated with PTSD remained unexplained even when adjusting for a wide range of risk factors. To be actionable, factors underlying the remaining PTSD-IHD association warrant timely investigation.