Patients will be consented and enrolled at the time of their clinic visit or admission to the hospital for a planned EVAR, in accordance with institutional review board guidelines. Demographic, risk factor and medication regimen data will be obtained from the patient's clinical chart. Patients will be randomized to doxycycline therapy (100 mg taken twice daily) or a placebo. The patients will receive their first dose of study medication on the day following surgery, and continue the study therapy for 6 months.