This study is a double-blind, placebo controlled, cross-over design in which treatment order to ranolazine and placebo will be randomly assigned. Note: The participant's usual medication regimen will be continued throughout study participation. Following enrollment into the study, participants will be randomized to treatment #1 (either placebo or ranolazine). Ranolazine will be dosed as 500 mg orally twice daily for 2 weeks and, assuming tolerance, followed by 1000 mg orally twice daily for an additional 2 weeks. If the participant is unable to increase dose secondary to side effects, she will remain on 500 mg twice daily for the second 2 week interval. The first end of treatment CMR (CMR 1) will be scheduled at the end of the 4th week of treatment, approximately 4 hours after the morning dose of study drug. At this visit (Vis 2), concurrent medications, symptoms, and adverse events will be reviewed. Clinical measurements will be taken (weight, BP, waist and hip circumference) and questionnaires will be completed (SAQ, WISE angina frequency, DASI and SF-36).