Background: The goal of the Affordable Care Act was to improve health outcomes through expanding insurance, including through Medicaid expansion. We systematically reviewed the available literature on the association of Affordable Care Act Medicaid expansion with cardiac outcomes. Methods: Consistent with Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we performed systematic searches in PubMed, the Cochrane Library, and Cumulative Index to Nursing and Allied Health Literature using the keywords such as Medicaid expansion and cardiac, cardiovascular, or heart to identify titles published from 1/2014 to 7/2022 that evaluated the association between Medicaid expansion and cardiac outcomes. Results: A total of 30 studies met inclusion and exclusion criteria. Of these, 14 studies (47%) used a difference-in-difference study design and 10 (33%) used a multiple time series design. The median number of postexpansion years evaluated was 2 (range, 0.5–6) and the median number of expansion states included was 23 (range, 1–33). Commonly assessed outcomes included insurance coverage of and utilization of cardiac treatments (25.0%), morbidity/mortality (19.6%), disparities in care (14.3%), and preventive care (41.1%). Medicaid expansion was generally associated with increased insurance coverage, reduction in overall cardiac morbidity/mortality outside of acute care settings, and some increase in screening for and treatment of cardiac comorbidities. Conclusions: Current literature demonstrates that Medicaid expansion was generally associated with increased insurance coverage of cardiac treatments, improvement in cardiac outcomes outside of acute care settings, and some improvements in cardiac-focused prevention and screening. Conclusions are limited because quasi-experimental comparisons of expansion and nonexpansion states cannot account for unmeasured state-level confounders.