A director since 2018, Greenstein currently serves as Chief Strategy and Innovation Officer of LHC Group, Inc., a leading national provider of in-home healthcare services, guiding the company's value-based contracting, ACO management company, and alternative payment and delivery model strategies. He also leads the company's operations for technology and the innovations business segments and its healthcare vision initiatives.  

Previously, Greenstein served as Chief Technology Officer (CTO) for the U.S. Department of Health and Human Services (HHS) in Washington, D.C., as President-West for New York-based Quartet Health, CEO of Blend Health Insights, and managing director of Worldwide Health for Microsoft. Other public sector senior roles of Greenstein's include Secretary of the Louisiana Department of Health and Hospitals, a cabinet member appointment, and overseeing Medicaid-managed care and waivers and demonstrations at the federal Centers for Medicare & Medicaid Services (CMS).