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Executive Leadership


Mark Slyter

Chief Executive Officer

Mark F. Slyter, DSc, FACHE
President and CEO, Mercy Gilbert and Chandler Regional Medical Centers

Mark served as president and chief executive officer for General Health System, in Baton Rouge, La., a three-hospital system with 686 beds, two regional-referral and academic-medical-center campuses, a rehabilitation facility, and clinics. During his tenure, Baton Rouge General Mid-City Hospital transformed into a post-acute specialty campus, improved operating margins, reduced costs, and achieved high patient-satisfaction and employee-engagement scores.

Prior to joining General Health System, Mark was president and chief executive officer at Mississippi Baptist Health Systems, in Jackson, Miss., where he enhanced operating margins and efficiencies while dramatically increasing patient satisfaction. Mark has served in health-care administration since obtaining a master's degree in health services administration at the University of Kansas in 1996. Last year, he obtained a doctorate of science in health services administration from the University of Alabama at Birmingham.


Roger Bies

Chief Medical Officer

BiesRoger Bies, M.D., F.A.C.C., F.S.C.A.I.
Chief Medical Officer, Mercy Gilbert and Chandler Regional Medical Centers
As Chief Medical Officer for Mercy Gilbert and Chandler Regional, Dr. Bies acts as liaison between doctors and healthcare executives, to ensure patients receive the highest quality treatment. His role includes evaluating, and managing physicians on the medical staff and working to implement high quality, cost-effective, efficient medical therapies. Chief Medical Officers have the primary responsibility of managing their health organization’s doctors to provide safe, effective medical services to the public. In his role Dr Bies helps guide the entire healthcare team to implement valid action plans, and organize the financial, human resources, legal, and political aspects of healthcare with goal-oriented visioning for quality assurance. He currently serves as the Accountable Executive for all Research activities at both hospitals.

Prior to assuming this current position as CMO in 2016, Dr. Bies worked as an Interventional Cardiologist with Central Arizona Heart Specialist. He has 25 years of leadership experience as Executive Director of Heart Health Organization, Cardiovascular Dept. Chair, Cath Lab Director, and Faculty and Associate Director of Cardiology at University of Colorado Health Sciences Center. Dr Bies is an active teacher and writer, and has authored over 50 journal articles, books, abstracts, and monographs in medical sciences during his career.

Dr. Bies received his undergraduate degrees in Chemistry and Biology from the University of Colorado, and subsequently graduated with Honors from the University of Colorado Health Sciences Center. He completed his internship and residency at the University of Pittsburgh, Presbyterian University Hospital, and his Cardiology Fellowship & interventional training at Baylor College of Medicine, in Houston, Texas. 


Maryann Bowersox, DNP, RN

Chief Nursing Officer

Peg SmithMaryann Bowersox, DNP, RN, is the chief nursing officer for Dignity Health Chandler Regional Medical Center. 

Bowersox has 38 years of nursing experience with an extensive background in both clinical nursing and nursing leadership. She initially joined Dignity Health as a nurse traveler at Dignity Health St. Joseph’s Hospital and Medical Center and officially joined the hospital team in 2002. Two years later, Bowersox transferred to Chandler Regional’s Telemetry Department and served in several leadership roles before joining Dignity Health Mercy Gilbert Medical Center where she served as chief nursing officer from 2016 to 2020. During her tenure at Mercy Gilbert, she has provided leadership to help the hospital exceed quality metrics, reduce serious safety events, open the Weight Loss Center, and implement the Dignity Health East Valley tumor boards.

Bowersox earned her master’s degree in nursing from Grand Canyon University and her doctorate degree in nursing practice from Walden University. She is a Professor of Practice in the Edson College of Nursing and Health Innovation, and a member of the Arizona Nurse Association of Executive Leadership and the American Nurse Association.