Mason Shieh, MD

Mason Shieh, M.D., MBA is a healthcare leader and emergency physician recognized for driving clinical quality, operational excellence and hospital wide transformation across multiple health systems. As the Chair and Medical Director of the Emergency Department at UCI Health — Lakewood, he leads a high acuity Emergency Department with a Comprehensive Stroke Center and STEMI receiving facility, fostering multidisciplinary collaboration with neurology, cardiology, critical care, radiology and hospital administration. His leadership has been instrumental in elevating institutional performance, including guiding the hospital’s advancement from a Primary Stroke Center to full Comprehensive Stroke Center certification and sustaining five consecutive years of AHA Get With The Guidelines Gold Plus recognition. He has previously held leadership roles including Chief of emergency medicine and Medical Director at Placentia-Linda Hospital under Tenet Healthcare Pacific Coast.

Shieh’s impact extends well beyond departmental leadership. He chairs several hospital committees, including Sepsis Committee, Hospital Throughput Committee and Hospital Planning Committee, each focused on system level performance, quality metrics and long-term strategic growth. Under his direction, hospital wide sepsis compliance rose to exceed CMS benchmarks, and throughput initiatives significantly improved patient flow from ED arrival through inpatient admission and discharge. His leadership during the COVID 19 pandemic demonstrated exceptional operational resilience, guiding real time policy development, resource management, and adaptation to rapidly evolving clinical and regulatory demands.

Across the hospitals, Shieh has consistently delivered measurable improvements in quality, efficiency and patient experience. He holds dual engineering degrees in biomedical and electrical and computer engineering from Duke University, an MBA from UC Irvine and completed his Emergency Medicine residency at Mount Sinai Beth Israel. Board certified by ABEM, he is published across emergency medicine, neurology, radiology and healthcare systems, and has presented nationally and internationally on disaster response, ultrasound education, and clinical operations. His career reflects a sustained commitment to elevating emergency care, strengthening hospital performance, and shaping long term institutional strategy.

Services:

• Emergency Services