Mary Leier NP

Mary E. Leier, MSN, APRN, FNP-C

Lead Nurse Practitioner & Advanced Practice Provider (APP) Educator

Smidt Heart Institute at Cedars-Sinai Health System

Now with Atrial Health and Research Institute

Mary Leier is a highly accomplished, board-certified Family Nurse Practitioner specializing in cardiac electrophysiology, offering 21 years of dedicated nursing experience and 12 years of advanced practice expertise. Currently serving as the Lead Nurse Practitioner and APP Educator at the prestigious Smidt Heart Institute at Cedars-Sinai Health System, Mary is a recognized clinical leader in the comprehensive management of complex heart rhythm disorders, arrhythmia, and cardiac implanted electronic devices.Mary’s diverse clinical background spans both high-acuity inpatient settings and long-term outpatient care. Her advanced procedural capabilities include performing cardioversions and loop recorder implantations. Throughout her career, she has developed essential care protocols, expertly guiding patients through the complete perioperative and recovery lifecycle—from acute hospital interventions to long-term clinic follow-ups. Before joining Cedars-Sinai in 2015, Mary built a foundation in cardiovascular care across notable institutions, including Metropolitan Heart Associates and St. John’s Health Center's Intensive Care and Post-Anesthesia Care Units.An active contributor to the advancement of cardiovascular medicine, Mary serves as a clinical preceptor for the UCLA School of Nursing MSN program and is the founder of the APP Quarterly Lecture Series at the Cedars-Sinai Heart Institute. Her leadership extends to regional and national professional bodies; she serves as the Co-Chair for the Southern California American College of Cardiology (ACC) Cardiovascular Team and was selected for the Heart Rhythm Society (HRS) Leadership and Education for Allied Professionals (LEAP) class. Mary is heavily involved in clinical research, serving as a sub-investigator on prominent clinical trials focusing on atrial fibrillation and innovative pacemaker technology. She is a published author in peer-reviewed journals, including Heart Rhythm and the Critical Care Nurse Journal, and is a frequent invited speaker at national cardiology symposiums.Mary earned her Master of Science in Nursing (MSN) and Bachelor of Science in Nursing (BSN) from the University of California, Los Angeles (UCLA), following a Bachelor of Science in Biology from the University of California, Santa Barbara (UCSB).