Dr. Johnston's primary focus is prevention and treatment of cardiovascular disease, lipid disorders and women's heart disease. He was designated as a 2010 Physician of Excellence by Orange County Medical Association and Orange Coast Magazine, and was the 2008 recipient of the "Spirit of St. Joseph" award at St. Joseph Hospital. A part of the Department of Cardiology at St. Joseph Hospital for 21 years, he is currently the co-director of the Women's Heart Center. He has served as faculty at UCI, and is currently the Chairman of the Department of Cardiology at SJHMG. Dr. Johnston is accepting new general cardiology patients.