Dr. Mahmarian received his first faculty appointment in 1987 as an Instructor of Medicine at the Baylor College of Medicine in Houston, Texas. He quickly established himself as a leader in nuclear cardiology research and was promoted to full Professor in 2005 just prior to joining the Houston Methodist Specialty Physician Group and the faculty of the Weill Medical College of Cornell University.

Dr. Mahmarian´s early research efforts focused on quantification of ischemia as measured by SPECT sestimibi, thereby laying the groundwork for the use of this technique in international trials of ischemia. His current research is focused on combining the results of CT acquired coronary angiography with SPECT results (fusion imaging), as well as testing new agents for pharmacologic stress testing and imaging modalities (e.g. "hot spot" imaging).