Dr. Marcus was founder and first president of the Arizona Chapter of the American College of Cardiology in 1987-1988 and was president of the Association of University Cardiologists from 1990-1991. Among his honors are the Outstanding Achievement Award of the European Cardiac Arrhythmia Society in 2011; and Pioneer in Cardiac Pacing and Electrophysiology Award of the Heart Rhythm Society in 2011. Later in his career, Dr. Marcus turned his attention to the study of cardiac arrhythmias. He introduced radiofrequency energy for cardiac ablation procedures. From 2001 to 2008, Dr. Marcus was the principal investigator of an NIH-sponsored study “The Multi-Disciplinary Study of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia.” In 2013, NIH awarded him another four-year grant to further ARVC/D research ("Genetics, Mechanisms and Phenotypes of Arrhythmogenic Cardiomyopathies," 1R01HL116906-01A1).