Marcus is an American cardiologist and Emeritus Professor of Medicine at the University of Arizona Health Sciences Center, the author of more than 290 publications in peer-reviewed medical journals and of 90 book chapters.
He is considered a world expert on arrhythmogenic right ventricular cardiomyopathy (ARVC) and has been or is a member of the Editorial/Scientific Board of 14 Cardiovascular Journals as well as a reviewer for 26 other medical publications.