Daniel S. O'Connor, MD, PhD is an Associate Professor of Clinical Medicine at Columbia College of Physicians and Surgeons, Co-director of the Center for CardioOncology, Cardiologist for the Aortic Program and Cardiac Intensivist at Columbia University Medical Center in New York. His areas of expertise include consultative cardiology, critical care cardiology, and non-invasive imaging. Dr. O'Connor is board certified in internal medicine and cardiology.

Dr. O'Connor received his PhD studying vascular and cancer cell biology within the Department of Pharmacology at Yale University. He then received his MD degree at The State University of New York at Brooklyn Medical Center (SUNY Downstate). Dr. O'Connor was an Intern, Resident and Chief Resident at Mount Sinai Medical Center in New York. He then completed his training as a Fellow and Chief Fellow in cardiovascular medicine at Columbia University Medical Center.