Thomas O'Brien, MD, was born in Springville, New York. He earned a Doctor of Medicine degree from the University of Rochester. After rigorous training at Strong Memorial Hospital, he moved to Cincinnati in 2001, where he completed his residency in internal medicine and fellowship training in adult clinical cardiology and advanced heart failure and transplant cardiology. He earned both chief medical resident and chief cardiology fellow select honors at the University of Cincinnati and was voted both resident and fellow of the year among his peers.

Dr. O'Brien is triple-board-certified by the American Board of Internal Medicine, with a specialization in advanced heart failure and transplant, cardiovascular disease, and echocardiography. Dr. O'Brien is considered a leader in ultrafiltration and a specialist in LVADs. He has made contributions to cardiovascular research trials, has published articles in peer-reviewed scientific journals, and has been among Cincinnati's Top Doctors.

Dr. O'Brien is married to Dr. Hope O'Brien, an adult neurologist and headache specialist. He is actively involved in Solid Rock Church in Monroe, Ohio, and enjoys running and personal fitness.