Alexander Breitenstein is a specialist in internal medicine and cardiology, and has additionally trained in congenital heart defects, cardiac surgery and cardiovascular research. From January 2011 to June 2012 he served as assistant physician and from July 2013 to December 2013 as a senior physician p.p. in the cardiology ambulatory, in the echocardiography laboratory and in the heart failure clinic at the Department of Cardiology, University Hospital Zurich. In 2014 he moved to the Arrhythmia Unit of St. Bartholomew's Hospital in London to Prof. Richard J. Schilling.