Professor Weiss is chief physician for internal medicine with focus on cardiology at the Döbling Private Hospital in Vienna and interventional cardiologist at the Confraternität Private Hospital and University Hospital St. Pölten. He is specialized in the treatment of heart diseases. His research is focused on hypertension and coronary artery disease (coronary catheterization and percutaneous coronary angioplasty). In autumn of 2018 he became head of the Karl Landsteiner Institute for Cardiometabolics.
After graduating from the University of Vienna he spent 2 years at the Australian Centre for Blood Diseases, 2 years at the Monash University in Melbourne and another 4 years at the University Clinic for Cardiology in Oslo, Norway. Professor Weiss is a senior lecturer for vascular biology at the Medical University of Vienna. He holds a PhD from the University of Oslo and a professorship for cardiology at the Sigmund Freud University Vienna.