His research has always been focusing on cardiac arrhythmias, within the challenging interface between clinical medicine, scientific discovery and invention. Pierre Jaïs discovered a new and unexpected concept thereby pioneering the gold standard method for non-pharmacological treatment of atrial fibrillation (AF). In so doing, he revealed a paradigm - changing fact about arrhythmia-generation - that the cardiac tissue surrounding the great vessels, particularly the pulmonary veins, are the primary source for atrial arrhythmias. He then moved on to discover a wide range of new mechanisms for heart rhythm disorders and developed a wide range of new technological tools, including revolutionary new imaging approaches to visualize and target arrhythmia sources, with the obsession of providing more effective treatment for patients. He is currently working on improving catheter ablation for cardiac arrhythmias. Pulsed field (PF) ablation has the potential to revolutionize the field and replace thermal energies used for atrial and ventricular ablation. He is also leading an EU large randomized clinical trial aiming to demonstrate the superiority of PF over thermal energies.