Multimodality Cardiac Imaging for Disease Progression in ATTR-CM

The goal of this clinical trial is to investigate whether new imaging techniques can help us to better understand the cardiac amyloidosis. The disease can be slowed down with various medications (e.g., tafamidis, acoramidis, or vutrisiran). However, treatment is not effective in all patients-in about one-third of cases, the disease continues to progress. So far, we know little about the exact causes of this and what biological changes occur in the heart muscle. The main question it aims to answer is: Will new imaging techniques help us understand the course of the cardiac amyloidosis? Participants will have additional examinations: * At the beginning of the study: one additional heart ultrasound examination, one cardiac MRI and one cardiac PET, blood examination during the regular examination, questionnaires. * After a year: one additional heart ultrasound examination, one cardiac MRI and one cardiac PET, blood examination during the regular examination. Time required: * Heart ultrasound examination: 5-10 Minutes * Cardiac MRI: 2 hours * Cardiac PET: 2 hours * Questionnaires: 5-10 Minutes.