Cardiac amyloidosis is a relatively rare disease. However, with the newer imaging techniques that have become available to us in recent years, determining the diagnosis is becoming more common. There are several variants. Each variant involves protein accumulation between heart muscle cells. This leads to the heart stiffening and, as a result, the heart has a hard time filling. This can lead to heart failure with complaints such as fluid retention, cardiac arrhythmias such as atrial fibrillation, conduction abnormalities that sometimes require a pacemaker, and clot formation in the heart that can cause a stroke and narrowing of the aortic valve. Getting the correct diagnosis is important because specific treatment is available in some cases for the different variants of cardiac amyloidosis. This research is needed to better understand the course of this disease profile and which patients respond well to the specific treatment. The aim of this research is to find out more about the course of the cardiac amyloidosis disease. The investigators see to what extent patients deteriorate in their condition due to the disease and how often they need to be hospitalized. Furthermore, the investigators want to learn to what extent certain abnormalities (on e.g. cardiac ultrasound) can predict how quickly clinical deterioration occurs. Finally, for certain forms of cardiac amyloidosis there is a specific drug treatment. Through this research, the investigators want to try to determine who really benefits from the specific medication in order to prescribe it to the right patients.