Invasive diagnostic and therapeutic techniques are indispensable for the diagnosis and interventional treatment of coronary artery disease, valvular involvement and, in particular, if the specific components of the inflammatory or degenerative processes in rheumatic disease are to be identified in the different components of the heart. Although impairment of cardiac function and ischaemia can be suspected also by non-invasive techniques, coronary involvement needs the final proof by angiography. Endomyocardial or epicardial biopsy identifies the key players of autoreactivity: the infiltrating cells and the bound and circulating antibodies. Before corticoid treatment is started, a viral or microbial aetiology has to be excluded at the site of cardiac inflammation. This again can only be done by the analysis of cardiac tissue samples.