Myocardial and pericardial diseases often lie at the intersection of internal medicine, cardiology, and systemic pathology. They present not just clinical complexity, but diagnostic uncertainty - fuel for both medical challenge and medico-legal risk. This volume emerges from the recognition that subtle errors in recognizing myocarditis, cardiomyopathy, pericardial tamponade, or autoimmune cardiac involvement can lead to devastating outcomes - and legal scrutiny.