Myocarditis is a condition where inflammation develops in the myocardium, which is the middle muscular layer of the heart wall. This inflammation can weaken the heart and its ability to pump blood, leading to symptoms such as chest pain, fatigue, shortness of breath, fever, and rapid or irregular heartbeat. Some people with myocarditis dont have symptoms, while others have mild or severe signs. Myocarditis can be caused by viral infections, bacterial infections, fungal infections, medications, autoimmune disorders, and toxic substances. The condition can be diagnosed through a physical exam, blood tests, MRI, chest X-ray, EKG/ECG, echocardiograph, cardiac catheterization, and biopsy. Treatment targets symptoms and the underlying cause if its known, and those with mild myocarditis may not require treatment. Myocarditis can also occur after mRNA COVID-19 vaccination, although it is rare.