Typically young patients (20 - 50 years) with few risk factors for CAD
Chest pain
Pericardial friction rub
Flu-like symptoms
Fever, fatigue, myalgia, nausea and vomiting
Tachycardia (out of proportion to fever)
Tachypnea
New onset congestive heart failure
Pediatric patients:
Grunting
Retractions
Ronchi
Infants may have fulminant syndrome
Fever
Cyanosis
Respiratory distress
Tachycardia
Heart failure
Ventricular dysrhythmias
Fever, fatigue, myalgia, nausea and vomiting
Tachycardia (out of proportion to fever)
Tachypnea
Grunting
Retractions
Ronchi
Fever
Cyanosis
Respiratory distress
Tachycardia
Heart failure
Ventricular dysrhythmias
Consider this diagnosis in the septic-appearing patient who gets WORSE after receiving IV fluids
Myocarditis
Consider other causes of CHF
Endocarditis
Acute coronary syndromes 
Constrictive pericarditis
STEMI
Pericarditis
Non-STEMI