Symptoms often initially nonspecific in prodromal stage, may be misdiagnosed as URI, pneumonia, gastroenteritis, asthma
Prodrome typically lasts ~1-2 weeks
Most common presenting symptoms include 
Shortness of breath
Fever
URI symptoms
Vomiting or abdominal pain
Exercise intolerance
Poor feeding
Hypoperfusion (e.g. syncope or seizure
+/- chest pain, palpitations
Exam findings include
Tachycardia
Consider<unk> in any child who remains persistently tachycardic despite appropriate treatment for fever, dehydration, etc.
Only present in 46-58% of cases in 3 large reviews, so lack of tachycardia does not rule out<unk> Fever
Respiratory distress, tachypnea
Have a high index of suspicion on the child that has worsening respiratory status after receiving fluids
Hepatomegaly
Signs of poor perfusion (e.g. decreased cap refill, mottled skin)
Lethargy
Shortness of breath
Fever
URI symptoms
Vomiting or abdominal pain
Exercise intolerance
Poor feeding
Hypoperfusion (e.g. syncope or seizure
+/- chest pain, palpitations
Tachycardia
Consider<unk> in any child who remains persistently tachycardic despite appropriate treatment for fever, dehydration, etc.
Only present in 46-58% of cases in 3 large reviews, so lack of tachycardia does not rule out<unk> Fever
Respiratory distress, tachypnea
Have a high index of suspicion on the child that has worsening respiratory status after receiving fluids
Hepatomegaly
Signs of poor perfusion (e.g. decreased cap refill, mottled skin)
Lethargy
Consider<unk> in any child who remains persistently tachycardic despite appropriate treatment for fever, dehydration, etc.
Only present in 46-58% of cases in 3 large reviews, so lack of tachycardia does not rule out<unk> Have a high index of suspicion on the child that has worsening respiratory status after receiving fluids
Myocarditis 
Airway obstruction
Endocarditis
Anaphylaxis
Constrictive pericarditis
Angioedema
Pericarditis
Aspirated foreign body