Common in children esp teenagers, often at rest, sharp but brief. Extremely rare to find a cause…

Differential:

• Oesophagitis
• Asthma
• Pulmonary embolism
• Tachyarrhythmia – but you would expect palpitations and colour change, “on/off”
• Precordial catch syndrome
• Costochondritis (Tietze syndrome)
• Catecholamine secreting tumours??
• Cardiomyopathy? Ischaemic cardiomyopathy eg anomalous origin of left coronary artery (from pulmonary artery) – but in kids, either too young to describe pain (infants) or else too mild to present with angina (instead present with failure).  Arrhythmogenic ventricular cardiomyopathy (usually right, but biventricular involvement recognised) can present with pain but usually syncopal episodes.  [Circulation. 2019;140:e9–e68]
• Fabry’s as cause of bizarre pain (heart involvement but pain usually GI). 
• Aortic root problem – as seen in Marfan’s and other connective tissue problems.

So red flags would be syncope, colour change, sudden dizziness/confusion, sweating/clamminess suggesting cardiovascular compromise.

Assuming normal physical examination, and no family history of inherited cardiac problems (or sudden death), if not exertional then can be reassured. Pain killers not usually helpful as pain settles so quickly.

If exertional then needs ECG. Unlikely to be significant cardiac problem if normal.