<prompt> A young man repos chest pain retrosternal over last few hours. Pain is not related to . and relieved significantly on sitting and forward. Likely possibility is -Angina pectorisAcute pericarditisReflux esophagitisRib fracture  <response>: Acute pericarditis is a type of pericarditis inflammation of the sac surrounding the hea, the pericardium usually lasting less than 6 weeks. It is the most common condition affecting the pericardium. Ref Davidson 23rd edition pg 525 