Acute post-myocardial infarction syndrome, which occurs repeatedly in the weeks or months after myocardial infarction, manifests itself in pericardial inflammation, pleurisy, pneumonia, with symptoms of fever, chest pain, shortness of breath, and cough, probably due to an allergic reaction of the organism to necrotic substances, like early pericarditis, which occurs within 1-4 days after myocardial infarction, early pericarditis often occurs in the pericardium within the infarcted area, complicated by fibrinous inflammation caused by . Clinically, there may be a transient pericardial rubbing sound, also accompanied by progressively worsening chest pain. Late pericarditis may be of longer duration, occurring over several weeks or months, and may be recurrent and more severe.