Dressler’s syndrome (a.k.a. post-myocardial infarction syndrome) is an autoimmune phenomenon that can occur after myocardial infarction and manifests 2-3 weeks later as pericarditis and a pericardial effusion. The diagnosis is clinical and based on ECG changes of pericarditis. Treatment includes aspirin and colchicine to decrease inflammation. Anticoagulation should be avoided in order to prevent hemorrhage into the pericardium and cardiac tamponade.