Nitroglycerine is a vasodilator, and is used to relieve pain in cases of ischemia associated with angina and coronary thrombosis.  For patients experiencing a myocardial infarction, pain relief can reduce overall stress, which, in turn, reduces the myocardial oxygen demand during ischemia.  Vasodilation in the heart may also have the advantage of allowing for increased blood flow, distal to the infarction.  Both of these mechanisms may contribute to muscle salvage and better outcomes.