Aspirin plays a crucial role in survival of cases of myocardial infarction.  It prevents platelets from aggregating around a thrombus and further occluding a coronary artery.  The expedience with which aspirin is administered is of paramount importance.  In fact, aspirin should be given before nitroglycerine in all cases, as the goal in nitroglycerine use is pain management, not reperfusion. 
 
Chewing aspirin increases the surface area which increases the rate of absorption in the stomach and entry into general circulation.  Enteric coated aspirin is much less effective, as it survives the stomach, is absorbed in the small intestines, and must pass through the liver first, where some metabolization occurrs.    
 
It is also important that the tablets be flavored.  While legacy aspirin tablets are chewable, the flavor is extremely unpleasant which may prevent swallowing and encourage patients to spit the tablets out.