In a variant proportion of patients presenting with chest pain and electrocardiographic changes characteristic for ST - elevation myocardial infarction, percutaneous coronary intervention achieves epicardial coronary artery reperfusion but not the myocardial reperfusion (ranging from 5% to 50%). Furthermore, prolonged myocardial ischemia often breaks down the coronary microvasculature and the flow to the infarct myocardium may seem to be markedly reduced. This condition is known as no reflow - phenomenon. The no reflow - phenomenon is associated with an increased incidence of malignant ventricular arrhythmias, heart failure and 30-days mortality. In the recent years in literature, several articles (subsequently discussed in the present review) have been published and made relevant to the study of the pathophysiology regarding no reflow - phenomenon. This knowledge has assisted in the development of new treatment strategies, such as prophylactic use of vasodilators, mechanical devices and drugs inhibiting platelet. The review has focused on the current literature about intra - coronary injection of drugs to treat no - reflow and microvascular dysfunction.