As outlined above, in the majority of individuals the cause of a heart attack is a clot (thrombosis) in one of the coronary arteries. This clot can be dissolved by special drugs (thrombolytic agents). For this thrombolytic treat¬ment to be most effective, it should be given within three hours from the onset of the symptoms of a heart attack, that is, three hours from the onset of chest pain, which is the most common symptom. Beyond six hours, the chance of success with this treatment is remote, because the heart muscle cells become irreversibly damaged and die between four and six hours after the blood supply has been cut off. Many patients are given treatment from 6 to 12 h after the onset of their symptoms with the hope of saving a few lives. The number of lives saved by treating 1000 patients with thrombolytic therapy given at less than 1, 3, 6, and 12 h from the onset of symptoms are 65, 27, 25, and 8, respectively. Widespread advice to the population at risk is crucial. Less than 33% of heart attack victims presently receive therapy within four hours of the onset of symptoms.
It is important for all individuals age 35 and over to learn the symptoms and signs of a heart attack (see Section IV). Someone experiencing a heart attack should take two or three chewable aspirins [total dose 160 to 325 mg] and go immediately to the nearest emergency room of a hospital. All hospitals have the facilities to give drugs that dissolve clots in the coronary arteries. This life-saving treatment should be given within minutes of your arrival. If you need to wait more than 20 minutes to receive the drug, your spouse or person accompanying you to the hospital should complain. The choice of thrombolytic agent is not as important as the rapidity of administration. The real problem in the emergency room is the door-to-needle time. It is in excess of 30 minutes in more than 60% of patients admitted in the United States and in many countries worldwide. Fortunately in some countries facili¬ties for immediate angioplasty and stent deployment are available to maintain patency of the infarct-related coronary artery.