The management of acute myocardial infarction.

UNTIL recently approximately 30°4 of all patients entering hospital following a myocardial infarction died. This figure is remarkably consistent throughout the hospitals of the world. The majority of deaths occurred within the first few hours and up to 1 week following the infarction. The cause of death is not always clear but we can place it under the following headings: 1. Arrhythmias. 2. Myocardial weakness and failure. 3. Biochemical disturbances. 4. Embolism. 5. Misuse of drugs. In 1960, standing at the side of a bed of a patient seriously ill following a myocardial infarction, we felt that we were extremely ignorant of what was happening to the circulation and what effect our therapeutic endeavours were having. As a result we decided to set aside a special room in which a patient could be nursed and continuously observed with facilities for measuring intravenous pressures, output of the heart, respiratory function and renal function. At the same time the electrocardiogram could be continuously recorded on magnetic tape in a central recording room. Continuous recording of the electrocardiogram on magnetic tape has shown that some form of arrhythmia occurs in over 90°4 of all patients at some time in the first few days following a myocardial infarction. In fifty cases studied in our Coronary Care Unit the following incidence of arrhythmias was found: supraventricular tachycardia group 14°4, supraventricular bradycardia group 24%., nodal rhythm 6%Y, ventricular tachycardia 4°4, ventricular bradycardia 15%Y, extrasystoles only 20%4 and ventricular fibrillation 4%°. The arrhythmias are often transient and may last from a few seconds to hours or days. Their unpredictable behaviour often with spontaneous recovery makes assessment of the value of drugs in their treatment difficult. In many cases where the arrhythmia does not signify the risk of the development of more serious complications no specific treatment is indicated. In others, the right treatment may be life-saving. For the purposes of discussion the arrhythmias may be classified under the headings of extrasystoles, supraventricular and ventricular bradycardia, supraventricular and ventricular tachycardias and disturbances in atrioventricular conduction and asystole.