Comparison of incidence and prevalence of arrhythmias in acute myocardial infarction.

Current methods of handling quantitative arrhythmia data deal primarily with the incidence (I) of arrhythmias and the relation of incidence to morbidity and mortality in patients with acute myocardial infarction (MI). To evaluate a new parameter, prevalence (P), and compare it with I, data from 345 patients with MI were analyzed from a computerized data base. I was defined as the number of patients in whom an arrhythmia had occurred and P as the number of days the arrythmia persisted. A high I/P ratio is generally associated with a low prevalence and a low I/P ratio with a high prevalence. Incidence, prevalence, and I/P ratios are shown for supraventricular, junctional, and ventricular arrhythmias, and AV block. Further analysis of the data from 98 patients showed that when inferior MI was compared to anteroseptal MI there was an increased incidence of AV block, and an increased incidence of ventricular tachycardia. A high I/P ratio is shown for arrhythmias associated with a high mortality in our previous studies. The data suggest the need for newer techniques for handling quantative arrhythmia data.