RESUMO
To determine the risk of myocardial necrosis re-extension (RN) appearance in the first month of evolution of myocardial infarction (MI) confirmed clinically, by ECG, and enzymatically, 262 patients (mean age 64.5 years, 64.6% males) were studied. The incidence of RN was found present in 67 patients (25.6%). A complex statistical analysis (stepwise regression analysis) of the variables presented by the patients (clinical, ECG and laboratory) showed that only 5 variables are important in the determination of the risk of RN namely: nontransmural localization of initial necrosis, atrial fibrillation, past history of angor pectoris, prolonged pain at onset and presence of idioventricular rhythm. The introduction of these 5 variables in a multiple regression equation will allow the distribution of patients, already at entry, in subgroups of risk of re-extension necrosis within the first month of MI evolution thus allowing a more careful management of disease.