[The significance of lowered ejection fraction on prognosis after myocardial infarction ]

The subject of this study was a group of 757 patients hospitalized because of acute myocardial infarction in years 1992-1996, who survived the in-hospital course and were under observation for 2-6 years after the infarction. During the 14-18th day of the hospital stay they were made an echocardiographic test, including the ejection fraction (EF). The aim of this study was to define the influence of the ejection fraction value lowered below 40% on the long-term prognosis in patients after acute myocardial infarction. We compared two groups of patients; group I, consisting of 130 (17.2%) patients with EF lowered below 40% and group II, which included 627 patients with EF over 40%. To estimate the statistic significance we used the chi-square and t-Student test. The morbidity curves were made with the Kaplan-Meier method. The course of the myocardial infarction was much more grave in group I than in group II, what is confirmed by a more often anterior ventricular infarction and the quantity of dangerous complications which occurred during the in-hospital phase. The multi-factor regressive analysis showed that the ejection fraction lowered below 40% raises 2.47 times (95% confidence interval 1.50-4.07) (p < 0.001) the risk of death during the first year after myocardial infarction and nearly two times during the 5 year follow-up, compared to patients with a higher EF value. The influence of the EF value lowered below 40% on the creation of an infarction was not significant. The EF value lowered below 40% in patients after acute myocardial infarction was a significant risk factor in the long-term prognosis. More than 40% of deaths during the long-term prognosis in this group were caused by heart failure.