RESUMO
Background: diurnal variation in the onset of acute myocardial infarction has been demonstrated with a peak in the morning. Few data are available about the occurrence of left ventricular systolic dysfunction according to the time of infarct
Materials and methods: we performed a prospective study that. included 100 patients with acute myocardial infarction [AMI]. Left ventricular systolic dysfunction [LVSD] was determined by echo cardiography when ejection fraction [EF] was less than 55%
Results: out of 100 patients 65% had EF less than 55% and 53% of them experienced myocardial infarction between 6 AM and 5:59 PM [group 1] and 47% their AMI between 6 PM and 5:59 AM [Group 2]. Left ventricular EF less than 55% occurred in 51 % of group 1 compared with 77% in group 2 [p=0.004]. Mild and severe LVSD were also more frequent in group 2 patients [p=0.019]
Conclusion: the risk of mild and severe left ventricular systolic dysfunction after AMI is higher among infarctions that occur at night