Left atrial strain in acute myocardial infarction

Background. The ejection fraction (EF), diastolic dysfunction of the left ventricle (LV) and its volumes play the main role for prognosis assessment. Measurement of left atrial strain is a new method of noninvasive investigation of mechanical function.Aim: To investigate the mechanical function of the left atrium in patients with acute myocardial infarction (AMI) with different degrees of left ventricular ejection fraction reduction.Methods. We studied 60 patients with acute ST-segment elevation anterior myocardial infarction. Echocardiography was performed in the first day of acute infarction. The left atrium was assessed by phase volumes, as well as by strain and strain rate using speckle-tracking. 35 healthy subjects were investigated for control. The patients were divided into 4 groups: Group 1 – LV EF 50–60%, Group 2 – LV EF 40–49%, Group 3 – LV EF 30–39%, Group 4 – LV EF 20–29%.Results. There were no significant differences in left atrial volumes between patients in groups 1–3 and healthy patients. Left atrial volume was increased in the fourth group. In the first group, peak longitudinal atrial strain (PALS) was significantly reduced compared with control group (PALS 22% vs 32.4%, p < 0.000). In the second group PALS was 17.41%, in the third group it was 18.19%. In the group with LV EF less than 30%, PALS was 4.43%. In healthy subjects, the strain rate was – 2.14 cm/s-1, in Group 1 – 2.15 cm/s-1 (p < 0.297), in Group 2 – 1.19 cm/s-1(p < 0.000), in Group 3 – 1.58 cm/s-1 (p < 0.000), and in Group 4 – 1.14 cm/s-1(p < 0.000).Conclusion. In patients with AMI with LV EF more than 50%, significant violations of LA strain are detected, which may be a predictor of left heart dysfunction. As the LV EF decreases, LA strain decreases and LA volume increases.