Interaction effect of myocardial infarction and obesity on left atrial functions

Purpose: To determine whether myocardial infarction (MI) would lead to a greater decrease in left atrial (LA) functions in subjects with than without obesity.

Methods: A total of 310 consecutive patients were divided into four groups according to the presence or absence of obesity and MI. The functions of the LA were evaluated in terms of longitudinal deformation of the LA myocardium via 2D speckle-tracking echocardiography.

Results: The adjusted analysis showed a reduction in the strain and strain rate during the reservoir and contraction phases and in the strain rate during the conduit phase in patients with MI and in subjects with obesity (P < .05). In addition, there was a significant interaction effect of obesity and MI on the strain rate during the contraction phase (P = .048).

Conclusions: There is an independent and additional interaction effect of obesity and MI on the reservoir and conduit functions of the LA. MI was more deleterious to the contraction function in subjects without than with obesity, so that the contraction function was similar in MI patients without obesity and MI patients with obesity.