AUTHOR=Wen Yan , Deißler Peter M. , Primeßnig Uwe , Dushe Simon , Falk Volkmar , Parwani Abdul Shokor , Boldt Leif-Hendrik , Blaschke Florian , Knosalla Christoph , Grubitzsch Herko , Pieske Burkert M. , Heinzel Frank R. 

TITLE=Impaired Relaxation and Reduced Lusitropic Reserve in Atrial Myocardium in the Obese Patients

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2021.739907

DOI=10.3389/fcvm.2021.739907

ISSN=2297-055X

ABSTRACT=Background: Obesity can influence the structure and function of the atrium, but most studies focused on the relationship of body mass index (BMI) and overt left atrium (LA) dysfunction as assessed by clinical imaging. We combined the assessment of right atrial (RA) function in vivo and in vitro in obese and non-obese patients scheduled for elective cardiac surgery. 
Methods: Atrial structure and function were quantified pre-operatively by echocardiography. RA tissue removed for establishment of extracorporeal support was collected and RA trabeculae function was quantified in vitro at baseline and with adrenergic stimulation (isoproterenol). Fatty acid-binding protein 3 (FABP3) was quantified in RA tissue. Results were stratified according to the patients’ BMI.
Results: 76 patients were included pre-operatively for echocardiographic analysis. RA trabeculae function at baseline was quantified finally from 46 included patients, and RA function in 28 of them was also assessed with isoproterenol. There was no significant correlation between BMI and the parameters of atrial function measured by clinical echocardiography. However, in vitro measurements revealed a significant correlation between BMI and a prolonged relaxation of the atrial myocardium at baseline, which persisted after controlling for atrial fibrillation and diabetes by partial correlation analysis. Acceleration of relaxation with isoproterenol was significantly lower in the group obese (BMI≥30). As a result, relaxation with adrenergic stimulation in the group obese remained significantly longer than in group overweight (25≤BMI<30, P=0.027) and group normal (18.5≤BMI<25, P=0.036). There were no differences between groups in (systolic) developed force at baseline or with isoproterenol. The expression of FABP3 in group obese was significantly higher than it in group normal (P=0.049), and correlation analysis showed significant correlations between the level of FABP3 in right atrium and right atrial trabeculae function. 
Conclusions: A higher BMI is associated with early subclinical changes of right atrial myocardial function with slowed relaxation and reduced adrenergic lusitropy.