Background: The left atrium (LA) is closely related to left ventricular diastolic function. Two-dimensional speckle tracking strain and strain rate (SR) imaging have been applied in the study of LA function. We intended to explore the relationship between global LA deformation parameters and plasma NTproBNP levels in asymptomatic community residents with normal ejection fraction and normal LA volume.
Methods: A cross-sectional sample of Beijing residents underwent comprehensive Doppler echocardiography and medical record review in 2009.Global LA longitudinal strain and SR indexes were obtained in the apical four-chamber view. LA stiffness index (LASI) was calculated as the ratio of early diastolic velocity of transmitral flow/early diastolic mitral annular motion velocity (E/E') to LA reservoir strain.
Results: A total of 620 individuals (mean age=65 years, left ventricular ejection fraction=70.8%, LA volume index=17.9ml/m2) were investigated in our study. 117 individuals had increased plasma NTproBNP (≥125pg/ml). LA reservoir and contractile function by LA strain and SR indexes were significantly reduced in the abnormal NTproBNP group compared with the normal NTproBNP group. Multiple regression analysis indicated that LA contractile strain was a negative predictor of plasma NTproBNP in addition to indexed LA volume and E/E'. LASI was higher in the abnormal NTproBNP group and was significantly correlated with NTproBNP (r=0.342, P<0.001). The area under ROC analysis for LASI in predicting elevated plasma NTproBNP was 0.690, higher than that for LA strain, LA volume and E/E'. The cut-off value of LASI was 0.615.
Conclusions: LA reservoir and contractile functions demonstrated by LA strain and SR were significantly impaired in the community-based population with increased plasma NTproBNP levels. LA contractile strain adds incremental information in predicting abnormal NTproBNP levels. LASI was the best single index in the detection of abnormal NTproBNP.