Reduced left atrial contractile strain with speckle tracking analysis predicts abnormal plasma NTproBNP in an asymptomatic community population

BACKGROUND

The left atrium (LA) is closely related to left ventricular diastolic function. Two-dimensional speckle tracking strain and strain rate (SR) imaging has 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 = 65.8 years, left ventricular ejection fraction = 70.8%, LA volume index = 17.9 ml/m²) were investigated in our study. 117 individuals had increased plasma NTproBNP (≥ 125 pg/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, similar with LA contractile strain, E/E' and LAVI. The cut-off value of LASI was 0.612.

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. As a single index, LASI showed similar diagnostic value with LAVI and E/E' in predicting abnormal NTproBNP.

Left atrial stiffness index as a marker of early target organ damage in hypertension

This study aimed to evaluate left atrial (LA) mechanics using two-dimensional speckle-tracking echocardiography (2DSTE) and investigate their correlations with measures of target organ damage (TOD) in hypertension. We enrolled 42 healthy controls (Group I) and 286 hypertension patients: Group II (n = 79) had an LA volume index (LAVI) <28 ml/m²; Group III (n = 92) had an LAVI ≥28 ml/m²; and Group IV (n = 115) had hypertension with left ventricular hypertrophy (LVH). We measured the following parameters: LA reservoir strain and strain rate (LA_S-S, LA_SR-S), LA conduit strain and strain rate (LA_S-E and LA_SR-E), and LA booster strain and strain rate (LA_S-A and LA_SR-A). The LA stiffness index (LASI) was defined as the ratio of early diastolic transmitral flow velocity/lateral mitral annulus myocardial velocity (E/e') to LA_S-S. We performed correlation and regression analyses of individual TOD with LA phasic functions, the LASI, and cardiovascular risk factors. Our findings showed that there was a trend toward a gradual increase in the LASI from controls to normal LA and enlarged LA patients and finally to hypertrophic LV patients. The LASI was significantly higher in Group III [0.28 (0.20, 0.38)] than in Group I [0.20 (0.16, 0.23)] and Group II [0.22 (0.18, 0.27)] and was the highest in Group IV [0.33 (0.26, 0.43)]. The LA reservoir and conduit function gradually decreased from Group I to Group IV. Multivariate regression analysis revealed that the LASI was independently correlated with individual TOD. In conclusion, abnormal LA mechanics precede LA enlargement and LVH, and an increased LASI can be used as a marker of early TOD in hypertension.