Interaction effect of hypertension and obesity on left atrial phasic function: a three-dimensional echocardiography study

BACKGROUND: Hypertension (HT) and obesity often coexist and contribute to left atrial (LA) dysfunction. The present study aimed to compare LA function in hypertensive individuals and control participants with different body mass index (BMI) categories and to explore whether there is an interaction effect between HT and obesity on LA function. METHODS: In this cross-sectional study, a total of 258 individuals (145 hypertensive and 113 non-hypertensive patients) were prospectively enrolled from Fuwai Central China Cardiovascular Hospital from September 2020 to November 2021. Hypertensive and non-hypertensive patients were both divided into three study subgroups (n=35 per group) according to their BMI: normal weight (BMI 18.5–<25 kg/m(2)), overweight (BMI 25–<30 kg/m(2)), and obesity (BMI ≥30 kg/m(2)) groups. LA volume and strain parameters were obtained using three-dimensional echocardiography. RESULTS: A significant interaction effect between HT and obesity on LA function was observed [P(Interaction) =0.04, 0.03, 0.005, 0.01, and 0.002 for LA ejection fraction (LAEF), LA passive ejection fraction (LAPEF), LA active ejection fraction (LAAEF), LA reservoir longitudinal strain (LASr), and LA contraction longitudinal strain (LASct), respectively; P(Interaction) <0.001 for LA conduit longitudinal strain (LAScd)]. Univariate correlation analysis revealed that HT [LASr, r=−0.53, 95% confidence interval (CI): −0.62 to −0.42, P<0.001; LAScd, r=−0.49, 95% CI: −0.58 to −0.39, P<0.001; and LASct, r=−0.46, 95% CI: −0.55 to −0.34, P<0.001] and BMI categories (LASr, r=−0.68, 95% CI: −0.75 to −0.61, P<0.001; LAScd, r=−0.47, 95% CI: −0.57 to −0.35, P<0.001; and LASct, r=−0.73, 95% CI: −0.78 to −0.66, P<0.001) were negatively correlated with LA strains. A generalized linear model further demonstrated that there was an interaction effect between HT and obesity on LA strains after adjusting for confounding factors (Model 2: LASr, β(HT*Obesity) =−1.91, 95% CI: −3.48 to −0.35, P=0.01; LAScd, β(HT*Obesity) =−3.26, 95% CI: −4.83 to −1.70, P<0.001; LASct, β(HT*Overweight) =−1.97, 95% CI: −3.03 to −0.91, P<0.001; β(HT*Obesity) =−1.54, 95% CI: −2.67 to −0.41, P=0.007). CONCLUSIONS: Both HT and increasing BMI category had an adverse effect on LA function. The coexistence of HT and obesity further impaired LA performance in an interaction manner. Weight loss is essential to reduce the incidence of adverse cardiovascular events in hypertensive patients.