Background  Left atrial volume has an important prognostic value for a variety of cardiovascular diseases, and studies have shown that obesity is significantly associated with the risk of left atrial enlargement (LAE). Cardiac metabolic index (CMI) is a novel adiposity index and can comprehensively reflect abdominal obesity and blood lipid levels.

  Objective  To investigate the correlation between CMI and LAE.

  Methods  A cross-sectional study was performed for the residents from Gucheng and Jindingjie communities of Beijing who were investigated by REACTION study (risk evaluation of cancers in Chinese diabetic individuals: a longitudinal study) from April to September in 2015. Left atrial diameter (LAD) was used as the parameter for left atrial volume. Pearson correlation analysis was used to investigate the correlation between CMI and LAD, and binary logistic regression analysis was used to analyze the correlation between CMI and the risk of LAE.

  Results  A total of 7 955 subjects were included in this study, with 2 909 males and 5 046 females, and a mean age of 64.24 ± 7.83 years. LAD was positively correlated with CMI (r=0.227, P＜0.001). Based on the quartiles of CMI, the subjects were divided into Q1 group with 1 989 subjects (CMI ≤ 0.307 8), Q2 group with 1 989 subjects (CMI: 0.307 8-0.489 2), Q3 group with 1 989 subjects (CMI: 0.489 2-0.797 6), and Q4 group with 1 988 subjects (CMI＞0.797 6). Compared with Q1 group, odds ratio (OR) for the risk of LAE in Q3 and Q4 groups was 1.441 (95% CI: 1.024-2.027, P＜0.05) and 2.005 (95% CI: 1.432-2.807, P＜0.05), respectively. Stratified analysis showed that in the 130-140 mmHg blood pressure group(n=2 254), the risk of LAE increased significantly with the increase in CMI, and compared with Q1 group, OR of Q2, Q3, and Q4 groups was 2.370 (95% CI: 1.118-5.024, P=0.024), 2.653 (95% CI: 1.271-5.540, P=0.009), and 3.434 (95% CI: 1.654-7.131, P=0.001), respectively. In the prediabetes group(n=2 502), the risk of LAE increased significantly with the increase in CMI, and compared with Q1 group, OR of Q3 and Q4 groups was 2.792 (95% CI: 1.345-5.793, P=0.006) and 3.331 (95% CI: 1.614-6.878, P=0.001), respectively. In the gamma-glutamyl transpeptidase (GGT)＞40 U/L group(n=1 009), the risk of LAE increased significantly with the increase in CMI, and compared with Q1 group, OR of Q3 and Q4 groups was 3.845 (95% CI: 1.093-13.520, P=0.036) and 3.496 (95% CI: 1.010-12.100, P=0.048), respectively.

  Conclusion  The risk of LAE increases with the increase in CMI, especially in the population with elevated blood pressure, prediabetes, and elevated GGT.