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Left atrial strain measured by 4D Auto LAQ echocardiography is significantly correlated with high risk of thromboembolism in patients with non-valvular atrial fibrillation.

Background
The 4-dimensional automated left atrial quantification (4D Auto LAQ) tool is a new software for analysis of the structure and function of the left atrium (LA). This study aimed to evaluate the relationship between LA strain (LAS) as measured by 4D Auto LAQ echocardiography and thromboembolism risk in patients with non-valvular atrial fibrillation (NVAF).


Methods
Eight-five patients with NVAF were recruited from the cardiovascular center of our hospital, including 39 patients at high risk and 46 patients at low risk of thromboembolism. The study participants were assessed by routine echocardiography; 4D images were obtained, after which 4D Auto LAQ assessment was performed.


Results
In the thromboembolism high-risk group, the rates of impaired LA reservoir strain, LA contraction strain, LA reservoir circumferential strain, LA conduit circumferential strain, and LA contraction circumferential strain were found to be significantly higher than in the low-risk group. However, there was no significant difference in volume at onset of LA contraction or LA ejection fraction (LAEF) between the 2 groups. LA contraction circumferential strain was found to be an independent high risk factor for thromboembolism [odds ratio (OR): 2.52; P=0.008]. LA contraction circumferential strain >-4.5% was the cut-off for differentiating between participants with high and low risk of thromboembolism, with an area under the curve (AUC) of 0.95 (P<0.0001), a sensitivity of 0.872, and a specificity of 0.978. Sequential analysis revealed that LA contraction circumferential strain had a high diagnostic efficacy for stroke, as well as a specified accuracy in the diagnosis of hypertension and diabetes in patients aged ≥65 years old. However, it was not found to be effective in the diagnosis of heart failure and vascular diseases.


Conclusions
LAS is a useful index for the dynamic evaluation of LA function in patients with non-valvular AF, with higher sensitivity and accuracy than LA volume. LA contraction circumferential strain is an independent high risk factor for thromboembolism, and LA contraction circumferential strain >-4.5% is a valuable cut-off to guide the use of anticoagulant therapy in patients with non-valvular AF.