An increase of the left atrium sphericity index can serve as a marker of paroxysmal atrial fibrillation in patients with hypertension

Aim – to study the possibility of using the left atrium sphericity index (SI), calculated by echocardiography (EchoCG), to identify patients with hypertension with paroxysmal atrial fibrillation (AF).

Material and methods. The study included 298 patients with hypertension, of whom 77 (25.8%) showed paroxysmal AF during 24-hour electrocardiogram monitoring. The control group included 58 patients without cardiovascular diseases. The left atrium volume was determined and the maximum left atrium length was measured. The SI was calculated as the ratio of the left atrium volume to the volume of a sphere whose diameter is equal to the maximum left atrium length.

Results. The average values of SI (presented as the median and 95% confidence interval) increased from the control group to the group of patients with hypertension without AF and to the group of patients with hypertension and AF: 0.68 (0.64–0.72), 0.71 (0.69–0.72) and 0.92 (0.91–0.94), p <0.0001. Multiple linear regression analysis showed that 1-year increase of the age is associated with increase in SI by 0.0015 units, the presence of obesity is accompanied by an increase of SI by 0.0241 units, and the presence of paroxysmal AF leads to an increase in SI by 0.2031 units. All patients included in the study were randomly divided into derivation and validation cohorts (238 and 118 patients). In the derivation cohort, the AUC for SI, as a predictor of AF, was 0.955 (0.920–0.977), and cut-off point was 0.82. In the validation cohort, the ‘SI>0.82’ criterion, a sign of AF, demonstrated sensitivity of 100 (86.8–100.0) % and specificity of 93.5 (86.3–97.6) %.

Conclusion. The SI calculated by EchoCG has a high discriminating ability in relation to paroxysmal AF in patients with hypertension.