P647Measurement of the left atrium volume - does the method matter?

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Background: Several echocardiographic methods can be used to assess the left atrium (LA) volume. They provide different results and recommended threshold to define LA enlargement are different. We aimed at evaluating the agreement between methods for the assessment of the degree of LA enlargement.Method. We prospectively measured the LA volume in 70 healthy subjects using 4 methods cube, ellipsoid, biplane Simpson and biplane area-length method. A threshold for LA enlargement was defined as mean +2 standard deviation (SD) and threshold for severe LA enlargement, mean +4 SD. LA volume was prospectively measured using the same 4 methods in 371 consecutive patients referred for clinically indicated echocardiography. The area-length method, previously validated agons CT was used as reference. Agreement between methods for the degree of LA enlargement (normal, moderately enlarged and severely enlarged) was assessed by the Kappa value.Results: Normal values of LA volume using the 4 different methods and thresholds for LA enlargement are presented in the table. In the 371 patients, LA volume using the method of cube, ellipsoid method, biplane Simpson and biplane area-length method were 29 ±19, 47 ±27, 61 ±33 and 65 ±37 ml/m2respectively. As expected LA volumes were significantly different (p< 0.001). Agreement between the method of cube, the ellipsoid method, and the biplane Simpson with the area-length method was modest (kappa value 0.41, 0.66 and 0.68 respectively) and the percentage of the misclassified patients was 58%, 22% and 22% respectively.Conclusion: In this large series of patients we demonstrate that not only LA volume values are different according to the method used but also that the assessment of the degree of LA enlargement are poorly correlated. These results further emphasize the need of a standardization of LA volume measurement and may have important implications in the management of patients and the indication for anticoagulation therapy.

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