Quantification of left atrial volume using cardiac magnetic resonance imaging: comparison of left atrial volume index measurements using the Simpson's and bi-plane area-length methods

Background Increased left atrial volume index (LAVI) has been shown to be an independent predictor of hard cardiovascular events. It can be determined by calculating left atrial (LA) volume through the use of either Simpson’s method or area-length method and indexing it to body surface area (BSA). Although there is no standardized method of calculating LA volume using Cardiac Magnetic Resonance Imaging (CMR), the aforementioned methods, which were originally validated for 2-dimensional echocardiography, have been used. We sought to assess the agreement between LAVI, obtained with the use of cardiac gated steady state free precession cine pulse sequence of contiguous short axis slices (LAVI1) and area-length method (LAVI2). Methods Thirty-six patients (28 males, age 47.6 ± 16.7 years) who had adequate CMR imaging to analyze LA volumes using the two methods were retrospectively identified. LAVI1 was calculated using Simpson’s stack of discs method on short axis cine images (acquired as 8 mm slices with inter slice gap of 2 mm or 6 mm slices with no gap). LAVI2 was measured using the American Society of Echocardiography guidelines. Qmass software (Medis) was used to trace LA areas and volumes.