Clinical implications of different methods to assess left atrial remodeling: A comparative study between echocardiography and cardiac magnetic resonance imaging for left atrial volume index quantification

Background: Left atrial volume index (LAVI) serves as a crucial marker for assessing left atrial (LA) remodeling, particularly in patients with mitral valve regurgitation (MR). Recent guidelines recommend a LAVI exceeding 60 mL/m² as Class IIa recommendation for mitral valve repair surgery in asymptomatic MR patients with preserved left ventricular function. Traditionally, echocardiography is the standard for assessing LAVI in MR patients. However, cardiac magnetic resonance imaging (CMR) is increasingly recognized for its more precise measurements of cardiac dimensions and volumes. But still, literature remains scarce on comparing the efficacy of both modalities in assessing LAVI measurements.

Methods: This retrospective study included 168 MR patients undergoing both echocardiography and CMR assessments within a six-month period. LAVI measurements were compared using Pearson correlation and Bland-Altman plots. Patients were stratified based on MR grades, and clinical implications were assessed.

Results: Mean LAVI differed significantly between echocardiography and CMR (47.1 ± 20.8 mL/m² versus 70 ± 20.3 mL/m², p < 0.001, respectively). CMR consistently yielded higher LAVI measurements compared to echocardiography, with a mean difference of approximately 20 mL/m². CMR measurements resulted in an increased incidence of patients meeting the class IIa LAVI criterion (LAVI >60 mL/m²) by 37%. Variations in LAVI did not differ across MR grades.

Conclusion: Echocardiography systematically underestimates LAVI compared to CMR in MR patients. While current guidelines rely on echocardiography, CMR's precision suggests the need for CMR-specific LAVI cutoff values to guide clinical management effectively. Establishing such values could refine patient stratification and timing of surgery, potentially improving clinical outcomes for MR patients.