Echocardiographic assessment of left atrioventricular coupling index: technical approaches and clinical implementation strategies

Background: The Left Atrioventricular Coupling Index (LACI) is an emerging echocardiographic parameter for assessing left atrial and ventricular diastolic function. While accumulating evidence supports its prognostic value, technical standardization for clinical implementation remains lacking. Methods: This narrative review compares four LACI measurement approaches: two-dimensional echocardiography (2DE), real-time three-dimensional echocardiography (RT-3DE), speckle-tracking echocardiography (STE), and artificial intelligence (AI)-assisted analysis. We evaluate technical characteristics, standardization challenges, and evidence gaps. Results: Two-dimensional ultrasound is optimal for screening; RT-3DE shows highest consistency with cardiovascular magnetic resonance for precise diagnosis, and 3DE-LACI has demonstrated independent prognostic value in cardiac amyloidosis. STE aids mechanistic exploration but requires algorithmic standardization. AI demonstrates potential but needs multicenter validation. Key limitations include absent cross-platform calibration, fragmented reference values, and lack of externally validated cutoffs. Conclusion: LACI is a promising marker of diastolic function with proven prognostic value; however, technical heterogeneity and inconsistent thresholds have hindered its clinical application. Future efforts should focus on cross-manufacturer standardization, the establishment of reference values for specific populations, and randomized controlled trials evaluating LACI as a guide for treatment.