Prognostic value of left atrioventricular coupling index in non-ischemic dilated cardiomyopathy: a cardiovascular magnetic resonance study

Abstract Background Left atrioventricular coupling index (LACI) has been recognized for its prognostic significance across various cardiovascular diseases; however, its role in non-ischemic dilated cardiomyopathy (NIDCM) remains largely unexplored. This study aimed to evaluate the prognostic value of cardiovascular magnetic resonance (CMR)-derived LACI in patients with NIDCM and its ability to improve risk stratification. Methods This prospective, single-center cohort study enrolled 612 patients with NIDCM and 100 age- and sex-matched healthy volunteers who underwent CMR imaging between June 2012 and July 2019. LACI was defined as the ratio of left atrial end-diastolic volume (LAVmin) to left ventricular end-diastolic volume (LVEDV) assessed by CMR. The primary endpoint was a composite of all-cause mortality and heart transplantation. Cox proportional hazards models, Kaplan-Meier survival analysis, and model discrimination assessed by C-index were used to evaluate the prognostic value of LACI. Results During a median follow-up of 63 months, 183 patients reached the primary endpoint. Patients with NIDCM had significantly higher LACI values than healthy volunteers (30 ± 16% vs. 19 ± 6%, P < 0.001). In multivariable Cox regression analysis, LACI was independently associated with the primary endpoint (hazard ratio per 5% increase, 1.05; P = 0.001). A LACI threshold > 30% was associated with an increased risk of the primary endpoint (P < 0.001). Incorporation of LACI into clinical and conventional CMR models (age, sex, systolic blood pressure, New York Heart Association class, left ventricular ejection fraction, left ventricular mass index, and late gadolinium enhancement presence) improved model discrimination (C-index 0.757 vs. 0.738, p < 0.001). The discriminative performance of the LACI-based model was comparable to that of a component-based model including LVEDVi and LAVimin (C-index 0.757 vs. 0.755), further supporting its prognostic utility. Conclusions In patients with NIDCM, higher LACI is independently associated with adverse clinical outcomes and provides modest incremental prognostic information beyond established clinical and CMR parameters. LACI represents a simple and reproducible CMR-derived marker with potential value for risk stratification in NIDCM.