Cardiac magnetic resonance-derived left atrioventricular coupling index predicts outcome in reduced ejection fraction

Introduction The left atrioventricular coupling index (LACI) has emerged as a potential prognostic marker in several clinical settings. This study evaluated the prognostic value of cardiac magnetic resonance (CMR)-derived LACI in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). Methods Patients from the multicentre DERIVATE registry with LVEF <50% who underwent CMR were included. LACI was calculated as the ratio between left atrial and left ventricular end-diastolic volumes. Univariable and multivariable Cox regression models estimated hazard ratios (HR) with 95% confidence intervals (CI) for predicting all-cause mortality (ACM), ACM or HF, and HF alone (competing-risk analysis). Time-dependent receiver operating characteristic analysis identified optimal cut-offs for 3-year outcomes. Results A total of 2170 patients were included (mean age 59.8 +/- 13.9 years; 24.7% women; mean LVEF 31.6 +/- 11.3%). Median follow-up was 1016 days (580-1609). Median LACI was 19.4% (13.3-28.8). During follow-up, ACM occurred in 191 patients (8.8%), ACM or HF in 565 (26.0%), and HF in 442 (20.4%). After adjustment for clinical and CMR parameters, including LVEF and late gadolinium enhancement (LGE), each 5% increase in LACI was associated with higher risk of ACM (HR 1.06, 95% CI 1.01-1.11; P = .016), ACM or HF (HR 1.09, 95% CI 1.06-1.12; P < .001), and HF (HR 1.09, 95% CI 1.05-1.12; P < .001). The optimal cut-off for ACM was LACI >= 21% (AUC 0.617, 95% CI 0.561-0.673), identifying patients at higher risk of ACM, ACM or HF, and HF (log-rank P < .001 for all). Conclusion CMR-derived LACI independently predicts ACM and HF in patients with reduced LVEF and provides incremental prognostic value beyond LVEF and LGE. A cut-off of >= 21% identifies higher-risk patients and may support clinical risk stratification.