Clinical utility and prognostic value of left atrial volume assessment by cardiovascular magnetic resonance in non-ischaemic dilated cardiomyopathy

Aims: Echocardiographic studies have shown that left atrial volume (LAV) predicts adverse outcome in small heart failure (HF) cohorts of mixed aetiology. However, the prognostic value of LAV in non-ischaemic dilated cardiomyopathy (DCM) is unknown. Cardiovascular magnetic resonance (CMR) allows accurate and reproducible measurement of LAV. We sought to determine the long-term prognostic significance of LAV assessed by CMR in DCM.

Methods and results: We measured LAV indexed to body surface area (LAVi) in 483 consecutive DCM patients referred for CMR. Patients were prospectively followed up for a primary endpoint of all-cause mortality or cardiac transplantation. During a median follow-up of 5.3 years, 75 patients died and 9 underwent cardiac transplantation. After adjustment for established risk factors, LAVi was an independent predictor of the primary endpoint [hazard ratio (HR) per 10 mL/m(2) 1.08; 95% confidence interval (CI) 1.01-1.15; P = 0.022]. LAVi was also independently associated with the secondary composite endpoints of cardiovascular mortality or cardiac transplantation (HR per 10 mL/m(2) 1.11; 95% CI 1.04-1.19; P = 0.003), and HF death, HF hospitalization, or cardiac transplantation (HR per 10 mL/m(2) 1.11; 95% CI 1.04-1.18; P = 0.001). The optimal LAVi cut-off value for predicting the primary endpoint was 72 mL/m(2). Patients with LAVi >72 mL/m(2) had a three-fold elevated risk of death or transplantation (HR 3.00; 95% CI 1.92-4.70; P < 0.001). LAVi provided incremental prognostic value for the prediction of transplant-free survival (net reclassification improvement 0.17; 95% CI 0.05-0.29; P = 0.002).

Conclusions: LAVi is a powerful independent predictor of transplant-free survival and HF outcomes in DCM. Assessment of LAV improves risk stratification in DCM and should be incorporated into routine CMR examination.