Clinical Significance Of Left Atrial Ejection Fraction Measured By Mri In Patients With Suspected Heart Failure

Introduction: Left atrial (LA) dimensions and volumes are important markers of cardiac dysfunction and portend an adverse cardiovascular outcome for patients with heart failure (HF), but LA function is rarely measured. Methods: Out-patients referred with suspected heart failure between 2000 and 2010 who underwent cardiac magnetic resonance imaging (CMRI) were included in this analysis. HF was defined as the presence of relevant symptoms and signs and evidence of cardiac dysfunction: either a left ventricular ejection fraction (LVEF) 400 pg/ml (or >125 pg/ml for patients taking loop diuretics). LAEF was defined as (LA maximum volume-LA minimum volume)/LA maximum volume and was measured in both 2 and 4 chamber views. Results: Of 982 patients enrolled, 191 had atrial fibrillation, whilst 127 were considered not to have heart failure. The median (IQR) LAEF was 42 (31-51)% in patients with HF (in sinus rhythm) and 55 (48-61)% in patients with no HF (p<0.001). Comparing patients with HF in the lowest (23; IQR: 17-28%) and highest quartile of LAEF (56; IQR: 53-61%), those in the lowest quartile had lower LV and right ventricular (RV) EF, and increased LV and RV mass, as well as higher plasma NTproBNP. Overall, Log [LAEF] and log [NTproBNP] were correlated (r=-0.410, p<0.001). Of patients who had LAEF measured (those in sinus rhythm), 202 died during a median follow up of 1390 days (IQR: 763-2342). In a multivariable Cox regression model, LAEF, but not LVEF, was independently associated with an adverse outcome (HR for 10% change: 0.81 (95% CI: 0.74-0.90), p=0.001). NTproBNP and LAEF competed in the model with each providing similar prognostic information. During a median follow up of 1282 days (IQR: 701-2197), 101 patients developed atrial fibrillation (AF). Age (HR for 10 year change: 1.62 (95% CI: 1.23 - 2.14) p<0.001) and LAEF (HR for 10% change: 0.81 (95% CI: 0.66-0.90), p=0.044) were the only variables that independently predicted incident AF. Conclusions: In patients referred with suspected heart failure, LAEF identifies those with a higher risk of AF and an adverse outcome.