Left atrial size may predict exercise capacity and cardiovascular events in patients with heart failure

Abstract

Our aim was to investigate, in patients with heart failure, the relationship between left atrial size and exercise capacity and cardiovascular events. Seventy-five patients (67 men and 8 women; mean age, 53.4 +/- 8.8 yr) with left ventricular ejection fractions of < or =0.45 (New York Heart Association functional classes I-III) were matched by age and sex with 20 healthy control subjects. Echocardiographic examinations were performed, as was exercise testing by the modified Bruce protocol. Patients were monitored for a period of 330 to 480 days for cardiac death or for heart failure that required hospitalization. The indexed left atrial diastolic size (beta level = -0.534, P <0.001) and left ventricular late diastolic filling velocity (beta level = 0.247, P <0.017) were the most important values in predicting low exercise capacity. The only independent predictor of low exercise capacity (<5 METS) was the indexed left atrial diastolic size (odds ratio, 1.428; 95% confidence interval, 1.09-1.702; P <0.001). Every 1 mm/m2 increase in indexed left atrial diastolic dimension caused a 42.8% increase in the risk of severe heart failure (exercise capacity, <5 METS). Independent predictors for cardiovascular events were indexed as left atrial systolic size (odds ratio, 1.383; 95% confidence interval, 1.145-1.671; P <0.001) and left ventricular early diastolic/late diastolic filling velocity (odds ratio, 1.096; 95% confidence interval, 1.010-1.189; P <0.027). Indexed left atrial diastolic and left atrial systolic size predict exercise capacity and cardiovascular events, respectively, in New York Heart Association functional class I through III heart failure patients.

Keywords: Atrial function, left/physiology; ROC curve; cardiac output; cardiomegaly, dilated/ultrasonography; diastole; exercise test; exercise tolerance/physiology; exertion; heart atria; heart failure; myocardial contraction; predictive value of tests; prognosis; stroke volume; systole.

Fig. 1 A) Receiver operating characteristic analysis for indexed LAd dimension, as used in predicting exercise capacity, B) indexed LAd dimension, in predicting cardiovascular events, C) indexed LAs dimension, in predicting cardiovascular events, and D) left ventricular Em/Am, in predicting cardiovascular events. AUROC = area under receiver operating characteristic curve; CI = confidence interval; Em/Am = ratio of velocities of early (Em) and late (Am) diastolic waves; LA = left atrium; LAd = LA chamber at its greatest dimension (i.e., LA is at diastole and LV is at end-systole); LAs = LA chamber at its smallest dimension (i.e., LA is at systole and LV is at end-diastole); LV = left ventricle