Increased left atrial volume index is an independent predictor of raised serum natriuretic peptide in patients with suspected heart failure but normal left ventricular ejection fraction: implication for diagnosis of diastolic heart failure

Background: Left atrial volume index (LAVI) is increasingly recognised as a relatively load-independent marker of left ventricular (LV) filling pressures. We assessed the capacity of LAVI to predict LV diastolic dysfunction in comparison with N-terminal pro B-type natriuretic peptide (NTproBNP) in patients with suspected heart failure and a normal ejection fraction (EF). Methods: 137 patients with suspected heart failure (HF), referred from the community for echocardiography, prospectively underwent Doppler echocardiography, LAVI and NTproBNP estimation. Raised LAVI and reduced LV systolic function were defined as >26 ml/m2 and LV EF <50% respectively. Results: Of 137 patients, 21 were excluded (2 with significant mitral valve disease and 19 with atrial fibrillation). Of the remaining 116 subjects, 92 showed normal LV systolic function. The univariate predictors of serum log NTproBNP were age (p<0.001), LA dimension (p=0.001), LAVI (p<0.001), A wave (p=0.001), E:A (p=0.07) and septal wall thickness (p=0.004). However on multivariate analysis, LAVI was found to be the most consistent and significant predictor of NTproBNP. The area under the curve of the receiver operating characteristic (ROC) curve for NTproBNP in detecting patients with LVEF =50percnt; and LAVI >26ml/m2 was 0.81 (p<0.0001) and for patients with LAVI >26ml/m2 with and without LVEF =50% was 0.82 (p<=0.0001). Conclusion: This data confirms that LAVI on resting echocardiography, specifically in patients with suspected HF and normal LV systolic function is a powerful independent predictor of LV diastolic dysfunction as predicted by serum NTproBNP. In a population with a high suspicion of diastolic heart failure, LAVI may significantly contribute to diagnostic precision.