Clinical Relevance of Spectral Tissue Doppler-Derived E/E' in the Diagnosis of Heart Failure with Preserved Ejection Fraction

Despite experts' recommendations issued in 2007, the diagnosis of heart failure with preserved ejection fraction (HFpEF) remains difficult in daily practice and is based on the combination of preserved left ventricular ejection fraction (>50%) with abnormally elevated B-type natriuretic peptide levels and/or diastolic dysfunction at transthoracic Doppler echocardiography or catheterization. While the spectral tissue Doppler-derived E/e' ratio is considered to play a key role through a multi-parametric approach in this setting, its diagnostic relevance has recently been questioned because of poor correlations with invasive left ventricular filling pressures reported by some authors.1 Accurate measurement of invasive left ventricular filling pressures may be difficult, given the modest correlations and wide scatter between pulmonary capillary wedge pressures and left ventricular end-diastolic pressures.2 In this context, it appears of outstanding importance to highlight that the diagnostic relevance of E/e' has been established in the diagnosis of HFpEF by using clinical scores as diagnostic reference. A first work by Dokainish et al.3 reported the accuracy of this Doppler index in the diagnosis of HFpEF according to the Framingham criteria. Of the 46 patients with preserved ejection fraction, 19 had a clinical diagnosis of heart failure, and average E/e' > 15 had a sensitivity and specificity of 79% and 93%, respectively, in the diagnosis. Of note, E/e' performed similarly and independently to B-type natriuretic peptide levels. Other clinical studies have confirmed the diagnostic relevance of E/e' in this setting, irrespective of rhythm.4-7 In a study by Lam et al.6 that included 808 consecutive patients, septal E/e' > 12.5 had a sensitivity and specificity of 70% and 85%, respectively, in the diagnosis of HFpEF according to the Framingham criteria. Furthermore, this Doppler index emerged as a powerful predictor of this condition in multivariate analysis.6 In a work by Watanabe et al.7 that focused on 73 patients with atrial fibrillation in New York Heart Association functional class I to IV, septal E/e' > 11.7 had a sensitivity and specificity of 87% and 93%, respectively, in the diagnosis of HFpEF according to the Framingham criteria, and performed similarly to B-type natriuretic peptide levels and left atrial area. In the specific context of isolated exercise intolerance, the diagnostic relevance of E/e' is strengthened by its significant, inverse relation to peak oxygen consumption that has been reported in patients with HFpEF.8 In conclusion, irrespective of any controversy about correlations with invasive pressures, the large body of evidence at our disposal that links E/e' to clinical scores and functional capacity makes this user-friendly Doppler index one of the most simple and accurate non-invasive parameters to date for the diagnosis of HFpEF in daily clinical practice.