E/e' Ratio in Patients With Unexplained Dyspnea: Lack of Accuracy in Estimating Left Ventricular Filling Pressure

Abstract

Background: Elevated left ventricular filling pressure is a cardinal feature of heart failure with preserved ejection fraction. Mitral E/e' ratio has been proposed as a noninvasive measure of left ventricular filling pressure. We studied the accuracy of E/e' to estimate and track changes of left ventricular filling pressure in patients with unexplained dyspnea.

Methods and results: We performed supine and upright transthoracic echocardiography in 118 patients with unexplained dyspnea who underwent right heart catheterization. Supine E/e' ratio modestly but significantly correlated with supine pulmonary arterial wedge pressure (PAWP; r=0.36; P<0.001) and demonstrated poor agreement with PAWP values (Bland-Altman limits of agreement of -8.3 to 8.3 mm Hg; range, 6.5-21.2 mm Hg). Similarly, E/e' ratio cut off of 13 performed poorly in identifying patients with elevated left ventricular filling pressure (sensitivity 6%, specificity 90%). The receiver-operating characteristic area of E/e' was 0.65 (95% confidencce interval, 0.50-0.79). With change from the supine to upright position, PAWP decreased (-5±4 mm Hg; P<0.001) as did both E wave (-17±15 cm/s; P<0.001) and e' (-2.7±2.7 cm/s; P<0.001) velocities, whereas E/e' remained stable (+0.2±2.6; P=0.57). Positional change in PAWP correlated modestly with change in E-wave (r=0.37; P<0.001) velocity. There was no appreciable relationship between change in PAWP and change in average E/e' (r=-0.04; P=0.77) and in half the patients the change in PAWP and E/e' were directionally opposite.

Conclusions: In patients with unexplained dyspnea, E/e' ratio neither accurately estimates PAWP nor identifies patients with elevated PAWP consistent with heart failure with preserved ejection fraction. Positional changes in E/e' ratio do not reflect changes in PAWP.

Keywords: dyspnea; echocardiography; heart failure; hemodynamics; pulmonary wedge pressure.

© 2015 American Heart Association, Inc.

Figures

Figure 1

Relationship between PAWP measured by RHC and estimated by E/e’ ratio. Legend: The modest correlation between the PAWP derived by E/e’ and directly measured by RHC is shown in the scatter plot (A). The Bland-Altman plot (B) demonstrates no bias, but wide a limits of agreement (±7.7 mmHg).

Figure 2

Response of E wave, e’ average and E/e’ ratio to PAWP changes (supine to upright). Both E wave (A) and e’ average (B) had a positive correlation to PAWP changes, although the latter was not statistically significant. No linear relationship between E/e’ ratio and PAWP (C) was found.

Figure 3

Supine PAWP by average E/e’ ratio groups using the recommended cut-off of 13. Despite the observed differences of mean PAWP (11±4 vs 14±6 mmHg; p=0.001), the overlap between groups is significant.