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

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.