E/e′ Ratio in Patients With Unexplained Dyspnea

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.