FLOW-CORRECTED ESTIMATES OF PULMONARY PRESSURE FOR THE ASSESSMENT OF DIASTOLIC DYSFUNCTION IN PATIENTS WITH UNEXPLAINED DYSPNEA

Objective: An echocardiographic diastolic stress test (DST) may be useful in subjects with unexplained exertional breathlessness. The E/e′ ratio and tricuspid regurgitant jet velocity (TRV) are used to differentiate normal vs abnormal responses. However, absence of flow-corrected estimates of pulmonary pressure may reduce the diagnostic performance of the test. We sought to compare flow-corrected and flow-uncorrected estimates of pulmonary pressure during exercise in consecutive patients undergoing a DST, using as gold-standard reference exercise right heart catheterization (RHC). Design and method: Retrospective analysis of patients undergoing a DST. Echo estimates of mean pulmonary artery pressure (PAP) and cardiac output (Q) were used to generate PAP/Q relationship during exercise. The slope of the latter and the ratio between mean PAP and Q at peak exercise (TPR) were used as flow-corrected estimates of abnormal response of the pulmonary circulation. In a subset of patients, P/Q slope and TPR obtained at RHC were compared with echocardiographic results. Results: Out of 38 patients with tricuspid regurgitation during exercise, all had TRV > 2.8 m/s so that none could be classified to have normal diastolic function at exercise; 92% had “indeterminate” diastolic function. When a flow-corrected estimate of PAP was used, the DST could be defined “normal” in 6 cases (17%, with both TPR < 3 and P/Q slope <3). P/Q slope and TPR were both >3 in 18 subjects, nine of whom underwent also exercise RHC, allowing confirmation of HFpEF in 78% of them. When comparing the results of the 15 patients undergoing both DST and exercise RHC, we found a correlation between invasive measurements and non-invasive estimate of P/Q slope (R = 0.70) and TPR (R = 0.66). Echocardiographic estimates of P/Q slope and TPR were accurate as compared with RHC measurements, but showed large confidence intervals (figure 1).Conclusions: Our preliminary data suggest that flow-corrected estimates of pulmonary pressure might provide additional pathophysiological information during a noninvasive DST, but suffer of large limits of agreement as compared with RHC.