By Michael H. Crawford, MD
Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco
Dr. Crawford reports no financial relationships relevant to this field of study.
SYNOPSIS: In patients with pulmonary hypertension evaluated in a specialty clinic, echo/Doppler estimation of left ventricular end-diastolic pressure is not reliable for the determination of pre- vs. post-capillary pulmonary hypertension.
SOURCE: Cameron DM, McLaughlin VV, Rubenfire M, et al. Usefulness of echocardiography/Doppler to reliably predict elevated left ventricular end-diastolic pressure in patients with pulmonary hypertension. Am J Cardiol 2017;119:790-794.
If left ventricular end-diastolic pressure (LVEDP) can be estimated accurately by echocardiography/Doppler techniques, it could obviate the need for heart catheterization to distinguish pre- and post-capillary pulmonary hypertension (PH) and to determine volume status in PH patients. Cameron et al retrospectively evaluated 161 consecutive PH patients undergoing clinically indicated heart catheterization who were subjected to an echo/Doppler within three months of the cath and had no changes in medications or rhythm during the interval between tests. The 2009 American Society of Echocardiography (ASE) guidelines were used to identify patients with elevated LVEDP (> 15 mmHg). To improve the performance of the 2009 ASE guidelines, a new model also was developed using multivariate binary logistic regression analysis. The study patients exhibited a median mean pulmonary artery pressure of 34 mmHg and a pulmonary vascular resistance of 3.7 Wood units. An LVEDP > 15 mmHg was found in 81 patients. Median time between echo and cath was 23 days. The sensitivity and specificity as well as the positive and negative predictive values for detecting LVEDP > 15mmHg by the 2009 ASE criteria ranged from 54-66%. Only grade 3 diastolic dysfunction had an LVEDP significantly different from the other two grades (22 vs. 16, 15, 17 mmHg for grades 0, 1, 2, respectively; P < 0.05). The new model with the best performance yielded higher values between 63-68%, with sensitivity at 68%. This model used only three variables: left atrial diameter, E/A wave mitral valve inflow velocities, and E/e’ tissue Doppler velocities on the septal side of the mitral annulus. The receiver operating curve for this model was 0.70. The authors concluded that echo/Doppler estimation of LVEDP in patients with PH does not perform adequately enough to identify patients with elevated LVEDP.
COMMENTARY
This paper offers important clinical implications. Even though many echo/Doppler diastolic parameters correlate statistically with LVEDP, in the setting of patients referred to a specialty clinic to determine the etiology of PH, these parameters alone or in combination failed to reliably identify patients with post-capillary PH. This is important because the treatment of post-capillary PH is different from that of other causes. Although many echo/Doppler measures are associated with LVEDP, the correlations are weak. In fact, mitral inflow velocity E/A demonstrated the best correlation coefficient at R = 0.19. Also, one would expect the LVEDP to rise with ascending levels of diastolic dysfunction. However, only the highest grade (3) was significantly associated with elevated LVEDP. Cameron et al tried to develop a better model to predict LVEDP and found a three-variable model that was somewhat better than the ASE criteria, but it was not reliable enough (sensitivity 68%, specificity 63%). In 2016, the ASE revised the diastolic function guidelines. The changes were small and using these new criteria the performance was somewhat worse (sensitivity 51%, specificity 67%).
There are some limitations to this study. The echo and cath were not performed simultaneously or even on the same day. Thus, it is possible that lifestyle changes could have affected LVEDP between the two tests. However, patients were excluded who had any change in diuretics or PH medications and if they went into atrial fibrillation. Also, not all patients underwent left heart catheterization, so it was assumed that pulmonary capillary wedge pressure was a reasonable approximation of LVEDP. In addition, the authors did not adjudicate the classification of the PH patients, but relied on the caring clinicians’ determination. The largest of the PH groups were WHO class one (44%), but about one-third of these patients also exhibited an elevated LVEDP. This could have been a misclassification or, since this was a referral specialty clinic for PH, some may have had very high right ventricular pressures, which caused compression of the left ventricle, elevating its filling pressure. The bottom line is that echo/Doppler is not a reliable substitute for heart catheterization in distinguishing pre- from post-capillary PH.
In patients with pulmonary hypertension evaluated in a specialty clinic, echo/Doppler estimation of left ventricular end-diastolic pressure is not reliable for the determination of pre- vs. post-capillary pulmonary hypertension.
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