Accuracy and precision of echocardiography versus right heart catheterization for the assessment of pulmonary hypertension

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Abstract

Background

Echocardiographic studies have contributed to progress in the understanding of the pathophysiology of the pulmonary circulation and have been shown to be useful for screening for and prognostication of pulmonary hypertension, but are considered unreliable for the diagnosis of pulmonary hypertension. We explored this apparent paradox with rigorous Bland and Altman analysis of the accuracy and the precision of measurements collected in a large patient population.

Methods

A total of 161 patients referred for a suspicion of pulmonary hypertension were prospectively evaluated by a Doppler echocardiography performed by dedicated cardiologists within 1 h of an indicated right heart catheterization.

Results

Nine of the patients (6%) were excluded due to an insufficient signal quality. Of the remaining 152 patients, 10 (7%) had no pulmonary hypertension and most others had either pulmonary arterial hypertension (36%) or pulmonary venous hypertension (40%) of variable severities. Mean pulmonary artery pressure, left atrial pressure and cardiac output were nearly identical at echocardiography and catheterization, with no bias and tight confidence intervals, respectively ± 3 mm Hg, ± 5 mm Hg and ± 0.3 L/min. However, the ± 2SD limits of agreement were respectively of + 19 and − 18 mm Hg for mean pulmonary artery pressure, + 8 and − 12 mm Hg for left atrial pressure and + 1.8 and − 1.7 L/min for cardiac output.

Conclusions

Doppler echocardiography allows for accurate measurements of the pulmonary circulation, but with moderate precision, which explains why the procedure is valid for population studies but cannot be used for the individual diagnosis of pulmonary hypertension.

Section snippets

Background

Doppler echocardiography allows for estimates of pulmonary artery pressure (PAP), left atrial pressure (LAP) and cardiac output (Q), and thus for the calculation of pulmonary vascular resistance (PVR) [1]. Progress in technology and development of portable devices have made it possible to use Doppler echocardiography for the exploration of the effects of environmental stress on the pulmonary circulation, such as exercise [2], [3], [4] and hypoxia [5]. Interestingly, in these studies on normal

Methods

The study enrolled prospectively all consecutive patients referred to Pulmonary Hypertension Unit of Monaldi Hospital, Naples, Italy, between 1st June 2011 and 31st May 2012 for a suspicion of pulmonary hypertension who underwent a right heart catheterization. All of them gave an informed consent to the study, which was approved by the Institutional Review Board. The presence of an uncorrected intra- or extra-cardiac shunt, insufficient quality of echo imaging, an estimated systolic pressure at

Results

Nine out of 161 (5.6%) patients were excluded due to insufficient quality of echo imaging. No patient showed indirect echocardiographic signs of pulmonary hypertension in the presence of an estimated sPAP < 37 mm Hg. The demographics of the other 152 patients are summarized in Table 1. The majority of the patients had pulmonary arterial hypertension (PAH, 36%) or pulmonary venous hypertension (PVH, 40%) on left heart conditions. Ten patients (7%) did not meet the diagnostic criteria for pulmonary

Discussion

The present results indicate that trans-thoracic Doppler echocardiography compared to right heart catheterization is accurate and thus allows for valid population studies, but may be insufficiently precise for the diagnosis and estimation of severity of pulmonary hypertension on an individual basis.

Many previous studies aiming at the validation of Doppler echocardiographic measurements of pulmonary vascular pressures and flows relied on correlation calculations [9], [10], [11], [16], [17], [19]

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    This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation.

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