What is the accuracy of elevated Right Ventricular Systolic Pressure (RVSP) on Transthoracic Echocardiogram (TTE) in diagnosing pulmonary hypertension?

From the Guidelines

Elevated right ventricular systolic pressure (RVSP) on transthoracic echocardiography (TTE) is moderately accurate for diagnosing pulmonary hypertension, with sensitivity and specificity that can guide clinical decision-making, as noted in the 2015 ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension 1.

Key Points to Consider

• RVSP is calculated using the tricuspid regurgitation velocity and estimated right atrial pressure, with values above 35-40 mmHg suggesting possible pulmonary hypertension.
• The accuracy of RVSP can be affected by several factors, including the quality of the acoustic window, presence of significant tricuspid regurgitation, and proper alignment of the Doppler beam.
• For definitive diagnosis of pulmonary hypertension, right heart catheterization (RHC) remains necessary as it directly measures pulmonary artery pressure and allows classification of pulmonary hypertension type.
• TTE should be considered a screening tool that identifies patients who may need further evaluation with RHC, especially when clinical suspicion is high or when specific treatment decisions depend on accurate pressure measurements.

Clinical Application

The 2015 ESC/ERS guidelines suggest grading the probability of pulmonary hypertension based on tricuspid regurgitation velocity at rest and the presence of additional pre-specified echocardiographic variables suggestive of pulmonary hypertension 1.

Limitations and Considerations

• Technical challenges in obtaining adequate tricuspid regurgitation signals and operator dependence can limit the accuracy of TTE.
• Potential over- or underestimation of pressures is a consideration, highlighting the need for careful interpretation of TTE results in the context of clinical symptoms and other diagnostic findings.
• The guidelines recommend using the continuous wave Doppler measurement of peak tricuspid regurgitation velocity as the main variable for assigning the echocardiographic probability of pulmonary hypertension, rather than relying solely on estimated pulmonary artery systolic pressure (PASP) 1.

From the Research

Accuracy of Elevated Right Ventricular Systolic Pressure (RVSP) on Transthoracic Echocardiogram (TTE)

• The accuracy of elevated RVSP on TTE in diagnosing pulmonary hypertension is limited, with studies suggesting that RVSP alone is not a reliable predictor of pulmonary hypertension 2, 3.
• A study found that using RVSP in conjunction with parameters from pulmonary function tests (PFTs) and computed tomography (CT) scans can more accurately predict the presence or absence of pulmonary hypertension than RVSP alone 2.
• Another study found that the optimal RVSP threshold for screening pulmonary hypertension could not be detected, and that the performance characteristics of RVSP were only slightly improved when assessed in combination with PFT and 6-minute walk test parameters 3.
• The use of echocardiography to estimate pulmonary vascular resistance (PVR) has been found to be useful in diagnosing and following up pulmonary hypertension, but it may underestimate high PVR values 4.
• A recent study highlighted the importance of confirming significant pulmonary hypertension with right heart catheterization (RHC) in patients with suspected pulmonary hypertension based on echocardiography, as many patients with elevated RVSP on echocardiography did not have significant pulmonary hypertension on RHC 5.

Factors Affecting Accuracy

• The accuracy of RVSP on TTE can be affected by various factors, including the quality of the acoustic imaging window, the presence of lung disease, and the expertise of the operator 3, 5.
• The use of multiple parameters, including RVSP, PFTs, and CT scans, can improve the accuracy of diagnosing pulmonary hypertension 2.
• The development of new echocardiographic indices, such as the corrected pulmonary vascular resistance (PVR(c)), may provide more accurate estimates of pulmonary vascular resistance and help identify patients with significant pulmonary hypertension 4.

Clinical Implications

• The limited accuracy of RVSP on TTE highlights the importance of confirming significant pulmonary hypertension with RHC in patients with suspected pulmonary hypertension 3, 5.
• The use of echocardiography as a screening tool for pulmonary hypertension should be interpreted with caution, and patients with suspected pulmonary hypertension should undergo further evaluation with RHC to confirm the diagnosis 5.
• The development of new echocardiographic indices and the use of multiple parameters may improve the accuracy of diagnosing pulmonary hypertension and help identify patients who require further evaluation and treatment 2, 4.