Can Echocardiography Assess Pulmonary Hypertension Defined by Lower mPAP Cutoff?

How would the redefinition of pulmonary hypertension, proposed at the 2018 World Symposium on PH, affect echocardiographic prediction of PH?

A recent study, published in the European Respiratory Journal, indicates that the echocardiographic prediction strategy for pulmonary hypertension defined by the 2015 European Respiratory Society (ERS)/European Society of Cardiology (ESC) guidelines would remain a valid prediction strategy for pulmonary hypertension even when using the new cutoff value for defining PH that was proposed at the 5th World Symposium on Pulmonary Hypertension (WSPH) in 2018.

The WSPH proposed using a cutoff value of mean pulmonary artery pressure (mPAP) greater than 20 mm Hg for defining PH, rather than the currently-used cutoff value of an mPAP of at least 25 mm Hg, which was established by the 2015 ERS/ESC guidelines. Notably, the 2018 WSPH proposed guideline continues to define pulmonary vascular disease similarly to the ERS/ESC guidelines, with a pulmonary vascular resistance (PVR) of greater than 3 Wood units.

In the current study, researchers sought to compare the current and proposed mPAP cutoffs for defining PH (mPAP >20 mmHg vs mPAP ≥25 mmHg), as well as to explore the possibility of using a lesser value for defining pulmonary vascular disease (PVR >2 Wood units vs PVR >3 Wood units). The decision to assess the alternative Wood value was based on previous research suggesting that 2 Wood units is the upper limit of normal and that higher values are associated with decreased life expectancy.  Researchers said they expected the lower cutoffs for mPAP and PVR to be used for diagnosis of PH in the future.

The study included 396 consecutive patients were referred to the Pulmonary Hypertension Unit of Monaldi Hospital in Naples, Italy, from January 1, 2018, through December 31, 2019, for suspected PH. All individuals underwent a clinical evaluation that included comprehensive echocardiography. Of these patients, 278 underwent a right heart catheterization, which was performed at rest without sedation. In 5.4% (15 of 278) of these individuals, the quality of the echocardiography was insufficient for additional analysis. Therefore, a total of 263 patients were retrospectively assessed in the current study.

Results of the study showed that when PH was redefined by an mPAP of >20 mm Hg, 23 participants had no PH, 146 participants had precapillary PH, and 94 had postcapillary PH. This redefinition of PH decreased the “no PH” group from 40 to 23 participants and increased the precapillary PH group from 129 to 146 participants; the number of patients in the postcapillary PH group remained unchanged, at 94. 

Per univariate analysis, a maximum velocity of tricuspid regurgitation (TRV) of ≥2.9 m/s and ≤3.4 m/s, a left ventricle (LV) eccentricity index of >1.1, a right ventricle (RV) outflow tract (OT) notching or acceleration time of <105 ms, an RV-LV basal diameter of >1, and a pulmonary artery (PA) diameter were all predictive of PH; however, an inferior vena cava diameter and right atrial area did not predict PH.

Based on multivariable analysis, only a TRV of ≥2.9 m/s was independently predictive of PH. Additional independent prediction of PVR of >3 Wood units was provided by an LV eccentricity index of >1.1 and a right ventricular OT acceleration time of <105 ms and/or notching, but with no improvement in the optimal combination of specificity and sensibility or positive prediction. 

The results of this study validate those of the previously proposed echocardiographic strategy to predict pH in the 2015 ERS/ESC guidelines, with a central role played by TRV and the additional value of other estimates of PAP or PA, IVC, or right heart chamber dimensions. The investigators concluded that “the echocardiographic prediction strategy of PH as defined in the 2015 ERS/ESC guidelines is valid for the new definition of PH based on a mPAP >20 mmHg. The clinical probability of pulmonary vascular disease by either a PVR >3 or >2 Wood units can adequately be assessed by

the same combination of measurements, with however more indirect signs when a cut-off value for PVR of 2 Wood units is to be taken into consideration.”

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.  


D’Alto M, Di Maio M, Romeo E, et al. Echocardiographic probability of pulmonary hypertension: a validation study. Eur Respir J. Published online January 7, 2022. doi:10.1183/13993003.02548-2021