We read with great interest the report by Abbas et al . titled “Noninvasive Assessment of Pulmonary Vascular Resistance by Doppler Echocardiography,” as we have recently published a derivation and validation study of a single equation to estimate pulmonary vascular resistance (PVR). The intellectual foundation for our work stems largely from the pioneering report Abbas et al . published in 2003. Their earlier work elegantly steered the echocardiographic evaluation of pulmonary circulation toward estimating PVR, but this approach has not been widely implemented in clinical practice. This could be explained by the lack of accuracy with high PVR values, an issue addressed in their recent update. We would suggest, though, that equally problematic are the nonintuitive cutoffs and the lack of absolute agreement with invasive measurements of PVR. Requiring the use of an algorithm, no matter how straightforward, to choose one of two different equations adds complexity and makes widespread use in standard practice less likely.
We derived and validated, in independent samples of 108 and 109 subjects referred for clinical evaluation of pulmonary hypertension, a single, straightforward model accurate across the wide range of PVR seen in clinical practice:
PVR = PASP RVOT VTI + 3 if midsystolic notching of the RVOT envelope is present