Background: Several echocardiographic methods to estimate pulmonary vascular resistance (PVR) in patients with pulmonary hypertension (PH) have been proposed. So far, most studies have focused on relatively low PVR. We aimed to clarify the clinical usefulness of our new echocardiographic index of evaluating markedly elevated PVR in pre-capillary PH patients. Methods: We studied 129 consecutive patients with pre-capillary PH. We estimated the mean pulmonary artery pressure using echocardiography

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... (mPAPEcho) and measured LV internal diameter at end diastole (LVIDd). The ratio of mPAPEcho / LVIDd was then correlated with invasive PVR. Using receiver operating characteristic curve analysis, a cutoff value for the index was generated to identify patients with PVR > 15 Wood units (WU). Results: mPAPEcho / LVIDd correlated well with PVR (r = 0.70, P < 0.0001). There was a better correlation between PVR and mPAPEcho / LVIDd in patients with PVR > 15 WU compared with TRV2 /TVIRVOT and sPAPEcho / LVIDd. A cut-off value of 1.14 had an 80.0% sensitivity and 74.7% specificity to determine PVR > 15 WU (AUC=0.840, p<0.0001). Conclusions: The index of mPAPEcho / LVIDd could be a valuable noninvasive and simple method of estimating markedly elevated PVR in pre-capillary PH patients.