P947The ratio between tricuspid regurgitant velocity and right outflow tract velocity integral is a surrogate for the total pulmonary resistance and not for pulmonary vascular resistance

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Purpose: It is important to recognize increased right ventricular afterload as this affects treatment and prognosis in both left and right heart disease. The ratio between tricuspid regurgitant velocity (TRV) and right outflow tract velocity integral (VTI-RVOT) has been proposed as a surrogate for pulmonary vascular resistance (PVR). This ratio does not take the pulmonary capillary wedge pressure (PCWP) or right atrial pressure into consideration. Therefore, we hypothesized: 1) The TRV/VTI-RVOT ratio correlate better with the total pulmonary resistance (TPR) and 2) The estimated TPR from echocardiography data can be used to diagnose increased TPR (>5 WU).Methods: Echo and right heart catheterization were performed within one week in 108 patients. Pulmonary artery (PA) systolic pressure, cardiac output and right atrial pressure were assessed using standard echocardiography. The PA mean pressure was estimated using a regression equation (PAMP=0.65PASP-1.2). Doppler TPR was calculated as PAMP/CO. Cut-off values were generated using receiver-operating characteristics curve analysis.Results: The mean±SD age was 52±14 years, 44% were female. Forty-six percent had left heart disease, 21% were heart transplant patients and 18% had PA hypertension. Fifty-seven percent had increased TPR at catheterization. The linear relation between PVR and TRV/VTI-RVOT was weak (Figure). The AUC/sensitivity/specificity/negative and positive predictive values for TPR>5 WU was for TRV/VTI-RVOT 0.88/84%/76%/78%/83% (cut-off >0.21) and for Doppler TPR 0.95/90%/78%/85%/85% (cut off >5 WU).Conclusions: The TRV/VTI-RVOT ratio is not a surrogate for PVR but can be used to identify increased TPR. However, TPR can be calculated from echocardiography data with good diagnostic performance.

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