The Use of Transthoracic Echocardiogram to Quantify Pulmonary Vascular Resistance in Patients with Systemic Sclerosis
Abstract
Objective To explore the accuracy of tricuspid regurgitation velocity (TRV) to right ventricular outflow tract time-velocity integral (VTIRVOT) ratio by Doppler to determine pulmonary vascular resistance (PVR) in patients with systemic sclerosis (SSc).
Methods Thirty-five consecutive adult SSc patients, fulfilling the 2013 European League Against Rheumatism/American College of Rheumatology classification criteria, with sinus rhythm referred for right heart catheterisation (RHC) were retrospectively included. All patients underwent a transthoracic echocardiogram performed within 24 hours of right heart catheterisation. SSc patients were recruited regardless of disease activity, cardiac symptoms and treatment regimen. Doppler measurements were compared to RHC measurements. A linear regression equation was generated to predict PVR by echocardiogram based on the TRV/TVIRVOT ratio. The accuracy of Doppler measurements for predicting PVR > 3 Wood units was assessed by computing the areas under the receiver operating characteristic (ROC) curves.
Results There were 20 (57%) females in the study. The mean age was 65±12 years. Mean and systolic pulmonary arterial pressures were 31±8 and 53±15 mmHg, respectively. There was a good correlation between TRV/ VTIRVOT ratio assessed by Doppler and PVR measured by RHC (R=0.743, P<0.001). The equation generated by this analysis was: PVR by Doppler = 11.3 × (TRV/TVIRVOT) + 1.7. A cutoff value of 0.21 for TRV/TVIRVOT ratio provided the best sensitivity (86%) and specificity (86%) to determine PVR > 3 Wood units.
Conclusion Our study suggests that transthoracic echocardiogram using Doppler could be a usefull and non-invasive tool for estimating PVR in patients with SSc.