Imaging right ventricular function to predict outcome in pulmonary arterial hypertension

Abstract

Background Right ventricular (RV) function is a major determinant of outcome in pulmonary arterial hypertension (PAH). However, uncertainty persists about the optimal method of evaluation. Methods We measured RV end-systolic and end-diastolic volumes (ESV and EDV) using cardiac magnetic resonance imaging and RV pressures during right heart catheterization in 140 incident PAH patients and 22 controls. A maximum RV pressure (Pmax) was calculated from the nonlinear extrapolations of early and late systolic portions of the RV pressure curve. The gold standard measure of RV function adaptation to afterload, or RV-arterial coupling (Ees/Ea) was estimated by the stroke volume (SV)/ESV ratio (volume method) or as Pmax/mean pulmonary artery pressure (mPAP) minus 1 (pressure method) (n=84). RV function was also assessed by ejection fraction (EF), right atrial pressure (RAP) and SV. Results Higher Ea and RAP, and lower compliance, SV and EF predicted outcome at univariate analysis. Ees/Ea estimated by the pressure method did not predict outcome but Ees/Ea estimated by the volume method (SV/ESV) did. At multivariate analysis, only SV/ESV and EF were independent predictors of outcome. Survival was poorer in patients with a fall in EF or SV/ESV during follow up (n=44, p=0.008). Conclusion RV function to predict outcome in PAH is best evaluated by imaging derived SV/ESV or EF. In this study, there was no added value of invasive measurements or simplified pressure-derived estimates of RV-arterial coupling.

Simple functional imaging of the right ventricle in pulmonary hypertension: Can right ventricular ejection fraction be improved?

“…The increased resolution of SV/ESV in subjects with a relatively normal RVEF could be important in identifying and stratifying at-risk individuals (subjects with a RVEV above cut-off value in red in Figure 1A). From the relationship between RVEF and SV/ESV, an RVEF of 0.35 corresponds to a SV/ESV of 0.539 which is similar to cut-off values of 0.515 and 0.534 that were found to be associated with increased mortality in patients referred for pulmonary hypertension (6,11). It is not surprising both RVEF and SV/ESV are predictive of outcomes below a cutpoint but the nonlinear relationship suggests a possible explanation of why SV/ESV could be more predictive because it widens the physiological range of values allowing for more resolution.…”

“…In patients referred for pulmonary hypertension and who underwent a right heart catheterization and imaging of RV volumes, when both SV/ESV and EF were determined, SV/ESV, not EF emerged as an independent predictor of outcome (6,11). We wondered if this discrepancy could have happened by chance.…”

Pulmonary Pulse Wave Transit Time is Associated with Right Ventricular–Pulmonary Artery Coupling in Pulmonary Arterial Hypertension

“…[23][24][25][26] In a subgroup of patients (n = 8) who had cardiac magnetic resonance imaging (MRI), we also estimated RV-PA coupling using cardiac MRI-based volume method defined as endsystolic volume divided by stroke volume. 27,28 Table S1 lists the 3 formulae used to estimate RV-PA coupling.…”

Novel Noninvasive Assessment of Pulmonary Arterial Stiffness Using Velocity Transfer Function

“…Assessments of ventricular mass, volumes, and function were then obtained, as previously described 15, 16. RV‐PA coupling was assessed by a ratio of RV end‐systolic elastance (Ees)/arterial elastance (Ea) that was estimated by “volume” method (Ees/Ea=RV stroke volume/end systolic volume) 17, 18. Although the volume method underestimates Ees/Ea, it strongly correlates to Ees/Ea and appears to be a better predictor of PAH outcome 18, 19.…”

“…Although the volume method underestimates Ees/Ea, it strongly correlates to Ees/Ea and appears to be a better predictor of PAH outcome 18, 19. Ees was estimated as RV end systolic pressure/end systolic volume, and Ea was estimated as RV end systolic pressure/stroke volume 17, 18, 19, 20, 21. One patient completed only phase‐contrast portion of CMR and did not complete cine CMR because of claustrophobia.…”