Echocardiographic evaluations of right ventriculo-arterial coupling in experimental and clinical pulmonary hypertension

Background: Tricuspid annular systolic excursion (TAPSE) or velocities (s) and right ventricular (RV) end-systolic dimensions are predictors of outcome in patients with pulmonary hypertension (PH). We explored the value of combining peak s and RV end-systolic area index (RVESAi) as a surrogate of RV-pulmonary artery (RV-PA) coupling in a large animal of precapillary PH as well as clinically. Method: The first experimental group included four control and four piglets with thromboembolic disease. RV-PA coupling was assessed by ventricular to arterial elastance ratio (Ees/Ea) at baseline, after esmolol and dobutamine administration. Echocardiographic metrics included s ', TAPSE, fractional area change (RVFAC), and RVESAi. The findings were validated in six piglets with severe PH. Clinical cohorts were stable outpatients (n = 141) and acutely decompensated pulmonary arterial hypertension (n = 48). Results: In the first experimental group, the best linear correlates of Ees/Ea were s ' (R-2 = .51, p < .001) and RVESAi (R-2 = .50, p < .001), while RVFAC (R-2 = .17, p = .01) and TAPSE showed weaker association (R-2 = .21, p = .39). The ratio s '/RVESAi showed nominally but not significantly (higher) association with Ees/Ea (R-2 = .58, p < .01). The association between changes in s '/RVESAi and Ees/Ea was strong (R-2 = .56, p < .001). In more severe PH, Ees/Ea and changes in Ees/Ea correlated significantly with s '/RVESAi and changes in s '/RVESAi (R-2 = .69; p < .001 and R-2 = .64, p < .001, respectively). In the two clinical cohorts, the s '/RVESAi did not emerge as a stronger predictor of outcome than RVESAi. Conclusion: RV s'/RVESAi index represents a reasonable bedside-usable surrogate of RV-PA coupling and of its acute variations in PH. Its incremental prognostic value over end-systolic dimension alone remains to be proven.