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

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.

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).

In the first experimental group, the best linear correlates of Ees/Ea were s' (R²  = .51, p < .001) and RVESAi (R²  = .50, p < .001), while RVFAC (R²  = .17, p = .01) and TAPSE showed weaker association (R²  = .21, p = .39). The ratio s'/RVESAi showed nominally but not significantly (higher) association with Ees/Ea (R²  = .58, p < .01). The association between changes in s'/RVESAi and Ees/Ea was strong (R²  = .56, p < .001). In more severe PH, Ees/Ea and changes in Ees/Ea correlated significantly with s'/RVESAi and changes in s'/RVESAi (R²  = .69; p < .001 and R²  = .64, p < .001, respectively). In the two clinical cohorts, the s'/RVESAi did not emerge as a stronger predictor of outcome than RVESAi.

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.