Evaluation of right ventricular strain in two separate cohorts with precapillary pulmonary hypertension

Abstract

Evaluation for right ventricular (RV) dysfunction is an important part of risk assessment in care of patients with pulmonary hypertension (PH) as it is associated with morbidity and mortality. Echocardiography provides a widely available and acceptable method to assess RV function. RV global longitudinal strain (RVGLS), a measure of longitudinal shortening of RV deep muscle fibers obtained by two-dimensional echocardiography, was previously shown to predict short-term mortality in patients with PH. The purpose of the current study was to assess the performance of RVGLS in predicting 1-year outcomes in PH. We retrospectively identified 83 subjects with precapillary PH and then enrolled 50 consecutive prevalent pulmonary arterial hypertension (PAH) subjects into a prospective validation cohort. Death as well as combined morbidity and mortality events at 1 year were assessed as outcomes. In the retrospective cohort, 84% of patients had PAH and the overall 1-year mortality rate was 16%. Less negative RVGLS was marginally better than tricuspid annular plane systolic excursion (TAPSE) as a predictor for death. However, in the prospective cohort, 1-year mortality was only 2%, and RVGLS was not predictive of death or a combined morbidity and mortality outcome. This study supports that RV strain and TAPSE have similar 1-year outcome predictions but highlights that low TAPSE or less negative RV strain measures are often false-positive in a cohort with low baseline mortality risk. While RV failure is considered the final common pathway for disease progression in PAH, echocardiographic measures of RV function may be less informative of risk in serial follow-up of treated PAH patients.

Keywords: clinical studies; echocardiography; mortality/survival; prognosis; pulmonary hypertension.

Figure 1

Example echocardiogram for right ventricular strain measurement. In this two‐dimensional echocardiogram image, right ventricular septal and free wall segments are identified and global peak systolic longitudinal strain (right ventricular global longitudinal strain) is −13.6%.

Figure 2

Correlation between two objective measures of right ventricular function in patients with pulmonary hypertension. RVGLS and TAPSE were measured in a retrospective cohort of patients with precapillary PH (N = 83) and a prospective cohort of patients with PAH (N = 50). There was fair linear correlation of RVGLS and TAPSE. The R ² for the correlation was 0.35 in the pooled study sample. PAH, pulmonary arterial hypertension; PH, pulmonary hypertension; RVGLS, right ventricular global longitudinal strain; TAPSE, tricuspid annular plane systolic excursion.

Figure 3

Receiver operating characteristic curves for echocardiographic global longitudinal strain as a predictor of outcomes in patients with precapillary pulmonary hypertension. In a cohort of retrospectively identified patients with precapillary PH, the ability of RVGLS measured by echocardiogram was assessed for the ability to discriminate 1‐year outcome. (a) For death as the evaluated outcome, the area under the receiver operating characteristic curve was 0.773 suggesting acceptable discrimination. (b) For the combined outcome of death, transplantation, or additional PH‐directed therapy, the area under the receiver operating characteristic curve was 0.773 suggesting acceptable discrimination. AUC, the area under the receiver‐operating characteristic curve; PH, pulmonary hypertension; RVGLS, right ventricular global longitudinal strain.

Figure 4

Death and disease progression in pulmonary hypertension patients over 1 year stratified by echocardiographic predictor. In a retrospective cohort of 83 patients with precapillary pulmonary hypertension, Kaplan–Meier estimates of survival free from outcome events since the time of index echocardiogram are shown with risk tables showing number at risk. (a, b) Show all‐cause survival stratified by RVGLS and TAPSE, respectively. RVGLS more negative than −12.7% and TAPSE greater than 1.4 cm are each associated with higher survival (log‐rank test p < 0.001 and p = 0.03, respectively). (c, d) Show survival without progression for RVGLS and TAPSE, respectively. Survival without major worsening was defined as being alive without lung transplant or need for additional PAH therapy. Neither RVGLS nor TAPSE were predictive of progression over 1 year (log‐rank test p = 0.42 and p = 0.42, respectively). PAH, pulmonary arterial hypertension; RVGLS, right ventricular global longitudinal strain; TAPSE, tricuspid annular plane systolic excursion.