Two-dimensional speckle tracking echocardiography detected interventricular dyssynchrony predicts exercise capacity and disease severity in pre-capillary pulmonary hypertension

BACKGROUND: Right ventricular (RV) intraventricular mechanical dyssynchrony detected by two-dimensional speckle tracking echocardiography (2D-STE) has been reported to be correlated with a decrease in RV contractile efficiency in pulmonary hypertension (PH) patients, while little attention has been paid to biventricular dysfunction. Therefore, we aimed to evaluate the predictive value of 2D-STE detected interventricular dyssynchrony for exercise capacity and disease severity in patients with pre-capillary PH (PcPH). METHODS: Conventional transthoracic echocardiography, 2D-STE and cardiopulmonary exercise tests (CPETs) were performed in all participants. Intra- and interventricular dyssynchrony were calculated as the standard deviation (SD) of the time intervals corrected for heart rate between QRS onset and peak longitudinal strain. Multivariate linear regression analyses were performed to identify independent predictors of peak oxygen consumption (PVO(2)) during the CPET. Multivariable logistical regression modeling was used to analyze the associations between interventricular dyssynchrony and risk assessment. RESULTS: Sixty-six PcPH patients were consecutively recruited (19 male and 47 female, average 35 years old). WHO functional class, N-terminal pro-brain natriuretic peptide (BNP) and body mass index were included as independent predictors in the first multivariate regression analysis of clinical data without echocardiographic parameters (Model-1, r(2)=0.423, P<0.001). We subsequently added conventional echocardiographic parameters and 2D-STE parameters to the clinical data, RV fractional area change (Model-2, r(2)=0.417, P<0.001), RV global longitudinal strain (Model-3, r(2)=0.454, P=0.001), RV intraventricular dyssynchrony (Model-4: r(2)=0.474, P<0.001) and interventricular dyssynchrony (Model-5, r(2)=0.483, P<0.001) were identified as independent predictors of PVO(2). Interventricular dyssynchrony, calculated as the SD of the time intervals of nine segments, was independently associated with risk assessment (odd ratio 1.027, 95% CI: 1.003–1.052, P=0.03). The area under the receiver-operating characteristic curve (AUC) was 0.73 (P<0.001). CONCLUSIONS: Interventricular dyssynchrony detected by 2D-STE contributed to a better evaluation of exercise capacity and disease severity in PcPH patients.