5-Year prognostic value of the right ventricular strain-area loop in patients with pulmonary hypertension

Abstract

Aims: Patients with pre-capillary pulmonary hypertension (PH) show poor survival, often related to right ventricular (RV) dysfunction. In this study, we assessed the 5-year prognostic value of a novel echocardiographic measure that examines RV function through the temporal relation between RV strain (ϵ) and area (i.e. RV ϵ-area loop) for all-cause mortality in PH patients.

Methods and results: Echocardiographic assessments were performed in 143 PH patients (confirmed by right heart catheterization). Transthoracic echocardiography was utilized to assess RV ϵ-area loop. Using receiver operating characteristic curve-derived cut-off values, we stratified patients in low- vs. high-risk groups for all-cause mortality. Kaplan-Meier survival curves and uni-/multivariable cox-regression models were used to assess RV ϵ-area loop's prognostic value (independent of established predictors: age, sex, N-terminal pro B-type natriuretic peptide, 6-min walking distance). During follow-up 45 (31%) patients died, who demonstrated lower systolic slope, peak ϵ, and late diastolic slope (all P < 0.05) at baseline. Univariate cox-regression analyses identified early systolic slope, systolic slope, peak ϵ, early diastolic uncoupling, and early/late diastolic slope to predict all-cause mortality (all P < 0.05), whilst peak ϵ possessed independent prognostic value (P < 0.05). High RV loop-score (i.e. based on number of abnormal characteristics) showed poorer survival compared to low RV loop-score (Kaplan-Meier: P < 0.01). RV loop-score improved risk stratification in high-risk patients when added to established predictors.

Conclusion: Our data demonstrate the potential for RV ϵ-area loops to independently predict all-cause mortality in patients with pre-capillary PH. The non-invasive nature and simplicity of measuring the RV ϵ-area loop, support the potential clinical relevance of (repeated) echocardiography assessment of PH patients.

Keywords: echocardiography; prognostic value; pulmonary hypertension; right ventricular function; ultrasound.

Figure 1

Schematic overview of the RV ϵ-area loop and the derived characteristics. The black line represents the ε-area loop, the thick part represents the systolic phase and the thin line the diastolic phase.

Figure 2

Mean RV ϵ-area loops taken at baseline (i.e. start of the follow-up period) from surviving patients (black ϵ-area loop, n = 98) and deceased patients (grey ϵ-area loop, n = 45). The dotted black lines represent the ϵ-area loop in a control group as published previously. The thick lines represents the systolic phase while the thin lines represent the diastolic phase of the ϵ-area loop.

Figure 3

Kaplan–Meier survival curves (5-year follow-up) in 143 PH patients for individual characteristics of the RV ϵ-area loop that were categorized into low risk (blue line) and high risk (green line). The following loop characteristics were presented: ESslope (A), Sslope (B), peak strain (C), Uncoup (D), EDslope (E), and LDslope (F).

Figure 4

Kaplan–Meier survival curves for (A) the RV loop-score, categorised into low risk (blue line, n = 98) vs. high risk (green line, n = 45), (B) the 2015 ESC/ERS guidelines based model, categorised into low (green line, n = 23), intermediate (yellow line, n = 60), and high risk (red line, n = 39), and (C) the combined RV loop-score and ESC/ERS based model, categorized into low risk (green line, n = 23), intermediate risk (yellow line, n = 60), high risk—low RV loop-score (orange line, n = 20), and high risk—high RV loop-score (red line, n = 19).