Echocardiographic assessment of pulmonary arterial capacitance predicts mortality in pulmonary hypertension.

BACKGROUND: Pulmonary arterial capacitance (PAC) is one of the strongest predictors of clinical outcomes in patients with pulmonary hypertension (PH). We examined the value of an echocardiographic surrogate for PAC (ePAC) as a predictor of mortality in patients with PH. METHODS: We performed a retrospective study of 302 patients with PH managed at a PH comprehensive care center over a cumulative follow-up time of 858 patient-years. Charts from 2004 to 2018 were reviewed to identify patients in whom a right heart catheterization (RHC) was performed within two months of an echocardiogram. Standard invasive, non-invasive, functional, and biochemical prognostic markers were extracted from the time of RHC. The primary outcome was all-cause mortality. Cox proportional hazards models were used to model the time from RHC to the primary outcome or last medical contact. RESULTS: Variables associated with all-cause mortality included ePAC [standardized hazard ratio (HR) 0.68, 95% CI 0.48-0.98, p = 0.036], RHC-PAC (HR 0.68, 95% CI 0.48-0.96, p = 0.027), echocardiographic pulmonary vascular resistance (HR 1.29, 95% CI 1.05-1.60, p = 0.017), six-minute walk distance (HR 0.43, 95% CI 0.23-0.82, p = 0.01), and B-type natriuretic peptide (HR 1.29, 95% CI 1.03-1.62, p = 0.027). In multivariable-adjusted Cox analysis, ePAC predicted all-cause mortality independently of age, gender, and multiple comorbidities. There was a graded and stepwise association between low (<0.15 cm/mmHg), medium (0.15-0.25 cm/mmHg), and high (>0.25 cm/mmHg) tertiles of ePAC and all-cause mortality. CONCLUSIONS: We have demonstrated that ePAC is a readily available echocardiographic marker that independently predicts mortality in PH, and have provided clinically relevant ranges by which to risk-stratify patients and predict mortality.