Prognostic Value of Follow-Up Hemodynamic Variables After Initial Management in Pulmonary Arterial Hypertension

Hemodynamic variables such as cardiac index and right atrial pressure have consistently been associated with survival in pulmonary arterial hypertension (PAH) at the time of diagnosis. Recent studies have suggested that pulmonary arterial compliance may also predict prognosis in PAH. The prognostic importance of hemodynamic values achieved after treatment initiation is less well established.

Our objective was to evaluate the prognostic importance of clinical and hemodynamic variables during follow-up, including pulmonary arterial compliance, after initial management in PAH. We evaluated incident patients with idiopathic, drug- and toxin-induced, or heritable PAH enrolled in the French pulmonary hypertension registry between 2006 and 2016 who had a follow-up right-sided heart catheterization (RHC). The primary outcome was death or lung transplantation. We used stepwise Cox regression and the Kaplan-Meier method to assess variables obtained at baseline and at first follow-up RHC.

Of 981 patients, a primary outcome occurred in 331 patients (33.7%) over a median follow-up duration of 2.8 years (interquartile range, 1.1-4.6 years). In a multivariable model considering only baseline variables, no hemodynamic variables independently predicted prognosis. Median time to first follow-up RHC was 4.6 months (interquartile range, 3.7-7.8 months). At first follow-up RHC (n=763), New York Heart Association functional class, 6-minute walk distance, stroke volume index (SVI), and right atrial pressure were independently associated with death or lung transplantation, adjusted for age, sex, and type of PAH. Pulmonary arterial compliance did not independently predict outcomes at baseline or during follow-up. The adjusted hazard ratio for SVI was 1.28 (95% confidence interval, 1.11-1.49; P<0.01) per 10-mL/m² decrease and for right atrial pressure was 1.05 (95% confidence interval, 1.02-1.09; P<0.01) per 1-mm Hg increase. Among patients who had 2 (n=355) or 3 (n=193) low-risk prognostic features at follow-up, including a cardiac index ≥2.5 L·min^-1·m^-2, 6-minute walk distance >440 m, and New York Heart Association class I or II functional class, lower SVI was still associated with higher rates of death or lung transplantation (P<0.01).

SVI and right atrial pressure were the hemodynamic variables that were independently associated with death or lung transplantation at first follow-up RHC after initial PAH treatment. These findings suggest that the SVI could be a more appropriate treatment target than cardiac index in PAH.