Association of Borderline Pulmonary Hypertension With Mortality and Hospitalization in a Large Patient Cohort: Insights From the VA-CART Program
Background—Pulmonary hypertension (PH) is associated with increased morbidity across the cardiopulmonary disease spectrum. Based largely on expert consensus opinion, PH is defined by a mean pulmonary artery pressure (mPAP) ≥25 mmHg. Although mPAP levels below this threshold are common among populations at risk for PH, the relevance of mPAP <25 mmHg to clinical outcome is unknown.
Methods and Results—We analyzed retrospectively all US veterans undergoing right heart catheterization (RHC) (2007-2012) in the Veterans Affairs health care system (N=21,727; 908 day median follow-up). Cox proportional hazards models were used to evaluate the association between mPAP and outcomes of all-cause mortality and hospitalization, adjusted for clinical covariates. When treating mPAP as a continuous variable, the mortality hazard increased beginning at 19 mmHg (HR=1.183, 95% CI [1.004-1.393]) relative to 10 mmHg. Therefore, patients were stratified into three groups: referent (≤18 mmHg; N=4,207), borderline PH (19-24 mmHg; N=5,030), and PH (≥25 mmHg; N=12,490). The adjusted mortality hazard was increased for borderline PH (HR=1.23, 95% CI [1.12-1.36], P<0.0001) and PH (HR=2.16, 95% CI [1.96-2.38], P<0.0001) compared to the referent group. The adjusted hazard for hospitalization was also increased in borderline PH (HR=1.07, 95% CI [1.01-1.12], P=0.0149) and PH (HR=1.15, 95% CI [1.09-1.22], P<0.0001). The borderline PH cohort remained at increased risk for mortality after excluding the following high-risk subgroups: patients with pulmonary artery wedge pressure >15 mmHg, pulmonary vascular resistance ≥3.0 Wood units, or inpatient status at the time of RHC.
Conclusions—These data illustrate a continuum of risk according to mPAP level, and that borderline PH is associated with increased mortality and hospitalization. Future investigations are needed to test the generalizability of our findings to other populations and study the effect of treatment on outcome in borderline PH.