Borderline pulmonary hypertension linked to increased mortality

Patients with borderline pulmonary hypertension (PH) demonstrated poorer survival than those with lower arterial pressures, according to research published Oct. 25 in JAMA: Cardiology.

In a study of 4,343 patients, unadjusted five-year survival rates for normal mean pulmonary arterial pressure (mPAP), borderline PH and PH were 83 percent, 75 percent and 59 percent, respectively. Lead researcher Tufik R. Assad, MD, and colleagues retrospectively studied individuals undergoing right heart catheterization at Vanderbilt University Medical Center from 1998 to 2014.

The authors noted each incremental increase in mPAP was associated with greater risk of death, with the most pronounced effects occurring at the lower levels of mPAP.

“Small increases in mPAP, even at values currently considered normal, are independently associated with increased mortality,” they wrote.

Patients were defined as having PH if they tested for at least 25 millimeters of mercury. Tests of 19 to 24 mm HG represented borderline PH, while vales of 18 or lower constituted the study’s reference group.

After covariate adjustment, patients in the borderline PH and PH cohorts had increased mortality risks of 31 and 70 percent, respectively, when compared to the reference group.

“Our findings suggest that borderline PH is an early and intermediate pulmonary vascular phenotype in patients with exposure to numerous PH risk factors,” Assad and colleagues wrote. “The clinical profile of our cohort suggests most patients with borderline PH have existing or early left heart failure, rather than early PAH (pulmonary arterial hypertension). Additional studies are needed to determine whether the mortality risk in patients with borderline PH can be modified, for example, by aggressive treatment of left heart disease and the attendant clinical risk factors.”

The authors noted their study built on previous research by analyzing borderline PH with a younger and more gender-balanced sample. The median age of their cohort was 61, and 49 percent of patients were women.

In addition, the research added to the body of evidence that “borderline PH is clinically important and reconsideration of the diagnostic classification of PH may be warranted.” Assad et al. pointed out a group of experts “empirically and arbitrarily” came up with the 25 mm Hg threshold for PH in 1973, but that limit may be too far above the mean mPAP in healthy patients, which is 14 mm Hg.