Increased Mortality Rates Found in Patients With Borderline Pulmonary Hypertension

Patients with borderline pulmonary hypertension (PH) should be considered an at-risk subgroup with increased mortality compared with patients with lower mean pulmonary arterial pressures, according to a new study published by JAMA Cardiology.

Pulmonary hypertension is diagnosed by a mean pulmonary pressure (mPAP) of at least 25 mm Hg during right heart catheterization (RHC).

“Establishing the clinical profile, prognosis, and natural history of patients with borderline PH identified within a diverse patient population has important ramifications on characterizing the spectrum of clinical risk associated with pulmonary arterial pressures in clinical practice,” wrote the authors.

The authors analyzed a retrospective cohort study from 1998 to 2014 at Vanderbilt University Medical Center, including 4343 patients undergoing routine RHC for clinical inclination. Patients were categorized by mPAP values. Borderline PH was defined as having an mPAP of 19-24 mm Hg. The reference group of patients was defined as having an mPAP value of 18 mm Hg or less. Of the 4343 patients, 2684 were in the PH group, 783 were in the borderline PH group, and 876 were in the reference group.

Diabetes, atrial fibrillation, obstructive sleep apnea, anemia, heart failure, and connective tissue disease were more prevalent in patients with PH. Patients with borderline PH were older with a higher prevalence of metabolic, vascular, cardiac, and pulmonary diseases compared to the reference group.

Authors saw a gradient in the severity of pulmonary hemodynamics across the reference, borderline PH, and overt PH groups, including PVR, pulmonary arterial capacitance, and pulmonary arterial oxygen saturation. Cardiac function—measured by stroke volume, cardiac output, and cardiac index—was similar between the borderline PH and reference groups, but all were lower compared with the PH group.

The authors performed a univariate analysis of the patients with mPAP values less than 25 mm Hg in order to determine clinical echocardiographic factors associated with borderline PH. The analysis was adjusted for 34 demographic, clinical, laboratory, and echocardiographic indices and showed that only older age, higher body mass index, prevalent chronic obstructive pulmonary disease, higher hemoglobin, and increased left atrial diameter were independently associated with a higher likelihood of borderline PH.

The unadjusted mortality was intermediate for borderline PH relative to overt PH and the reference group. The 5-year survival was 59% for overt PH patients, 75% for borderline PH patients, and 83% for reference patients. The risk of all-cause mortality was higher for patients with overt PH and patients with borderline PH than reference patients.

Overall, the authors found that borderline PH is common in patients referred for RHC and is linked to increased cardiopulmonary disease burden and mortality compared with patients with lower mPAP values.

“This work builds on an evolving body of literature that suggests borderline PH is clinically important and reconsideration of the diagnostic classification of PH may be warranted,” concluded the authors.