Mildly High Pulmonary Arterial Pressure Linked to Risk of PH

People with mildly elevated pulmonary arterial pressure (PAP) are at higher risk of progression to pulmonary hypertension (PH) than are those with normal readings, according to a review study.

These people should be more closely monitored, and further study is needed to understand how best to treat them to avoid progression, its researchers wrote.

The study, “Mildly Elevated Pulmonary Arterial Pressure Is Associated With a High Risk of Progression to Pulmonary Hypertension and Increased Mortality: A Systematic Review and Meta‐Analysis,” was published in the Journal of the American Heart Association.

PH is currently defined as a mean PAP of 25 mmHg or higher, as measured by right heart catheterization (RHC) — a method to assess how well the heart is pumping, and to evaluate pressure in the heart and lungs. However, the upper limit of a normal mean PAP is 20 mmHg, meaning there is a gap between the upper limit of normal and the threshold for diagnosing PH.

Researchers at Chinese Academy of Medical Sciences and Peking Union Medical College investigated whether individuals with a mildly elevated PAP, defined as mean PAP between 20 and 25 mmHg, are at greater risk of PH progression or mortality than those with a normal PAP.

The team performed a systematic review and meta-analysis of studies evaluating the risk of developing PH and/or mortality in people with a mildly elevated PAP. This type of review and analysis is a pooled examination of data taken from a number of independent sources.

A search identified 1,213 studies, all published before March 31, 2020. Eight, published between 2012 and 2019, met the researchers’ defined criteria — such as mean PAP measured by RHC — and were included in their analysis.

Data covered a total of 2,015 people (64% to 87% female, mean or median age ranging from 56.2 to 71.2 across studies). Among these patients, 802 had a normal PAP, 333 a mildly elevated PAP, and 880 were diagnosed with PH. All had been followed for a mean of 2.1 to 4.2 years.

Analysis of four studies showed that individuals with mildly elevated PAP were 1.81 to 2.45 times more likely to progress to PH during follow-up than those with a normal arterial pressure in the lungs.

In seven studies, the researchers found that the risk of all-cause of mortality to be 2.48 times more likely in people with mildly elevated PAP than in those with normal PAP.

Pooled survival rates, analyzed in six studies, were also poorer in the mildly elevated PAP group than in the normal PAP group at one year (97% vs. 97.7%), three years (89.4% vs. 93.3%), five years (77% vs. 88.8%), seven years (64.5% vs. 81%), and nine years (49.6% vs. 74.9%).

Study findings “revealed that individuals with a mildly elevated PAP were at an increased risk of progression to PH and mortality than those with a normal PAP,” the investigators wrote.

“Our results suggest that individuals with a mildly elevated PAP should receive more attention and closer follow-up than they do currently,” they added. “Further studies concerning the time-to-progression to PH and proper management for individuals with a mildly elevated PAP are needed.”

This last point was emphasized by the researchers, who noted that “early treatment is beneficial in patients with pulmonary arterial hypertension,” while its potential in “individuals with a mildly elevated PAP has not yet been verified.”