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

BACKGROUND: Pulmonary hypertension (PH) is defined as a mean pulmonary arterial pressure (PAP) ≥25 mm Hg measured by right heart catheterization. However, the upper limit of a normal mean PAP is 20 mm Hg. There is a gap between the upper limit of normal and the threshold for diagnosing PH. Therefore, we aimed to investigate whether individuals with a mildly elevated PAP, defined as 20 mm Hg < mean PAP <25 mm Hg, are at an increased risk of progression to PH or mortality than those with a normal PAP. METHODS AND RESULTS: We reviewed studies evaluating the risk of progression to PH and/or mortality in individuals with a mildly elevated PAP versus those with a normal PAP. The mean PAP value of each participant was confirmed by right heart catheterization. We reviewed 1213 studies and 8 fulfilled our inclusion criteria. Our results indicated that individuals with a mildly elevated PAP were 1.81 to 2.45 times more likely to progress to PH than individuals with a normal PAP. There was a statistically significant difference in mortality between the mildly elevated PAP and normal PAP groups (hazard ratio, 2.48; 95% CI, 1.69–3.64). We also pooled survival probabilities in each arm to obtain a summary survival curve for each group, and the pooled survival rates in the mildly elevated PAP group were numerically lower than those in the normal PAP group. CONCLUSIONS: Our study 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.