An estimated right ventricular systolic pressure (eRVSP) — a measure of the pressure inside the artery that supplies blood to the lungs (pulmonary artery) — greater than 30.0 mmHg is related to an increased risk of mortality in patients with pulmonary hypertension (PH), according to a new Australian study.
The study, “Threshold of Pulmonary Hypertension Associated With Increased Mortality,” was published in the Journal of the American College of Cardiology.
Currently, there are significant limitations in therapies available to patients with PH. Consequently, a diagnosis of PH is associated with poor long-term outcomes. Even patients with mild PH are at an increased risk of mortality — one study found that mild PH patients have 1.52 times the risk of mortality compared to the general population.
Borderline PH is defined as having an average pulmonary arterial pressure between 20 and 25 mmHg. Given the rapid progression of borderline PH to clinically define PH (defined as pulmonary arterial pressure greater than 25 mmHg), researchers are starting to recognize the importance of identifying patients who are at increased risk of progressing, and those who could benefit from disease-specific therapies.
Hence, there is a need to identify “optimal cutoffs,” or thresholds, for pulmonary arterial pressure that can be easily used to identify at-risk populations with PH. “There is increasing evidence that current thresholds for diagnosing pulmonary hypertension underestimate the prognostic impact of PH,” the researchers said.
The researchers conducted a study (ACTRN12617001387314) to determine the long-term outcomes and prognostic impact of increasing pulmonary pressures in patients with PH within the National Echocardiography Database of Australia cohort.
Echocardiography is the first-line diagnostic and screening tool for PH, as it can help assess eRVSP levels. Using echocardiography, researchers were able to examine the association between short- and long-term mortality with increasing pulmonary pressures.
Researchers evaluated eRVSP levels for 74,405 men and 83,437 women who were, on average, 65.6 years of age.
Overall, results indicated that 17,955 (11.4%) patients had mild PH (40-49 mmHg), 7,016 (4.4%) patients had moderate PH (50-59 mmHg), and 4,515 (2.9%) patients had severe PH (60 mmHg or more).
Researchers confirmed previous data by showing that 9.4% of patients with eRVSPs higher than 40 mmHg had almost three times the risk for 5-year mortality. Additionally, an increased mortality risk in patients with mild or borderline PH was found.
After conducting statistical analysis and adjusting the results for age, sex, and evidence of left heart disease, researchers were able to establish a clear and consistent threshold of increased mortality that corresponded to an eRVSP of 30.0 mmHg or above.
In fact, patients with eRVSP levels between 30.0-39.9 mmHg were, after adjusting for other factors, 1.4 to 1.9 times more likely to die compared to patients with lower eRVSP levels.
“Our unique findings suggest that those currently considered to be at intermediate risk for underlying PH have a significant risk for mortality once they reach the threshold of eRVSP [higher than] 30.0 mm Hg,” the researchers concluded.
The team said that “future studies should characterize patients with borderline PH on the basis of eRVSP to determine the mechanisms of excess mortality, and evaluate the efficacy of therapeutic interventions to prolong survival.”