Low Risk of PH With Pregnancy Linked to Better Overall Heart Health

Pregnant women with high pressure in the pulmonary artery of the heart, but who are not considered at risk of pulmonary hypertension (PH), are likely to also be at lower risk of other major cardiac problems, researchers reported.

In this study, the level of PH probability was judged based on an echocardiogram — a non-invasive and common test for PH that uses sound waves to show how the heart is working. Its findings suggest this test could help to identify those at higher PH risk, who may require further invasive testing and specialized medical care.

The study, “Correlation of echocardiographic probability of pulmonary hypertension with maternal outcomes in pregnant women with elevated right ventricular systolic pressure,” was published in the journal Echocardiography.

To help doctors define how likely PH is to occur in a person based on an echocardiogram, the European Society of Cardiology (ESC) published a series of criteria in 2015. However, these guidelines have not yet been applied to pregnant women — a population in which PH is associated with various adverse outcomes.

Researchers at The Ohio State University investigated the medical records of women who had had their heart assessed during a pregnancy, and applied the ESC criteria to see if they could provide an accurate picture of the level of probability for developing PH.

“This is the first study to use simplified ESC criteria to correlate echocardiographic PH probability with outcomes in pregnant women,” the researchers wrote.

The study included 77 women, mean age of 30, who while pregnant had a right ventricular systolic pressure (RVSP) greater than 35 mmHg (millimeter of mercury) or a tricuspid regurgitant velocity (TRV) equal to or greater than 2.8 meters per second.

Both RVSP and TRV are used to estimate the pressure inside the artery that pumps blood into the lungs, and a high pressure in this artery is indicative of PH. They are also used to grade the level of probability of PH according to the ESC criteria.

An RVSP of 35 mmHg is the “upper limit of normal” for the public at large, the study noted, but “44 mmHg has been reported as the upper limit of normal in pregnant women.”

Of the 77 women, 45 (58%) were considered to have an intermediate to high probability of developing PH, and 32 (42%) were considered to have a low probability.

Researchers then looked at some medical characteristics between the two groups. They found that pre-existing high blood pressure, or hypertension, was more common among women with an intermediate-to-high PH probability than in women with a low probability (55% versus 25%).

Echocardiograms in these two groups also showed that major adverse cardiac events (MACE) — a combined measure of adverse events relating to the heart — and poorer pregnancy outcomes were more frequent in women with a greater PH risk than in those with a low risk. MACE includes such events as heart failure, a heart attack, and sustained ventricular arrhythmias (abnormal, rapid heart beats), while pregnancy outcomes includes pre-eclampsia (a complication characterized by high blood pressure and high protein levels in the urine), preterm birth, and low birth weight.

Importantly, the scientists found that the simplified ESC criteria for intermediate-to-high PH risk identified women also at risk for MACE with an 85% sensitivity and 52% specificity, suggesting these criteria are useful for risk stratification. Sensitivity refers to the ability of a test to correctly identify people with a certain condition, while specificity is the ability to correctly identify people without that condition.

Women with a high RVSP during pregnancy but at low risk of developing PH had a 91% probability of also not having a MACE.

In the same way as an echocardiogram is used to estimate the likelihood of PH happening — rather than providing a definite diagnosis — the risk of MACE should not be excluded in women with a low probability of PH, the researchers noted.

Still, “while the use of echocardiographic PH probability should not be used in isolation to exclude the possibility of MACE, this may provide a tool for clinicians to further risk-stratify pregnant women when an elevated RVSP is identified on echocardiogram,” they wrote.

“These criteria, along with clinical risk factors, and evaluation of [heart health], could be used to determine the need for tertiary care referral, guide management in resource-constrained settings, and aid in decision-making for cardiac catheterization [a procedure to examine the heart] in this population where invasive testing is not without significant risk,” they added.