In PAH, pulmonary artery strain may predict risk of death, study finds

Closer monitoring, intensive therapy urged for patients at higher risk

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by Andrea Lobo |

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Among people with pulmonary arterial hypertension (PAH), a measure of artery deformity called pulmonary artery longitudinal strain may be a predictor of risk of death, a study in Singapore reports.

A GLS — or artery global longitudinal strain — below 9% was associated with a higher risk of death. Moreover, the measure was found to have a significantly better prognostic ability when added to standard risk scores.

“Our study has demonstrated an approach for identifying patients with PAH at high risk of death using [pulmonary artery] GLS,” the researchers wrote.

According to the team, those patients at higher risk “may be targeted for closer monitoring and/or intensified therapy.”

The study, “Pulmonary Artery Strain Predicts Prognosis in Pulmonary Arterial Hypertension,” was published in the journal JACC: Cardiovascular Imaging.

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Testing measure’s accuracy in assessing risk of death

PAH is characterized by the narrowing of the blood vessels that transport blood through the lungs, increasing blood pressure.

This might cause the swelling (distension) and stiffening of the pulmonary artery, along with impairments to the right ventricle — the part of the heart that pumps blood to the lungs to pick up oxygen.

A measure reflective of circumferential pulmonary artery strain is predictive of mortality in PAH patients. Research in rats has reported differential changes at early and late stages of the disease.

Now, scientists in the Asian nation Singapore hypothesized that pulmonary artery GLS reflects a combination of artery stiffness and right ventricle function. They sought to determine if pulmonary artery strain could be a prognostic marker in PAH patients.

To that end, the team analyzed longitudinal strain by cardiac magnetic resonance using data from 169 PAH patients retrieved from two patient registries. Data from 82 healthy people, who served as controls, also were used.

The patients’ mean age was 57, and the majority (80%) were women.

Slightly more than half of the patients had PAH associated with a connective tissue disease. Most of the remaining patients had idiopathic PAH, meaning the disease has no identified cause. Connective tissue diseases are a group of conditions that affect the tissues that hold the structures of the body together, such as sclerodermalupus, and rheumatoid arthritis.

Nearly two-thirds of patients (61%) were classified as World Health Organization functional class III-IV, meaning functional impairment during normal activities or even at rest, respectively.

Results showed that pulmonary artery GLS was significantly lower in PAH patients compared with the healthy controls (10% vs. 23%). The right ventricle measures GLS, ejection fraction — the amount of blood pumped every time the heart beats — and TAPSE, an indicator for right ventricle health that is short for tricuspid annular plane systolic excursion, also were lower in the PAH group.

Reduced pulmonary artery GLS was associated with higher disease risk, according to the REVEAL 2.0 and COMPERA 2.0 risk scores. It also correlated with artery stiffness and right ventricle GLS, with both variables being independently associated with pulmonary artery strain.

Pulmonary artery GLS also was a good predictor of disease prognosis, with better performance than right ventricle GLS, ejection fraction, and artery stiffness.

Among the patients, 45 (26.6%) died during the follow-up period, at a median of 34 months or just shy of three years. These patients had shown higher right ventricle functional impairment and higher risk score values.

A multivariate analysis, which analyzes multiple variables to find potential associations among them, identified patients’ age, a higher risk score, and pulmonary artery GLS under 9% as independent mortality predictors in PAH.

Specifically, pulmonary artery GLS less than 9% was associated with a risk of mortality 2.93 times higher than among those with a value of 9% or higher.

We show for the first time that impairment of PA [pulmonary artery] GLS is a significant and independent predictor of mortality in PAH.

Adding pulmonary artery GLS to both REVEAL 2.0 and COMPERA 2.0 significantly increased the prognostic capability of both risk scores.

“We show for the first time that impairment of PA [pulmonary artery] GLS is a significant and independent predictor of mortality in PAH,” the researchers wrote, adding that the measure “provides independent prognostic information as well as incremental prognostic utility in patients with PAH.”

This method offers several advantages over existing methods, according to the researchers. For one, artery strain can be measured noninvasively using routine clinical images, in contrast to other parameters that require invasive methods. Moreover, the quantification of GLS is rapid and reliable, requiring minimal input from the operator.

This “supports its potential role in the clinical management of patients with PAH,” the team concluded.

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