Nearly 1 in 10 lupus patients also develop pulmonary arterial hypertension (PAH), a condition where the blood pressure is too high in the arteries that go from the heart to the lungs, according to researchers.
But despite it being life-threatening, the condition may remain undiagnosed if there are no symptoms, suggesting that lupus patients should be actively monitored for the development of PAH.
A research team at the Mashhad University of Medical Sciences in Iran suggests that the levels of pro b-type natriuretic peptide (proBNP) could be an effective, noninvasive approach for the early diagnosis of asymptomatic PAH in lupus patients.
The study, “Correlation of echocardiographic findings of pulmonary hypertension with six-minute walk test and plasma pro b-type natriuretic peptide level in systemic lupus erythematous,” was published in the Electronic Physician Journal.
More clinicians are recognizing that systemic lupus erythematosus (SLE) can be accompanied by the complications of PAH, which may remain undiagnosed due to its nonspecific symptoms such as shortness of breath, fatigue, irregular heartbeat, and syncope (temporary loss of consciousness). If left undiagnosed, PAH can lead to higher rates of morbidity and death.
The gold standard for the diagnosis of PAH is known as right heart catheterization (RHC). But this is a fairly invasive and expensive detection method, which makes it an inconvenient tool to use. Echocardiography, which is a method of visualizing the organ, is a safe, sensitive, and specific tool for the diagnosis of PAH.
Therefore, the researchers set out to determine the prevalence of PAH in lupus patients using echocardiography. They also evaluated the use of pulmonary function tests, the six-minute walk test (6MWT), and proBNP levels as screening tests for PAH. Levels of proBNP were found to be an accurate biomarker of PAH in previous studies.
The study included 50 lupus patients from the Rheumatology Clinic at the Imam Reza Hospital in Mashhad, Iran, from July 2013 to September 2014. Echocardiography was used to determine the systolic pulmonary artery pressure (sPAP), which was then used to determine a diagnosis of PAH.
Results showed that approximately 10 percent, or five out of 50 lupus patients, were diagnosed with PAH, based on the criteria that sPAP is greater than 30 mmHg.
While pulmonary function tests did not show any significant difference in PAH-lupus and lupus patients, results from the 6MWT did. Patients with lupus alone walked at 484.76 meters, compared to 443.20 meters in patients with PAH and lupus.
Patients with PAH-lupus had a mean serum proBNP level of 347 pg/ml, while patients with lupus alone had a mean serum proBNP level of 72.16 pg/ml.
Interestingly, there was a correlation between high sPAP and high serum proBNP levels, but not with 6MWT results. This suggests that proBNP could be a valuable biomarker for the early diagnosis of PAH in lupus patients.
One of the limitations of the study is that the lupus patients had overall mild PAH, which could be masking some significant differences.
“All five of the patients diagnosed with PAH in our study had sPAP less than 40 mmHg, suggesting that PAH in this study was predominantly mild with no symptoms,” the researchers wrote. “To confirm these results, larger cohort studies on SLE-PAH patients with more severe PAH disease should be conducted.”
“We recommend regular evaluation of patients with SLE, regardless of disease duration, for the development of PAH,” the authors concluded.