The exercise capacity of people with scleroderma who have yet to develop pulmonary arterial hypertension (PAH) diminishes over time, according to an Austrian study.
Their lung function during exercise also deteriorates little by little, researchers at the Medical University of Graz reported.
The findings raise the question of whether PAH treatment in this patient group could prevent deterioration of lung function, and even prevent development of PAH, the team said.
The study, “Changes in pulmonary exercise haemodynamics in scleroderma: a 4-year prospective study,” was published in the European Respiratory Journal.
To see what happens to scleroderma patients’ lung function over time, the researchers followed 99 patients over four years.
Only 58 stayed in the study to the end. Seventy-six percent had limited cutaneous scleroderma, 16 percent diffuse cutaneous disease, and 9 percent mixed connective tissue disease.
All patients were examined at the start and end of the research. None had PAH when the study began, but three developed it over the four years.
The patients’ average lung artery pressure during exercise increased between the first and second examinations. In addition, their peak oxygen consumption during exercise increased, and they had slightly higher levels of NT-proBNP, a factor associated with heart disease.
In contrast, the blood pressure in their lung artery during rest did not increase.
A subgroup of 28 patients had at least two right heart catheterization examinations — a procedure to diagnose cardiovascular conditions, including PAH. Researchers also discovered an increase in their mean pulmonary artery pressure and an increase in their resistance to blood flow in the lung vessels during exercise. In addition, their lung blood pressure increased in relation to the amount of blood their heart pumped out during each beat.
Again, researchers observed no deterioration in these measures when patients were at rest.
Although only three patients developed PAH, the results suggested that the group as a whole was progressing toward lung vascular disease.
“Scleroderma patients without PAH develop a mild but significant deterioration of pulmonary exercise hemodynamics [blood flow] and exercise capacity over a four-year follow-up period, indicating a progression of pulmonary vascular disease,” the researchers wrote.
Since the changes were seen only during exercise, researchers argued that measures during exercise might be more sensitive barometers of deterioration than examinations at rest.
At one point, the team speculated that some patients’ exercise capacity had not deteriorated more than it had because they were taking Tracleer (bosentan). Tracleer is a PAH drug, but is often prescribed to treat digital ulcers in scleroderma patients. Twenty-eight percent of those in the study were using it by the end.
The evidence failed to support the speculation because Tracleer users’ deterioration was similar to that in those who were not using the drug. Nearly a third of the patients were also treated with immunosuppressive drugs.
Researchers said clinical trials are needed to understand how drugs used to treat scleroderma influence patients’ risk of developing pulmonary hypertension.
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