"Ours is the first study to show that heart rate recovery at 1 minute of rest following a 6-minute walking distance test is a strong predictor of clinical worsening in idiopathic pulmonary arterial hypertension patients," Dr. Omar A. Minai of the Cleveland Clinic said in a statement.
Clinical worsening was defined as death, lung transplantation, hospitalization for worsening pulmonary hypertension or escalation of pulmonary hypertension therapy.
The study enrolled 75 patients diagnosed with idiopathic pulmonary arterial hypertension, confirmed by right heart catheterization. Their heart rate was recorded at the end of the 6-minute walking distance test and then 1 minute after completing the test.
The cutoff value for abnormal heart rate recovery at 1 minute following the 6-minute walking distance test was identified as 16 beats. A greater reduction in heart rate after exercise indicates a better-conditioned heart.
Minai said predicting long-term prognosis in patients with pulmonary arterial hypertension "usually requires analysis of several pieces of data in complicated risk scores.
"This easily measured, cost-free biomarker may ultimately advance patient care in view of its ability to accurately predict clinical worsening even in patients receiving treatment for pulmonary hypertension," he said.
The findings were published online ahead of print publication in the Journal of Respiratory and Critical Care Medicine.
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