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Heart Rate Recovery Predicts Clinical Worsening in Pulmonary Hypertension
Heart rate recovery at one minute after a six-minute walking distance (6MWD) test is highly
predictive of clinical worsening and time to clinical worsening in patients with idiopathic
pulmonary arterial hypertension (IPAH), according to a new study.
“Ours is the first study to show that heart rate recovery at one minute of rest (HRR1) following a
6MW test is a strong predictor of clinical worsening in IPAH patients,” said Omar A. Minai,
MD, staff physician in the Department of Pulmonary, Allergy, and Critical Care Medicine at the
Cleveland Clinic. “Predicting long-term prognosis in these patients 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.”
The findings were published online ahead of print publication in the American Thoracic
Society’s American Journal of Respiratory and Critical Care Medicine.
The study enrolled 75 patients with a diagnosis of IPAH, confirmed by right heart
catheterization. Heart rate was recorded at the end of the 6MW test and then one minute after
completing the test. Clinical worsening was defined as any of the end points of death, lung
transplantation, hospitalization for worsening PH, or escalation of PH therapy. The cutoff value
for abnormal HRR at one minute following the 6MW test was identified as 16 beats. A greater
reduction in heart rate after exercise indicates a better-conditioned heart.
“Patients with HRR1 <16 were significantly more likely to have clinical worsening events and
also had significantly shorter time to clinical worsening (6.7 months versus 13 months) than
those patients with HRR1≥16,” according to Dr. Minai. “The odds of clinical worsening were
significantly greater among patients with HRR1 <16 at all time points during follow-up.”
HRR1<16 was a better predictor of clinical worsening than 6MWD alone, and when added to
6MWD improved the ability of 6MWD to predict time to clinical worsening. “HRR1<16 was
also associated with known predictors of poor prognosis in IPAH,” Dr. Minai added. “Patients
with HRR1<16 were more likely to need supplemental oxygen during the 6MW test, be in World
Health Organization functional class 4, and have more severe right ventricular dysfunction and
pericardial effusion.”
The study had some limitations, including its retrospective design. In addition, the time lag
between right heart catheterization and the 6MW test may have biased the results, because
treatment may have altered baseline hemodynamic parameters.
“HRR1 is highly predictive of clinical worsening and time to clinical worsening in patients with
IPAH,” concludes Dr. Minai, “and is highly correlated with known indicators of poor prognosis
in these patients. Clinical worsening and time to clinical worsening have been used as end-points
in a number of clinical trials in patients with IPAH. The strong predictive ability of HRR1 in
these patients could make it a valuable new tool for measuring treatment response. Further study
in larger prospective studies will better define its role in both IPAH and other forms of PAH.”
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About the American Journal of Respiratory Research and Critical Care Medicine:
With an impact factor of 10.191, the AJRRCM is a peer-reviewed journal published by the
American Thoracic Society. It aims to publish the most innovative science and the highest
quality reviews, practice guidelines and statements in the pulmonary, critical care and sleeprelated fields.
Founded in 1905, the American Thoracic Society is the world's leading medical association
dedicated to advancing pulmonary, critical care and sleep medicine. The Society’s 15,000
members prevent and fight respiratory disease around the globe through research, education,
patient care and advocacy.
Contact for article: Omar A. Minai, MD, Department of Pulmonary, Allergy, and Critical Care
Medicine Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio, 44195.
Phone: 216-445-2610
Email: minaio@ccf.org