Heart Rate Response Predicts 6-Minutes Walking Distance in Pulmonary Arterial Hypertension

Area of Science:

• Cardiopulmonary Exercise Testing
• Clinical Exercise Physiology
• Pulmonary Hypertension Research

Background:

• The 6-minute walking distance (6MWD) is influenced by effort, which is hard to quantify.
• Pulmonary arterial hypertension (PAH) patients have reduced exercise capacity compared to healthy individuals.
• Standardizing the 6-minute walking test (6MWT) is crucial for accurate assessment.

Purpose of the Study:

• To identify the optimal indicator of perceived effort during the 6MWT.
• To investigate factors associated with 6MWD in PAH patients and healthy controls.
• To determine if heart rate response can improve exercise capacity assessment.

Main Methods:

• Prospective enrollment of 76 PAH patients and 152 healthy participants.
• Participants performed two 6MWTs: one at leisure speed and one at standard, increased speed.
• Multiple linear regression analysis was used to identify predictors of 6MWD.

Main Results:

• The ratio of heart rate change to resting heart rate (ΔHR/HR_{at rest}) was significantly higher after standard 6MWT.
• ΔHR/HR_{at rest} independently predicted 6MWD in both groups.
• PAH patients and those with higher cardiac functional class showed lower 6MWD and ΔHR/HR_{at rest}.

Conclusions:

• ΔHR/HR_{at rest} is a reliable indicator of combined physical and effort factors during the 6MWT.
• Incorporating heart rate response into 6MWD assessment enhances the evaluation of exercise capacity.
• This approach is valuable for both clinical populations like PAH and healthy individuals.