Relationship between chronotropic incompetence and β-blockers based on changes in chronotropic response during...

Area of Science:

• Cardiology
• Exercise Physiology

Background:

• Chronotropic incompetence (CI) is a common condition in cardiovascular disease patients, characterized by an inadequate heart rate (HR) increase during physical activity.
• Assessing CI is crucial for optimizing exercise capacity and rehabilitation outcomes in these individuals.

Purpose of the Study:

• To evaluate changes in chronotropic response (CR) during cardiopulmonary exercise testing (CPET) in patients undergoing cardiac rehabilitation.
• To investigate the impact of beta-blocker medication on CR and the metabolic chronotropic relationship (MCR).

Main Methods:

• Patients with CI undergoing cardiac rehabilitation performed CPET.
• The metabolic chronotropic relationship (MCR) was calculated at four exercise stages using the Wilkoff model.
• Improvement in CR was defined as an increase in MCR at three or more stages.

Main Results:

• Patients with elevated BNP levels exhibited lower MCR values across all exercise stages.
• Beta-blocker use was prevalent in patients showing improved peak VO2 and anaerobic threshold (AT), and in those with improved CR.
• The MCR pattern differed based on beta-blocker use: MCR-AT was lower than MCR-Rc in non-users, and higher in users.

Conclusions:

• An attenuated HR response during exercise may be more pronounced in the initial stages.
• Comparing MCR-AT and MCR-Rc effectively identifies the influence of beta-blockers on HR response during CPET.