Sigmoidal heart rate response pattern during exercise in patients with chronic heart failure

Area of Science:

• Cardiology
• Exercise Physiology
• Heart Failure Research

Background:

• Detailed heart rate (HR) response patterns during exercise in heart failure (HF) patients with sinus rhythm are not well-defined.
• Understanding these patterns is crucial for managing HF and chronotropic incompetence.

Purpose of the Study:

• To statistically classify and characterize HR response patterns during cardiopulmonary exercise testing in HF patients.
• To identify distinct groups based on HR behavior and their clinical correlates.

Main Methods:

• Screened 99 HF patients with sinus rhythm undergoing cardiopulmonary exercise tests.
• Applied logistic differential equation models to classify HR response patterns.
• Analyzed demographic, clinical, and exercise parameters for each pattern group.

Main Results:

• Two distinct HR patterns were identified: sigmoidal (75 patients) and exponential (24 patients).
• The sigmoidal pattern group was older, had higher B-type natriuretic peptide levels, and showed blunted HR increase beyond the anaerobic threshold.
• Patients with the sigmoidal pattern exhibited significantly lower oxygen consumption (V̇o2)/kg beyond the anaerobic threshold compared to the exponential group.

Conclusions:

• HR response during maximal exertion in HF patients with sinus rhythm can be categorized into sigmoidal and exponential patterns.
• The sigmoidal pattern may indicate sinus node dysfunction and warrants further investigation for clinical implications in chronotropic incompetence.