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Abnormal heart rate recovery after exercise as a reflection of an abnormal chronotropic response
M Y Desai1, E De la Peña-Almaguer, F Mannting
1Division of Nuclear Cardiology, Department of Radiology, Brigham & Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Insights
Abnormal heart rate (HR) decline after exercise is linked to cardiac mortality. This study shows chronotropic incompetence significantly impacts HR recovery, with beta blockers playing a key role.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Abnormal heart rate (HR) decline post-exercise is associated with increased cardiac mortality.
- Understanding HR recovery dynamics is crucial for assessing cardiac health.
Purpose of the Study:
- Compare HR decline in coronary artery disease (CAD), normal, and transplant (Tx) patients.
- Elucidate the relationship between HR increase/decrease during exercise and recovery.
- Investigate the influence of beta blockers on post-exercise HR recovery.
Main Methods:
- Bruce protocol exercise testing was performed on 100 CAD patients, 50 normal subjects, and 21 Tx patients.
- Peak HR, HR reserve, and HR decline at 1, 3, 5, and 8 minutes were recorded.
- Analysis included subgroups based on beta blocker use.
Main Results:
- Significant differences in HR recovery were observed between CAD, normal, and Tx groups.
- Beta blocker use significantly affected HR recovery within normal and CAD groups.
- After adjusting for peak HR and HR reserve, group differences in HR recovery diminished.
- Beta blockers significantly impact HR decline due to their chronotropic effects.
Conclusions:
- Chronotropic incompetence is the primary factor explaining abnormal post-exercise HR recovery.
- Beta blockers significantly influence HR recovery by affecting chronotropism.
- HR recovery rate is highly dependent on the chronotropic response to exercise.
Abstract:
Abnormal decline in heart rate (HR) after exercise has been linked to increased cardiac mortality. This study compares the decrease in HR in different patient types, elucidates the relation between the increase and decrease of HR with exercise, and studies the role of beta blockers on the recovery of HR after exercise. One hundred patients with coronary artery disease (CAD), 50 subjects with a very low likelihood of CAD (normals), and 21 postcardiac transplant (Tx) patients underwent Bruce protocols. Peak HR, percent of peak HR achieved, HR reserve percent, and decline in HR at 1, 3, 5, and 8 minutes were obtained for all groups and also for subgroups based on the use of beta blockers. HR recovery at 1, 3, 5, and 8 minutes differed significantly between patients with CAD, normals, and Tx patients. HR recovery at 1, 3, 5, and 8 minutes also differed significantly within the groups (normal and CAD) based on the use of beta blockers. There was highly significant correlation between decrease in HR and peak HR, percent peak HR and HR reserve percent in normal and CAD groups. After correction of the HR recovery for dependence on peak HR and HR reserve percent, the difference in HR recovery between normal and CAD groups was markedly reduced. The difference in the decrease of HR within each group (normal and CAD), based on the use of beta blockers or not, was also markedly reduced. beta blockers have a significant impact on the decrease in HR due to its effect on chronotropism. HR recovery rate is highly dependent on the chronotropic response. Hence, the main portion of the abnormality in HR recovery after exercise can be explained by chronotropic incompetence.