Chronotropic incompetence (CI), the inability of the heart rate to increase appropriately in response to an increase in activity or metabolic demand,1,2  occurs because of altered balance between the sympathetic and parasympathetic branches of the autonomic nervous system.3,4  Chronotropic incompetence is common in various types of cardiac disease including sick sinus syndrome, atrioventricular (AV) block, coronary artery disease, and heart failure5,6  and is also seen in patients with no structural heart disease.7–9  Chronotropic incompetence first appeared in the literature in 1975 when a high rate of cardiac events was observed in those with a decreased heart rate (HR) response during treadmill exercise test.10 

Although often not recognized, CI is frequently present in heart failure, which is a common reason for hospital admission and a common comorbid condition in patients admitted...

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