International journal of cardiology
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The exercise limitation of patients with chronic heart failure may be due in part to an inability to increase heart rate as normal, a limitation sometimes referred to as chronotropic incompetence. This may be due to down regulation of beta receptors. ⋯ Chronotropic incompetence was seen in < 30% of patients with chronic heart failure. However, there are few differences between the group with chronotropic incompetence and the group without. Chronotropic incompetence is thus unlikely to be a major factor limiting exercise capacity in unselected patients with chronic heart failure and is likely to be the major factor limiting exercise in a much smaller proportion of patients.