Chronotropic incompetence--Part II: Clinical implications.

The definition of chronotropic incompetence as inadequate chronotropic response to metabolic demand is, in theory, quite satisfactory. However, the method used in clinical practice for determination of chronotropic incompetence is far from established. The determination of chronotropic incompetence has important diagnostic, therapeutic, and prognostic implications although the exact mechanism underlying chronotropic incompetence is at present unclear. From a pacing viewpoint, chronotropic incompetence is clinically relevant only when there is a functional improvement associated with rate-responsive pacing. Rate-responsive pacing has improved the physiologic approach to artificial pacing.