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Continuous heart rate variability from an implanted device: a practical guide for clinical use.

Continuous measurement of spontaneous heart rate variability is now possible from permanently implanted devices and may contain information useful in the chronic management of patients with congestive heart failure. Since heart rate variability semi-quantifies autonomic control of the heart, changes noted from continuous measurement provide insight into cardiac control system status, which may reflect clinical status of the patient. This review outlines clinical evidence supporting the use of heart rate variability derived from implanted electronic devices and suggests a practical application in an every day clinical setting for its use. Changes in continuously measured heart rate variability coupled with the absolute value of the standard deviation of the atrial-to-atrial activation period predict subsequent risk for decompensation and hospitalization. Prospective clinical trials will evaluate this approach and the use of such markers on health care utilization in populations of patients with long-term chronic heart failure.