Monitoring of heart rate variability in heart failure patients with cardiac resynchronisation therapy: Interest of continuous and didactic algorithm

Decreased autonomic function is known to be predictive of death, especially in chronic heart failure (CHF) patients. We sought to report mid-term heart rate and heart rate variability (HRV) changes after cardiac resynchronization therapy (CRT), using a continuous device-based measurement, which should facilitate daily management of CHF patients. Stored data were retrieved for 92 CHF patients who were enrolled in a prospective multicentre study and received a CRT pacemaker capable of continuous assessment of HRV. This parameter was recorded daily as a footprint plot, a graphic visualization of the distribution of HRV. Decreases in mean heart rate (from 75.4 ± 11.7 to 71.4 ± 8.4 bpm) and increases in HRV as attested by footprint area (from 33.5 ± 13.5% to 40.7 ± 14.5%) were statistically significant after 12 months follow-up (p < 0.001). Patients with no change in footprint area were at greater risk for death, compared with other patients (HR 17.2, 95%CI 2.0-142.9, p < 0.002). In conclusion, CRT provides sustained improvement of autonomic function, associated with an increased survival. The footprint plot is a simple graphic diagram, which may facilitate the practical and daily application of continuously measured HRV, thus assisting in the identification of high-risk CHF patients.