Background: Cardiac resynchronization therapy devices provide effective therapy for heart failure. Heart rate variability (HRV) parameters in the device such as HRV footprint and SD of average 5-minute intrinsic R-R intervals (SDANN) are related to autonomic function and may be used to identify patients with a higher risk of mortality.
Methods: We examined the relationship between HRV and mortality in a prospective cohort study. The 842 patients (mean age, 67.7 +/- 11.2; 23.5 % female; New York Heart Association class III, 88.6%; class IV, 11.4%) included in the analysis were implanted with a cardiac resynchronization therapy with defibrillation device and had baseline HRV measurements available.
Results: During a median of 11.6 months of follow-up, 7.8% (66/842) of patients died. Heart rate variability footprint and SDANN were significant predictors of mortality (all P < .05); patients with lower HRV values were at greater risk for death, compared with patients with higher HRV values. Heart rate variability changes over time tended to predict the risk of mortality in follow-up (P = nonsignificant); patients with low baseline HRV and small changes in HRV during the follow-up period were at the highest risk for death (7% mortality for SDANN and 8.9% for HRV footprint), and patients with high baseline HRV and large changes in HRV were at the lowest risk (1.5% mortality for SDANN and 2.4% for HRV footprint). Results were consistent when adjusted for age, sex, body mass index, and diastolic blood pressure.
Conclusions: Continuously measured device HRV parameters provide prognostic information about patient mortality that may be helpful for risk stratification.