Abstract 11505: Predictive Value of Heart Rate Variability for Appropriate ICD Discharge in Cardiac Resynchronization Therapy Patients
Heart rate variability (HRV) is used to evaluate autonomic regulation in patients with cardiovascular disease. Decreased HRV is associated with adverse outcomes in patients with congestive heart failure. The objective of this study was to examine whether changes in HRV predict freedom of appropriate implantable cardioverter defibrillator (ICD) shocks in patients with heart failure and cardiac resynchronization therapy with defibrillator (CRT-D) device. In 100 patients with a Boston Scientific Contak Renewal or Cognis device implanted for either primary (73 %) or secondary prevention (27 %), the time domain HRV variables standard deviation of normal beat to normal beat interval (SDANN) and footprint percentage (FPP) were collected after implantation until latest available follow-up with a maximum of 1460 days (4 years). In case of appropriate shock, HRV before shock was assessed. Using time-dependent Cox regression models, with adjustments for identified predictors of appropriate shock, the relation between dichotomized SDANN or FFP and appropriate shock was investigated. Baseline characteristics between patients with or without shocks were similar, with exception of secondary prevention patients using more often antiarrhythmic drugs and receiving more shocks. During follow-up (median 447, range 6-1460 days), appropriate shocks occurred in 16 of 100 (16 %) patients. SDANN (63 ± 20 vs. 74 ± 29 ms; P = 0.14) and FPP (30 ± 11 % vs. 32 ± 11 %; P = 0.37) at baseline did not differ significantly between patients with or without shocks. However, after dichotomization of HRV parameters based on the median, time dependent Cox regression analysis showed that patients were at significantly lower risk for appropriate shock (SDANN: HR 0.12 95% CI (0.04 - 0.38) P < 0.01 and FPP: HR 0.37 95% CI (0.14 - 0.95) P = 0.04) when HRV values were above the median during follow-up, also after adjustment for identified predictors (antiarrhythmic drug use, type of prevention). These results imply that HRV is an independent predictor for appropriate shock and indices are decreased in patients prior to appropriate shock. Therefore, low HRV could be of additional use in predicting imminent appropriate shocks and could possibly guide concomitant medical therapy.
- © 2012 by American Heart Association, Inc.