Independent and incremental prognostic value of heart rate variability in patients with chronic heart failure

Background Decreased heart rate variability (HRV), indicating derangement i n card ac autonomic control, has been reported in patients with chronic hea rt failure. However, the independent and incremental prognostic value of HR V over clinical data and measures of left ventricular dysfunction has been less thoroughly investigated. This study was designed to evaluate the predi ctive value of HRV and Poincare plots as assessed by 24-hour Hotter recordi ng in patients with chronic heart failure. Methods Ninety-seven patients, mean age 55 +/- 13 years, with radionuclide left ventricular ejection fraction less than or equal to 40% underwent echo cardiographic examination and 24-hour Holier recording. Heart failure was c aused by coronary artery disease in 57 patients (59%) and idiopathic dilate d cardiomyopathy in 40 (41%). Results During follow-vp (39 +/- 18 months), 32 cardiac deaths occurred. By Cox multivariate analysis, significant predictors of death were left ventr icular end-systolic volume (hazard ratio 1.04), low- to high-frequency rati o (hazard ratio 0.09), percentage of differences between successive normal R-R intervals >50 ms (hazard ratio 0.93), and age (hazard ratio 1.06). Furt hermore, HRV analysis improved (P <.001) the prognostic power of a model in cluding clinical and echocardiographic data, left ventricular election frac tion, and ventricular arrhythmias at Holter recording, whereas the inclusio n of Poincare plots did not add further predictive value. Conclusions Our investigation demonstrated that HRV has independent and inc remental prognostic value in patients with chronic heart failure and seems useful to stratify patients at high risk of cardiac death.