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

Background Decreased heart rate variability (HRV), indicating derangement in card ac autonomic control, has been reported in patients with chronic heart failure. However, the independent and incremental prognostic value of HRV over clinical data and measures of left ventricular dysfunction has been less thoroughly investigated. This study was designed to evaluate the predictive value of HRV and Poincare plots as assessed by 24-hour Hotter recording 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 echocardiographic examination and 24-hour Holier recording. Heart failure was caused by coronary artery disease in 57 patients (59%) and idiopathic dilated 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 ventricular end-systolic volume (hazard ratio 1.04), low- to high-frequency ratio (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). Furthermore, HRV analysis improved (P <.001) the prognostic power of a model including clinical and echocardiographic data, left ventricular election fraction, and ventricular arrhythmias at Holter recording, whereas the inclusion of Poincare plots did not add further predictive value. Conclusions Our investigation demonstrated that HRV has independent and incremental prognostic value in patients with chronic heart failure and seems useful to stratify patients at high risk of cardiac death.