Prognostic value of heart rate variability in time domain analysis in congestive heart failure

Aims: Analysis of heart rate variability is a noninvasive tool that allows to study autonomic control of the heart. Several studies have shown disturbed heart rate variability in patients with chronic heart failure (CHF). We sought to assess the prognostic value of time domain measures of heart rate variability in CHF. Methods and Results: We prospectively enrolled 190 patients with CHF in sinus rhythm, mean age 61 +/- 12 years, 109 (57.4%) in NYHA class II and 81 (42.6%) in class III or IV, mean cardiothoracic ratio 57.6 +/- 6.4% and mean left ventricular ejection fraction 28.2 +/- 8.8 %, 85 (45%) with ischemic and 105 (55%) with idiopathic dilated cardiomyopathy. Time domain measures of heart rate variability were obtained from 24 h Holter ECG recordings. During follow-up (22 +/- 18 months), 55 patients died. In multivariate analysis, independent predictors for all-cause mortality were: ischemic heart disease, cardiothoracic ratio greater than or equal to 60% and standard deviation of all normal RR intervals < 67 ms (RR = 2.5, 95% CI 1.5-4.2). Conclusions: Depressed heart rate variability has independent prognostic value in patients with CHF.