BACKGROUND: Left ventricular assist devices (LVAD) are an effective therapeutic option for end-stage heart failure (HF). Reduced heart rate variability (HRV) as a result of autonomic derangement is evident in chronic heart failure and several studies have established the independent prognostic value of HRV in chronic heart failure. OBJECTIVE: In the present study we investigated whether autonomic function is restored in patients after LVAD implantation with persistent, severely depressed left ventricular function. METHODS: Ambulatory Holter ECG recordings were collected in heart failure patients with an LVAD (n=8) und age-matched heart failure patients without an LVAD (n=7) both on optimal medical therapy. Cardiac dimensions and function were assessed by echocardiography or angiography. RESULTS: Analysis for heart rate variability revealed reduced SDNN (67+/-4 ms), SDANN (56+/-4 ms) and triangular index (18+/-1) in heart failure patients on optimal medical therapy. However patients with LVAD demonstrated a restoration in heart rate variability with normal SDNN (108+/-9 ms), SDANN (103+/-8 ms) and triangular index (29+/-2). Compared to patients without LVAD this difference was statistically significant (p<0.01). CONCLUSIONS: In end-stage heart failure patients autonomic imbalance indicated by severely reduced heart rate variability is restored after LVAD implantation with unloading of the failing heart.