The patient was a 64-year-old man with chronic atrial fibrillation with bradycardia. Left ventricular ejection fraction was 34%. He was treated with biventricular pacing. Heart failure improved from NYHA class III to II. Sympathetic nerve activity (SNA. was recorded during 6 minutes of biventricular (BV), right ventricular apical (RVA. and left ventricular (LV. pacing. SNA was significantly lower during biventricular pacing (49.5 ± 4.0/min. compared with RVA (58.8 ±6:9/min, p = 0.016. and LV (63.3 ± 4.3/min, p = 0.002. pacing. BV pacing improves hemodynamics and decreases SNA compared with RVA or LV pacing.