Cardiac resynchronization therapy modulates peripheral sympathetic activity

Abstract

Background: Heightened sympathetic nerve activity has been associated with poorer prognosis in patients with reduced left ventricular systolic function (ie, heart failure with reduced ejection fraction [HFrEF]).

Objective: The purpose of this study was to investigate the effects of cardiac resynchronization therapy (CRT) on sympathetic nerve activity, measured by average skin sympathetic nerve activity (aSKNA).

Methods: This prospective study enrolled 36 patients with HFrEF who received CRT. Ten patients who received an implantable cardioverter-defibrillator for primary prevention served as controls. Patient clinical data, echocardiographic variables, and aSKNA at baseline and 3-month follow-up were collected.

Results: CRT patients who exhibited wider QRS duration had higher aSKNA (1.52 ± 0.65 μV vs 0.97 ± 0.49 μV; P = .027) compared to the control group at baseline. In the CRT group, patients with QRS duration ≥150 ms had higher aSKNA than those with QRS duration <150 ms (1.67 ± 0.63 μV vs 1.19 ± 0.51 μV; P =.039). After CRT, left ventricular ejection fraction (LVEF) improved from 29.6% to 35.4% (P = .001). aSKNA decreased significantly (1.52 ± 0.65 μV vs 1.31 ± 0.63 μV; P = .018). Seventeen of the 36 CRT patients were CRT responders, with LVEF improvement ≥5% at 3-month follow-up. aSKNA significantly decreased from 1.47 to 1.15 μV (P = .003) in CRT responders but was unchanged in nonresponders (1.44 ± 0.69 to 1.37 ± 0.70; P = .61). After CRT, a significant reduction in aSKNA was associated with improvement in LVEF (r = 0.638; P = .001).

Conclusion: CRT reduces elevated sympathetic activity in HFrEF patients, accompanied by improvement in systolic function at short-term follow-up. The reduction of sympathetic activity is mainly seen in CRT responders.

Keywords: Cardiac resynchronization therapy; Heart failure; Heart rate variability; Skin sympathetic nerve activity; Sympathetic nerve system.