Efficacy and safety of Lingbao Huxin Dan in the treatment of sick sinus syndrome: a randomized, single-blind, placebo-controlled, crossover trial.

BACKGROUND: Permanent pacemaker implantation is the standard treatment for symptomatic sick sinus syndrome (SSS), but it does not reverse the underlying sinus node dysfunction. Lingbao Huxin Dan (LBHXD) may benefit patients with bradyarrhythmia. However, robust clinical evidence regarding its efficacy and safety in patients with SSS, particularly those with pacemakers, is lacking. METHODS: A randomized, crossover trial was conducted. Thirty patients with SSS and implanted DDD pacemakers were enrolled and randomly assigned to one of two treatment sequences: LBHXD followed by placebo, or placebo followed by LBHXD. Each treatment period lasted 4 weeks, separated by a 2-week washout interval. RESULTS: 25 patients completed the trial. Following propensity score matching, 17 patients were included in the final analysis. Compared to the placebo phase, LBHXD administration resulted in a significantly greater reduction in AP% (38.99% ± 20.67% vs. 48.03% ± 21.95%, P < 0.01). LBHXD also significantly increased several HRV indices, including SDNN, SDANN, rMSSD, and SDNN index (all P < 0.05), and elevated the mean and maximum HR (P < 0.05). No significant changes were observed in ventricular pacing percentage, left atrial diameter, or left ventricular ejection fraction. CONCLUSION: Adjunctive therapy with Lingbao Huxin Dan can effectively reduce atrial pacing dependency, improve heart rate variability, and increase heart rate in patients with SSS and pacemakers, demonstrating a favorable safety profile. These findings suggest that LBHXD may enhance intrinsic sinoatrial node function and autonomic regulation, supporting its potential role as a complementary therapy in an integrative medicine approach to managing SSS. CLINICAL TRIAL REGISTRATION: https://www.chictr.org.cn/showproj.html?proj=187346, Chinese Clinical Trial Registry ChiCTR2300067497.