Is cardiac autonomic modulation influenced by beta blockers in adolescents with Duchenne Muscular Dystrophy?

Abstract Objectives As the Duchenne Muscular Dystrophy (DMD) is a progressive neuromuscular disorder frequently associated with cardiac dysfunction, this study aimed to evaluate the influence of beta-blocker therapy on cardiac autonomic modulation in adolescents with DMD by analyzing heart rate variability (HRV) indices in patients with and without beta-blockers. Methods A cross-sectional study was conducted with 90 participants divided into three groups: (1) participants with DMD receiving beta-blocker therapy (DMDB, n=30), (2) participants with DMD without beta-blocker therapy (GMDM, n=30), and (3) age- and sex-matched typically developing participants (GDT, n=30). HRV was assessed using validated beat-to-beat heart rate monitoring (RS800CX, Polar) under controlled conditions. Linear and non-linear HRV indices (including Detrended Fluctuation Analysis and Symbolic Dynamics) were analysed using Kubios HRV software. Results DMD patients exhibited autonomic impairment, characterized by decreased HRV, increased sympathetic dominance, and reduced parasympathetic modulation. Beta-blocker therapy was associated with significantly higher Mean Beat-to-beat interval (RR) and lower Mean Heart Rate (HR) compared to the non-beta-blocker DMD group, with values approaching those observed in typically developing participants. Non-linear indices suggested that DMD patients receiving beta-blockers demonstrated increased HRV complexity and fractal properties compared to those not receiving beta-blockers, although differences remained between the DMD and control groups. Conclusions Autonomic dysfunction in DMD is characterized by reduced HRV and altered sympathovagal balance. In our results, beta-blocker therapy was associated with improved HRV and enhanced autonomic control. These findings highlight the potential cardioprotective role of beta-blockers in DMD management and emphasize the need for further research into optimizing autonomic function in DMD.