Beta-blocker therapy appears to be beneficial in Duchenne muscular dystrophy (DMD) complicated by cardiac dysfunction, according to a recently published study in Translational Exercise Biomedicine.
In advanced stages, DMD can lead to dilation of the heart ventricles, which in turn impairs cardiac function and increases the risk of dangerous cardiac rhythm abnormalities (arrhythmias).
Research indicates that cardiac arrhythmias in DMD are not solely caused by musculoskeletal deterioration but are also associated with dysfunction of the autonomic nervous system.
The autonomic nervous system regulates vital bodily functions such as breathing, heart rate, blood pressure and digestion. Under normal conditions, it adjusts heart rate based on the body’s needs — during sleep, exercise, meals or relaxation — through a mechanism called heart rate variability (HRV).
Studies have shown that patients with DMD exhibit reduced HRV. Reduced HRV is linked to an increased risk of cardiovascular death.
In this context, beta-blockers — drugs that inhibit certain autonomic receptors responsible for accelerating heart rate and raising blood pressure — have emerged as a potentially valuable therapeutic option in DMD. However, their specific effects on HRV remain unclear.
To further evaluate the effects of beta-blocker therapy on HRV in patients with DMD, the authors conducted a cross-sectional study involving 90 adolescents, divided into three groups: DMD patients receiving beta-blockers, DMD patients not receiving beta-blockers and healthy individuals (controls).
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Results showed that DMD patients had significantly reduced HRV compared to healthy controls. However, those receiving beta-blocker therapy demonstrated improved HRV compared to untreated DMD patients, although their HRV levels did not reach those of the healthy group.
While the observed difference in HRV between treated and untreated patients was not statistically significant, the authors emphasized that the study cannot establish a causal relationship between beta-blocker therapy and improved HRV.
“While our cross-sectional design cannot establish causation, the consistent pattern of improved autonomic parameters in the beta-blocker group provides preliminary evidence supporting current clinical practice guidelines that recommend beta-blocker therapy for DMD patients with cardiac involvement,” the authors wrote.
They further highlighted that these findings may have implications for exercise prescription in DMD patients, as beta-blocker therapy could potentially enhance exercise tolerance.
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