Baroreflex Sensitivity in Facioscapulohumeral Muscular Dystrophy

Abstract

Facioscapulohumeral muscular dystrophy (FSHD), the third most common muscular dystrophy, is caused by a genetic mutation that alters DUX4 gene expression. Although cardiac muscle is known to be spared in people with FSHD, they can develop significant morbidities and physical disabilities because of their reduced mobility. Autonomic dysregulation via heart rate variability has been demonstrated in people with FSHD. It is unknown, however, if baroreflex function, an important regulator of blood pressure, is impaired in people with FSHD. OBJECTIVE To examine if baroreflex sensitivity is impaired in patients with FSHD. METHODS Thirty minutes of resting blood pressure, heart rate, and baroreflex sensitivity (via the sequence method) was measured in 7 patients with FSHD (age: 48 ± 8 yrs, avg ± SD) and 7 sex‐ and age‐matched controls (age: 40 ± 7 yrs, p > 0.05). RESULTS People with FSHD were less active (FSHD Activity Metabolic Index (AMI): 17.8 ± 23.0 kcal/day; controls AMI: 151 ± 105 kcal/day; p = 0.01), but had a similar body mass index compared to controls (FSHD: 25 ± 4; controls: 26 ± 3; p > 0.05). Baroreflex sensitivity was similar among FSHD participants and controls (FSHD: 12.6 ± 8.3 ms/mmHg; controls: 16.6 ± 9.6 ms/mmHg; p = 0.40). Mean arterial pressure was also similar for FSHD participants compared to controls (FSHD: 95.3 ± 6.1 mmHg; controls: 91.6 ± 8.6 mmHg; p = 0.37). Heart rate was elevated in FSHD participants compared to controls (FSHD: 66.6 ± 7.5 BPM; controls: 56.8 ± 6.2 BPM; p = 0.03). CONCLUSIONS These findings suggest that baroreflex regulation is not diminished in people with FSHD, but an elevated heart rate may indicate physical deconditioning due to limited mobility. Support or Funding Information Scholarly Inquiry at TJU, Greg Marzolf Jr. Foundation, Friends of FSH Foundation.