Walking 10K steps per day may slow aortic dilation in pediatric Marfan syndrome
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A 6-month intervention with an exercise target of 10,000 steps per day may slow aortic root dilation in pediatric patients with Marfan syndrome, according to study data published in the Journal of the American Heart Association.
“Artic root dissection remains the most life-threatening complication of Marfan syndrome,” Elif Seda Selamet Tierney, MD, pediatric cardiologist at Stanford Medicine Children’s Health and professor of pediatrics at Stanford University, and colleagues wrote.
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For this study, Tierney and colleagues enrolled 24 patients with Marfan syndrome aged 8 to 19 years in a 6-month physical activity intervention of 10,000 steps per day, counted via activity tracker (Garmin). The control arm included 15 age-matched patients with Marfan syndrome.
Background in a Marfan syndrome mouse model
“In our recent published report using a well-established mouse model of Marfan syndrome that carries a missense mutation in the gene encoding for fibrillin-1 protein ... we showed that daily mild aerobic exercise (55%-65% maximal oxygen consumption) can block progression of aortic root aneurysm in mice, while significantly improving aortic wall elasticity and elastin fiber structural integrity,” the researchers wrote. “In this study, we investigated if these results could be translated to pediatric patients with Marfan syndrome.”
Researchers measured aortic root dimension and arterial stiffness at baseline and 6 months. Z scores for all aortic root measurements were calculated with the Boston Children’s Hospital’s z score website.
Participants were excluded if they had preexisting ventricular dysfunction or a history of aortic surgery.
In addition, two participants failed to return for testing after the interventions period and another two received non-study related injuries that temporarily affected their ability to adhere to the intervention.
Exercise and aortic dilation in Marfan syndrome
Accelerometer data indicated that nearly three-quarters of participants had sedentary lifestyles at baseline.
The average number of daily steps in the intervention arm was 7,709 steps per day (median, 7,267) and the activity tracker was worn for a median of 92.8% of the study intervention.
At baseline, there were no difference in aortic root z scores or stiffness between the intervention and control arms.
After the intervention period ended, researchers observed no differences in any of the testing indices in the intervention arm compared with baseline.
Aortic root dimension rate of change per year was 0.13 cm per year among controls compared with 0.01 cm per year in the intervention group (P = .17). Aortic root z score rate of change per year was 0.008 among controls compared with a rate of 0.24 in the intervention group (P = .01), according to the study.
Aortic stiffness rate of change per year was 3.83 among controls compared with 0.37 in the intervention group (P = .25).
“We demonstrated that a simple physical activity intervention of 10,000 steps per day for 6 months was feasible in this population and has the potential to decrease the aortic root dilation rate,” the researchers wrote. “Because the focus has been more on exercise restrictions for patients with Marfan syndrome rather than promotion of exercise, these results might help shift the paradigm in this patient population. Our preliminary findings warrant further clinical studies to carefully evaluate the impact of exercise, possibly different types of exercise, on aortic root dilation in this patient population, probably best achieved by a multicenter randomized exercise intervention.”
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I mainly am excited that research into effects of exercise in this population are being conducted, and so far, the benefits outweigh the risk, and hopefully this will start to shift the limiting paradigm that has been present for so long restricting activity in young people with Marfan syndrome. Although there were no detectable changes in CV health from baseline to after the intervention in this small cohort, the aortic root did appear to grow more slowly than in patients not undergoing the intervention.
This seems to be a healthy goal. While not everyone can achieve this if they have orthopedic, CV or visual limitations, for the vast majority of young people with Marfan syndrome, these data show possible benefit in slowing aortic growth without untoward effects.
In general, exercise restrictions placed upon patients with Marfan syndrome in the name of caution and safety may have had detrimental effects on mental health, overall CV health and self-confidence. If we can continue to rigorously study exercise in this population, I hope we can show beneficial effects and allow them to enjoy most exercise like other young people.
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