Cardiopulmonary fitness and physical activity levels were significantly lower in children with inherited cardiac disease than in healthy controls, according to a study published Feb. 25 in JAMA Network Open.

Luc Souilla, PhD, and colleagues of the Quality of Life in Children With Inherited Cardiomyopathy or Arrhythmia Study Group conducted a prospective, cross-sectional trial from Feb. 1, 2021 to June 20, 2023 in seven pediatric hospitals in France. They compared the levels of cardiovascular fitness and daily physical activity of 100 pediatric patients aged six to 17 years (mean age, 12.7 years; 52% male) with inherited cardiomyopathy or arrhythmia and 107 healthy age- and sex-matched control participants.

A cardiopulmonary exercise test (CPET) was used to evaluate cardiovascular fitness, and daily physical activity levels were tracked using an accelerometer. The study's primary outcome was maximum oxygen uptake (Vo₂max) expressed as a z score from the pediatric CPET reference equations, derived from a nonlinear model using natural logarithms of Vo₂max, height and BMI.

Results showed that Vo₂max was lower in patients than controls, expressed as a pediatric z score (mean score, –1.49 vs. –0.16; p<0.001) or raw values (mean value, 32.2 vs. 40.2 mL/kg/min; p<0.001). Similarly, moderate to vigorous physical activity levels were lower in patients than in controls (mean level, 42.0 vs. 48.2 min/d; p=0.009).

In examining the factors associated with maximum oxygen uptake, the final multivariable model explained 80% of Vo₂max by integrating clinical (lower NYHA functional class, absence of ventricular dilatation and absence of an ICD), functional (higher forced vital capacity and ventilatory anaerobic threshold), sociodemographic (male sex, normal progression of schooling, and higher maternal educational level), and behavioral (higher self-reported physical activity and motivation toward physical activity) parameters.

The authors write that assessing cardiopulmonary fitness in this population "can be incorporated into the shared decision-making process for sports participation and may help identify eligible patients for early preventive cardiac rehabilitation programs."

In an accompanying editorial comment, William W. Russell, MD, and Jonathan B. Edelson, MD, MSCE, FACC, write the study provides "strong evidence that there is a concerning lack of cardiopulmonary fitness" in this population, and that "the deficits in physical activity and cardiopulmonary fitness are multifactorial, including both clinical and sociodemographic determinants." Furthermore, the findings "will help inform the development of interventions designed to increase the physical activity."