Physical activity measured by accelerometry in hypertrophic cardiomyopathy: findings from the AFFECT-HCM study

Abstract Introduction Hypertrophic cardiomyopathy (HCM) has been associated with sudden cardiac death during exercise. Restrictive exercise guidance has therefore been advised in HCM patients, but more recent guidelines advocate less stringent exercise restriction and an active lifestyle because of the salutary effects of exercise. Since the dosing of exercise remains debated, we quantified physical activity and related this to the HCM phenotype and quality of life in HCM patients. Methods This study included HCM patients and genotype-positive, phenotype-negative (G+/P-) individuals. HCM patients were divided based on their phenotype into obstructive HCM and non-obstructive HCM, and on symptomatology (by NYHA class). All participants wore an accelerometer (Actigraph) during one week. Physical activity was quantified by measuring daily steps, sedentariness, time performing moderate-to-vigorous physical activity (MVPA %/day), and additional metabolic energy expenditure (AEE, kcal/kg/day). Quality of life was assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ) and EuroQoL 5-domain-5-level questionnaire (EQ-5D-5L). Results A total of 203 HCM patients (67% male, mean age 59 years) and 37 G+/P− individuals (32% male, mean age 48 years) were included. Accelerometry data revealed that HCM patients took significantly fewer daily steps than G+/P- individuals (5254 vs 6573 steps/day, p=0.005), performed less MVPA (30 minutes of MVPA/day: 54% vs 22%, p0.001) and were more often sedentary (more than 80%/day sedentary: 61% vs 35%, p=0.003). A substantial proportion (n=79, 39%) of HCM patients experienced limiting symptoms (NYHA class II–III), which was associated with a significant decrease in physical activity. Asymptomatic non-obstructive HCM patients were as physically active as G+/P- individuals; however, those with asymptomatic obstructive HCM exhibited reduced physical activity (with decreased daily steps, MVPA %/day and AEE, all p0.01) comparable to symptomatic HCM patients. Obese patients (BMI ≥30 kg/m²) more often experienced limiting symptoms than other patients (53% vs 36%, p=0.039) and took fewer daily steps than non-obese patients (4554 vs 6089, p=0.005). An increase of 250 steps/day was associated with a 2.15-point increase in the KCCQ Overall Summary Score, and an increase of 1000 steps/day was associated with a 0.05-point increase in the EQ-5D-5L. The majority (n=125, 62%) of HCM patients reported recalling exercise guidance from a cardiologist, and more than half of these individuals (n=74, 59%) reported decreasing their exercise intensity as a direct consequence. Conclusion Accelerometry measurements indicate reduced physical activity in HCM patients, particularly among symptomatic and obese individuals. Increased physical activity correlated with better quality of life. These findings support promoting physical activity in HCM patients to improve general fitness, and likely, improve long-term cardiovascular outcomes.Measures of physical activity Physical activity compared by phenotype