Association between Lifelong Physical Activity and Disease Characteristics in HCM

Abstract

Purpose: Hypertrophic cardiomyopathy (HCM) is characterized by inappropriate left ventricular (LV) wall thickness. Adaptations to exercise can occasionally mimic certain HCM characteristics. However, it is unclear whether physical activity affects HCM genotype expression and disease characteristics. Consequently, we compared lifelong physical activity volumes between HCM gene carriers with and without HCM phenotype, and compared disease characteristics among tertiles of physical activity in phenotypic HCM patients.

Methods: We enrolled n = 22 genotype positive/phenotype negative (G+/P-) HCM gene carriers, n = 44 genotype positive/phenotype positive (G+/P+) HCM patients, and n = 36 genotype negative/phenotype positive (G-/P+) HCM patients. Lifelong physical activity was recorded using a questionnaire and quantified as metabolic equivalent of task hours per week.

Results: We included 102 participants (51 ± 16 yr, 49% male). Lifelong physical activity volumes were not different between G+/P+ and G+/P- subjects (16 [10-29] vs 14 [6-26] metabolic equivalent of task-hours per week, P = 0.33). Among phenotypic HCM patients, there was no difference in LV wall thickness, mass, and late gadolinium enhancement across physical activity tertiles. Patients with the highest reported physical activity volumes were younger at the time of diagnosis (tertile 1: 52 ± 14 yr, tertile 2: 49 ± 15 yr, tertile 3: 41 ± 18 yr; P = 0.03), and more often had a history of nonsustained ventricular tachycardia (4% vs 30% vs 30%, P = 0.03).

Conclusions: Lifelong physical activity volumes are not associated with genotype-to-phenotype transition in HCM gene carriers. We also found no difference in LV wall thickness across physical activity tertiles. However, the most active HCM patients were younger at the time of diagnosis and had a higher arrhythmic burden. These observations warrant further exploration of the role of exercise in HCM disease development.

FIGURE 1

Flowchart of study design. MRI could not be performed in 13 participants because of noncompatible implantable cardiac defibrillators/pacemakers (n = 8), for logistic reasons (n = 3), because of claustrophobia (n = 1), or because of dental prosthesis (n = 1).

FIGURE 2

Distribution of physical activity volumes over time of HCM gene carriers according to phenotype status (A) and of phenotypic HCM patients according to tertiles of lifelong physical activity volume (B). Individuals included per decade differ because of the heterogeneity in age of the participants, and numbers are shown below x-axis. Physical activity shown in panel A is prediagnosis physical activity for G+/P+ and lifelong physical activity for G+/P−. Physical activity shown in panel B is lifelong physical activity. Data are shown as median with interquartile range.