High Intensity Exercise for Increasing Fitness in Patients With Hypertrophic Cardiomyopathy
Condition: Hypertrophic Cardiomyopathy
MeSH terms: Cardiomyopathies; Cardiomyopathy, Hypertrophic; Hypertrophy
Study type: Interventional

Summary: 
      Although current clinical guidelines stipulate that patients with hypertrophic cardiomyopathy
      should not partake in high intensity exercise (HIE) or competitive sport due to safety
      concerns, there is no clear evidence to support this notion. In fact, two exercise training
      interventions in this population indicates that regular moderate to vigorous intensity
      exercise is efficacious for improving exercise capacity and cardiorespiratory fitness, and
      does not increase arrhythmia burden or adverse events. Moreover, moderate intensity exercise
      and HIE training significantly increases cardiorespiratory fitness in patients with cardiac
      disease. Such improvements are associated with substantial reductions in cardiovascular
      mortality and might outweigh the risk of adverse events in patients with hypertrophic
      cardiomyopathy (HCM). Having a genetic cardiomyopathy does not grant immunity against
      lifestyle related cardiometabolic diseases and inactivity is rife in HCM patients likely due
      to misinformation/education. It is therefore paramount to further explore the benefits of
      regular moderate intensity exercise and HIE in patients with HCM for proper therapeutic
      management of the condition.
    

Detailed description: 
      Regular exercise reduces the risk of all-cause and cardiovascular mortality in the general
      population. Specifically, higher cardiorespiratory fitness is associated with a 10 - 20 %
      reduction in mortality risk for every 1 MET (metabolic equivalent tasks) improvement in
      fitness. A high degree of fitness is also protective against the development of heart failure
      and exercise training has become the standard of care for most patients with cardiovascular
      disease to improve functional capacity, and reduce morbidity and mortality. However,
      hypertrophic cardiomyopathy, the most common inherited cardiovascular disease, may be an
      exception. For more than 30 years, hypertrophic cardiomyopathy (HCM) has been identified as
      the most common cause of death in young athletes, and patients with HCM are excluded from
      participation in competitive sports. The fear of provocation of sudden cardiac death has
      often been extended to non-competitive athletic activities in such patients, though there is
      a distinct lack of evidence about the safety of exercise in this population. A recent
      multicenter clinical trial provided evidence that moderate intensity exercise (MIE) may be
      safe in this population, though the increase in fitness with this training paradigm was
      modest. Alternatively, an extensive series of reviews published over the last five years
      advocate for high intensity interval training (HIIT) as an efficacious stimulus for
      increasing cardiorespiratory fitness in clinical adult populations, including those with
      heart failure. While a pilot investigation and preliminary findings suggest that moderate to
      vigorous intensity exercise may be safe and efficacious in patients with HCM, and even
      protective in animal models, there is no Level A or B evidence comparing the efficacy or
      safety of MIE and high intensity exercise (HIE) training in this patient population to guide
      exercise prescription. Therefore, the primary purpose of this exercise trial is to compare
      the efficacy and safety of supervised MIE and HIE training in adults with HCM. Specific aims
      and hypotheses of the project are as follows:

      Aim 1: Compare the efficacy of a high intensity and moderate intensity exercise intervention
      to improve cardiorespiratory fitness and functional diastolic reserve in patients with HCM.

        -  Primary hypothesis: HIE will result in greater increases in maximal oxygen uptake
           (V̇O2max) than MIE in patients with HCM.

        -  Secondary hypothesis: HIE will improve stroke volume reserve to a greater degree than
           MIE in patients with HCM.

      Aim 2: To evaluate the safety of HIE training in patients with HCM.

        -  Hypothesis: Regular exercise training of a high or moderate intensity will be safe (no
           serious adverse events) in this patient population. Specifically, it is hypothesised
           that HIE will not increase arrhythmia burden in patients with HCM.
    

Intervention name(s): High intensity exercise; Moderate intensity exercise
Intervention type(s): Behavioral; Behavioral
Intervention description(s): The exercise groups will receive identical exercise prescription for the first two months of the intervention, after which the HIE group will incorporate HIIT in their exercise regimen. The reason for this approach is to include a period of general conditioning and progressively increase intensity prior to submitting volunteers to HIE. This approach considers participant safety as arrhythmias may be uncovered during the first two months of MIE training. It will also improve participant compliance by increasing exercise self-efficacy and confidence prior to commencing HIIT.; A training program will be developed individually for each subject with the goal of increasing duration and intensity consistent with exercise training principles. Workouts will vary with respect to mode (walk, cycle) and duration (30 - 60 minutes). Each subject will be assigned an exercise physiologist and a heart rate monitor so that each session can be tracked and recorded. The first few exercise training sessions in both exercise groups (MIE and HIE) will supervised at our hospital based fitness centre until the subject is confident to complete the training independently.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: High intensity exercise; Cardiorespiratory fitness; Stroke volume reserve; Arrhythmia burden