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Cardiovascular Disease Mortality and Excessive Exercise in Heart Attack Survivors

      To the Editor:
      In an in-depth study of 2377 patients (mean age, 62.9 years; 32% women) published in the September 2014 issue of Mayo Clinic Proceedings, Thompson et al
      • Williams P.T.
      • Thompson P.D.
      Increased cardiovascular disease mortality associated with excessive exercise in heart attack survivors.
      reported that higher levels of physical activity up to 7.2 metabolic equivalent of task-h/d were associated with survival benefits in heart attack survivors. Notably, physical activity beyond this level was found to be associated with poorer prognosis—a 2.6- and 3.2-fold increase in risk for all-cause and ischemic heart disease–related mortality, respectively.
      The finding by Thompson et al in these extremely active survivors—representing the most active 5% of their cohort—is thought provoking and deserves attention. However, other studies of heart attack survivors, including our own, have failed to identify this increase in mortality risk from higher levels of physical activity or fitness, despite possible transient increases in risk associated with exercise.
      • Hung R.K.
      • Al-Mallah M.H.
      • McEvoy J.W.
      • et al.
      Prognostic value of exercise capacity in patients with coronary artery disease: the FIT (Henry Ford ExercIse Testing) Project.
      • Heran B.S.
      • Chen J.M.
      • Ebrahim S.
      • et al.
      Exercise-based cardiac rehabilitation for coronary heart disease.
      In the subset of 7794 heart attack survivors in The FIT (Henry Ford ExercIse Testing) Project—a retrospective cohort of patients referred for exercise testing—higher levels of physical fitness were consistently associated with greater survival, with the most fit 8% of heart attack survivors having a 76% lower risk for mortality compared with the least fit patients. Similarly, among 37,855 patients in The FIT Project who were free of coronary artery disease, we did not find any increased risk from higher fitness, even among the most fit patients.
      • Feldman D.I.
      • Al-Mallah M.H.
      • Keteyian S.J.
      • et al.
      No evidence of an upper threshold for mortality benefit at high levels of physical fitness.
      Although we recognize the value of cautioning heart attack survivors to avoid excessive exercise, disproportionate amounts of media attention are commonly given to novel findings at the expense of the larger public health message. We submit that the main message to be taken away by heart attack survivors should not be “exercising too much is dangerous,” simply because, for the overwhelming majority of these patients, increasing physical activity and fitness has tremendous benefit. Such a benefit is a testament to the efficacy and safety of exercise prescriptions and cardiac rehabilitation programs.
      • Williams P.T.
      • Thompson P.D.
      Increased cardiovascular disease mortality associated with excessive exercise in heart attack survivors.
      • Heran B.S.
      • Chen J.M.
      • Ebrahim S.
      • et al.
      Exercise-based cardiac rehabilitation for coronary heart disease.
      Unfortunately, only 1 in 2 adults in the United States today is satisfying the minimum exercise recommendations, and even these individuals typically overestimate the amount of exercise they are performing.
      • Dyrstad S.M.
      • Hansen B.H.
      • Holme I.M.
      • Anderssen S.A.
      Comparison of self-reported versus accelerometer-measured physical activity.
      Coupling the tendency for patients to overestimate physical activity with cautions about potential hazards of exercise, we fear that both active and inactive individuals may not be fully capitalizing on the maximum survival benefits that can be obtained from lifestyle change.
      More research will be needed to verify the relationship between excessive exercise, cardiotoxicity, and mortality in both heart attack survivors and healthier individuals. For now though, we believe it is still too early to sound the alarm on the potential hazards of exercise for all survivors because most patients would not engage in the level of physical activity reported as being potentially harmful. Patients should be encouraged to be as active as their body can tolerate and to avoid strenuous activity that their body is unaccustomed to. We applaud the sound research performed by Thompson et al
      • Williams P.T.
      • Thompson P.D.
      Increased cardiovascular disease mortality associated with excessive exercise in heart attack survivors.
      and will read with great interest their future findings.

      References

        • Williams P.T.
        • Thompson P.D.
        Increased cardiovascular disease mortality associated with excessive exercise in heart attack survivors.
        Mayo Clin Proc. 2014; 89: 1187-1194
        • Hung R.K.
        • Al-Mallah M.H.
        • McEvoy J.W.
        • et al.
        Prognostic value of exercise capacity in patients with coronary artery disease: the FIT (Henry Ford ExercIse Testing) Project.
        Mayo Clin Proc. 2014; 89: 1644-1654
        • Heran B.S.
        • Chen J.M.
        • Ebrahim S.
        • et al.
        Exercise-based cardiac rehabilitation for coronary heart disease.
        Cochrane Database Syst Rev. 2011; : CD001800
        • Feldman D.I.
        • Al-Mallah M.H.
        • Keteyian S.J.
        • et al.
        No evidence of an upper threshold for mortality benefit at high levels of physical fitness.
        J Am Coll Cardiol. 2014; ([in press])
        • Dyrstad S.M.
        • Hansen B.H.
        • Holme I.M.
        • Anderssen S.A.
        Comparison of self-reported versus accelerometer-measured physical activity.
        Med Sci Sports Exerc. 2014; 46: 99-106

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