High Intensity Exercise Training In Patients With Hypertrophic Cardiomyopathy

Abstract

Patients with hypertrophic cardiomyopathy (HCM) are excluded from high intensity activities due to perceived fear of sudden cardiac death though data from athletes with HCM suggest competitive sport may be safe for some. Low cardiorespiratory fitness in sedentary HCM patients may confer a greater lifetime cardiovascular event risk than exercise per se. While moderate intensity exercise training in patients with HCM modestly increases fitness, high intensity exercise may be superior. PURPOSE: To compare the efficacy of five months of moderate intensity exercise and high intensity exercise training to improve cardiorespiratory fitness (V̇O2max) in patients with HCM. METHODS: Eight patients with HCM (50 ± 7 years, 3 female) were assessed for maximal oxygen uptake (V̇O2max, Douglas Bag method), cardiac output (Q̇c, acetylene rebreathing), and peripheral oxygen extraction (av-O2 diff, Fick equation) before randomization and after 5 months of moderate or high intensity exercise training. Patients completed 3-4 sessions of moderate intensity exercise each week, while the high intensity group also incorporated a weekly interval training session. RESULTS: Five months of moderate intensity exercise increased absolute V̇O2max by 3% and relative V̇O2max by 4%, while high intensity exercise consistently increased absolute V̇O2max by 6% and relative V̇O2max by 5% (Figure). Maximal Q̇c did not change after moderate intensity exercise (+0.0L [95% CI -2.0 to 1.7]) but increased in all three patients after high intensity exercise (+1.2L [95% CI -1.4 to 3.9]), while maximal av-O2 diff remained stable in both groups (moderate intensity: +0.8mL/100mL [95% CI -1.0 to 2.6]; high intensity: -0.5mL/100mL [95% CI -3.6 to 2.7]). CONCLUSION: Preliminary findings show similar increases in cardiorespiratory fitness following five months of moderate and high intensity exercise training in patients with HCM, although improvements were more consistent after high intensity exercise.