Cardiopulmonary exercise testing parameters in healthy athletes vs. equally fit individuals with hypertrophic...

Cardiopulmonary exercise testing (CPET) is often used when athletes present with suspected hypertrophic cardiomyopathy (HCM). While low peak oxygen consumption (pV˙O2) augments concern for HCM, athletes with HCM frequently display supranormal pV˙O2, which limits this parameter's diagnostic utility. We aimed to compare other CPET parameters in healthy athletes and equally fit individuals with HCM.

Using cycle ergometer CPETs from a single centre, we compared ventilatory efficiency and recovery kinetics between individuals with HCM [percent predicted pV˙O2(ppV˙O2) > 80%, non-obstructive, no nodal agents] and healthy athletes, matched (2:1 ratio) for age, sex, height, weight and ppV˙O2. Consistent with matching, HCM (n = 30, 43.6 ± 14.2 years) and athlete (n = 60, 43.8 ± 14.9 years) groups had similar, supranormal pV˙O2 (39.5 ± 9.1 vs. 41.1 ± 9.1 mL/kg/min, 125 ± 26 vs. 124 ± 25% predicted). Recovery kinetics were also similar. However, HCM participants had worse ventilatory efficiency, including higher early V˙E/V˙CO2 slope (25.4 ± 4.7 vs. 23.4 ± 3.1, P = 0.02), higher V˙E/V˙CO2 nadir (27.3 ± 4.0 vs. 25.2 ± 2.6, P = 0.004) and lower end-tidal CO2 at the ventilatory threshold (42.9 ± 6.4 vs. 45.7 ± 4.8 mmHg, P = 0.02). HCM participants were more likely to have abnormally high V˙E/V˙CO2 nadir (>30) than athletes (20 vs. 3%, P = 0.02).

Even in the setting of similar and supranormal pV˙O2, ventilatory efficiency is worse in HCM participants vs. healthy athletes. Our results demonstrate the utility of CPET beyond pV˙O2 assessment in 'grey zone' athlete cases in which the diagnosis of HCM is being debated.