C. McHugh, Massachusetts General Hospital,  Boston, MA 02114, USA.
S. K. Gustus, B. J. Petek, M. W. Schoenike, K. S. Boyd, J. B. Kennett, et al.

Eur J Prev Cardiol 2025

AIMS: 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.
METHODS AND RESULTS: 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).
CONCLUSION: 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.
We sought to examine exercise test findings in healthy athletes and equally fit individuals with a form of heart enlargement that commonly gets confused with ‘athlete’s heart’ called hypertrophic cardiomyopathy (HCM) to see if elements of the exercise test could distinguish between these two groups. This is relevant as fit individuals often present for exercise testing as part of the work up to see if they have HCM or not, and getting the answer right is important because HCM is amongst the most common causes of sudden cardiac death in athletes.By design, individuals with HCM in this study were equally fit as the athletes, with both groups having fitness levels (‘VO2 max’ levels) around 25% higher than expected for individuals of similar age and sex.Despite this similar and supranormal fitness, individuals with HCM had worse ventilatory efficiency than athletes. This is a metric that reflects how well the heart and lungs work together to get rid of the waste gas carbon dioxide during exercise. This finding should focus more attention on this parameter when exercise tests are being performed to evaluate for HCM in clinical practice.