Abstract 18847: Apples to Apples: Cardiopulmonary Exercise Testing Findings in Healthy Athletes versus Equally Fit Patients With Hypertrophic Cardiomyopathy
Cliodhna McHugh, Sarah K Gustus, Bradley J Petek, Meagan M Wasfy- Physiology (medical)
- Cardiology and Cardiovascular Medicine
Introduction: CPET is often used when athletes present for clinical evaluation of suspected pathology, including HCM. While lower than expected peak oxygen consumption (pVO 2 ) may raise suspicion for HCM, athletes with HCM frequently display normal or supranormal pVO 2 , limiting the diagnostic utility of this parameter.
Hypothesis: We hypothesize that there will be differences in other CPET parameters between healthy athletes and equally fit individuals with established HCM. Aim: The aim of this study was to compare CPET parameters in healthy athletes and equally fit individuals with established HCM.
Methods: Healthy athletes and HCM patients (percent predicted pVO 2 (ppVO 2 ) >90%, non-obstructive, no nodal agents) were identified who had cycle ergometer CPETs for research or clinical evaluation in a single lab. CPETs were compared between HCM patients and athletes matched (2:1 ratio) for age, sex, race, height, weight, and cardiorespiratory fitness (ppVO 2 ).
Results: Consistent with matching, HCM (n=30, 43.6 ± 14.2 years) and athletes (n=60, 43.8 ± 14.9 years) groups had similar, supranormal pVO 2 (40.4 ± 9.0 vs. 41.2 ± 8.9 mL/kg/min, 125% vs. 124% predicted, n.s.). While many CPET parameters were similar between groups, HCM patients had worse ventilatory efficiency with lower end-tidal CO 2 at the ventilatory threshold (VT) (42.9 ± 6.4 vs. 45.7 ± 4.8, p= 0.02), higher early VE/VCO 2 slope (through VT, 25.4 ± 4.7 vs. 23.4 ± 3.1, p=0.02), and higher nadir of VE/VCO 2 (27.3 ± 4 vs. 25.2 ± 2.6, p<0.001). When stratified by ppVO 2 , these differences remained significant for those with ppVO 2 < and ≥100%. Using the recommended cut-off of <30, HCM patients were more likely to have abnormally high VE/VCO 2 nadir than athletes (20% vs. 5%, p= 0.03).
Conclusion: Amongst equally fit individuals, ventilatory efficiency was worse in patients with HCM than in healthy athletes. Our results suggest ventilatory efficiency may be useful to integrate in with other diagnostic testing in “gray zone” clinical cases in which the diagnosis of HCM is being debated in athletes with LVH. Given ventilatory efficiency has been increasingly recognized as a key prognostic CPET parameter, future work should establish the prognostic value of VE/VCO 2 in HCM patients with intact cardiorespiratory fitness.