Abstract 4146533: Association of Quantitative Echocardiographic Parameters with Peak VO2, Heart Rate Recovery, and VE/VCO2 from Cardiopulmonary Exercise Testing

Background: Cardiopulmonary Exercise Testing (CPET) analyzes physiologic information with gas exchange during exercise. Peak oxygen volume consumption (absolute peak VO2 and percent predicted peak VO2), minute ventilation divided by carbon dioxide volume (VE/VCO2 slope) and heart rate reduction after 1 minute of recovery (heart rate recovery, HRR) all have well-established prognostic cardiovascular implications. Aim: Given the wider use of echocardiography, we aimed to see if important CPET data could be determined from resting transthoracic echocardiography (TTE). Methods: In this retrospective study, cardiology patients above 18 years who underwent both resting TTE and a max-effort CPET within 3 months of each other (2017-2022) were included. Patients with a history of coronary artery bypass grafting, valve surgery, pacemakers, congenital heart disease, severe valve dysfunction and pulmonary hypertension were excluded before analysis. Univariate analysis with Spearman correlations was used to assess the relationship between 4 CPET measurements {absolute peak VO2 per kg, percent predicted peak VO2/kg (adjusted for age, sex and body surface area), HRR, and VE/VCO2}; and 22 quantitative TTE parameters. Bonferroni correction was applied within each set of correlations, with significance set at p-values <0.025. Multivariate linear regression models were built for all the related TTE measurements to assess relationship with the 4 CPET parameters, adjusting for age and sex. Results: Table 1 shows, out of 1909 patients analyzed, our regression model is strongest for absolute peak VO2/kg (R-squared=0.57), with 3 significantly associated TTE parameters. For percent-predicted peak VO2 per kg, 4 TTE variables were significantly associated. For heart rate recovery, only LV stroke-volume index was correlated. No TTE parameters were associated with VE/VCO2. Conclusion: Notably, echocardiographic stroke volume and tricuspid valve regurgitation peak velocity exhibited a strong correlation with absolute peak VO2/kg and percent predicted peak VO2/kg. LV stroke volume index was correlated with heart rate recovery. VE/VCO2 was not associated with any resting echocardiographic parameters, suggesting this parameter is truly exercise-dependent.