Heart rate estimation at ventilatory thresholds in cardiometabolic disease: do resting echocardiographic markers add value beyond effort parameters?

Background Cardiopulmonary exercise testing (CPET) provides the most accurate method for determining ventilatory thresholds (VT1 and VT2) and for guiding individualized aerobic exercise prescriptions. However, the limited availability of CPET restricts its routine use in clinical settings. When gas exchange analysis is unavailable, alternative approaches are needed to estimate heart rate (HR) at ventilatory thresholds. Purpose This study investigated whether incorporating resting echocardiographic indices with conventional exercise-derived predictors improves the accuracy of HR estimation at VT1 and VT2 in patients with cardiometabolic disease (CMD). Methods A cohort of 126 adults with CMD underwent CPET combined with resting echocardiography. Multivariate models were developed to predict HR at VT1 and VT2 using conventional parameters (resting HR and peak HR) and echocardiographic variables including left atrial volume index (LAVi), left ventricular end-diastolic volume index (LVEDVi), and E/e′ ratio. Results Previously developed predictive equations for estimating heart rate (HR) at ventilatory thresholds demonstrated strong performance: HR at VT1 = 4.866 + (0.405 × HR_peak) + (0.542 × HR_rest) (R² = 0.77) HR at VT2 = –2.606 + (0.773 × HR_peak) + (0.254 × HR_rest) (R² = 0.88) The integration of resting echocardiographic indices did not enhance HR prediction at VT1, while at VT2, inclusion of LVEDVi yielded only a minimal incremental improvement (R² = 0.839 vs. 0.832). Conclusion Although echocardiography remains essential for cardiac assessment in CMD, its contribution to predicting HR at ventilatory thresholds beyond resting and peak HR parameters are negligible. Predictive equations based solely on exercise-derived variables provide a practical alternative when CPET is unavailable.