Stroke volume increase during exercise, measured by Δ(VO₂/HR)/ΔWR, decreases significantly as mitral regurgitation severity worsens in patients with EF≥40%.
Does the severity of resting mitral regurgitation correlate with the rate of stroke volume increase during exercise in patients with EF >40%?
The rate of increase in VO₂/HR per watt during exercise testing correlates inversely with resting mitral regurgitation severity, serving as a non-invasive index of true stroke volume impairment.
Tasa de eventos absoluta: 0% vs 0%
Abstract Background and Purpose The severity of heart failure can be assessed by peak VO₂. One of the factors that determines VO₂ is cardiac output. In mitral regurgitation (MR), the effective stroke volume (SV) decreases due to regurgitation. Generally, when the degree of MR at rest is low, the peak VO₂ is also low. A possible reason is that the increase in cardiac output during exercise is reduced in proportion to the severity of the MR, resulting in a decreased increase in VO₂. However, there are cases where SV increase is favorable even with severe MR, and conversely, cases where SV increase is poor despite less severe MR. This suggests that the severity of MR during exercise cannot be evaluated by resting echocardiography. In this study, we examined the relationship between the severity of MR at rest and the response of SV increase during exercise. Methods Among 1121 patients who underwent cardiopulmonary exercise test (CPX) at our institution from January 2023 to July 2024, we focused on 850 patients (274 females, 576 males, mean age 67.0±14.6 years old) who had Ejection fraction 40% over where precise analyses of Δ(VO₂/HR)/ΔWR up to AT was possible. The rate of increase in VO₂/HR per watt during an incremental loading (Δ(VO₂/HR)/ΔWR) was used as an indicator of SV increase. Typically, SV increases up to 60% of maximum load, around AT, after which it stops increasing and plateaus. Therefore, the slope of Δ(VO₂/HR)/ΔWR was examined from the initiation of ramp loading to AT. The degree of reflux was evaluated by echocardiography and classified as none/trivial, mild and moderate/severe. The number of people in each group of None/trivial, mild, moderate/severe was, 722, 92, 36 for MR, Δ(VO₂/HR)/ΔWR was evaluated for each degree of reflux, using ANOVA to determine whether there was a difference between groups. Results As shown in the Figure1, Δ(VO₂/HR)/ΔWR until AT decreased as the regurgitant flow rate increased for MR. Conclusion The Δ(VO₂/HR)/ΔWR obtained through CPX has been shown to be an index that can evaluate the severity of MR. Additionally, it was also demonstrated that as MR flow increased, true stroke volume decreases, which is correlated with a reduction in peak VO₂.Figure1
Kubota et al. (Sat,) reported a other. Stroke volume increase during exercise, measured by Δ(VO₂/HR)/ΔWR, decreases significantly as mitral regurgitation severity worsens in patients with EF≥40%.