In HFpEF, Mechanism Behind Exercise Limitation Is Identified
In patients with heart failure with preserved ejection fraction (HFpEF), an impaired dynamic starling mechanism may contribute to exercise limitations, according to new data presented at the American Heart Association Scientific Sessions 2021.
The dynamic starling mechanism quantifies the modulation of stroke volume for each heartbeat via changes in left ventricular filling pressure mediated by respiration. This mechanism also clarifies the relation between changes in left‑ventricular compliance and stroke-volume response during exercise.
To test the hypothesis that low stroke-volume reserve during exercise would accompany greater impairment in dynamic starling mechanism gain in patients with HFpEF, researchers from the University of Texas Southwestern Medical Center studied 11 such patients at rest and during 20 Watts of upright cycling. Seven were women, and the mean age of the group was 68 years.
They then categorized these patients into higher or lower stroke-volume reserve groups based on median stroke-volume response. The lower-volume group had a median increase in response of 20% or less, and the higher-volume group had more than a 20% increase.
The dynamic starling mechanism was measured by transfer function analyses of changes in pulmonary artery diastolic pressure and stroke volume with each heartbeat, and the researchers used Hedges’ g to compare the magnitude of differences between conditions and groups.
The researchers found that the lower-volume group had blunted increases in stroke volume compared with the higher‑volume group. Although both groups had a decrease in dynamic starling mechanism gain from rest to exercise, the lower-volume group had a greater decrease than the higher-volume group.
As a result, the researchers concluded that “Impaired [dynamic starling mechanism] may explain low [stroke-volume] response and contribute to exercise limitations in patients with HFpEF.”
Hughes SB, Wakeham DJ, Macnamara JP, et al. Impaired stroke volume response during exercise in patients with heart failure with preserved ejection fraction (HFpEF): the role of dynamic starling mechanisms. Paper presented at: American Heart Association Scientific Sessions 2021; November 13-15, 2021; Virtual. https://www.abstractsonline.com/pp8/?_ga=2.35875360.1285494533.1632235753-403355333.1630439276#!/9349/presentation/930