Key result
Paradoxical low-flow, low-gradient severe AS linked to ~20% lower VO2 versus non-paradoxical AS.
Why the study?
The mechanism of reduced stroke volume index in paradoxical low-flow, low-pressure gradient aortic stenosis remains unclarified.
Is reduced stroke volume index in paradoxical low-flow, low-pressure gradient severe aortic stenosis associated with reduced whole body O2 consumption?
Observational (n=59)
Is reduced stroke volume index in paradoxical low-flow, low-pressure gradient severe aortic stenosis associated with reduced whole body O2 consumption?
Reduced stroke volume in paradoxical low-flow, low-pressure gradient severe aortic stenosis is strongly associated with reduced whole-body oxygen consumption, providing insight into its central pathophysiology.
Lower O2 consumption in PLFLPG severe AS may reflect reduced stroke volume; hypothesis-generating for pathophysiology, needs prospective validation.
The mechanism of reduced stroke volume index (SVi) in paradoxical low-flow, low-pressure gradient (PLFLPG) aortic stenosis (AS) remains unclarified. Guyton et al. ( 21 ) demonstrated that SVi is determined by whole body O 2 consumption (V̇o 2 ) in many subjects, including patients with heart disease. We hypothesized that reduced SVi in PLFLPG AS is associated with reduced V̇o 2 by the whole body. This study investigated the relationship between V̇o 2 , SVi, and AS severity in patients with AS to examine the association between reduced V̇o 2 and PLFLPG AS. In 59 patients (24 men and 35 women, mean age: 78 ± 7 yr old) with severe AS, SVi, AS severity, and type were evaluated by echocardiography, and V̇o 2 was measured by the fraction of O 2 in expired gases. SVi and V̇o 2 were significantly decreased in 20 patients with PLFLPG AS compared with 39 patients with non-PLFLPG AS (30 ± 4 vs. 41 ± 7 ml/m 2 and 2.4 ± 0.5 vs. 3.0 ± 0.5 ml·min −1 ·kg −1 , respectively, P < 0.01). The SVi-to-V̇o 2 ratio was not different between the two groups (13.1 ± 2.6 vs. 13.6 ± 2.1, not significant). SVi was independently correlated with V̇o 2 ( r = 0.74, P < 0.01) but not with the aortic valve area index. Categorized PLFLPG AS was also significantly associated with reduced V̇o 2 ( P < 0.001). PLFLPG AS is associated with reduced V̇o 2 by the whole body, which may offer insights into the mechanism of PLFLPG AS. NEW & NOTEWORTHY Paradoxical low-flow, low-pressure gradient severe aortic stenosis (PLFLPG AS) is an important and problematic subtype, and its central pathophysiology with reduced stroke volume is yet to be clarified. We hypothesized and subsequently clarified that reduced stroke volume in PLFLPG AS is associated with reduced O 2 consumption by the whole body. This study suggests important insights into the mechanism of PLFLPG AS and may further promote studies to investigate further mechanisms and novel treatment.
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Onoue et al. (2019) conducted an observational in Severe aortic stenosis (n=59). Paradoxical low-flow, low-pressure gradient (PLFLPG) severe aortic stenosis vs. Non-PLFLPG severe aortic stenosis was evaluated on Whole body O2 consumption (VO2) (p=<0.01). Paradoxical low-flow, low-pressure gradient severe aortic stenosis was associated with reduced whole body O2 consumption compared to non-PLFLPG AS (2.4 vs 3.0 ml/min/kg; P<0.01).
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