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Background: The aortic valve area index (AVAI) in aortic stenosis (AS) is measured by echocardiography with a continuity equation using the stroke volume index by Doppler (SVI Doppler ) or biplane Simpson (SVI Biplane ) method. AVAI Doppler and AVAI Biplane often show discrepancy due to differences between SVI Doppler and SVI Biplane . The degree of discrepancy and utility of combined AVAIs have not been investigated in a large population of AS patients, and the characteristics of subjects with larger discrepancies are unknown., Methods and results: We studied 820 patients with significant AS (AVA Doppler <1.5 cm 2 ) enrolled in the Asian Valve Registry, a prospective multicenter registry at 12 Asian centers. All-cause death and aortic valve replacement were defined as events. SVI Doppler was significantly larger than SVI Biplane (49±11 vs. 39±11 mL/m 2 , P<0.01) and AVAI Doppler was larger than AVAI Biplane (0.51±0.15 vs. 0.41±0.14 cm 2 /m 2 , P<0.01). An increase in (AVAI Doppler - AVAI Biplane ) correlated with shorter height, lower weight, older age, smaller left ventricular (LV) diameter and increased velocity of ejection flow at the LV outflow tract. Severe AS by AVAI Doppler or AVAI Biplane enabled prediction of events, and combining these AVAIs improved the predictive value of each., Conclusions: Discrepancy in AVAI by Doppler vs. biplane method was significantly more pronounced with increased LV outflow tract flow velocity, shorter height, lower weight, older age and smaller LV cavity dimensions. Combining the AVAIs enabled mutual and incremental value in predicting events.

We report a case of a 77-year-old male who had been diagnosed with normal-flow high-pressure gradient severe aortic stenosis (AS) two years previously. In accordance with his wishes, it was decided not to perform surgery. He visited our hospital with anorexia and weight loss and was diagnosed with gastric cancer. Echocardiography showed a change to paradoxical low-flow low-pressure gradient severe AS (PLFLPG AS). A decrease in stroke volume is typically associated with a smaller LV size, but the reason for a smaller LV size in PLFLPG AS remains unclear. In this case, the change to PLFLPG AS was thought to be due to a decrease in whole body oxygen consumption, and this may help to understand the pathology.

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.