Indexing Aortic Valve Area by Body Surface Area Increases the Prevalence of Severe Aortic Stenosis
In patients with aortic stenosis (AS), how does an indexed aortic valve area (AVAindex) impact the prevalence of severe AS and patient outcomes?
This study examined two cohorts of patients, including a retrospective cohort of 2,843 patients with AS and 1,525 patients with AS prospectively evaluated as part of the SEAS (Simvastatin and Ezetimibe in Aortic Stenosis) trial. The study compared the prevalence of severe AS as defined by AVAindex <0.6 cm2/m2 and/or AVA <1.0 cm2, compared to the use of AVA alone. It further compared the association between these cutoffs and rates of adverse valve-related events in the SEAS study (cardiovascular death, aortic valve replacement, or heart failure due to AS).
The prevalence of severe AS increased by incorporating AVAindex criteria (vs. AVA alone) in both the retrospective cohort (79.8% vs. 70.7%, p < 0.001) and the SEAS cohort (43.8% vs. 30.8%, p < 0.001). At a mean follow-up of 46 months, there was no difference between AVA and AVAindex in their respective ability to identify patients with subsequent valve-related adverse events (area under the curve, 0.67 vs. 0.68; p = NS). Among the 213 patients in the SEAS study diagnosed with severe AS using the AVAindex but not the AVA, they had lower rates of adverse valve-related events in comparison to patients diagnosed with severe AS by AVA (p < 0.001).
The use of the AVAindex increases the prevalence of severe AS, although it did not improve identification of patients at risk of adverse valve-related events.
The use of AVA indexed to body surface area significantly increases the proportion of patients defined as having severe AS. Individuals with severe AS defined by AVAindex but not AVA have fewer adverse valve-related events, suggesting that these patients may represent a lower-risk cohort. A major limitation of indexing AVA for body size is that it does not account for obesity, and can result in shifting patients from moderate to ‘severe’ AS simply by weight gain. These findings raise concerns that the current cutoff may be inadequate, and gain import by the increasing prevalence of obesity. Future investigation is needed to determine the appropriate use and optimal cutoff for AVAindex, and caution is needed in patients who meet criteria for severe AS by AVAindex only.
Keywords: Prevalence, Body Surface Area, Azetidines, Heart Failure, Obesity, Body Size, Weight Gain, Simvastatin
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