Echocardiographic Assessment of Aortic Stenosis under Sedation Underestimates Stenosis Severity

Abstract

Sedation can impact aortic stenosis (AS) classification, which depends on left ventricular ejection fraction (<≥ [less than or greater than and/or equal to] 50%), aortic valve area (AVA<≥ 1cm2), mean pressure gradient (<≥ 40mm Hg), peak velocity <≥ 400cm/sec, and stroke volume index (SVI <≥35mL/m2). We compared AS classification by transthoracic echo (TTE) during wakefulness versus sedation. Immediately following a baseline TTE performed during wakefulness, another TTE was done during sedation delivered for a concomitant transesophageal study in 69 consecutive patients with AS (mean age 78±7years, 32 males). AVA was calculated through the continuity equation using the relevant hemodynamic parameters measured by each TTE study and same left ventricular outflow tract. AS class was defined as moderate, severe high gradient (HG), low ejection fraction low flow low gradient (LF-LG), paradoxical LF-LG (PLFLG), and normal flow low gradient (NF-LG). Based on conservative versus invasive treatment implication, AS classes were aggregated into group A (moderate AS and NFLG) and group B (HG, low-EF LF-LG, and PLFLG). During sedation, systolic and diastolic blood pressure decreased by 14.3±29 and 8±22mm Hg, respectively, mean pressure gradient from 30.4±10.9 to 27.2±10.8mm Hg, peak velocity from 345.3±57.7 to 329.3±64.8cm/m2, and SVI from 41.5±11.3 to 38.3±11.8mL/m2 (all P<.05). Calculated AVA was similar (delta=-0.009±0.15cm2). Individual discrepancies in hemodynamic parameters between the paired TTE studies resulted in an overall 17.4% rate of AS intergroup misclassification with sedation, with a relative risk of 1.09 of downgrade misclassification from group B to A versus upgrade misclassification (P<.001). Sedation TTE assessment downgrades AS severity in a significant proportion of patients, with a conversely smaller proportion of patients being upgraded, and therefore cannot be a substitute for wakefulness assessment.