Abstract 10985: Survival by Stroke Volume Index in Patients With Low Gradient Normal Ejection Fraction Severe Aortic Stenosis
Background: Patients with low-gradient (LG) severe aortic stenosis (AS) and preserved ejection fraction (EF) with reduced stroke volume may have an adverse prognosis, but the ideal cutpoint for defining reduced stroke volume index (SVI) is unknown. We investigated the prognostic impact of SVI using different cutpoints in this population.
Methods and Results: We examined 405 consecutive patients aged ≥18 years with preserved EF (≥50%) and severe AS (aortic valve area (AVA) <1.0 cm2) with LG (<40 mmHg) using 2-D and Doppler echocardiography. Patients were stratified into quartiles based on distribution of SVI (group 1: <38 ml/m2 (n=90), group 2: 38-43 ml/m2 (n=105), group 3: 43-48 ml/m2 (n=104),and group 4: >48 ml/m2 (n=106)). Groups 1 and 2 had the poorest survival with medical management compared to 3 and 4 (2 year estimate 62% and 74% vs. 83% and 88%, respectively, p=0.002) although referral rate for aortic valve replacement was similar among groups (53-62%, p=0.57). After multivariate analysis, SVI <43 ml/m2 was an independent predictor of all-cause mortality (HR 2.32 (1.57, 3.50) p<0.0001). Survival in patients with SVI ≥43 was similar to age and sex-matched expected (3 year estimate 84%, p=0.24), whereas patients with SVI <43 had significantly reduced survival compared to expected (3 year estimate 63%, p<0.001). Using c-statistics, SVI <43 ml/m2 had better discrimination for predicting mortality than SVI <35 ml/m2 and identified more patients at risk (48% vs. 13%, p =<0.001).
Conclusions: Low flow, LG severe AS with preserved EF is associated with reduced survival compared to normal flow. SVI <43 ml/m2 identifies a larger low-flow group compared to the traditional cutpoint of <35 ml/m2 and enhances risk prediction, allowing more patients the potential benefit of AVR. These findings have implications for classification of AS severity, identification of high-risk groups, and subsequent management.
- © 2013 by American Heart Association, Inc.