Survival by stroke volume index in patients with low-gradient normal EF severe aortic stenosis

Low-gradient (LG) severe aortic stenosis (AS) and preserved EF with reduced stroke volume are associated with an adverse prognosis, but the relationship of stroke volume index (SVI) with mortality among a range of values is unknown. We investigated the prognostic impact of SVI in this population.We examined 405 consecutive patients with preserved EF (≥50%) and severe AS (valve area1.0 cm(2)) with LG (40 mm Hg) using echocardiography. Patients were stratified into quartiles based on SVI distribution (group 1:38 mL/m(2) (n=90), group 2: 38-43 mL/m(2) (n=105), group 3: 43-48 mL/m(2) (n=104) and group 4:48 mL/m(2) (n=106)).Groups 1 and 2 had poorer survival with medical management compared with 3 and 4 (3-year estimate 46% and 67% vs. 78% and 73%, respectively, p=0.002) although aortic valve replacement referral rate was similar (53%-62%, p=0.57). An inverse relationship was observed between SVI and mortality (HR 1.28 (1.11 to 1.46) per every 5 mL/m(2) decrease in SVI). After multivariable analysis, SVI was the strongest predictor of mortality (HR 0.92 (0.89 to 0.95), p0.0001). Using different SVI cutpoints, SVI35 was associated with highest mortality (HR 2.36 (1.49 to 3.73), p0.001), followed by SVI38 (HR 2.09 (1.39 to 3.16), p0.001) and by SVI43 (HR 2.05 (1.38 to 3.05), p0.001). Survival with SVI ≥43 was similar to age and sex-matched controls (3-year estimate 84%, p=0.24); survival for SVI43 was significantly worse (3-year estimate 63%, p0.001).Lower SVI is incrementally associated with mortality in LG severe AS with preserved EF. These findings have implications for classification of AS severity, identification of high-risk groups and subsequent management.