Abstract 10881: Importance of Stroke Volume Index Assessed by Echocardiography for Stratification of Low Gradient Severe Aortic Stenosis With Normal Left Ventricular Function
Background: The prognosis and need for aortic valve intervention in patients with low-gradient (LG) severe aortic stenosis (AS) and normal left ventricular (LV) function remain controversial. We hypothesized that echocardiography (echo) could be used for the stratification of high risk patients when accurate assessment of stroke volume (SV) is obtained.
Methods: The study included 207 patients with LG severe AS (aortic valve area (AVA) ≤ 1.0cm2, mean gradient < 40mmHg) and normal LV function (LVEF ≥ 50%). In order to improve the accuracy of SV calculation by echo, we measured the LV outflow tract diameter (LVOT) at two locations: 5mm below the aortic annulus (recommended by the American Society of Echocardiography) and at the aortic valve annulus (common in clinical practice). Patients were divided into two groups based on SV index (SVi). Group I had SVi < 35mL/m2 (n=75) and Group II had SVi ≥ 35mL/m2 (n=97) calculated based on both locations using continuity equation. Patients with discrepancy in SVi calculation at the two LVOT locations (potential LVOT-velocity mismatch) were excluded (n=35). Mean follow-up time was 3.0±1.6 years.
Results: There was no significant difference in age (78±11 vs. 77±11 years), LVEF (58±6 vs. 60±6%), mean aortic valve gradient (30±5 vs. 31±5 mmHg) and LV mass index (115±34 vs. 109±31 g/m2) between Group I and Group II. Group I had larger body surface area (1.97±0.25 vs. 1.84±0.25 m2), smaller AVA index (0.36±0.08 vs. 0.50±0.09 cm2/m2), higher valvuloarterial impedance (6.1±1.6 vs. 4.0±0.8 mmHg/mL/m2) and lower 3-year cumulative survival (61% vs. 75%, p=0.03) than Group II. Multivariable analysis showed SVi was a strong predictor of mortality among LG severe AS patients (HR 0.95, CI: 0.91-0.99, P=0.02). For Group I, those with medical management had a two-fold increased risks of death compared to those who underwent AS intervention (HR: 2.74, CI: 1.13-6.67, p=0.03). However, there was no survival benefit associated with AS intervention in Group II (HR: 0.73, CI: 0.29-1.80, p=0.49).
Conclusion: LG severe AS with normal LV function consists of heterogeneous patients carrying different prognosis depending on SVi. If low SVi is accurately assessed by Doppler echo, AS intervention may be beneficial. Further clinical trials are warranted.
Author Disclosures: H. Shen: None. B. Stacey: None. B. Applegate: None. D. Zhao: None. S. Vasu: None. B. Upadhya: None. S. Gandhi: None. M. Pu: None.
- © 2015 by American Heart Association, Inc.