Predictors of Mortality and Outcomes of Therapy in Low-Flow Severe Aortic Stenosis

Abstract

BACKGROUND: The prognosis and treatment of patients with low flow (LF) severe aortic stenosis (AS) is controversial. METHODS AND RESULTS: The PARTNER trial randomized patients with severe AS to medical management (MM) vs transcatheter (TAVR) aortic valve replacement ("inoperable" cohort) and surgery (SAVR) vs TAVR (high risk cohort). Among 971 patients with evaluable echocardiograms (92%), LF (stroke volume index (SVI) ≤35 ml/m2) was observed in 530 (55%), LF and low ejection fraction (<50%, LEF) in 225 (23%), LF, LEF, and low mean gradient (<40 mmHg, LG) in 147 (15%). Two-year mortality was significantly higher in patients with LF compared with normal SVI (47% vs 34%, HR 1.5, 95%CI [1.25,1.89], p=0.006). In the inoperable cohort, patients with LF had higher mortality than those with normal flow, but both groups improved with TAVR (46% vs 76% with LF and 38% vs 53% with normal flow, p<0.001). In the high-risk cohort, there was no difference between TAVR and SAVR. In patients with paradoxical LF and LG (preserved EF), TAVR reduced 1-year mortality from 66% to 35% (HR 0.38, p=0.02). LF was an independent predictor of mortality in all patient cohorts (HR ~1.5), whereas EF and gradient were not. CONCLUSIONS: Low flow is common in severe AS and independently predicts mortality. Survival is improved with TAVR as compared to MM and similar with TAVR and SAVR. A measure of flow (SVI) should be included in the evaluation and therapeutic decision making of patients with severe AS. CLINICAL TRIAL REGISTRATION INFORMATION: clinicaltrial.gov. Identifier: NCT00530894.