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 are controversial. Methods and Results— The Placement of Aortic Transcatheter Valves (PARTNER) trial randomized patients with severe aortic stenosis to medical management versus transcatheter aortic valve replacement (TAVR; inoperable cohort) and surgical aortic valve replacement versus TAVR (high-risk cohort). Among 971 patients with evaluable echocardiograms (92%), LF (stroke volume index ≤35 mL/m 2 ) was observed in 530 (55%); LF and low ejection fraction (<50%) in 225 (23%); and LF, low ejection fraction, and low mean gradient (<40 mm Hg) in 147 (15%). Two-year mortality was significantly higher in patients with LF compared with those with normal stroke volume index (47% versus 34%; hazard ratio, 1.5; 95% confidence interval, 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% versus 76% with LF and 38% versus 53% with normal flow; P <0.001). In the high-risk cohort, there was no difference between TAVR and surgical aortic valve replacement. In patients with paradoxical LF and low gradient (preserved ejection fraction), TAVR reduced 1-year mortality from 66% to 35% (hazard ratio, 0.38; P =0.02). LF was an independent predictor of mortality in all patient cohorts (hazard ratio, ≈1.5), whereas ejection fraction and gradient were not. Conclusions— LF is common in severe aortic stenosis and independently predicts mortality. Survival is improved with TAVR compared with medical management and similar with TAVR and surgical aortic valve replacement. A measure of flow (stroke volume index) should be included in the evaluation and therapeutic decision making of patients with severe aortic stenosis. Clinical Trial Registration— URL: http://www.clinicaltrial.gov . Unique identifier: NCT0053089.4.