Intervention Versus Observation in Symptomatic Patients With Normal Flow Low Gradient Severe Aortic Stenosis

Objectives: The purpose of this study was to describe patients with severe symptomatic aortic stenosis with normal flow and low gradients and determine whether they benefit from intervention. Background: Severe symptomatic aortic stenosis is a progressive disease with high mortality. Although surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR) are indicated for patients with high gradients (>40 mm Hg) or low gradients due to low flow, the approach for patients with normal flow and low gradients is poorly defined. Methods: Consecutive adult patients who underwent echocardiography between 2012 and 2015 at Tel-Aviv Medical Center and had an aortic valve area of ≤1.0 cm², a mean gradient of <40 mm Hg, a stroke volume index of >35 ml/m², and symptoms formed the study group. Patients designated for intervention (SAVR or TAVR) had their procedure within 6 months of the echocardiogram; the others were treated conservatively. The endpoints were all-cause mortality and cardiac-related mortality. Results: During the study period, 1,358 patients with an aortic valve area of ≤1.0 cm² and symptoms were identified; 34% of these had normal flow and low gradient aortic stenosis and 303 were included. After mean follow-up of 652 days, 60 patients (20%) had died, with overall mortality rates of 28%, 10%, and 12% for conservatively treated, TAVR, and SAVR patients, respectively (p < 0.001). Using Cox regression with adjustment for other variables, TAVR was associated with improved survival versus conservative treatment (hazard ratio [HR]: 0.49; 95% confidence interval [CI]: 0.26 to 0.93; p = 0.03), and lower cardiac mortality (HR: 0.30; 95% CI: 0.10 to 0.74; p = 0.007) with no significant difference for SAVR versus TAVR. After propensity score matching of TAVR and conservatively treated patients, 25 of 94 (28%) conservatively treated and 10 of 94 (12%) TAVR patients had died (p = 0.016). In the matched cohort, Cox regression showed that TAVR had a significant association with improved survival (HR: 0.42; 95% CI: 0.20 to 0.86; p = 0.03). Conclusions: Symptomatic patients with an aortic valve area of ≤1.0 cm², normal flow, and low gradient may benefit from intervention as opposed to conservative treatment.