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

Background:
Aortic stenosis (AS) is a progressive disease with high mortality and bleak prognosis. While surgical aortic valve replacement (SAVR) or transcutaneous aortic valve insertion (TAVI) are indicated for patients with severe symptomatic AS and high gradients (>40 mmHg), or low flow and low gradient, the approach for patients with normal flow with low gradient (NFLG) is less well-defined.

Methods:
Adult patients who underwent echocardiographic evaluation between the years 2012-2015 in Tel-Aviv Medical Center, that had an aortic valve area (AVA) ≤ 1 cm², symptoms, a gradient 35 mL/m² were included. Patients were assessed for operational status provided it was performed no later than 6 months within the index exam.

Results:
Out of 1358 patients with severe symptomatic AS, 34% had NFLG-AS of which 303 were included. Of the conservative patients with subsequent echo data (N=61), 15 (25%) transitioned to low flow-low, and 13 (21%) progressed to high gradient. After a mean follow-up of 652 days, 60 (20%) patients had died, with overall mortality rates of 28%, 10% and 12% for conservatively treated, TAVI and SAVR patients respectively, (p<0.001). By survival analysis, the association of type of intervention with survival was significant (p=0.002). Using Cox regression with adjustment for other variables conservative vs. TAVI showed a significant association with mortality (0.5 HR, CI 0.26 -0.97, p=0.04) with no significant difference for SAVR vs TAVI. The difference persisted after matching by propensity score of TAVI and conservative patients.

Conclusions:
Patients with normal flow, low gradient and AVA of ≤ 1 cm² might benefit from intervention as opposed to conservative treatment.