Patients with low-flow, low-gradient severe symptomatic aortic stenosis associated with severe impairment of the left ventricular systolic function have shown acceptable outcomes after transcatheter aortic valve replacement (TAVR), according to the multicenter TOPAS-TAVI registry, which demonstrated a relatively low 30-day mortality rate.

Considering the very high risk presented by this population involved, a 30-day mortality rate of 4.3% and a 1-year mortality rate of 19.6% seem very reasonable.

Most patients (50%-70%) with severe aortic stenosis present normal left ventricular systolic function associated with normal flow and low gradient. A lower percentage (10%-25%) has paradoxical low-flow, low-gradient disease with normal systolic function. Finally, there is a minority, 5% to 10%, with classical low-flow, low-gradient disease and severe impairment of the systolic function.

This last group has a very high level of risk, and, without treatment, the mortality rate is 50% to 60% at 3 years (which can be higher for patients without contractile reserve on dobutamine stress echo).

The TOPAS-TAVI registry included 276 patients (from 14 sites) with symptomatic aortic stenosis associated with an ejection fraction of 40% or lower, an aortic valve area of 1 cm² or smaller, and a mean gradient less than 35 mm Hg.

The average EuroSCORE 2 was 13% and the STS PROM score was 10.3%, a risk comparable to that for inoperable patients included in the PARTNER 1 trial.

The baseline echocardiogram revealed a mean ejection fraction of 29.9%, a mean gradient of 25.5 mm Hg, and a mean aortic valve area of 0.75 cm². Of all patients who underwent a dobutamine stress echo, only 45.2% presented contractile reserve, defined as an increase of at least 20% in systolic volume.

Most patients received a balloon-expandable valve (Edwards Lifesciences), through a transfemoral approach.

At 30 days, the mortality rate was 4.3%, the need for a permanent pacemaker was 4%, the rate of major cardiovascular complications was 4.7%, and the rate of major bleeding was 6.5%.

There was no difference in mortality at 1 year between patients with contractile reserve when compared to those without it. A multivariable analysis confirmed that the presence of contractile reserve is not a predictor of any type of event.

At 1 year, 70% of the population showed some kind of improvement in the left ventricular systolic function, which could not be predicted by presence or absence of contractile reserve.

Original title: Transcatheter Aortic Valve Implantation in Patients with Low-Flow, Low-Gradient Aortic Stenosis: The Prospective Multicenter TOPAS-TAVI Study.

Reference: Ribeiro HB et al. TCT 2016. Washington, DC.

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