TAVR Provides ‘Acceptable’ Outcomes in Low-Flow, Low-Gradient Aortic Stenosis Patients With Poor Ventricular Function

WASHINGTON, DC—Patients with classical low-flow, low-gradient severe symptomatic aortic stenosis appear to do well following TAVR, with the multicenter TOPAS-TAVI registry demonstrating a relatively low 30-day mortality rate of 4.3%.

“Considering this is a very high-risk population, we figure this is a very acceptable outcome,” Henrique Ribeiro, MD PhD (Laval University, Quebec City, Canada), said during a presentation at TCT 2016. At 1 year, freedom from death was 80.4%.

John Webb, MD (St. Paul’s Hospital, Vancouver, Canada), who was a panelist at the session in which Ribeiro presented the results, told TCTMD that the finding of relatively low mortality in this population is “very important,” because prior research has shown that patients with low-flow, low-gradient aortic stenosis and poor LVEF do not necessarily do well with surgery.

The apparently better outcome achieved with TAVR is probably due to the less-invasive nature of the procedure, he said, adding that these findings will likely encourage clinicians to use of TAVR in these patients.

Small but High-Risk Group

Ribeiro noted that most patients with aortic stenosis—50% to 70%—have normal LVEF, normal flow, and a high gradient. Another 10% to 25% have paradoxical low-flow, low-gradient disease with a normal ejection fraction, whereas only 5% to 10% have classical low-flow, low-gradient disease with low LVEF.

That last group has a very high level of risk, he said, with only 50% to 60% of patients alive at 3 years. Surgery is an option, but operative mortality is substantial. And for those who do not have contractile reserve on dobutamine stress echo and choose to undergo surgery, survival is only about 40% at 1 year and 13% at 5 years.

Very few data exist regarding the use of TAVR in this population, Ribeiro said.

Considering this is a very high-risk population, we figure this is a very acceptable outcome. Henrique Ribeiro

Investigators formed the TOPAS-TAVI registry to help fill that gap. Enrolling at 14 sites in the United States, Canada, and Europe, the registry included 276 patients with severe symptomatic aortic stenosis who had an LVEF of 40% or lower, an aortic valve area of 1.0 cm2 or smaller, and a mean gradient less than 35 mm Hg.

The patients were very sick, with an average EuroSCORE 2 of 13% and STS PROM score of 10.3%. That is comparable to the inoperable patients included in the PARTNER 1 trial, Ribeiro said.

Baseline echo revealed a mean LVEF of 29.9%, a mean gradient of 25.5 mm Hg, and a mean aortic valve area of 0.75 cm2. Of the patients who underwent dobutamine stress echo, 45.2% had contractile reserve, defined by at least a 20% increase in stroke volume.

About three-quarters of the procedures (77%) were deemed successful. Sapien valves (Edwards Lifesciences) and a transfemoral approach were used in most patients.

In the first 30 days, the following outcomes were reported:

·      Death (4.3%)

·      New pacemaker (4.3%)

·      Major vascular complications (4.7%)

·      Major/life-threatening bleeding (6.5%)

·      Stroke (1.8%)

·      Need for hemodynamic support (6.1%)

·      Need for second valve (3.6%)

There was no difference in mortality between patients with versus without contractile reserve through 1 year. And multivariable analysis confirmed that the presence of contractile reserve was not a predictor of that or any other outcome.

Of patients who had echo data available at 1 year, 70% had some improvement in LVEF; contractile reserve was not related to the degree of improvement.

Role for Dobutamine Stress Echo?

Aside from demonstrating the benefits of TAVR in patients with low-flow, low-gradient aortic stenosis and poor LVEF, the study may also have an impact on the use of dobutamine stress echo, Webb said. Determining which patients had contractile reserve before the procedure according to that test did not help identify a subgroup more likely to benefit.

“So that changes our perspective a little bit on whether this test is going to be useful in many of these patients. It doesn’t really define high- versus low-risk patients for transcatheter aortic valve implantation,” he said, noting that dobutamine stress echo is routinely used in patients with low-flow, low-gradient aortic stenosis at many centers. It looks like the test could be useful for diagnosis but not for predicting outcome, he added. “So probably we would do less of these studies.”