TAVR safe in low-risk patients with severe aortic stenosis

Ron Waksman

MUNICH — In a prospective trial, no patients with low surgical risk had died or experienced disabling stroke at 30 days after transcatheter aortic valve replacement for symptomatic severe aortic stenosis, Ron Waksman, MD, from MedStar Heart & Vascular Institute at MedStar Washington Hospital Center, said at the European Society of Cardiology Congress.

Moreover, he noted, the unadjusted 30-day all-cause mortality rate — the study’s primary endpoint — in the 200 low-risk patients undergoing TAVR was significantly lower than in the 719 low-risk patients undergoing surgical AVR (0% vs. 1.7%; P = .079).

In terms of in-hospital procedure-related outcomes, patients undergoing TAVR vs. surgical AVR had a shorter mean length of hospital stay (2 vs. 6.4 days; P < .001) and lower rates of Valve Academic Research Consortium-2 life-threatening or major bleeding (2.5% vs. 10.3%; P < .001) and new-onset atrial fibrillation (3% vs. 40.8%; P < .001). There were no significant differences between the TAVR and surgical AVR groups in all-cause death (0% vs. 0.7%; P = .591), stroke (0% vs. 0.6%; P = .582) or permanent pacemaker implantation (5% vs. 4.5%; P = .742).

“TAVR is safe and effective in low-risk patients in the short term, and short-term TAVR outcomes compare favorably to surgical AVR,” Waksman said.

Aside from all-cause death, 30-day outcomes were not available for patients who underwent surgical AVR. For patients who underwent TAVR, the 30-day rates of non-disabling stroke (0.5%), new-onset AF (4.5%) and permanent pacemaker implantation (6.5%) remained low, and there was no disabling stroke, endocarditis or acute kidney injury.

At 30 days, hemodynamics were satisfactory, according to Waksman, with an aortic valve area of 1.65 cm² and a gradient of 12.9 mm Hg. Additionally, overall total aortic regurgitation was acceptable, he noted, with only one patient who underwent TAVR having moderate paravalvular leak. New York Heart Association class was also significantly improved in the TAVR group.

The researchers also evaluated subclinical leaflet thrombosis in the low-risk patients who underwent TAVR. Of 194 patients who had four-dimensional contrast-enhanced CT or transesophageal echocardiography at 30 days, 14% had hypoattenuated leaflet thickening, 11.2% had reduced leaflet motion and 7.4% had hypoattenuation affecting motion. Of note, no hypoattenuated leaflet thickening was seen with use of self-expanding valves (CoreValve Evolut R or Evolut Pro, Medtronic) based on core-lab analysis, according to Waksman.

Further, 78.8% of patients were treated with antiplatelet therapy, of whom 15.8% had hypoattenuating leaflet thickening. Of the 20.2% of patients who were treated with oral anticoagulants only, 7.7% had hypoattenuating leaflet thickening.

“Subclinical leaflet thrombosis is present in in low-risk TAVR patients without clinical sequelae at 30 days, but the long-term clinical impact is unknown,” Waksman said.

The Low Risk TAVR trial is a prospective, multicenter registry of 200 patients with symptomatic severe aortic stenosis and a Society of Thoracic Surgeons (STS) score less than 3% who underwent transfemoral TAVR with a commercially available device from January 2016 to February 2018. All patients were screened by the institutional heart team and an independent clinical review committee to ensure low-risk status before enrollment. All data were monitored and event-adjudicated and echocardiography and CT core labs were used to evaluate findings.

To compare outcomes with TAVR vs. surgical AVR, the researchers used a historical cohort of low-risk patients who underwent isolated surgical AVR at the same institutions and data derived from the STS database.

Baseline characteristics were well balanced between groups, according to Waksman, including STS score, which was 1.7% in the TAVR and surgical AVR patients. However, patients in the TAVR group had a higher prevalence of peripheral vascular disease (16.6% vs. 5.5%; P < .001), slightly higher left ventricular ejection fraction (63.2% vs. 58.7%; P < .001) and less prior MI (3.3% vs. 7.7%; P = .006). The valve size used was also greater in patients undergoing TAVR vs. surgical AVR (25.8 mm vs. 22.6 mm).

The choice of TAVR device was left to investigator preference, with 88.2% choosing a balloon-expandable valve (Sapien 3, Edwards Lifesciences) and 11.8% choosing a self-expanding valve.

The Low Risk TAVR trial is the first FDA-approved Investigational Device Exemption trial in the United States to study TAVR in low-risk patients, according to Waksman. Notably, he said, only one of the 11 sites that participated in the study was a high-volume TAVR center.

“To place these findings in context, we’ve come a long way from the 30-day all-cause mortality rate of 5% in PARTNER 1 and 8.4% in the CoreValve study in extreme-risk patients. Then, we moved to moderate-risk patients and the mortality dropped to 3.9% in PARTNER 2 and 2.8% in SURTAVI. We’re now at 0% mortality at 30 days in low-risk patients,” he said. “If the pivotal trials corroborate the Low Risk TAVR trial results, then TAVR should be approved for low-risk patients.” – by Melissa Foster

References:

Waksman R, et al. Late Breaking TAVI Registries. Presented at: European Society of Cardiology Congress; Aug. 25-29, 2018; Munich.

Waksman R, et al. J Am Coll Cardiol. 2018;doi:10.1016/j.jacc.2018.08.1033.

Disclosure: Waksman reports he is on the advisory board for Abbott Vascular, Amgen, Boston Scientific, Cardioset, Medtronic, Philips Volcano and Pi-Cardia Ltd; he is a consultant for Abbott Vascular, Amgen, Biosensors, Biotronik, Boston Scientific, Cardioset, Medtronic, Philips Volcano and Pi-Cardia Ltd; he received grant support from Abbott Vascular, AstraZeneca, Biosensors, Biotronik, Boston Scientific and Chiesi; he is on the speakers bureau for AstraZeneca and Chiesi; and he is an investor in MedAlliance.