Mix of Patient, Procedural, and Device Factors All Drove TAVI Advances

BOSTON, MA—As TAVI outcomes have improved over the years, different factors seem to be driving changes in short-term complications and mortality, according to data from the Society of Thoracic Surgeons/American College of Cardiology TVT Registry.

Suzanne V. Arnold, MD (Saint Luke’s Mid America Heart Institute/University of Missouri-Kansas City), who presented an analysis of 30-day and 1-year outcomes for TAVIs performed between 2011 and 2018 in a late-breaking session on Sunday, pointed out that many aspects of TAVI have evolved. The patients themselves became younger and healthier, for instance, while use of femoral access grew, sheath sizes shrank, use of general anesthesia waned, contrast volumes decreased, and new valve designs entered the scene.

We believe that [our] findings emphasize the importance of device iterations and nondevice procedural factors to improving short-term mortality and complications of TAVR. Suzanne V. Arnold

Over the 8-year time frame, there were decreases in both 30-day mortality (from 6.7% to 2.4%) and 1-year mortality (from 19.9% to 10.1%), she pointed out. There also were reductions in the 30-day composite of death, stroke, major/life-threatening bleeding, stage 3 acute kidney injury, and moderate/severe paravalvular leak (from 25.3% to 10.5%).

“Trying to determine why those outcomes have improved is somewhat difficult, because there have been a lot of moving parts during that time period,” Arnold explained to the media at a press briefing.

She and her colleagues, in order to address this unknown, analyzed data from the TVT Registry on 161,196 TAVI patients treated at 596 hospitals over this time period. The analysis was “truncated” at 2018 “because that’s where we saw a plateau in the improvement in outcomes,” she told TCTMD.

Investigators examined five categories of variables that might influence outcome:

• Demographics (age and sex)
• Noncardiovascular comorbidities (body surface area, severe lung disease, home oxygen, renal function, dialysis, and diabetes)
• Cardiovascular comorbidities (peripheral artery disease; prior MI, cardiac surgery, and stroke/TIA; atrial fibrillation; tricuspid and mitral regurgitation; ejection fraction; disease-specific health status; and bicuspid aortic valve)
• Device factors (access site and sheath size)
• Procedural factors (conscious sedation, contrast volume, and cerebral embolic protection)

Serially adjusting for these categories, the researchers calculated how much each one mediated the improvement in outcomes across the study period, Arnold said. The closer the odds ratio approached a value of 1.00, the more influential the factor.

For 30-day death and adverse events, evolutions in device technology and procedural care mattered the most. Some portion of the change in adverse events seemed to relate to institutional-level learning curve. And finally, for 1-year death, changes in patient comorbidities had the biggest impact.

Yet “there remained a strong association of changes in device and procedural factors with changes in long-term mortality, likely driven by their association with short-term complications,” Arnold said. These two factors explained 45% of the improvement in 1-year mortality, as compared with 70% of the improvement in 30-day mortality and 67% of the improvement in 30-day complications.

“We believe that [our] findings emphasize the importance of device iterations and nondevice procedural factors to improving short-term mortality and complications of TAVR, and may have important implications for future device innovation, particularly as [we] move to the treatment of other forms of valvular heart disease,” she noted.

Elaborating further during her presentation, Arnold said that “identifying the complications with the most-negative impact on survival and health status, and adapting devices and procedural care to reduce these, can be an effective tool for quickly improving both short- and long-term outcomes.”

[This] is really what the TVT Registry was designed for: to be able to understand the changes over time and how we improve quality, not just measure what is happening there. Howard C. Herrmann

Session moderator Michael J. Reardon, MD (Houston Methodist DeBakey Heart & Vascular Center, TX), said these results reflect clinicians’ experience. “For all of us that do this, it’s pretty clear that we’re doing patients that are both less risky and at the other end we’re cutting off the people that we shouldn’t do, the Cohort C,” he commented. “What I want to know is: we have hundreds of sites that do this now. We’re adding new sites every year that are often low-volume sites as we go over time. How do you adjust for the difference in the sites that we’re adding now versus the sites we added 10 years ago? And then do you think as we add new valves to the mix that’s going to start the learning curve all over again?”

Arnold said that, unfortunately, they were unable to look at site-specific factors, such as volume, but rather took a “within-site” perspective of procedures and patients. But since the vast majority of improvement could be explained by the latter in their analysis, she predicted that institutional characteristics might not play a “huge role.” Only time will tell how TAVI will evolve in the future, Arnold added.

Howard C. Herrmann, MD (Hospital of the University of Pennsylvania, Philadelphia), praised the study for asking practical questions.

This sort of analysis “is really what the TVT Registry was designed for: to be able to understand the changes over time and how we improve quality, not just measure what is happening there,” Herrmann said.

Nicolas M. Van Mieghem, MD (Erasmus Medical Center, Rotterdam, the Netherlands), also part of the panel discussion, said the lessons provided by this US-based analysis could be valuable for Europe: “I think a very important finding is the impact of devices and procedure-related factors, because it really emphasizes how we as a community need to keep on improving, iterating, and refining [both aspects].”