TAVR enters a new risk-scoring era

A potential TAVR patient was a man in his 60s with end-stage renal disease, oxygen-dependent lung disease, and poor functional status. Applying the risk calculator to this patient “changed the conversation a surgeon and I had with the patient,” she said. “We let him know that TAVR might not make him feel better and it wouldn’t fix his kidneys or his lungs. Given his [relatively young] age, the patient still wanted to proceed, and we performed balloon aortic valvuloplasty, after which he seemed to do much better. He eventually underwent TAVR and did okay.”

This was a good application of the Saint Luke’s prediction model, Dr. Arnold said. As a consequence of the risk quantification, it provided that “the patient more fully understood the risk of the TAVR procedure” and had a better understanding of his prospects for recovery.

The heart teams at Saint Luke’s Mid America that perform TAVR began running this risk calculator on every high-risk patient evaluated in their valve clinic, about five patients each week, starting in mid-March 2016. The results are displayed in the patient’s chart next to the STS risk score.

By late April 2016, the staff at Health Outcomes Services, the commercial partner to Saint Luke’s that will offer the calculator online to the public, planned to have this risk calculator ready for routine use online by sometime in May. They said the company will make access to it available to any physician, surgeon, or other member of a heart team at no charge.*

Pros and cons of the Saint Luke’s risk calculator

While others applauded the creation of the Saint Luke’s risk calculator and the broader range of outcomes it predicts, they also questioned the generalizability of a risk assessment that is modeled against the selected patients enrolled in the PARTNER trial and registry, and some uncertainty on how to best use this information to inform clinical decision making.

“We certainly need to assess benefit as well as risk,” commented Dr. Edwards. The Kansas City–led group “is solidly on the right track,” and “I hope people will use their model,” he said.

In fact, the TVT Registry panel he heads is currently moving toward producing a similar expansion of their in-hospital mortality risk calculator that takes into account midterm changes in KCCQ status. Dr. Edwards said he hopes this expanded version of the TVT calculator might be ready in another year or two.

“KCCQ data are hard and time-consuming to collect, and clinicians who participate in the TVT Registry do not always do it,” he explained. “It’s an administrative burden” to make a KCCQ assessment both at baseline and at 6 or 12 month follow-up after TAVR.

“We’ve done a lot of education with registry participants to improve KCCQ data collection.” Dr. Edwards said he hopes that within another year this aspect of patient assessment will occur for about 90% of patients enrolled in the TVT Registry.

Dr. Edwards also highlighted the inherent limitations of applying the Saint Luke’s risk-assessment model, developed and validated in patients enrolled in the PARTNER and CoreValve trials and PARTNER registry, an aggregate of roughly 5,000 selected patients, to the more diverse patients seen in routine practice today and entered into the TVT Registry.

“The advantages of the TVT Registry are the huge numbers and the all-comers population,” he said. “You need to ask whether the randomized trial populations are truly representative.”

That’s a concern shared by Dr. Dangas, who also highlighted the challenges of assessing the risk a patient faces from noncardiovascular comorbidities and how that might affect a decision of whether or not to perform TAVR.

“These are elderly patients with many comorbidities. I’m not sure how well the noncardiac comorbidities were captured in the databases” for the PARTNER and CoreValve trials and registry, he said. “I’m not sure the noncardiac comorbidities were as well figured out” in those trials run several years ago as they might be today. “It’s not exactly what TAVR is about in 2016.” Despite his skepticism, Dr. Dangas acknowledged that a scoring formula that reliably captures and follows data collected by the KCCQ “would be useful.”

Another challenge is using a risk assessment tool that takes into account patient “frailty” as a way to judge whether TAVR might be “futile” for a specific patient, Dr. Dangas said.

“It’s a tough discussion to have prospectively with a patient. The question is valid, but how confident can we be prospectively, at the time of TAVR, that the procedure will be futile within a year?” He envisions that with more time and data, researchers will create a reliable risk assessment formula to gauge a patient’s midterm benefit from TAVR, but for now the Saint Luke’s scoring formula probably needs “more refinement,” he said.