AKI After TAVR Is Decreasing, but More Efforts Needed to Prevent Stage 3

NATIONAL HARBOR, MD—The incidence of acute kidney injury (AKI) after TAVR is on the decline, and patients who do develop it tend to have relatively mild renal insufficiency, data from the Society of Thoracic Surgeons/American College of Cardiology TVT Registry show. New findings presented here at CRT 2020 indicate that procedural and patient-specific characteristics linked to greater risk of stage 3 renal failure include conversion to open surgery, anemia, general anesthesia, and diabetes.

“I think the next step will be the development of a risk prediction tool. That's something I'm hopeful about and looking forward to working on and helping to develop,” lead investigator Howard M. Julien, MD, MPH (Penn Heart and Vascular Center, Philadelphia, PA), told TCTMD. “It would allow us to take specific patient characteristics and say ‘This is your risk of developing kidney injury’ and have it be tailored towards that individual patient.”

Observational studies have suggested that anywhere from 3.4% to 57% of TAVR procedures may result in kidney injury, but the actual incidence and clinical outcomes as they occur in real-world patients are currently unknown, Julien said.

In a late-breaking trial session he explained how data from the TVT Registry was used to calculate the annual incidence of AKI and create a predictive model based on a subset of 107,814 TAVR patients treated between 2016 and 2018. Part of the predictive model involved the creation of a multivariable modeling process to assess possible predictors of AKI. These variables included baseline demographic information, intraprocedural risk factors, and procedural events. The cohort was divided into whether they developed into mild (stage 1), moderate (stage 2), or severe (stage 3) AKI.

Patients at greatest risk for developing stage 3 AKI were those who required conversion to open surgery, in whom there was a 10.8-fold increased odds. There also was a cluster of patients who were unstable at the time of their procedure who were more likely to develop the more severe forms of AKI, Julien said. Furthermore, having anemia carried a twofold increased risk of stage 3 AKI compared with not having anemia, while use of general sedation compared with moderate sedation carried a 1.6-fold increased risk.

“This is this is a developing topic of interest within the entire community, and this is one potential signal that conscious sedation may be beneficial for these patients,” Julien observed.

Increased Mortality Risk at 1 Year

Other findings were that having diabetes was associated with a 1.6-fold increased risk of stage 3 AKI. There also was a trend in terms of a greater risk among black versus white patients, as well as an increased risk in patients who were implanted with a self-expanding valve versus a balloon-expandable valve. All of these associations, Julien said, should be investigated further.

Looking at 2012 through 2016, Julien noted the general decrease in AKI incidence over time.

“When we turn to our 1-year mortality results, we notice that across the spectrum, AKI is associated with increased mortality, ranging from 2.6% to 10.3%,” he said. The hazard ratio for mortality at 1 year in those patients who developed stage 3 AKI was 7.03 (95% CI 6.00-8.24). It is unclear from the data what percentage of patients who develop AKI are able to recover their renal function successfully.

In a press conference prior to his presentation, co-moderator William Weintraub, MD (MedStar Washington Hospital Center, Washington, DC), asked Julien if he had any idea why the incidence of AKI  has decreased and what could be done further that trend. 

“I think that as we get more experience with TAVR, we will be able to figure out best practices in terms of anesthesia,” Julien said. “As we have more stable patients that go in to TAVR with lower risk, that also may explain some of this trend that we see over this time period.”

Furthermore, although contrast amounts did not appear to be different between any of the groups after multivariable adjustment, Julien noted that additional evaluation of temporal contrast trends is needed.

Following the presentation, panelist Jeffrey Popma, MD (Beth Israel Deaconess Medical Center, Boston, MA), noted that TAVR patients “get repeated contrast loads” in the pre-TAVR period during imaging. Some of that, he added, is due to the “one-stop shop” mentality of trying to get all of the preprocedural necessities out of the way, but it may be something that bears further scrutiny.

With regard to the predictive risk factors for AKI, panelist Mayra Guerrero, MD (Mayo Clinic, Rochester, MN), pointed out that while being aware of them is useful, some of them may not be modifiable. For example, while switching from general anesthesia to conscious sedation is “easily fixable,” she said, other things like anemia may not be something that can be controlled prior to a TAVR.